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Patients receiving CD19 CAR T-cell therapy for relapsed/refractory lymphoma experience prolonged and profound B-cell aplasia and hypogammaglobulinemia, placing them at a higher risk for severe COVID-19. Independently, Oh et al and Atanackovic et al demonstrate that despite attenuated humoral response to mRNA-based vaccines, patients demonstrate normal or heightened functional T-cell responses, including antiviral T-cell activity against SARS-CoV-2 variants including Omicron. Collectively, these data reinforce the importance of COVID-19 vaccination following CD19 CAR T-cell therapy, despite long-term B-cell aplasia.

We examined the meaning of metabolically active lesions on 1 month restaging nuclear imaging of patients with relapsed/refractory (R/R) large B-cell lymphoma (LBCL) receiving axicabtagene ciloleucel (axi-cel) by assessing the relationship between total metabolic tumor volume (MTV) on positron emission tomography (PET) scans and circulating tumor DNA (ctDNA) in the plasma. In this prospective multicenter sample collection study, MTV was retrospectively calculated via commercial software at baseline, 1 and 3 months post chimeric antigen receptor (CAR) T-cell therapy; ctDNA was available pre and post axi-cel. Spearman correlation coefficient (rs) was used to study the relationship between the variables and a mathematical model was constructed to describe tumor dynamics 1 month post CAR T-cell therapy. The median time between baseline scan and axi-cel infusion was 33 (range, 1-137) days for all 57 patients. For 41 of the patients with imaging within 33 days of axi-cel or imaging before that time but no bridging therapy, the correlation at baseline became stronger (rs 0.61, P< 0.0001) compared to all patients (rs 0.38, P= 0.004). Excluding patients in complete remission with no measurable residual disease, ctDNA and MTV at 1 month did not correlate (rs 0.28, P= 0.11), but did correlate at 3 months (rs 0.79, P= 0.0007). Modeling of tumor dynamics, which incorporated ctDNA and inflammation as part of MTV, recapitulated outcomes of patients with positive radiologic 1-month scans. Our results suggested that non-progressing hypermetabolic lesions on 1 month PET represent ongoing treatment response and their composition may be elucidated by concurrent ctDNA.

Introduction: Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 Chimeric Antigen Receptor (CAR) T-cell therapy that induces durable responses in patients with relapsed or refractory large B-cell lymphoma. At a median of 27.1 months follow-up on the ZUMA-1 trial, median overall survival (OS) was 25.8 months with 39% progression free survival (PFS) at 2 years post-infusion (Locke, Lancet Onc 2019). We previously reported outcomes of axi-cel patients treated with standard of care therapy at a median follow up of 12.9 months, including 42% who did not meet eligibility criteria for ZUMA-1 based on co-morbidities (Nastoupil, JCO 2020). Here we report results from this cohort at a median follow up of 32.4 months, as well as late outcomes of interest including cytopenias, infections and secondary malignancies. Methods and Results: The US Lymphoma CAR-T Consortium comprised of 17 US academic centers who contributed data independent of the manufacturer. Two hundred and ninety-eight patients underwent leukapheresis with intent to manufacture standard of care axi-cel as of September 30, 2018. In infused patients (n=275), OS and PFS were calculated from date of infusion. After median follow-up of 32.4 months (95% CI 31.1 - 34.3), median OS was not reached (95% CI 25.6 - not evaluable) (Figure 1A) with 1-, 2- and 3-year OS of 68.5% (95% CI 62.6-73.7), 56.4% (95% CI 50.1-62.2) and 52.2% (95% CI 45.7-58.2%), respectively. Median PFS was 9 months (95% CI 5.9-19.6) (Figure 1B); 1-, 2- and 3-year PFS was 47.4% (95% CI 41.4-53.2), 41.6% (95% CI 35.6-47.5) and 37.3% (95% CI 31.3-43.2), respectively. Twenty-seven PFS events occurred at or after 1 year post infusion;19 events were progressive lymphoma, with the latest relapse observed 28 months after axi-cel infusion. Eight patients died while in remission from their lymphoma: 4 from secondary malignancy, 3 from infection, and 1 from unknown causes. Results of multivariable modeling were similar to our prior analysis: factors associated with both a shorter PFS and shorter OS included male sex, elevated pre-lymphodepletion LDH, and poor ECOG status. Complete blood count and B- and T-cell recovery data were collected at 1 and 2-years post-infusion, excluding patients who had relapsed or been treated for secondary malignancy at time of collection (Table 1). Rates of neutropenia (absolute neutrophil count ≤1000) at 1- and 2- years were 9.2% (10/109) and 11.2% (9/80) and rates of CD4 count ≤200/ul were 62% (23/37) and 27% (7/26). Recovery of B cells was seen in 54% (15/28) and 57% (13/23) at 1-and 2-years post infusion. Infections were reported in 31.2% (34/109) patients between 6- and 12-months post infusion, and 17% (18/109) were severe, requiring either hospitalization and/or IV antibiotics. Twenty-one patients (24%, 21/89) had an infection between 1- and 2- years, 11% of which were severe. Twenty percent (10/49) of patients between 2- and 3-years had an infection and 4 (8%) were severe. Neutropenia, low CD4 counts, and IgG levels were not associated with infection, though patients with infection between 6-12 months were more likely to have received IVIG (p Twenty-two of 275 (8%) patients were diagnosed with subsequent malignancy after axi-cel treatment: 14/275 (5%) patients were diagnosed with myeloid malignancies (MDS (n=12), AML (n=1), CMML (n=1)); other malignancies included squamous cell carcinoma of skin (n=3); sarcoma (n=1); endometrial (n=1); lung (n=1); mesothelioma (n=1) and AITL (n=1). Patients with myeloid malignancy had a median age of 62 at axi-cel apheresis (IQR 56-67), 64% were male and median lines of prior therapy was 4 (IQR 3-6), including 36% with a prior autologous stem cell transplant. Eleven patients were in remission from lymphoma at myeloid malignancy diagnosis, while 3 were diagnosed after progression and interval therapy. Conclusion: This multi-center retrospective study showed similar long-term results to the ZUMA-1 trial, despite including patients who did not meet ZUMA-1 eligibility criteria based on comorbidities. Sixteen percent of PFS events were seen after 1 year, largely due to disease progression. Late infection was common but was not explained by persistent neutropenia or low CD4 counts. Subsequent malignancy, including MDS, occurred in 8% of patients and require further study to better identify patients at risk. J.Y.S and M.D.J contributed equally; S.D and M.L contributed equally. Figure 1 Figure 1. Disclosures Jain: BMS, Kite/Gilead, Novartis, Precision Biosciences, Takeda: Consultancy. Nastoupil: Pfizer: Honoraria, Research Funding; MorphoSys: Honoraria; Takeda: Honoraria, Other: DSMC, Research Funding; ADC Therapeutics: Honoraria; IGM Biosciences: Research Funding; Genentech: Honoraria, Research Funding; Epizyme: Honoraria, Research Funding; Caribou Biosciences: Research Funding; Gilead/Kite: Honoraria, Research Funding; TG Therapeutics: Honoraria, Research Funding; Denovo Pharma: Other: DSMC; Bayer: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Bristol Myers Squibb/Celgene: Honoraria, Research Funding. Ghobadi: Atara: Consultancy; Amgen: Consultancy, Research Funding; Wugen: Consultancy; Celgene: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding. Lin: Gamida Cell: Consultancy; Juno: Consultancy; Merck: Research Funding; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Sorrento: Consultancy; Legend: Consultancy; Takeda: Research Funding; Vineti: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. Reagan: Seagen: Research Funding; Kite, a Gilead Company: Consultancy; Genentech: Research Funding; Curis: Consultancy. Oluwole: Curio Science: Consultancy; Janssen: Consultancy; Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. McGuirk: EcoR1 Capital: Consultancy; Gamida Cell: Research Funding; Bellicum Pharmaceuticals: Research Funding; Novartis: Research Funding; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; Novartis: Research Funding; Juno Therapeutics: Consultancy, Honoraria, Research Funding; Astelllas Pharma: Research Funding; Pluristem Therapeutics: Research Funding; Fresenius Biotech: Research Funding; Allovir: Consultancy, Honoraria, Research Funding; Magenta Therapeutics: Consultancy, Honoraria, Research Funding. Deol: Kite, a Gilead Company: Consultancy. Sehgal: Juno/Celgene: Research Funding; Kite/Gilead: Research Funding. Goy: AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; LLC(Targeted Oncology): Consultancy; Xcenda: Consultancy, Honoraria; Xcenda: Consultancy; Acerta: Consultancy, Research Funding; AbbVie/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Vincerx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Elsevier's Practice Update Oncology, Intellisphere, LLC(Targeted Oncology): Consultancy; Hoffman la Roche: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; AbbVie/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Phamacyclics: Research Funding; Bristol Meyers Squibb: Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Michael J Hennessey Associates INC: Consultancy; Genentech/Hoffman la Roche: Research Funding; MorphoSys: Honoraria, Other; Karyopharm: Research Funding; Vincerx pharma: Membership on an entity's Board of Directors or advisory committees; Physicians' Education Resource: Consultancy, Other: Meeting/travel support; Incyte: Honoraria; Medscape: Consultancy; Novartis: Consultancy, Honoraria; Genomic Testing Cooperative: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Infinity/Verastem: Research Funding; Rosewell Park: Consultancy; Bristol Meyers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; OncLive Peer Exchange: Honoraria; Elsevier PracticeUpdate: Oncology: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Constellation: Research Funding; COTA (Cancer Outcome Tracking Analysis): Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Hackensack Meridian Health, Regional Cancer Care Associates/OMI: Current Employment. Hill: Pfizer: Consultancy, Honoraria; Beigene: Consultancy, Honoraria, Research Funding; Gentenech: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Celgene (BMS): Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Andreadis: CRISPR Therapeutics: Research Funding; GenMAB: Research Funding; Novartis: Research Funding; Roche: Current equity holder in publicly-traded company, Ended employment in the past 24 months; Epizyme: Honoraria; Incyte: Honoraria; TG Therapeutics: Honoraria; Kite: Honoraria; Karyopharm: Honoraria; Atara: Consultancy, Honoraria; BMS: Research Funding; Merck: Research Funding. Muñoz: Seagen: Consultancy, Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Kite, a Gilead Company: Consultancy, Speakers Bureau; Pfizer: Consultancy; Janssen: Consultancy, Speakers Bureau; Juno/Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Alexion: Consultancy; BeiGene: Consultancy, Speakers Bureau; Fosunkite: Consultancy; Innovent: Consultancy; Debiopharma: Consultancy; Karyopharm: Consultancy; Genmab: Consultancy; ADC Therapeutics: Consultancy; Epizyme: Consultancy; Servier: Consultancy; Acrotech: Speakers Bureau; Verastem: Speakers Bureau; AstraZeneca: Speakers Bureau; Celgene/Bristol Myers Squibb: Speakers Bureau; Genentech: Speakers Bureau; Aurobindo: Speakers Bureau; Physicians' Education Resource: Honoraria; Kyowa Kirin: Consultancy, Honoraria, Speakers Bureau; OncView: Honoraria; Targeted Oncology: Honoraria. Westin: AstraZeneca: Consultancy, Research Funding; 47 Inc: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Morphosys: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Umoja: Consultancy; Iksuda Therapeutics: Consultancy; MorphoSys: Consultancy, Research Funding; Curis: Research Funding; Genentech: Consultancy, Research Funding. Chavez: Bristol Myers Squibb: Speakers Bureau; Karyopharm Therapeutics: Consultancy; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Kite/Gilead: Consultancy; Abbvie: Consultancy; MorphoSys: Speakers Bureau; BeiGene: Speakers Bureau; Novartis: Consultancy; Adaptive: Research Funding; Epizyme: Speakers Bureau; AstraZeneca: Research Funding. Bennani: Kyowa Kirin: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Verastem: Other: Advisory Board; Vividion: Consultancy, Other: Advisory Board. Vose: Kite, a Gilead Company: Honoraria, Research Funding. Miklos: Pharmacyclics: Patents & Royalties; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy; Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding. Neelapu: Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees. Locke: GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; Calibr: Consultancy, Other: Scientific Advisory Role; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; Wugen: Consultancy, Other; Takeda: Consultancy, Other; Novartis: Consultancy, Other, Research Funding; Umoja: Consultancy, Other; Cowen: Consultancy; EcoR1: Consultancy; Emerging Therapy Solutions: Consultancy; Gerson Lehrman Group: Consultancy; Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Legend Biotech: Consultancy, Other; Janssen: Consultancy, Other: Scientific Advisory Role; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role. Dahiya: Kite, a Gilead Company: Consultancy; Atara Biotherapeutics: Consultancy; Miltenyi Biotech: Research Funding; Jazz Pharmaceuticals: Research Funding; BMS: Consultancy. Lunning: Spectrum: Consultancy; AstraZeneca: Consultancy; Acrotech: Consultancy; Legend: Consultancy; Novartis: Consultancy; Kyowa Kirin: Consultancy; Karyopharm: Consultancy; Morphosys: Consultancy; TG Therapeutics: Consultancy; Janssen: Consultancy; AbbVie: Consultancy; Verastem: Consultancy; Myeloid Therapeutics: Consultancy; Celgene, a Bristol Myers Squibb Co.: Consultancy; Daiichi-Sankyo: Consultancy; Beigene: Consultancy; ADC Therapeutics: Consultancy; Kite, a Gilead Company: Consultancy.

Introduction: Brexucabtagene autoleucel (brexu-cel) was approved by US FDA for relapsed/refractory (R/R) mantle cell lymphoma (MCL) on July 24, 2020 based on results from the pivotal ZUMA-2 (NCT02601313) study, in which an objective response rate (ORR) of 93% and a complete response (CR) rate of 67% were achieved among the 60 treated patients with at least 7 months of follow-up. The study had stringent eligibility criteria, including prior treatment with a BTK inhibitor (BTKi), and only allowed BTKi and/or corticosteroid for bridging therapy. We report here the safety and efficacy of brexu-cel in standard of care practice among centers in the US Lymphoma CAR-T Consortium. Methods: Fourteen centers participated in this retrospective study. Patients who underwent leukapheresis by 6/15/2021 with an intent to manufacture brexu-cel were included. Baseline clinical characteristics, bridging therapy, adverse events after brexu-cel infusion, and post-infusion outcome data were collected. Eligibility for ZUMA-2 was retrospectively determined based on characteristics at the time of leukapheresis. Duration of response (time from initial response to disease progression or death from any cause), progression-free survival (PFS; time from infusion to disease progression or death from any cause) and overall survival (OS; time from infusion to death from any cause) were analyzed using the Kaplan-Meier method. Results: At the data cut-off date of 7/9/2021, 107 patients underwent leukapheresis, among whom 93 (87%) completed brexu-cel infusion, 2 (2%) were waiting for infusion, and 12 (11%) did not receive infusion (manufacture failure n=6, organ dysfunction n=1, death n=5). Baseline clinical characteristics of the 93 infused patients are shown in Table 1. The median age was 67 years and 81% were male. 32% had high risk simplified MIPI, 77% had Ki-67≥30%, 45% had blastoid or pleomorphic variant, 46% had TP53 alteration, 29% had complex karyotype, and 7% had CNS involvement. The median number of prior lines of therapy was 3. Eighty-two percent had prior BTKi treatment, and 44% had refractory disease to the last line of therapy. Sixty-eight (73%) patients would not have met ZUMA-2 eligibility criteria. Reasons for ineligibility included ECOG PS ≥2 (n=8), CNS involvement by lymphoma (n=6), prior therapies (n=33), cytopenia (n=11), renal or hepatic dysfunction (n=13), other medical conditions (n=18), and active infection (n=2). Sixty (65%) of the 93 patients received bridging therapy, which included BTKi (n=27), venetoclax (n=14), chemotherapy (n=19), CD20 antibody (n=26), lenalidomide (n=3), corticosteroid (n=9), and radiotherapy (n=13). Only 13 (14%) patients received BTKi or corticosteroid alone as in ZUMA-2. Among 93 infused patients, cytokine release syndrome (CRS) rate was 88% (8% grade ≥3), and immune effector cell-associated neurotoxicity syndrome (ICANS) rate was 58% (33% grade ≥3). No grade 5 CRS or ICANS occurred. Medications used to manage CRS and ICANS were 71 (76%) for tocilizumab, 64 (69%) for steroid, and 16 (17%) for anakinra. Twenty-four (26%) patients required ICU admission, 9 patients required vasopressors, and 4 patients required mechanical ventilation. With a median follow-up of 3.0 months (range 0.1-9.6), day 30 response was evaluable in 81 patients, and the ORR was 86%, with 64% CR (Table 2). The ORR/CR rates were 94%/70% for blastoid or pleomorphic variants, 82%/50% for TP53 altered, 84%/61% for BTKi-exposed, 94%/76% for BTKi-naïve, and 88%/67% for those not meeting ZUMA-2 eligibility criteria. The ORR/CR rates were 87%/69% for patients who received bridging therapy and 85%/56% for those who did not. For patients who achieved a response at day 30, the rate of continued response at 3-month was 83.7% (95% CI 68.3%-92.0%). The 3-month PFS rate was 80.6% (95% CI 68.6%-88.4%), and the 6-month OS rate was 82.1% (95% CI 67.7%-90.5%). Conclusions: This multicenter retrospective study demonstrated encouraging safety and efficacy data of brexu-cel in R/R MCL in the real world practice. The CRS and ICANS incidences were comparable to those reported in ZUMA-2, but use of tocilizumab and steroid was more frequent than in ZUMA-2. Although 73% of the patients would have been ineligible for ZUMA-2, the ORR and CR rate were comparable to those reported in ZUMA-2. Longer follow-up is necessary to confirm long term safety and efficacy. YW, PJ and FLL are co-first authors, and YL, MW and MDJ are co-senior authors. Figure 1 Figure 1. Disclosures Wang: Novartis: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; InnoCare: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; MorphoSys: Research Funding. Jain: Kite: Consultancy; Lilly: Membership on an entity's Board of Directors or advisory committees. Locke: Gerson Lehrman Group: Consultancy; Emerging Therapy Solutions: Consultancy; EcoR1: Consultancy; Cowen: Consultancy; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Umoja: Consultancy, Other; Janssen: Consultancy, Other: Scientific Advisory Role; Wugen: Consultancy, Other; Legend Biotech: Consultancy, Other; Takeda: Consultancy, Other; Novartis: Consultancy, Other, Research Funding; Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; Calibr: Consultancy, Other: Scientific Advisory Role; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding. Munoz: Bayer, Gilead/Kite Pharma, Celgene, Merck, Portola, Incyte, Genentech, Pharmacyclics, Seattle Genetics, Janssen, and Millennium: Research Funding; Kite, a Gilead Company, Kyowa, Bayer, Pharmacyclics/Janssen, Seagen, Acrotech/Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/BMS, Genentech/Roche.: Speakers Bureau; Targeted Oncology, OncView, Kyowa Kirin, Physicians' Education Resource, and Seagen: Honoraria; Pharmacyclics/Abbvie, Bayer, Kite, a Gilead Company, Pfizer, Janssen, Juno/Celgene, Bristol Myers Squibb, Kyowa Kirin, Alexion, Fosun Kite, Innovent, Seagen, BeiGene, Debiopharm, Epizyme, Karyopharm, ADC Therapeutics, Servier, and Genmab: Consultancy, Other: advisory role; Alexion, AstraZeneca Rare Disease: Other: Study investigator. Maurer: BMS: Research Funding; Genentech: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Nanostring: Research Funding. Beitinjaneh: Kite/Gilead: Other: Ad Board Event Attendee. Frank: Allogene Therapeutics: Research Funding; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Research Funding. Dahiya: Miltenyi Biotech: Research Funding; Kite, a Gilead Company: Consultancy; Jazz Pharmaceuticals: Research Funding; Atara Biotherapeutics: Consultancy; BMS: Consultancy. McGuirk: Magenta Therapeutics: Consultancy, Honoraria, Research Funding; Gamida Cell: Research Funding; Novartis: Research Funding; Bellicum Pharmaceuticals: Research Funding; Fresenius Biotech: Research Funding; Astelllas Pharma: Research Funding; Novartis: Research Funding; Allovir: Consultancy, Honoraria, Research Funding; Pluristem Therapeutics: Research Funding; Juno Therapeutics: Consultancy, Honoraria, Research Funding; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; EcoR1 Capital: Consultancy. Goy: Vincerx pharma: Membership on an entity's Board of Directors or advisory committees; Michael J Hennessey Associates INC: Consultancy; Elsevier's Practice Update Oncology, Intellisphere, LLC(Targeted Oncology): Consultancy; Phamacyclics: Research Funding; Vincerx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Rosewell Park: Consultancy; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; AbbVie/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Research Funding; Incyte: Honoraria; Hoffman la Roche: Consultancy; LLC(Targeted Oncology): Consultancy; Xcenda: Consultancy, Honoraria; OncLive Peer Exchange: Honoraria; Infinity/Verastem: Research Funding; Genentech/Hoffman la Roche: Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medscape: Consultancy; Xcenda: Consultancy; Bristol Meyers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; Bristol Meyers Squibb: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Elsevier PracticeUpdate: Oncology: Consultancy, Honoraria; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Genomic Testing Cooperative: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Physicians' Education Resource: Consultancy, Other: Meeting/travel support; MorphoSys: Honoraria, Other; Novartis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Constellation: Research Funding; COTA (Cancer Outcome Tracking Analysis): Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Hackensack Meridian Health, Regional Cancer Care Associates/OMI: Current Employment. Vose: Kite, a Gilead Company: Honoraria, Research Funding. Hill: Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Celgene (BMS): Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Gentenech: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria. Oluwole: Pfizer: Consultancy; Curio Science: Consultancy; Janssen: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. Deol: Kite, a Gilead Company: Consultancy. Shah: Jazz Pharmaceuticals: Research Funding; Incyte: Research Funding; Pfizer: Consultancy, Other: Expenses; Novartis: Consultancy, Other: Expenses; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; BeiGene: Consultancy, Honoraria; Amgen: Consultancy; Precision Biosciences: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Acrotech/Spectrum: Honoraria; Servier Genetics: Other; Adaptive Biotechnologies: Consultancy. Paludo: Karyopharm: Research Funding. Miklos: Pharmacyclics: Patents & Royalties; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy. Ghobadi: Wugen: Consultancy; Atara: Consultancy; Amgen: Consultancy, Research Funding; Celgene: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding. Neelapu: Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding. Lin: Legend: Consultancy; Novartis: Consultancy; Gamida Cell: Consultancy; Vineti: Consultancy; Bluebird Bio: Consultancy, Research Funding; Sorrento: Consultancy; Takeda: Research Funding; Merck: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Juno: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. Wang: Moffit Cancer Center: Honoraria; Chinese Medical Association: Honoraria; InnoCare: Consultancy, Research Funding; Epizyme: Consultancy, Honoraria; Hebei Cancer Prevention Federation: Honoraria; Newbridge Pharmaceuticals: Honoraria; Genentech: Consultancy; OMI: Honoraria; Physicians Education Resources (PER): Honoraria; Clinical Care Options: Honoraria; CAHON: Honoraria; VelosBio: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; CStone: Consultancy; Loxo Oncology: Consultancy, Research Funding; BioInvent: Research Funding; Juno: Consultancy, Research Funding; DTRM Biopharma (Cayman) Limited: Consultancy; BGICS: Honoraria; Bayer Healthcare: Consultancy; Janssen: Consultancy, Honoraria, Research Funding; Kite Pharma: Consultancy, Honoraria, Research Funding; Molecular Templates: Research Funding; Imedex: Honoraria; Miltenyi Biomedicine GmbH: Consultancy, Honoraria; Dava Oncology: Honoraria; Oncternal: Consultancy, Research Funding; Lilly: Research Funding; Celgene: Research Funding; Anticancer Association: Honoraria; AstraZeneca: Consultancy, Honoraria, Research Funding; The First Afflicted Hospital of Zhejiang University: Honoraria; BeiGene: Consultancy, Honoraria, Research Funding; Scripps: Honoraria; Mumbai Hematology Group: Honoraria; Acerta Pharma: Consultancy, Honoraria, Research Funding. Jain: BMS, Kite/Gilead, Novartis, Precision Biosciences, Takeda: Consultancy.

Introduction: CD19 Chimeric Antigen Receptor T-cell (CAR-T) therapy is now a commonly used treatment for relapsed/refractory (R/R) Large B-cell Lymphoma (LBCL). However, predictors of long-term response remain poorly defined. In particular, partial response (PR) at first tumor assessment at Day 28 (D28) is a source of uncertainty both for clinicians and patients. In the pivotal CAR-T trials for LBCL, approximately half of these patients eventually achieved a complete remission (CR), while the other half experienced progressive disease (PD) (Neelapu et al, NEJM 2017). Herein, we present real-world data on 24 patients achieving a PR on D28 by PET/CT imaging following CAR-T therapy for R/R LBCL. We explore whether differences between baseline and D28 PET/CT imaging might predict progression free survival (PFS), overall survival (OS), best overall response rate (B-ORR), or last overall response rate (L-ORR). Methods: Out of 75 patients receiving CAR-T therapy at a single institution, we retrospectively identified and reviewed 24 (32%) as achieving a PR on D28. Two independent radiologists collected baseline (pre-CAR-T therapy) and D28 PET/CT Standard Uptake Value (SUV) max and Total Tumor Metabolic Volume (TMV, in cm 3) using ROVER software. The Intraclass Correlation Coefficients (ICC) as a measure of absolute agreement between two readers was 0.99 for SUV the 0.97 for TMV. There was a strong absolute agreement between the two radiologists. For simplicity of data interpretation and given this concordance we present the results of one reviewer. Univariable Cox regression model was used to calculate PFS and OS. All statistical tests were 2-sided and conducted at the 0.05 level of significance. Results: Of the 24 patients with PR on D28 PET/CT, median follow-up time was 1.9 years with 17 patients (71%) still alive at last follow-up (see Fig 1a). Median age was 51 years-old, 46% were female, 66.7% had stage III/IV disease, all patients had ECOG ≤2, 58% received bridging therapy, and half had ≥3 lines of prior therapy (see Table 1A). Results of the univariable Cox regression model revealed that a lower D28 SUV max (p=0.004), lower TMV at both baseline (p=0.03), and at D28 (p=0.01) may be predictive of better OS. Longer PFS was found with lower D28 SUV max (p=0.002) and lower TMV at both baseline (p=0.01), and D28 (p=0.04). In analysis of B-ORR achieved by PET/CT, half of patients in PR at D28 ultimately achieved a CR (see Table 1B). OS was significantly lower in those with a B-ORR of PR vs CR (p In analysis of outcome by L-ORR by PET/CT, 11 patients were in CR, while 13 had PD (see Table 1C). The median SUV max at baseline was 14 in those in CR vs 15 in PD (NS); at D28 median SUV max was 5 in those with CR vs 6 in PD (NS). The median baseline TMV was 298 in those with CR vs 591 in PD (NS); the median TMV at D28 was 15 in those with CR vs 21 in PD (NS). There was no significant difference in absolute or percent change between baseline and D28 of either SUV max or TMV based on L-ORR. Conclusion: In this analysis of patients in PR at D28 following CD19-directed CAR-T therapy, D28 but not baseline SUV max was significantly higher in those with a B-ORR of PR; and, in our modeling, lower D28 SUV max may predict favorable PFS and OS. Lower TMV, both at baseline and D28, may also be predictive of longer PFS and OS. Collectively, these findings suggest that for patients achieving a PR at D28, the best predictive factor by imaging for ultimately achieving a CR is lower SUV max at D28 and lower TMV at baseline and D28. These characteristics were also associated with longer PFS and OS. These findings indicate that there may be an intrinsic quality to the tumor itself (e.g. FDG-avidity and metabolic volume) that determines the ultimate outcome from a D28 PR. While further study is warranted, we demonstrate that patients with such characteristics should be identified, monitored closely for relapse, and perhaps be considered for further early intervention. Figure 1 Figure 1. Disclosures Hardy: InCyte: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees.

Introduction Chimeric Antigen Receptor (CAR) T-cell therapy has emerged as a powerful immunotherapy for various forms of cancer, especially hematologic malignancies. However, several factors limit use of CAR T-cells to a wider number of patients. Long manufacturing time (usually 3-4 weeks with standard of care products) poses a big challenge in treating these chemorefractory patients in a timely fashion. Thus, we evaluated the feasibility of a fresh in and fresh out, short, eight-day manufacturing process performed locally to expedite CAR T-cell drug product delivery. Herein we report the results of two experimental runs using this modified short eight-day culture process. Methods We used the CliniMACS Prodigy® closed manufacturing system and modified the 12-day T Cell Transduction (TCT) activity matrix protocol to produce anti-CD19 CAR T-cells in eight days. Normal donor mononuclear cells were collected by leukapheresis and enriched for CD4 and CD8 cells by immunomagnetic bead selection in three stages. Enriched T-cells were activated with MACS GMP T Cell TransACT and cultured at 37°C with 5% CO 2 for 16-24 hours in media supplemented with 12.5mcg/L each of IL-7 and IL-15, and 3% heat-inactivated human AB serum. On day 1 of the process, activated T-cells were transduced with lentiviral vector encoding the anti-CD19 CAR (Lentigen, LTG1563) at a multiplicity of infection (MOI) of 7-10. On day 3, the cells were washed twice and the media volume adjusted to feed the expanding cells. The culture was again fed on day 5 by exchanging half the volume of spent media with fresh supplemented media. Media supplemented with cytokines alone was used for the remaining four washes on day 6, 7 and 8. Transduction efficiency and T-cell subset frequencies were assessed by flow cytometry on the MACSQuant-10 and CAR-T Express Mode package on days 3, 6 and 8. Subsequently, we performed ELISPOT assay for CAR T-cell potency testing and in-vivo efficacy testing in NSG mice bearing Raji B cell lymphoma. Results Refer to Table 1 for details on cell populations of interest for experiment number 1 and 2. The total number of CD3 T-Cells increased from 97% on day 0 to >99.5% on the harvest day (day 8). CD3 T-cells expanded 11.6- and 34.2-fold on day 8 when compared to day 0. Transduction efficiency of ~40% was observed in both experimental runs. Final CD19 CAR T-cells numbers ranged from 9.3-13.3 x 10e8 with viability of CD3+ cells >93% for both the runs. Day 3 of the culture is an important day since a clinical decision to proceed with lymphodepletion must be made to facilitate the fresh in and fresh out approach. Here we observed reliable transduction of T-cells on day 3 with an average efficiency of 15.9%. Day 3 data reliably provided information to proceed with lymphodepletion. A total of 100,000 CD19 CAR T-cells produced in experiment #1 were exposed to beads coated with CD19 protein, BCMA control protein, or T cell-activating beads coated with anti-CD3 and anti-CD28 antibodies in an ELISPOT plate. Spots in figure 1 represents individual CAR T-cells producing IFN-gamma. This novel ELISPOT assay shows high IFN-gamma by CD19 CAR T-cells in response to the target antigen or unspecific stimulation using CD3/CD28 beads. Subsequently, NSG mice received injections of 5x10e5 Raji B cell lymphoma cells stably expressing luciferase into the tail vein. One week later, 4 mice per group received individual i.v. injections of 4x10e6 CD19 CAR T-cells, 0.3x10e6 CD19 CAR T-cells, 4x10e6 mock-transduced CAR T-cells, or media. Survival curves in figure 2 represent survival of the mice after receiving the treatment with best survival seen with 4x10e6 dose. Conclusions In these experimental runs, we were able to generate CD19 CAR+ T-cells in a short eight-day manufacturing process. The final product characteristics (viability, transduction efficiency and doses) were comparable to clinical formulations. Further, point-of-care potency assay suggests high IFN-gamma production and elimination of CD19 tumor in the in vivo murine model. The point-of-care CAR T-cell production allows for shorter vein-to-vein time and offers dramatic reduction in the product cost. Lastly, the novel potency assay via ELISPOT testing allows for rapid and visual functional analysis of the CAR T-cell product. Figure 1 Figure 1. Disclosures Hardy: Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees; InCyte: Membership on an entity's Board of Directors or advisory committees. Abramowski-Mock: Miltenyi Biotec: Current Employment. Mittelstaet: Miltenyi Biotec: Current Employment. Dudek: Miltenyi Biotec: Current Employment.

B cell lymphoma is the most common hematologic malignancy in the United States. Although treatment options have greatly improved in the past several decades, outcomes for patients with relapsed B cell lymphoma remain poor. Chimeric antigen receptor (CAR) T cells have recently entered the clinic with promise to address the gap in effective therapies for patients relapsed B cell lymphoma. However, antigen loss and poor CAR T cell persistence has been shown to drive resistance to the widely approved CD19-targeted CAR in some patients, demonstrating the need for additional therapies. Here, we demonstrate CD229-targeted CAR T cell therapy as a promising option for the treatment of relapsed B cell lymphoma, addressing an important group of patients with typically poor outcomes. CD229 is an immune-modulating receptor expressed on the surface of B cells that we recently found to be highly expressed in the plasma cell neoplasm multiple myeloma (Radhakrishnan et al. 2020). We utilized semi-quantitative PCR and flow cytometry to assess whether CD229 is also expressed on malignant B cells earlier in development as found in B cell lymphoma. Expression analysis revealed the presence of CD229 in a panel of 11 B cell lymphoma cell lines and 45 primary B cell lymphoma samples comprising several subsets of disease including aggressive B cell lymphomas such as diffuse large B cell lymphoma (DLBCL), mantle cell lymphoma (MCL) and Burkitt lymphoma as well as indolent subtypes of B cell lymphoma including chronic lymphoblastic leukemia (CLL) and follicular lymphoma. Of note, CD229 was found to be overexpressed on primary B cell lymphoma cells when compared to autologous normal B cells. Given the high levels of CD229 expression throughout all B cell lymphoma subtypes analyzed, we generated CD229 CAR T cells in order to determine whether CAR T cell therapy is an effective way to target CD229 expressing B cell lymphoma cells. CD229 CAR T cells exhibited robust cytotoxicity when cocultured with B cell lymphoma cell lines and primary samples characterized by significant production of TH1 cytokines IL-2, TNF and IFNγ and rapid loss of B cell lymphoma cell viability when compared to control CAR T cells lacking an antigen binding scFv domain (∆scFv CAR T cells). In vivo analysis revealed effective tumor control in NSG mice carrying B cell lymphoma cell lines JeKo-1 (MCL) and DB (DLBCL) when treated with CD229 CAR T cells versus ∆scFv CAR T cells. Finally, we sought to determine the efficacy of CD229 CAR T cells in the context of CD19 CAR T cell therapy relapse. Here, a 71-year-old patient with CLL had an initial response when treated with CD19 CAR T cells but quickly relapsed only 2 months after treatment. Malignant cells from the CLL patient retained CD229 expression as identified by flow cytometry and an ex vivo coculture with CD229 CAR T cells revealed robust killing of CLL cells by CD229 CAR T cells. Transfer of antigen from target cell to CAR T cell by trogocytosis was recently suggested to drive relapse following CAR T cell therapy by decreasing antigen on tumor cells and promoting CAR T cell fratricide (Hamieh et al. 2019). We cocultured CD19 and CD229 CAR T cells with primary CLL cells and assessed CD19 and CD229 expression as well as CAR T cell viability by flow cytometry. In contrast with CD19 CAR T cells, CD229 CARs did not strip their target antigen from the surface of CLL cells. The transfer of CD19 from CLL cells to CD19 CAR T cells resulted in poor CAR T cell viability while CD229 CAR T cell viability remained high following coculture. In summary, we demonstrate that CD229 is a promising therapeutic target in B cell lymphoma due to its high levels of expression throughout many subtypes of disease. CD229 CAR T cells effectively kill B cell lymphoma cells in vitro and control growth of aggressive B cell lymphomas in vivo. Finally, CD229 CAR T cells are effective against primary CLL cells from patients that have relapsed from CD19 CAR T cell therapy and do no exhibit antigen loss by trogocytosis. Taken together, these data suggest that CD229 CAR T cell therapy may be a promising option to address the poor outcomes for patients with relapsed B cell lymphoma. Disclosures No relevant conflicts of interest to declare.

Background: Tabelecleucel is an investigational, off-the-shelf, allogeneic Epstein-Barr virus (EBV)-specific T-cell immunotherapy being studied in patients (pts) with serious EBV-driven diseases, including post-transplant lymphoproliferative disease (EBV + PTLD). The median overall survival (OS) after treatment failure of rituximab is short at ~1.7 months in EBV + PTLD following hematopoietic cell transplant (HCT) (Socié EBMT 2020) and ~3 months in solid organ transplant (SOT) recipients with EBV + PTLD whose disease relapsed after rituximab and who did not respond to or did not receive chemotherapy (CT) (Zimmerman EHA 2019). These poor outcomes demonstrate an urgent unmet need for effective therapies in this ultra-rare serious disease. Promising outcomes have previously been demonstrated (Prockop JCI 2020). Additionally, we have shown clinical benefit with a >60% objective response rate (ORR) and >80% estimated 2-year OS rates (Prockop EBMT 2021, Prockop ATC 2021) in pts with EBV + PTLD, irrespective of pts achieving a complete response (CR) or partial response (PR) to tabelecleucel. Safety data have been assessed in >150 pts with EBV + PTLD treated with tabelecleucel with tumor flare reaction (TFR) as the only identified risk. Here, for the first time, we report interim efficacy and safety results from the pivotal phase 3 clinical trial ALLELE (NCT03394365) - a multicenter, open-label study of tabelecleucel after failure of rituximab ± CT in pts with EBV + PTLD following SOT or HCT. Methods: ALLELE is evaluating the clinical benefit of tabelecleucel in two cohorts: (1) pts with EBV + PTLD following SOT after failure of rituximab ± CT (n=33), and (2) pts with EBV + PTLD following HCT after failure of rituximab monotherapy (n=33). Tabelecleucel is administered at a dose of 2 x 10 6 cells/kg on days 1, 8, and 15, followed by observation through each cycle lasting 35 days. Response per clinical and radiographic assessment (by PET/CT) is evaluated by the investigator and by independent review using Lugano Classification with LYRIC modification. Key efficacy endpoints include ORR, duration of response (DOR), time to response (TTR), and OS. After treatment is completed or discontinued, pts are assessed every 3 months up to 24 months, and every 6 months thereafter for survival status up to 5 years. Results: As of May 2021, 38 pts (24 SOT, 14 HCT) were evaluable for response assessment by independent oncologic response adjudication (IORA) and had the opportunity for 6 months follow-up (Table 1). SOT and HCT pts received a median (range) of 2.0 (1-6) and 3.0 (1-5) cycles of tabelecleucel, respectively. ORR was 50% (19/38, 95% CI: 33.4, 66.6) in the overall population, 50.0% (12/24, 95% CI: 29.1, 70.9) in SOT, and 50.0% (7/14, 95% CI: 23.0, 77.0) in HCT, with a best overall response of CR (n=5, SOT; n=5, HCT) or PR (n=7, SOT; n=2, HCT; Table 2). Overall, median TTR was 1.1 months (0.7-4.7), 11 of 19 responders had a DOR lasting >6 months, and median DOR was not reached (Table 2). Median OS was 18.4 (95% CI: 6.9, NE) months overall, 16.4 (95% CI: 3.5, NE) months for SOT, and not yet reached for HCT. 1-year survival rate was 61.1% (95% CI: 42.9, 75.0) overall, 57.4% (95% CI: 35.2, 74.5) for SOT, and 66.8% (95% CI: 32.4, 86.6) for HCT. Those who responded had a longer survival compared to the non-responders, with a median OS of NE (95% CI: 16.4, NE) and 1-year survival rate of 89.2% (95% CI: 63.1, 97.2). Non-responders had a median OS of 5.7 (95% CI: 1.8, 12.1) months and 1-year survival rate of 32.4% (95% CI: 12.1, 54.9) (Table 3). Serious treatment emergent AEs (TEAEs) were reported in 62.5% of SOT and 57.1% of HCT pts. Fatal TEAEs were reported in 16.7% of SOT and 7.1% of HCT pts; none of the fatal TEAEs were related to study treatment. Tabelecleucel was well-tolerated with no reports of TFR and no confirmed evidence for graft vs host disease, organ rejection, infusion reactions, or cytokine release syndrome in relation to tabelecleucel in these treatment refractory and immunocompromised pts. Conclusions: Tabelecleucel phase 3 interim data are reported here for the first time and show clinically meaningful outcomes and promising ORR and OS in a pt population with no approved treatment options and otherwise poor survival. Tabelecleucel, an allogeneic cell therapy, was well tolerated without evidence of safety concerns typically observed with autologous chimeric antigen receptor cell therapies. Figure 1 Figure 1. Disclosures Prockop: Memorial Sloan Kettering Cancer Center: Other: S Prockop receives support for the conduct of sponsored clinical trials through MSK from Atara Biotherapeutics, Jasper and AlloVir. , Patents & Royalties: S Prockop is a co-inventor on intellectual property (IP) licensed to Atara. S Prockop has waived rights to this IP to MSK and has no personal financial interests in Atara. MSK has financial interests in Atara and IP interests relevant to this abstract. ; Atara Biotherapeutics: Other: support for the conduct of sponsored trials and Inventor; Jasper: Other: support for the conduct of sponsored trials; AlloVir: Other: support for the conduct of sponsored trials; Neovii: Consultancy; ADMA Biologics: Consultancy; MSK: Other: Inventor. Mahadeo: Atara Biotherapeutics: Consultancy. Beitinjaneh: Kite/Gilead: Other: Ad Board Event Attendee. Choquet: Sanofi, Celegene, Roche, Abbvie, Sandoz, Janssen, Takeda: Consultancy. Stiff: Cellectar: Research Funding; CRISPR: Consultancy; Gamida-Cell, Atara, Amgen, Incyte, Takeda, Macrogenetics, Eisai: Research Funding. Reshef: Bayer, BMS, Regeneron, TScan, Synthekine, Atara, Jasper: Consultancy. Dahiya: Kite, a Gilead Company: Consultancy; Miltenyi Biotech: Research Funding; Atara Biotherapeutics: Consultancy; Jazz Pharmaceuticals: Research Funding; BMS: Consultancy. Parmar: Atara Biotherapeutics: Current Employment. Ye: Atara Biotherapeutics: Current Employment. Gamelin: Atara Biotherapeutics: Current Employment. Dinavahi: Atara Biotherapeutics: Current Employment.

Background: Outcomes are poor for patients with large B-cell lymphoma (LBCL) who relapse early or are refractory to first-line therapy. Furthermore, patients receiving second-line standard-of-care (SOC) therapy often report poor health-related quality of life (QoL; Lin V, et al. J Clin Oncol. 2020;38:e20070). In the ZUMA-7 (NCT03391466) pivotal Phase 3, randomized, open-label, multicenter study of axi-cel (an autologous anti-CD19 chimeric antigen receptor [CAR] T-cell therapy) versus SOC, we conducted the first comparative analysis of patient-reported outcomes (PROs) with CAR T-cell therapy versus SOC as second-line treatment in relapsed/refractory (R/R) LBCL. Methods: PRO instruments, including the EORTC QLQ-C30 (cancer-specific 30-item questionnaire including global health status, functional, and symptom scales) and the EQ-5D-5L (a general questionnaire with 5 QoL domains plus a global assessment), were administered at baseline (prior to treatment), Day 50, Day 100, Day 150, Month 9, and every 3 months from randomization up to 24 months or time of event-free survival event (disease progression, death from any cause, or new lymphoma therapy), whichever occurred first. The QoL analysis set was defined as all patients who had a baseline PRO and ≥1 measure completed at Day 50, Day 100, or Day 150. Prespecified hypotheses for 3 PRO domains (EORTC QLQ-C30 Physical Functioning, EORTC QLQ-C30 Global Health Status/QoL, and EQ-5D-5L visual analog scale [VAS]) were tested using a mixed-effect model with repeated measures at Day 100 and subsequent time points if previous time points were statistically significant. False Discovery Rate was used to adjust P values across key endpoints; sensitivity analyses were conducted to control for covariates and patterns of missingness. A clinically meaningful change was defined as 10 points for each EORTC QLQ-C30 score and 7 points for EQ-5D-5L VAS score. Exploratory analyses on other domains of EORTC QLQ-C30 and EQ-5D-5L were also performed. Results: Of 359 patients enrolled in the ZUMA-7 study, 296 patients (165 axi-cel, 131 SOC) had baseline PROs and ≥1 follow-up measure and were included for analysis. Overall, 70% of patients had primary refractory disease, 42% had high second-line age-adjusted International Prognostic Index (2-3), and 30% were ≥65 years old. For patients in the QoL analysis set treated with axi-cel versus SOC, there was a statistically significant (P Additional exploratory analyses of PRO endpoints (eg, EORTC QLQ-C30 role functioning, social functioning, fatigue, nausea/vomiting, dyspnea, insomnia, appetite loss, diarrhea, and EQ-5D-5L index [US value set]) also showed improvements with axi-cel over SOC. Conclusion: ZUMA-7, the first randomized, global, multicenter Phase 3 study of axi-cel versus SOC in second-line R/R LBCL, showed that treatment with axi-cel results in clinically meaningful improvement in QoL over SOC at Day 100 as measured by multiple validated PRO instruments. Score comparisons at later timepoints warrant cautious interpretation, particularly in the SOC arm, as attrition due to disease progression, new lymphoma therapy, or death may select patients with the best outcomes. The data also suggest faster recovery to pretreatment QoL with axi-cel compared with SOC. The superior clinical outcomes and patient experience with axi-cel over SOC should help inform treatment choices in second-line R/R LBCL. These data are reported on behalf of all ZUMA-7 investigators and contributing Kite members. Figure 1 Figure 1. Disclosures Elsawy: Kite, a Gilead Company: Consultancy, Honoraria; Celgene/BMS: Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; BMS: Consultancy. Chavez: MorphoSys, AstraZeneca, BeiGene, Genentech, Kite, a Gilead Company, and Epizyme: Speakers Bureau; ADC Therapeutics: Consultancy, Research Funding; MorphoSys, Bayer, Karyopharm, Kite, a Gilead Company, Novartis, Janssen, AbbVie, TeneoBio, and Pfizer: Consultancy; AstraZeneca: Research Funding; BMS: Speakers Bureau; Merk: Research Funding. Avivi: Novartis: Speakers Bureau; Kite, a Gilead Company: Speakers Bureau. Larouche: Gilead: Consultancy. Wannesson: Novartis: Consultancy, Research Funding; MSD: Consultancy; BMS: Consultancy; AstraZeneca: Consultancy; Roche: Consultancy, Research Funding. Cwynarski: Kite, a Gilead Company: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Takeda: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Celgene: Consultancy; Atara: Consultancy; Gilead: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; BMS/Celgene: Other: travel to scientific conferences; Janssen: Consultancy, Other: travel to scientific conferences; Roche: Consultancy, Other: travel to scientific conferences, Speakers Bureau. Osman: Kite, a Gilead Company: Consultancy. Davison: Merck: Consultancy; AstraZeneca: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Gilead: Consultancy; Abbvie: Consultancy; Celegene: Consultancy. Rudzki: Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy; MSD: Consultancy; Roche: Consultancy, Speakers Bureau; BMS-Celgene: Consultancy. Dahiya: Jazz Pharmaceuticals: Research Funding; Miltenyi Biotech: Research Funding; Kite, a Gilead Company: Consultancy; Atara Biotherapeutics: Consultancy; BMS: Consultancy. Dorritie: OncLive/Institutional Perspectives on Cancer presentation: Honoraria; Janssen: Research Funding; University of Pittsburgh/UPMC Hillman Cancer Center: Current Employment; Juno/BMS: Research Funding; F. Hoffman-La Roche Ltd: Research Funding; Kite, a Gilead Company: Research Funding; Genmab: Research Funding; SITC presentation: Honoraria. Jaglowski: CRISPR Therapeutics: Consultancy; Takeda: Consultancy; Juno: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Radford: AstraZeneca: Current holder of individual stocks in a privately-held company; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; ADC Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company, Honoraria, Speakers Bureau; BMS: Honoraria. Morschhauser: Servier: Consultancy; Roche: Consultancy, Speakers Bureau; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria; Genmab: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy; Janssen: Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZenenca: Membership on an entity's Board of Directors or advisory committees. Cunningham: AstraZeneca: Research Funding; Clovis Oncology: Research Funding; MedImmune: Research Funding; Roche: Research Funding; Celgene: Research Funding; Bayer: Research Funding; 4SC: Research Funding; Eli Lilly: Research Funding; OVIBIO: Membership on an entity's Board of Directors or advisory committees. Martin Garcia-Sancho: Kern Pharma: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Incyte: Consultancy; Takeda: Honoraria; Novartis: Consultancy; Eusa Pharma: Consultancy; Clinigen: Consultancy; Kyowa Kirin: Consultancy; Morphosys: Consultancy; Gilead: Consultancy, Honoraria; Servier: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Janssen: Honoraria, Research Funding; Celgene/BMS: Consultancy; Celgene: Honoraria, Other: travel; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses. Tzachanis: Partner: Consultancy; Takeda: Consultancy, Speakers Bureau; EUSA: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Kyowa Kirin: Consultancy; Magenta: Consultancy; Bristol Myers Squibb: Research Funding; Genentech: Research Funding; Incyte: Research Funding; Fate Therapeutics: Research Funding. Karmali: Roche: Consultancy; BMS/Celgene/Juno: Consultancy, Research Funding; EUSA: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Morphosys: Consultancy, Speakers Bureau; Epizyme: Consultancy; Janssen/Pharmacyclics: Consultancy; AstraZeneca: Speakers Bureau; Genentech: Consultancy; Karyopharm: Consultancy; BeiGene: Consultancy, Speakers Bureau; Takeda: Research Funding. Kekre: Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Thieblemont: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses , Research Funding; Bristol Myers Squibb/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Cellectis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Hospira: Research Funding; Bayer: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses . Enblad: Kite, a Gilead Company: Consultancy; Gilead Sciences: Consultancy. Dreger: Riemser: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Bluebird Bio: Consultancy; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau; BMS: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau. Malladi: Gilead: Honoraria, Other: Travel support; Gilead Science: Consultancy. Joshi: Open Health: Current Employment; Kite, a Gilead Company: Consultancy, Research Funding; various clients via employment: Consultancy, Research Funding. Wang: Kite, a Gilead Company: Consultancy, Research Funding; additional companies through employment with Open Health: Consultancy, Current Employment, Research Funding. Solem: OPEN Health: Current Employment; Kite, a Gilead Company: Consultancy; multiple clients through employment at OPEN Health: Research Funding. Thornton Snider: Kite, a Gilead Company: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Gilead: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. To: Kite, a Gilead Company: Current Employment, Other: stock or other ownership ; NantWorks: Ended employment in the past 24 months. Kersten: BMS/Celgene: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Other: Travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel support; Miltenyi Biotec: Consultancy, Honoraria, Other: Travel support; Celgene: Research Funding; Takeda: Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding.

Introduction Chimeric antigen receptor T-cell (CAR-T) therapy has emerged as a powerful therapy for relapsed and refractory (R/R) B-cell malignancies. A growing body of research suggests that CAR-T therapy can be safe and effective in patients who have previously received allogeneic hematopoietic stem cell transplantation (alloHSCT). "Pseudo-allogeneic" CAR-T therapy refers to manufacture of engineered T-cells collected from an alloHSCT recipient exhibiting 100% donor chimerism. This CAR-T approach poses theoretical risks due to alloreactivity and increased CAR-T toxicity. Most studies to date in this area have enrolled patients with leukemia. We present here a single-center experience with pseudo-allogeneic CAR-T following alloHSCT in 6 patients with large B-cell lymphoma (LBCL). Patients and Methods Patients with R/R LBCL who underwent treatment with axicabtagene ciloleucel (axi-cel) CAR-T after prior alloHSCT were identified. All patients underwent lymphodepletion with cyclophosphamide and fludarabine prior to CAR-T infusion. CAR-T toxicities, namely cytokine release syndrome (CRS) and immune effector-cell associated neurotoxicity syndrome (ICANS) were graded in accordance with the 2019 American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading. Results Six patients who underwent axi-cel CAR-T due to post-alloHSCT R/R LBCL were identified. All patients had stage ≥II disease. At the time of CAR-T apheresis, all patients had ≥95% donor chimerism and were off immunosuppression, without evidence of GVHD. Manufacturing failure occurred in only one patient (case 2) due to low viability and upon second apheresis, manufacture was successful. All 6 pseudo-allogeneic CAR-T therapy patients tolerated infusion and did not show increased incidence or severity of CRS or ICANS compared to our center's experience with standard CAR-T patients, with only one patient experiencing greater than grade 2 toxicity. Three of six patients developed graft-versus-host disease (GVHD); however, one case was in the setting of PD-1 blockade and two were isolated cutaneous manifestations. There was no incidence of severe GVHD. All three cases of GVHD underwent CAR-T within ten months after alloHSCT, whereas the three patients without GVHD were >1 year post-HSCT at time of CAR-T. Two cases who had donor lymphocyte infusions prior to CAR-T did not develop GVHD. In terms of efficacy, three patients achieved a complete remission. There was no perceptible relationship between the development of GVHD and the response to CAR-T. Four of six had cytopenias at day 30 after CAR-T, with only two exhibiting persistent cytopenias at day 90. Lastly, in this small sample size, no differences were seen in incidence of GVHD or treatment response between haploidentical, matched-related, and matched-unrelated alloHSCT donors. Conclusion In our experience, pseudo-allogeneic CAR-T therapy following alloHSCT appears to be a safe and well-tolerated treatment modality for R/R B-cell lymphoma. The efficacy of this modality will need to be borne out in further studies. Disclosures No relevant conflicts of interest to declare.

Background: Nonmyeloablative (NMA) and reduced-intensity conditioning (RIC) regimens are offered for patients with hematologic malignancies requiring allogeneic stem cell transplantation (HSCT) but are not candidates for myeloablative conditioning (MAC). The intensity of the conditioning regimen (CR) is important and contributes to the ability of HSCT to provide a cure. There is no consensus regarding the best RIC regimen and efficacy is not equal amongst RIC regimens. The combination of 2 days of intravenous Busulfan (total of 6.4 mg/Kg) and Fludarabine (total of 120-160 mg/m2) (Flu/Bu2) has been validated and widely adopted. While this regimen is well tolerated, relapses are common and remain the leading cause of death. Total body irradiation (TBI) has been widely used in the CR and provides the advantage of potent anti-cancer effect, immunosuppression and the ability to reach certain 'sanctuary sites' for chemotherapy (i.e. CNS). The 2 most commonly used TBI levels are 1200 cGy in MAC regimens and 200 cGy in NMA and RIC regimens. We hypothesize that the addition of 400 cGy (200 cGy two fractions per day, 6 hours apart) TBI to Flu/Bu2 will reduce the relapse rate without increasing its toxicity. In this retrospective study, we compared the safety and efficacy of Flu/Bu2/TBI400 with Flu/Bu2 CR amongst a diverse group of hematologic diseases. Methods: From 2006 to 2018, 137 adult patients with different hematological diseases were treated using one of two RIC regimens, either Flu/Bu2/TBI400 or Flu/Bu2 followed by HSCT from HLA-matched related or unrelated donors. The primary endpoint was OS defined as the time from the date of transplant to death from any cause. The secondary endpoints included PFS, relapse rate, cumulative incidence of relapse (CIR), non-relapse mortality (NRM), causes of death, aGVHD, cGVHD and engraftment. PFS was defined as the time from the date of transplant to disease progression as documented by the treating physician, based on pathological, imaging or clinical findings of the individual disease, or death from any cause. NRM was defined as time of death without evidence of progressive disease with relapse or progressive disease as a competing risk event (data not shown in the abstract). Relapse was defined as progression or disease relapse with NRM as a competing risk event. These endpoints were censored at the time of last follow-up. Results: A total of 137 patients were included in this study. 74 patients were treated with Flu/Bu2/TBI400 and 63 patients were treated with Flu/Bu2. The 2 groups were comparable in terms of patient-, disease- and transplant-related characteristics; however, Flu/Bu2/TBI400 patients had a higher HCT-CI score and a lower KPS. CNI-MTX GVHD prophylaxis was used in a higher proportion in Flu/Bu2/TBI400. Most of the Flu/Bu2 transplants occurred from 2006 to 2012. The median age was 62 in both groups and patients had comparable disease type distribution and DRI (Table 1). The median follow-up time was 4.62 years. Flu/Bu2/TBI400 showed improvement of PFS over Flu/Bu2; the 5-year PFS was 50% in the TBI arm vs. 34% in the no-TBI arm (p=0.06 of marginal statistical significance). There was a numerical improvement of OS in favor of the TBI arm but this was not statistically significant; The 5-year OS was 53% with TBI vs. 39% without TBI (p=0.13). Cumulative incidence of relapse was not different between the 2 groups (p=0.29), see figures 1, 2 and 3. There was no difference in aGVHD incidence between the 2 groups (p=0.21). The TBI arm had significantly lower incidence of cGVHD compared to no-TBI arm (29% vs. 54%, p=0.005). Advanced DRI, grade III-IV aGVHD, cGVHD, use of ATG and MUD were associated with worse OS (univariate analysis). The same factors, with the exception of cGVHD, were associated with worse PFS. Multivariable Cox regression model revealed that grade III-IV aGVHD was associated with worse OS (p=0.001) while advanced DRI was associated with marginally inferior OS (p=0.07) (Table 2). Conclusion: This is the largest retrospective study of RIC Flu/Bu2/TBI400 regimen for HSCT with a median follow-up approaching 5 years. Our data suggests that RIC Flu/Bu2/TBI400 is safe and efficacious for different hematological malignancies. When compared to Bu/Flu2 without TBI, Flu/Bu2/TBI400 had lower incidence of cGVHD and showed a strong trend towards improved PFS and OS though not statistically significant at this time. Grade III-IV aGVHD was associated with poor OS in both groups. Disclosures Hardy: Incyte Corporation: Other: Advisory Board Member; Kite/Gilead: Other: Advisory Board Member; American Gene Technologies: Other: DSMB Member.

Introduction: Secondary hemophagocytic lymphohistiocytosis (HLH) is an aggressive life-threatening activation of the immune system triggered by an underlying condition. Use of chimeric antigen receptor therapy (CAR-T) to treat relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) is associated with cytokine release syndrome (CRS), Immune Effector Cell Associated Neurotoxicity Syndrome (ICANS) and development of secondary HLH. Application of HLH scoring systems such as the H-score or HLH-2004 criteria to identify CAR-T triggered HLH is not validated in this setting. Inability to promptly recognize the development of secondary HLH in CAR-T patients and to distinguish it from CRS may lead to delay in HLH specific therapy and increased mortality. We analyzed the utility of applying the H-score and the HLH-2004 criteria to identify possible patients with HLH post-CAR-T for R/R DLBCL. Methods: A single center retrospective analysis of 75 patients with R/R DLBCL following CAR-T was performed. Using a peak ferritin of 500 mcg/L or higher within 30 days of CAR-T administration, 43 out of 75 patients were identified at risk for HLH. The H-score and HLH-2004 criteria were applied retrospectively. Measurement of NK activity was not available for any patients and soluble IL2 was collected intermittently. The mean H-score was calculated, and two sample t-test performed to evaluate for a difference in the mean H-score between low versus high grade CRS, low versus high grade ICANS, as well as presence versus absence of cytopenias at days 30, 90 and 180. Low grade CRS/ICANS was defined as 1, and high grade as 2 or higher. CRS was graded per Lee 2014 criteria and ICANS per CTCAEv.4. The 43 patients were then subdivided by H-score threshold of 169 into H-score Low (< 169) and H-score High (≥ 169). The threshold of 169 was used given a prior validation study showing optimal sensitivity and specificity for identifying acquired HLH in adult patients with an H-score equal to or higher than 169. Both Progression Free Survival (PFS) and Overall Survival (OS) were defined as time from CAR-T infusion until an event of last follow up. Kaplan-Meier curves were produced to describe the distribution of PFS and OS between two subpopulations of low and high H-Score. Results: Median peak ferritin was 1571.8 mcg/L (range: 375 mcg/L - >50,000 mcg/L, table 1). Median H-score was 135 (range 61 -250). Four patients were treated with HLH directed therapy receiving steroids with either tocilizumab, siltuximab and/or anakinra. Of these 4 patients, only 2 met five HLH-2004 criteria. All 4 patients had H-scores above 169 (209, 211, 228 and 250). Of these 4 patients, one died from complications thought secondary to HLH. Fourteen patients (14/43, 32%) had an H-score >169. Ten patients did not require any HLH directed therapy and had no clinical evidence of HLH. The mean H-score was not different between patients with low vs high grade CRS (148.2 vs 141.8, p=0.7) or low vs high grade ICANS (145.9 vs 142.6, p=0.8). No statistical correlation was seen between H-score and cytopenias at any time point. There was no significant difference in PFS or OS between the H-score low vs high subgroups (p=0.7, p=0.1 respectively, figure 1 and 2). Patients with higher H-score tended to have longer length of hospitalization for CAR-T (Pearson correlation coefficient 0.289). Conclusions: In patients with R/R DLBCL post CAR-T, the use of either the H-score or application of HLH-2004 criteria had low utility in identifying possible HLH in patients who screened in based on peak ferritin within 30 days of CAR-T administration. While apparent differences between the H-score high and low categories may not reach statistical significance due to the small number of patients, our exploratory analysis does not support the use of H-Score to evaluate for HLH post-CAR-T. The immediate post-CAR-T period is characterized by a high inflammatory state, which likely results in high H-scores. Results from our study suggest a need for further characterization of HLH following CAR-T and the role for a CAR-T specific HLH scoring system to distinguish secondary HLH from CAR-T related inflammation in this specific patient population. Disclosures Hardy: American Gene Technologies: Other: DSMB Member; Kite/Gilead: Other: Advisory Board Member; Incyte Corporation: Other: Advisory Board Member.

Introduction:The spread of SARS-CoV-2 virus continues to pose a major public health threat. Patients with cancer are thought to be at increased risk from SARS-COV-2 infection due to the immunodeficiency that results from the underlying neoplasm and treatment. The immune response to this infection has been the subject of great interest, with an extreme variation in clinical severity between infected individuals. Variation in the immune cell response (B, T, and NK lymphocytes, monocytes, and myeloid derived suppressor cells (MDSCs), among others) and their function have been hypothesized to be responsible for this range of presentation. Methods:Two patients with a history of hematologic malignancies were matched with three non-cancer patients with similar baseline clinical characteristics and severity of COVID related illness. The critical group (CG) was defined as those requiring mechanical ventilation (MV) due to COVID related respiratory failure and the non-critical group (NCG) were hospitalized but did not require MV. All samples studied were obtained from peripheral blood and processed within 4-hours of collection. Peripheral blood mononuclear cell (PBMC) were isolated using ficoll density gradient separation. Flowcytometric analysis using CytekTM Aurora was done on fresh PBMC samples. Thirty antibody-based flow markers were used to identify 54 distinct immune cell populations. IRB approval was obtained. Results: Critical Group (CG):The CG included case 1, a 47 year-old (y.o.) female (F) with a history (hx) of acute myeloid leukemia and had an matched related donor allogeneic hematopoietic stem cell transplant (alloHSCT) 10-years prior remaining in remission, with hematologic recovery, and off immunosuppressants treated with remdesivir and coritcosteroids for COIVD directed therapy; and case 2, a 55 y.o. F with a hx of HIV treated with corticosteroids for COIVD directed therapy (see Figure 1a). Non-Critical Group (NCG):The NCG included case 3, a 73 y.o male (M) with hx of relapsed/refractory Philadelphia chromosome negative Acute Lymphoblastic Leukemia with loss of CD19 and CD22 expression following treatment with blinatumumab and inotuzumab, and most recently treated with decitabine/venetoclax; case 4, a 66 y.o. M with hx of cardiomyopathy; and case 6, a 54 y.o. M with hx of obesity. None of the NCG cases were treated with COVID directed therapy. See Table 1 for further clinical information. Immunophenotypic expression:Flow cytometry gating strategy done as outlined in Fig 1a. Case 1 had a high proportion of B-cells, CD8+ T-cells, and cells with exhaustion markers (CD8+CD94+ T-cells, CD4+PD1+ T-cells, CD4+PD1+CD94+ T-cells, PD1-CD94+ NK T-cells, Lag3+Cd11b- non-TB leukocytes) and MDSC immunophenotypes compared with matched case 2. Case 3 also had a high proportion of exhaustion markers (Lag3+CD39 low B-cells, CD8+PD1+ T-cells, CD8+CD94+PD1+ T-cells, CD4+PD1+CD94+ T-cells, PD1+CD94+ NK T-cells, PD1-CD94+ NK T-cells, Lag3+CD11b+, Lag3+CD11b- non-TB leukocytes) and high expression of immunosuppressive Treg and all MDSC; although high expression of granulocytic MDSC. Case 2 had a significant number of exhaustion and immunosuppressive cells as well. Cases 4 and 5 had a higher predominance of all T-cell subtypes and also had variable expression of exhaustion and immunosuppressive immunophenotypes (See Fib 1b). Conclusion:In our study of one critical and one non-critical patient with a history of hematologic malignancy matched with three non-cancer patients we demonstrate the high predominance of exhaustion markers (Lag3,PD1,CD94) and immunosuppressive cell types (Treg, granulocytic and monocytic MDSC). These findings are consistent with the fact that both CG and NCG, as hospitalized patients, represent the most severely ill COVID patient cohort. Of notable interest to the cancer population, cases 1 and 3 had a significant number of exhaustion and immunosuppressive immunophenotypes, suggestive of baseline exhaustion following alloHSCT even years after engraftment in case 1 and attenuated functional immunity in a patient undergoing active treatment in case 3. Interestingly, case 3 had lower expression of all MDSC, a known treatment effect of decitabine. Paired cytokine measurement and its effect on immunophenotype is underway. Additionally, we plan to present an atlas of the peripheral immune cell response on fifteen additional non-cancer COVID patients. Disclosures No relevant conflicts of interest to declare.

Introduction: Axicabtagene Ciloleucel (axi-cel), a CD19 chimeric antigen receptor (CAR) T-cell therapy, was approved for the treatment of relapsed/refractory aggressive B-cell non-Hodgkin lymphoma in October, 2017. In the ZUMA-1 trial leading to axi-cel FDA approval, patients (pts) with prior or active secondary central nervous system (CNS) lymphoma involvement were excluded. A recent publication of 8 pts with secondary CNS lymphoma who underwent Tisagenlecleucel CAR T cell therapy was reported (Frigault M.J.2019). Since the two FDA approved CAR T cell products have a different neurotoxicity profile, understanding outcomes of axi-cel in this setting is important. We report here the real-world experience of 17 pts treated with axi-cel who had a history of secondary CNS involvement or had active CNS disease at time of CAR T infusion. Methods: Seventeen academic centers from the US Lymphoma CAR T Consortium contributed data independently from the manufacturer. Data regarding secondary CNS involvement, management, and outcome were obtained in addition to CAR T therapy outcome for pts who were identified as having active, secondary CNS involvement at the time of evaluation for CAR-T therapy. Nine centers reported data on 17 cases with CNS involvement. Follow-up data was missing for one pt in the CNS cohort. Lee criteria or the modified Lee grading scale were used for cytokine release syndrome (CRS). CTCAEv4 or CARTOX grading were used for immune effector cells associated neurotoxicity syndrome (ICANS). All leukapheresed pts were included in the intention to treat (ITT) analysis for response rate and event-free survival (EFS). EFS was defined as date of leukapheresis until progression or death due to any cause. EFS was evaluated using Kaplan Meier curves with log-rank test. Differences in clinical characteristics and response between CNS and non-CNS pts were not formally tested due to small sample size and multiple comparison concerns. Results: With a data cut-off of 4/30/2019, 300 pts underwent leukapheresis with intention to manufacture standard of care axi-cel. By the time of leukapheresis, 17 (6%) had secondary CNS involvement (4 parenchymal disease, 10 leptomeningeal/CSF, 3 data not available). Compared to the non-CNS cohort, baseline demographics were comparable (Panel A). Manufactured axi-cel was within specification for 100% of the CNS cohort. There was a higher rate of bridging therapy use in the CNS cohort 82% (1 steroids only, 2 radiation therapy, 12 systemic therapy) vs 52% in non-CNS cohort; p=0.022. Time from leukapheresis to CAR T infusion was 3.5 days longer in the CNS cohort as opposed to the non-CNS cohort: median time of 29.5 (range 20-76) vs. 26 days (range 5-67), (p=0.029), respectively. The CAR T infusion rate was 88% for the CNS cohort (15/17) compared to 93% (262/283) in the non-CNS cohort. Among the 15 infused pts in the CNS cohort, 10 had resolution of CNS involvement, and 5 had persistent active CNS disease at time of CAR T infusion. After axi-cel infusion, the incidence of CRS and ICANS, of any grade or grade 3 or higher, were comparable between the CNS and non-CNS cohorts. Tocilizumab and steroid use were comparable between the two groups (Panel B). No seizures or cerebral edema were noted in the CNS cohort. With a median follow-up of 10.1 months from leukapheresis (range 7.6-12.6), the ITT best overall response rates (CR+PR) and ongoing responses at month 6 between CNS and non-CNS cohorts were 75% vs. 59%, and 41% vs. 31%, respectively (Panel B). In the 5 pts with active CNS disease at time of CAR T infusion, the response of CNS disease were 2 CR, 1 PR and 2 PD as best response. In the 10 pts with resolved CNS disease at time of CAR T infusion, 2 PD were seen and both occurred systemically. EFS from leukapheresis was not statistically significantly different between CNS and non-CNS cohorts (6 months EFS: CNS cohort, 36%; non-CNS cohort 57%. HR=1.58, 95% CI: 0.83-3.01, p=0.16, Panel C). Six month EFS from the date of infusion for the CNS cohort was 49.9% (Panel D). Conclusions: Pts attempting CAR T therapy with secondary CNS disease in the real world setting had similar rates of CAR T infusion, toxicity, and outcomes when compared to patients without CNS disease. Small sample size and limited follow-up caution the strength of conclusions for application to clinical practice, but these results support further investigation of CAR T in pts with history of or active secondary CNS lymphoma. Figure Disclosures Bennani: Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board; Purdue Pharma: Other: Advisory board; Purdue Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Kite Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Kite Pharma: Other: Advisory board. Maurer:Celgene: Research Funding; Nanostring: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees. Nastoupil:Bayer: Honoraria; Spectrum: Honoraria; TG Therapeutics: Honoraria, Research Funding; Novartis: Honoraria; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Genentech, Inc.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Jain:Kite/Gilead: Consultancy. Chavez:Novartis: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees. Cashen:Seattle Genetics: Other: Speaker's Bureau; Novartis: Other: Speaker's Bureau; Celgene: Other: Speaker's Bureau. Reagan:Kite, A Gilead Company: Consultancy; Curis: Consultancy; Seattle Genetics: Research Funding. Oluwole:Pfizer: Consultancy; Spectrum: Consultancy; Gilead Sciences: Consultancy; Bayer: Consultancy. McGuirk:Novartis: Research Funding; Fresenius Biotech: Research Funding; Astellas: Research Funding; Bellicum Pharmaceuticals: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gamida Cell: Research Funding; Pluristem Ltd: Research Funding; ArticulateScience LLC: Other: Assistance with manuscript preparation; Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Deol:Novartis: Other: Advisory board; Kite: Other: Advisory board; Agios: Other: Advisory board. Sehgal:Juno/Celgene: Research Funding; Merck: Research Funding; Kite/Gilead: Research Funding. Goy:COTA: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: leadership role for profit healthcare company; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Astrazenca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; University of Nebraska: Research Funding; Hakensackumc: Research Funding; Takeda: Other: Grants outside of the submitted work; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work; Pharmacyclics/Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; Genentech: Other: Grants outside of the submitted work, Research Funding; Hackensack University Medical Center, RCCA: Employment; Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding. Hill:Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG therapeutics: Research Funding; AstraZeneca: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Celegene: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Research Funding; Takeda: Research Funding; Amgen: Research Funding. Vu:Celgene: Other: Stock. Andreadis:Genentech: Equity Ownership, Other: Spouse is Employee; Novartis: Honoraria, Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Gilead: Consultancy; Jazz Pharmaceuticals: Consultancy; Bayer: Consultancy. Munoz:Incyte: Research Funding; Portola: Research Funding; Celgene: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Speakers Bureau; AstraZeneca: Speakers Bureau; Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding, Speakers Bureau; Kite Pharma: Consultancy, Research Funding, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Fosunkite: Speakers Bureau; Kyowa: Consultancy, Honoraria, Speakers Bureau. Vose:Acerta Pharma: Honoraria, Other: Grants, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Celgene Corporation: Research Funding; Incyte Corporation: Research Funding; Kite Pharma: Honoraria, Other: Grants, Research Funding; Novartis: Research Funding; Seattle Genetics: Research Funding; AbbVie: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Legend Pharmaceuticals: Honoraria. Miklos:Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; Becton Dickinson: Research Funding; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Locke:Kite: Other: Scientific Advisor; Novartis: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy. Neelapu:Unum Therapeutics: Consultancy, Research Funding; BMS: Research Funding; Pfizer: Consultancy; Incyte: Consultancy; Poseida: Research Funding; Allogene: Consultancy; Merck: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Karus: Research Funding; Precision Biosciences: Consultancy; Cell Medica: Consultancy; Acerta: Research Funding; Cellectis: Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy. Lin:Novartis: Membership on an entity's Board of Directors or advisory committees; Juno: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; BlueBird Bio: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sorrento: Membership on an entity's Board of Directors or advisory committees.

MDJ and MTJ contributed equally; FLL and AG contributed equally. Introduction Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are autologous anti-CD19 CAR T-cell therapies approved for the treatment of adults with relapsed or refractory large B-cell lymphoma (LBCL) who have failed at least two lines of systemic therapy. In the ZUMA-1 trial that led to axi-cel approval, the median time between apheresis and delivery of CAR T cells to the treating facility was 17 days (Neelapu, Locke et al. NEJM 2018). Bridging therapy, defined as lymphoma therapy given between apheresis and the start of lymphodepleting chemotherapy, was not permitted on ZUMA-1. By contrast, the pivotal JULIET trial for tisa-cel (Schuster et al. NEJM 2019) had a median time from enrollment to infusion of 54 days and 92% of patients received bridging therapy. Whether bridging therapy affects lymphoma CAR T outcomes is unknown. Here we evaluate patients receiving bridging therapy for axi-cel in a large multicenter cohort. Methods and Results The US Lymphoma CAR T Consortium includes seventeen US academic centers that contribute data from lymphoma patients treated with standard of care (SOC) CAR T-cell therapy independently of manufacturers. As of 8/31/2018, 300 patients were apheresed with intent to manufacture SOC axi-cel for LBCL. Of the 23 patients that underwent apheresis for axi-cel and did not receive it, 20 had lymphoma progression or death that precluded CAR T infusion, of which 16 received bridging therapy. In this study, we analyze the modified intent-to-treat (mITT) population of 276 patients receiving CAR T infusion with a median follow up of 9 months. In this group, 146 (53%) patients received bridging therapy while 130 (47%) patients received no bridging therapy. Bridging therapy consisted of steroids alone (n = 35, 24%), chemotherapy (n = 73, 50%), radiation (n = 24, 16%), or targeted therapies (n = 14, 10%). At baseline, a higher proportion of patients in the bridging therapy group had an ECOG score of 2 - 4 vs. 0 - 1 (bridging 24.8%, no bridging 6.1%, p After axi-cel infusion, patients in the bridging group had similar rates of severe (grade 3 or higher) cytokine release syndrome (CRS) (8.2% vs. 5.3%, p = 0.34) and ICANS (35.2% vs. 28.2%, p = 0.25). However, the rate of ICU admission was higher in the bridging group (41.4% vs. 22.9%, p = 0.001) as was median length of hospital stay (15 vs. 14 days, p = 0.02). While data on cytopenias was not collected, use of G-CSF after CAR T therapy was higher in the bridging group (48.2% vs. 32.1%, p = 0.006). In terms of outcomes, in multivariate analysis correcting for confounding features, there was no statistically significant difference in overall response rate (p = 0.2), complete response rate (p = 0.19), and progression free survival (p = 0.3) between bridging and no bridging groups; but bridging therapy was associated with significantly poorer overall survival (p = 0.001) and lymphoma specific survival (p = 0.019) (figure 1.). Both death due to lymphoma (33.1% vs. 13.0%) and death due to treatment-related mortality (TRM) (6.9% vs. 1.5%) were higher in the bridging group (p Conclusions Lymphoma patients receiving bridging therapy had poorer prognostic factors at baseline and after axi-cel infusion experienced decreased lymphoma-specific and overall survival compared with patients with no bridging. This inferior outcome raises the possibility that bridging therapy may identify a sub-group of lymphoma patients with a different biology, or alternatively, bridging therapy may have an effect on the host or the tumor microenvironment that may impact CAR-T efficacy. With or without bridging, 7% of patients in our series did not receive axi-cel due to lymphoma progression and/or death. In addition, there may have been patients where bridging prevented progression or death prior to axi-cel infusion. Prospective evaluation of different bridging strategies is warranted to determine if any can improve outcomes after axi-cel, and/or if they should be utilized only for patients requiring emergent disease control during the manufacture period. Disclosures Jain: Kite/Gilead: Consultancy. Nastoupil:Bayer: Honoraria; Celgene: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Honoraria; TG Therapeutics: Honoraria, Research Funding; Spectrum: Honoraria. Lin:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; BlueBird Bio: Research Funding; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Sorrento: Membership on an entity's Board of Directors or advisory committees. Lunning:Curis: Research Funding; Janssen Scientific Affairs, LLC: Consultancy, Research Funding; Juno Therapeutics: Consultancy, Research Funding; MiRagen: Research Funding; TG Therapeutics: Consultancy, Research Funding; AbbVie: Consultancy; Bayer: Consultancy; DAVA: Consultancy; Gilead Sciences, Inc.: Consultancy; Kite: Consultancy; Novartis: Consultancy; OncLive: Consultancy; Portola: Consultancy; Seattle Genetics: Consultancy; Spectrum: Consultancy; VANIUM: Consultancy; Verastem: Consultancy. Reagan:Kite, A Gilead Company: Consultancy; Curis: Consultancy; Seattle Genetics: Research Funding. Oluwole:Pfizer: Consultancy; Spectrum: Consultancy; Gilead Sciences: Consultancy; Bayer: Consultancy. McGuirk:Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Fresenius Biotech: Research Funding; Astellas: Research Funding; Bellicum Pharmaceuticals: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gamida Cell: Research Funding; Pluristem Ltd: Research Funding; ArticulateScience LLC: Other: Assistance with manuscript preparation. Deol:Novartis: Other: Advisory board; Kite: Other: Advisory board; Agios: Other: Advisory board. Goy:University of Nebraska: Research Funding; Hakensackumc: Research Funding; Astrazenca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Hackensack University Medical Center, RCCA: Employment; Genentech: Other: Grants outside of the submitted work, Research Funding; Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; Pharmacyclics/Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work; Takeda: Other: Grants outside of the submitted work; COTA: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: leadership role for profit healthcare company. Hill:Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite: Consultancy, Honoraria; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Takeda: Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria; Genentech: Consultancy, Research Funding; TG therapeutics: Research Funding; Amgen: Research Funding. Munoz:Kyowa: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene/Juno: Consultancy, Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy; Alexion: Consultancy; Pfizer: Consultancy; Fosunkite: Speakers Bureau; AstraZeneca: Speakers Bureau; Portola: Research Funding; Incyte: Research Funding; Pharmacyclics /Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Merck: Consultancy. Chavez:Janssen Pharmaceuticals, Inc.: Speakers Bureau; Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Genentech: Speakers Bureau. Vose:Acerta Pharma: Honoraria, Other: Grants, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Celgene Corporation: Research Funding; Incyte Corporation: Research Funding; Kite Pharma: Honoraria, Other: Grants, Research Funding; Novartis: Research Funding; Seattle Genetics: Research Funding; AbbVie: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Legend Pharmaceuticals: Honoraria. Miklos:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; Becton Dickinson: Research Funding; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees. Neelapu:Cellectis: Research Funding; Allogene: Consultancy; Incyte: Consultancy; BMS: Research Funding; Novartis: Consultancy; Karus: Research Funding; Celgene: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Merck: Consultancy, Research Funding; Acerta: Research Funding; Poseida: Research Funding; Unum Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy; Precision Biosciences: Consultancy; Cell Medica: Consultancy. Bennani:Kite Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Seattle Genetics: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board; Purdue Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board. Andreadis:Pharmacyclics: Research Funding; Novartis: Research Funding; Roche: Equity Ownership; Celgene: Research Funding; Juno: Research Funding; Jazz Pharmaceuticals: Consultancy; Genentech: Consultancy, Employment; Merck: Research Funding; Gilead: Consultancy; Kite: Consultancy. Sehgal:Juno/Celgene: Research Funding; Merck: Research Funding; Kite/Gilead: Research Funding. Locke:Novartis: Other: Scientific Advisor; Kite: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy.

Background: Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are known complications of chimeric antigen receptor T-cell (CAR-T) therapy. These clinical syndromes develop as a result of CAR-T activation, proliferation, and tumor lysis with resultant cytokine secretion. In prior reports of CD19 CAR-T therapy patients, those who developed ICANS showed evidence of endothelial activation and disruption of the blood-brain barrier as a result of cytokine release while only approximately one-third demonstrated changes on Brain MRI (Gust et al. Cancer Discov 2017). As such, further predictive markers and studies are needed to identify patients at risk for ICANS to allow for expedited management and improved outcomes. Herein we report a single-center analysis exploring glycolytic activity on PET/CT and the association with clinical outcomes for patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) after CAR-T therapy. Methods: An organ-based evaluation of uninvolved sites was conducted in R/R DLBCL patients (n=32) who underwent CD19 CAR-T therapy with evaluable PET/CT imaging at baseline immediately prior to CAR-T therapy and at 30 days post-infusion (D+30). All patients in this analysis were treated with axicabtagene ciloleucel as standard of care therapy after 2 or more lines of therapy. Tumor metabolic volume (TMV) and mean standard uptake value (SUVmean) of various organs were quantified using ROVER [Region of interest (ROI) visualization, evolution, and image registration] software (ABX advanced biochemical compounds GmbH, Radeberg, Germany). Statistical analysis was completed using STATA 14 (StataCorp. 2015. Stata Statistical Software: Release 14. College Station, TX: StataCorp LP). All tests were performed after testing the normality distribution assumption. Temporal changes were assessed using paired t-tests, and between-group analyses were completed with two-sample t-tests. Results: SUVmean increased significantly after CAR-T therapy in the following organs (D+30 v baseline pre-CAR-T PET/CT): cerebral cortex (8.23 v 7.09, p=0.036), cerebellum (6.26 v 5.56, p=0.024), basal ganglia (9.22 v 7.61, p=0.005), parotid gland (1.61 v 1.42, p=0.004), liver (2.47 v 2.17, p=0.002), spleen (2.08 v 1.84, p=0.043), and pancreas (1.76 v 1.48, p Conclusion: For patients with R/R DLBCL undergoing CD19 CAR-T therapy, significantly increased CNS glycolytic activity is seen on PET/CT at D+30 post-infusion when compared to baseline. Interestingly, these changes do not correlate with development of ICANS or lymphoma response; however, changes in cortical activity were associated with CRS grade ≥2. Overall, our findings illustrate a functional and radiographic link between cytokine release and subsequent disruption of the blood-brain barrier as quantified by increased cortical glycolysis 30 days post-CAR-T therapy. While findings are limited by small sample size, further validation in a larger data set is warranted. Disclosures Hutnick: Kite/Gilead: Other: Yescarta Speakers Bureau, Speakers Bureau. Badros:Celgene Corporation: Consultancy; Amgen: Consultancy.

M.T.J. and M.D.J. contributed equally; A.G. and F.L.L. contributed equally. Introduction Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 CAR T-cell therapy that is approved for the treatment of adults with relapsed or refractory large B-cell lymphoma (LBCL) who have failed at least two prior systemic lines of therapy. In the ZUMA-1 trial that led to axi-cel approval, 93% of patients developed cytokine release syndrome (CRS) (Neelapu, Locke et al. NEJM 2018). CRS is a non-antigen-specific toxicity that occurs as a result of CAR T and bystander immune cell activation. Whether lack of development of CRS after treatment with axi-cel is associated with inferior lymphoma outcomes is unknown. Here we evaluate the outcomes of patients that did not develop CRS after receiving axi-cel in a large multicenter cohort. Methods and Results The US Lymphoma CAR T Consortium includes seventeen US academic centers that contribute data independently of manufacturers. As of 8/31/2018, 300 patients were apheresed with intent to manufacture standard of care axi-cel for LBCL. In this study, we analyzed the modified intent-to-treat (mITT) population of 276 patients receiving CAR T infusion with a median follow up of 9 months. In this group, 25 patients (9%) did not develop CRS and 251 patients (91%) developed CRS following axi-cel infusion. CRS was graded according to Lee criteria (Lee et al. Blood 2014) or CARTOX (Neelapu SS et al. Nat Rev Clin Oncol. 2018). At baseline, a higher proportion of patients in the no CRS group had ECOG score of 0-1 (no CRS group 100% vs. CRS group 82%, p= 0.019) and IPI score of 0-2 (no CRS group 72% vs. CRS group 46%, p = 0.019) After CAR T cell infusion, patients who did not develop CRS had a lower chance of developing grade 3 or higher neurotoxicity (no CRS group 4% vs. CRS group 35%, p=0.001), lower rates of ICU admission (no CRS group 8% vs. CRS group 35%, p = 0.006), and shorter length of hospital stay (median 10 days for no CRS group vs 14 days for CRS group, p < 0.001). Of the 25 patients who had grade 0 CRS, 23 (92%%) also had grade 0 neurotoxicity. In univariate analysis, no CRS was associated with lower complete response (CR) rate (no CRS group 40% vs. CRS group 66%, p=0.015) but no statistically significant difference in overall response rate (ORR) (no CRS group 72% vs. CRS group 84%, p= 0.158). In relation to CRS there was no difference in treatment related mortality among the two groups (CRS group 4% vs. no CRS group 4.4%, p = 0.85). In multivariate analysis correcting for confounding features, no CRS was associated with statistically significant lower complete response rate (p = 0.002), but there was no significant difference in ORR (p = 0.13), overall survival (P=0.15), progression free survival (P=0.16), and time to progression (P= 0.14) between the two groups (figure 1.). Conclusions In this large cohort of LBCL patients receiving axi-cel with median follow up of 9 months, patients that did not develop CRS, compared with those that developed CRS, achieved lower rates of complete response but there was no difference in overall response rate, progression free survival, time to progression, overall survival, and treatment related mortality between the two groups. Disclosures Jain: Kite/Gilead: Consultancy. Nastoupil:Bayer: Honoraria; TG Therapeutics: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Honoraria; Spectrum: Honoraria. Lunning:Spectrum: Consultancy; Seattle Genetics: Consultancy; Portola: Consultancy; OncLive: Consultancy; Novartis: Consultancy; Kite: Consultancy; Gilead Sciences, Inc.: Consultancy; DAVA: Consultancy; Bayer: Consultancy; AbbVie: Consultancy; TG Therapeutics: Consultancy, Research Funding; MiRagen: Research Funding; Juno Therapeutics: Consultancy, Research Funding; Janssen Scientific Affairs, LLC: Consultancy, Research Funding; Curis: Research Funding; VANIUM: Consultancy; Verastem: Consultancy. Reagan:Kite, A Gilead Company: Consultancy; Curis: Consultancy; Seattle Genetics: Research Funding. Oluwole:Pfizer: Consultancy; Spectrum: Consultancy; Gilead Sciences: Consultancy; Bayer: Consultancy. McGuirk:Novartis: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gamida Cell: Research Funding; Pluristem Ltd: Research Funding; ArticulateScience LLC: Other: Assistance with manuscript preparation; Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bellicum Pharmaceuticals: Research Funding; Fresenius Biotech: Research Funding; Astellas: Research Funding. Deol:Agios: Other: Advisory board; Novartis: Other: Advisory board; Kite: Other: Advisory board. Sehgal:Juno/Celgene: Research Funding; Merck: Research Funding; Kite/Gilead: Research Funding. Goy:Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; University of Nebraska: Research Funding; Astrazenca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Hakensackumc: Research Funding; Hackensack University Medical Center, RCCA: Employment; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work; Takeda: Other: Grants outside of the submitted work; COTA: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: leadership role for profit healthcare company; Pharmacyclics/Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; Genentech: Other: Grants outside of the submitted work, Research Funding. Hill:Kite: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Takeda: Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celegene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Research Funding; TG therapeutics: Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding. Andreadis:Juno: Research Funding; Celgene: Research Funding; Novartis: Research Funding; Roche: Equity Ownership; Jazz Pharmaceuticals: Consultancy; Kite: Consultancy; Gilead: Consultancy; Genentech: Consultancy, Employment; Pharmacyclics: Research Funding; Merck: Research Funding. Munoz:Incyte: Research Funding; Portola: Research Funding; AstraZeneca: Speakers Bureau; Fosunkite: Speakers Bureau; Pfizer: Consultancy; Alexion: Consultancy; Bristol-Myers Squibb: Consultancy; Pharmacyclics /Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Merck: Consultancy; Kyowa: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene/Juno: Consultancy, Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Research Funding, Speakers Bureau. Chavez:Janssen Pharmaceuticals, Inc.: Speakers Bureau; Genentech: Speakers Bureau; Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Bennani:Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Kite Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Purdue Pharma: Other: Advisory board. Vose:Acerta Pharma: Honoraria, Other: Grants, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Celgene Corporation: Research Funding; Incyte Corporation: Research Funding; Kite Pharma: Honoraria, Other: Grants, Research Funding; Novartis: Research Funding; Seattle Genetics: Research Funding; AbbVie: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Legend Pharmaceuticals: Honoraria. Miklos:Becton Dickinson: Research Funding; Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Neelapu:Poseida: Research Funding; Cellectis: Research Funding; Precision Biosciences: Consultancy; Cell Medica: Consultancy; Novartis: Consultancy; Incyte: Consultancy; Celgene: Consultancy, Research Funding; Allogene: Consultancy; Acerta: Research Funding; Unum Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; BMS: Research Funding; Merck: Consultancy, Research Funding; Karus: Research Funding. Ghobadi:Wugen: Consultancy; Celgene: Consultancy; EUSA: Consultancy; Kite Pharma a Gilead Company: Consultancy, Research Funding, Speakers Bureau. Locke:Novartis: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy; Kite: Other: Scientific Advisor.

Introduction: The autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, axicabtagene ciloleucel (Axi-cel) improved long-term survival of patients with relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL). Long-term analysis of the pivotal ZUMA-1 trial indicates a 2-year PFS of ~40% (Locke, Lancet Oncology 2018). Early identification of patients with increased relapse risk may allow for early intervention and improved outcomes. In a pilot study of 6 ZUMA-1 patients, minimal residual disease (MRD) evaluation via a next-generation sequencing MRD assay (Adaptive Biotechnologies, Seattle, WA) to assess for circulating tumor (ct)DNA, mirrored clinical outcome as assessed by PET-CT (Hossain et. al. Leukemia & Lymphoma 2019). Based on these promising results, a multi-institutional prospective study utilizing cell-free MRD assessments to predict outcomes in r/r DLBCL patients after Axi-cel therapy was initiated. Methods: To identify tumor clonotype(s), tumor DNA extracted from archival paraffin-embedded tissue underwent PCR amplification of IgH-VDJ, IgH-DJ and IgKappa/Lambda regions using universal consensus primers. CtDNA levels were measured pre-LD, 0, 7, 14, 21, 28, 56, 90, 180, 270, and 365 days following Axi-cel infusion. PET-CT scans were obtained at baseline, Day 28, Month 3, 6, and 12 with response assessed per Lugano criteria. Deauville 1-3 was considered PET-negative. The protocol prespecified that patients with less than Day 28 follow-up be excluded from analysis. Any detectable ctDNA was considered MRD positive. Results: Here we report on the pre-planned analysis of the first 50 study patients with at least a Day 28 MRD assessment and 3 months of follow up. An additional 4 patients with at least 3 months of follow-up but who did not have a Day 28 MRD assessment were also included. Baseline characteristics and clinical outcomes of patients were similar to ZUMA-1 and a real-world analysis of 295 patient who received Axi-cel (Nastoupil et al ASH 2018). The median age was 61 years old (range 19-76) (53.7% male, 46.3% female) and 59% of patients received 3 or more prior lines of therapy (range 1-6). After a median follow-up of 7.5 months, the best overall response rate was 87% (47 of 54) and complete response rate was 57% (31 of 54). The median OS was not reached and median PFS was 4.6 months (panel A). At Day 28, 56% (28 of 50) of patients were MRD negative (MRD-neg) and 44% (22 of 50) were MRD positive (MRD-pos). As compared to MRD-pos, MRD-neg correlated with improved median PFS (not reached vs. 2.96 months, p Conclusion: MRD monitoring using high-throughput sequencing of ctDNA has the potentially to make an impact on the clinical management of patients undergoing Axi-cel therapy. Furthermore, ctDNA is an informative tool to compare CAR19 therapies that vary by costimulatory domains or production methods. This technology potentially overcomes fundamental limitations of DLBCL imaging (cost, radiation exposure & limited repetition) and may minimize the need for surveillance PET-CT scans. These results provide a rationale for designing MRD-based risk-adaptive CAR T cell clinical trials. Figure Disclosures Kirsch: Adaptive Biotechnologies: Employment. Jacob:Adaptive Biotechnologies: Employment, Other: shareholder. Mullins:Adaptive Biotechnologies: Employment. Lee:Adaptive Biotechnologies: Employment, Equity Ownership. Mackall:Obsidian: Research Funding; Lyell: Consultancy, Equity Ownership, Other: Founder, Research Funding; Nektar: Other: Scientific Advisory Board; PACT: Other: Scientific Advisory Board; Bryologyx: Other: Scientific Advisory Board; Vor: Other: Scientific Advisory Board; Roche: Other: Scientific Advisory Board; Adaptimmune LLC: Other: Scientific Advisory Board; Glaxo-Smith-Kline: Other: Scientific Advisory Board; Allogene: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Locke:Cellular BioMedicine Group Inc.: Consultancy; Kite: Other: Scientific Advisor; Novartis: Other: Scientific Advisor. Miklos:Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; Becton Dickinson: Research Funding.

History of prior cancer is a widespread exclusion criterion in cancer trials. Up to 80% of NCI-sponsored and 80% of industry-sponsored lung cancer trials exclude patients with a prior cancer. We suspect this exclusion is commonly applied in other cancer trials, although no definitive data exist. Prior cancer is especially common among older patients and those with certain cancer types. Among patients >65 years, 15.1% overall have prior cancer. In Multiple Myeloma, the most common plasma cell disorder (PCD), prevalence of prior cancer is as high as 17.4%. Examining the prior cancer exclusion criterion is important because the number of US cancer survivors is large and rapidly growing. Arbitrarily excluding cancer survivors from trials is not evidence-based and exclusion presumably arises from assumptions that higher mortality of patients with prior cancer could hinder study conduct and bias trial outcomes. However, few data exist to support this assumption of higher mortality. In fact, we demonstrated that lung cancer patients with a prior cancer have similar or lower mortality risk, compared to those without prior cancer. In this abstract, we reviewed prior cancer related eligibility criteria in three of the most common PCD (Multiple Myeloma, Amyloidosis and Waldenström Macroglobulinemia) clinical trials sponsored or endorsed by 5 major Co-Operative groups in North America (Table 1). We use descriptive statistics (n, %) and Fisher's exact tests to describe characteristics of trials with and without exclusion criteria. Of 33 trials, 26 (79%) excluded patients with prior cancer as follows - active cancer (12%), within 2-3 years of PCD diagnosis (9%), or within 5 years of PCD diagnosis (55%). Many trials had exceptions to prior cancer exclusion. Specifically, 67% of trials allowed non-melanoma skin cancer, 58% allowed in-situ cervical cancer, 12% allowed early stage prostate cancer. Table 2 shows the association between clinical trial characteristics and prior cancer exclusion. There was no association between prior cancer exclusion and phase of study, transplant studies, or survival end point. Exclusion criteria varied across year of activation (p=0.01); for example, 75% of studies activated 1990-1999 excluded prior cancer, compared to 100% of studies activated after 2010. Type of PCD was marginally associated with exclusion criteria (p=0.08); 74% of Multiple Myeloma trials excluded patients with prior cancer compared to 100% of the Amyloidosis and Waldenström Macroglobulinemia trials. Conclusion: A substantial proportion of potential participants may be excluded from PCD clinical trials because of a history of prior cancer. This practice impacts accrual, generalizability, and fair access to cutting-edge treatments and the highest level of clinical care. As treatment outcomes for other cancers continue to improve, it is likely that the prevalence of multiple primary cancers will increase. This exclusion criterion is applied widely across studies, including more than two-thirds of those with non-survival endpoints. Our study is the first to examine the prevalence and potential impact of prior cancer exclusion in PCD clinical trials. Using population-based cancer registry data, we plan to undertake further research to understand the appropriateness and ramifications of this standard exclusion policy in PCD cancer trials. Disclosures Collins: Agios: Research Funding; Bristol Myers Squibb: Research Funding; Celgene Corporation: Research Funding; Arog Pharmaceuticals: Research Funding. Devine:Kiadis Pharma: Consultancy. Usmani:Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding; Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy. Anderson:Amgen: Speakers Bureau; Takeda: Speakers Bureau; Celgene: Speakers Bureau. Kumar:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Introduction: Approximately 1.5% of population will be diagnosed with leukemia in their lifetime (SEER Cancer Statistics Review). Diagnosis of acute leukemia has an overwhelming effect on the patient and their families. Besides the diagnosis, effect of chemotherapeutic agents and agony over the ultimate outcome can also affect emotional-behavioral wellbeing. Evolution of depression as a disorder, along the course of acute leukemia has been reported in the past (David et al Procedia Soc & Behav Sci 2014). We investigated the prevalence of mental health disorders in hospitalized patients admitted with acute leukemia diagnosis utilizing Healthcare Utilization Project National Inpatient Sample (HCUP NIS), 2002-2014. HCUP-NIS is the largest publicly available all-payer inpatient health care database in the United States, and is a 20% stratified sample of all hospital discharges. Methods: We identified hospitalizations for acute leukemia using ICD-9 codes (203.XX, 204.XX, 205.XX, 206.XX, 207.XX and 208.XX) in the NIS database. We included patients with a primary diagnosis of acute leukemia (myeloid, lymphoid and plasma cell leukemia) including admissions for inpatient chemotherapy and/or complications requiring hospitalization. Similarly, ICD-9 codes were used to identify patients with mental health disorders of interest (ADHD, adjustment disorder, alcohol abuse, anxiety disorder, mood disorders, personality disorders, schizophrenia, substance abuse, childhood disorders). "Surveyfreq" was used to calculate proportions while "Surveymeans" was used to calculate median length of stay and hospital charges. Cochran-Armitage test was used to analyze trends; Kruskal-Wallis test was used for non-parametric data. We used chi-square for categorical data frequency, P value of < 0.05 was considered statistically significant. All analysis was performed using SAS 9.4. Results: We identified a total of 59,223 patients with mental health disorders (18.4%) out of a total of 321223 hospitalizations for acute leukemia (table 1). Median age for patients with mental health disorders is 56 years. Mood disorder was most prevalent at 8% followed by anxiety disorder at 6%. Within all mental disorders, mood disorders comprised 44% of all cases followed by anxiety disorder at 32% (figure 1). Over 60% of mental health disorders were in patient age group above 50 years (figure 2). Prevalence of mental health disorders has increased from 10% to 28% between 2002 and 2014 (figure 3). Prevalence of anxiety disorder has increased 6 fold between 2002 (2%) and 2014 (12%). It is unclear if this change is due to an actual increase in the prevalence of this condition or better recognition of mental health disorders leading to better coding. Median length of stay (LOS) is significantly longer in patients with mental health disorders compared to those without (18 days vs 9 days respectively). Median charges for hospitalization are also significantly increased in patients with mental health disorders than those without ($119,245 vs $62,132 respectively). Conclusion: Mental health disorders are common in patients with acute leukemia. One in four patients (28%) in 2014 had a mental health disorder compared to 9% in 2002. Given the retrospective nature of our study, it is difficult to determine if this is an actual increase in the incidence and prevalence of mental health disorders or if better recognition and medical coding contributes to this finding. Our study shows a disproportionate burden of mental health disorders in patients above the age 50, which constitutes the majority of the patients diagnosed with acute leukemia. Use of mental health screening tools in this population could provide an avenue for recognition and possible early intervention. Given the retrospective nature of our study, these findings need to be validated in a prospective patient population. Disclosures No relevant conflicts of interest to declare.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy is an FDA-approved therapy for relapsed or refractory diffuse large B-cell lymphoma (DLBCL) and acute lymphoblastic leukemia (ALL). A common side effect of CAR-T therapy is cytokine release syndrome (CRS), and its severity ranges from mild to severe, and occasionally resulting in death. Patients at particularly high risk for severe CRS may benefit from earlier supportive care and rescue therapies, such as tocilizumab. Although the median onset of CRS has been reported as two days, no existing prognostic tools adequately assist the bedside clinician with triaging which patients will decompensate and warrant escalation of care. For example, biomarkers such as CRP and ferritin are ineffective in predicting CRS severity. Evaluation of the sublingual microcirculation of patients receiving CAR-T therapy may serve as a valuable surveillance tool. The sublingual microcirculation (defined as blood vessels Methods: Video images are collected in real time. Prior to interpretation, all video clips were assessed for quality based on the current microcirculation consensus document. Each acceptable clip was then analyzed by using two point-of-care (POC) scoring systems: 1) the microvascular flow index (MFI) and 2) the point-of-care microcirculation (POEM) score. The MFI is determined by dividing the video monitor into four equal quadrants and grading the overall flow of each quadrant with a score from 0-3 (0 = no flow; 1 = intermittent flow; 2 = sluggish flow; 3 = normal flow). The POEM score utilizes an ordinal 1-5 scale (1 = critically impaired; 2 = impaired; 3 = normal with marked heterogeneity; 4 = normal with mild heterogeneity; 5 = normal) that is a composite of four measurements assessing flow impairment and heterogeneity. For each enrolled patient, a baseline measurement was made immediately prior to CAR-T cell infusion with follow up measurements occurring every six hours beginning at hour 18 after cell infusion until hour 72. After hour 72, measurements were made daily until they were deemed no longer at risk for CRS. Results: At this time there is mature data on 7 patients. All patients received Axicabtagene Ciloleucel- a CD19 directed CAR-T cell therapy (Yescarta, Kite Pharma). All patients had normal baseline microcirculation (MFI > 2.6, POEM=5) and normal or near-normal microcirculation at the end of the study period. No patients developed severe CRS (grade 3 and above). Three patients developed grade 2 CRS that required tocilizumab. Patients #1 and #2 both had significant microcirculatory impairments ≥12 hours prior to developing symptoms severe enough to warrant tocilizumab. Patient #3 had normal microcirculation through the first four days of therapy and developed hypotension on day six. We captured a subtle change from a normal MFI and POEM score to mild impairment with both scoring algorithms on day five, one day prior to clinical manifestations of decompensation. For logistical reasons, subsequent data were unable to be obtained. MFI and POEM scores for all patients are listed below in Table 1. The remaining four patients developed grade 1 CRS with associated mild microcirculatory changes. Conclusions: In this pilot study, POC microcirculatory assessments were successfully used to monitor patients undergoing CAR-T therapy. Patients with more severe CRS manifested lower MFI and POEM scores and maintained their nadir longer than those with milder CRS. Our data suggest that CAR-T patients developing CRS manifest early signs of sublingual microcirculatory dysfunction. Moreover, these microcirculatory defects present prior to the development of standard clinical abnormalities, such as macrocirculatory derangements. While further investigation is ongoing, this tool could be used for earlier identification of patients at risk for CRS in order to deliver earlier appropriate therapies, and ultimately to improve patient outcomes. Disclosures No relevant conflicts of interest to declare.

Introduction Axi-cel is an autologous anti-CD19 CAR T-cell therapy approved by the US FDA 10/18/2017, for the treatment of adults with relapsed or refractory (r/r) large B-cell lymphoma (DLBCL), primary mediastinal large B-cell lymphoma (PMBCL), transformed lymphoma (tFL), and high-grade B-cell lymphoma (HGBCL) who have failed at least two prior systemic lines of therapy. In the pivotal ZUMA-1 trial, 108 patients (pts) with r/r DLBCL were treated with axi-cel: the best overall response rate (ORR) was 82% and complete response (CR) rate was 58%. At a median follow-up of 15.4 months, 42% of the pts had ongoing remission (Neelapu and Locke et al. NEJM 2017). Grade 3 or higher cytokine release syndrome (CRS) by Lee criteria and neurologic events (NEs) occurred in 13% and 31% of the pts, respectively. Here, we evaluated the real world outcomes of pts treated with standard of care axi-cel under the commercial FDA label. Methods and Results Seventeen US academic centers contributed data to this effort independently of the manufacturer. As of 6/30/2018, 211 pts were leukapheresed with intention to manufacture commercial axi-cel. Of these, 165 (78%) pts completed axi-cel infusion as of 6/30/18 and a further 23 (11%) pts are scheduled for axi-cel infusion in July 2018. Of the 23 remaining pts, 7 (3%) received axi-cel therapy on ZUMA-9 expanded access trial (NCT03153462) due to non-conforming cell therapy product, 15 (7%) pts died before axi-cel infusion (14 from lymphoma progression and 1 from sepsis) and 1 (1%) patient attained CR from bridging therapy and was not infused. Safety was evaluable in 163 pts receiving axi-cel. Grade ³3 CRS and NEs occurred in 7% and 31% of pts. Tocilizumab was administered in 62% of pts and 57% received corticosteroids. Outside of lymphoma progression, 3 deaths occurred post-axi-cel; 1 due to HLH, 1 due to systemic candidiasis, and a third due to septic shock. There were no grade 5 NEs observed. Response assessment was done for pts infused with axi-cel and who were re-staged at day 30 and/or day 100, or were deemed to have clinical progression. Of 112 pts evaluable at day 30, ORR was 79% with 50% CR, 29% PR, 6% SD and 14% with PD. Of 39 pts evaluable at day 100, 59% of pts had ongoing response (CR 49%, PR 10%). At the time of abstract submission, more detailed patient characteristics and treatment course data were available in 134/165 pts infused. Median age was 59 (range 21-82) with 57% male. Performance status (PS) was ECOG 0-1 (81%), ECOG 2 (16%) and ECOG 3 (3%). By histology, 61% of pts had DLBCL including HGBCL, 31% had tFL and 8% PMBCL. Thirty-one percent had a prior autologous stem cell transplant. Bridging therapy between apheresis and infusion was given in 56% of patients, the majority of which consisted of chemotherapy. Sixty-six of 134 (49%) would not have met eligibility criteria for ZUMA-1 at the time of leukapheresis. Common criteria that would have made these patients ineligible for ZUMA-1 included ECOG PS >1 (n = 22), platelets Conclusions This multicenter retrospective study delineates the real world outcomes of axi-cel CAR T-cell therapy for r/r aggressive B-cell lymphoma when used as a standard of care. Though limited by relatively short follow up, 30 day responses in the real world setting are comparable to the best responses observed on the pivotal ZUMA-1 clinical trial (Table 1). Importantly, safety appears comparable to the ZUMA-1 trial despite nearly half the pts failing to meet ZUMA-1 eligibility criteria. Updated results including PFS and OS will be presented at the meeting. L.J.N. and M.D.J. contributed equally; D.B.M., S.S.N. and F.L.L. contributed equally. Disclosures Nastoupil: Merck: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; TG Therappeutics: Research Funding; Karus: Research Funding; Genentech: Honoraria, Research Funding; Janssen: Research Funding; Gilead: Honoraria; Juno: Honoraria; Novartis: Honoraria; Spectrum: Honoraria. Lunning:Celgene: Consultancy; Spectrum: Consultancy; Portola: Consultancy; Genzyme: Consultancy; Janssen: Consultancy; Seattle Genetics: Consultancy; Kite: Consultancy; Juno: Consultancy; AbbVie: Consultancy; Astra-Zeneca: Consultancy; Genentech: Consultancy; Gilead: Consultancy; Genentech: Consultancy; Bayer: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy. Reagan:Seattle Genetics: Research Funding. McGuirk:Gamida Cell: Research Funding; Astellas Pharma: Research Funding; Fresenius Biotech: Research Funding; Bellicum Pharmaceuticals: Research Funding; Novartis Pharmaceuticals Corporation: Honoraria, Other: speaker, Research Funding; Kite Pharma: Honoraria, Other: travel accommodations, expenses, speaker ; Pluristem Ltd: Research Funding. Deol:Novartis: Consultancy; Kite Pharmaceuticals: Consultancy. Hill:Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Andreadis:Gilead: Consultancy; Genentech: Consultancy, Employment; Astellas: Consultancy; Bayer: Consultancy; Celgene: Consultancy; Seattle Genetics: Consultancy; Pharmacyclics: Consultancy; Juno: Research Funding; Kite: Consultancy; Novartis: Consultancy, Research Funding. Munoz:Pfizer: Consultancy; Bayer: Consultancy, Speakers Bureau; Juno: Consultancy, Honoraria; Janssen: Consultancy; Genentech: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy; Pharmacyclics: Consultancy, Honoraria; Kite: Consultancy, Honoraria, Speakers Bureau; Alexion: Consultancy; Gilead: Speakers Bureau. Westin:Novartis Pharmaceuticals Corporation: Membership on an entity's Board of Directors or advisory committees; Celgen: Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Apotex: Membership on an entity's Board of Directors or advisory committees. Vose:Kite Pharma: Research Funding; Acerta Pharma: Research Funding; Celgene: Research Funding; Novartis: Honoraria, Research Funding; Roche: Honoraria; Seattle Genetics, Inc.: Research Funding; Legend Pharmaceuticals: Honoraria; Merck Sharp & Dohme Corp.: Research Funding; Abbvie: Honoraria; Epizyme: Honoraria; Bristol Myers Squibb: Research Funding; Incyte Corp.: Research Funding. Miklos:Genentech: Research Funding; Kite - Gilead: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pharmacyclics - Abbot: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding. Locke:Kite Pharma: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy; Novartis Pharmaceuticals: Other: Scientific Advisor.

Background: Sickle cell disease (SCD) is a common hemoglobinopathy, characterized by vaso-occlusive crises and affects over 100,000 people in United States. It afflicts long-lasting organ damage with a spectrum of clinical severity. Median survival for SCD is shortened to the 6th decade of life despite advances in medical care (Elmariah et al Am J Hematol 2014). Allogeneic stem cell transplant (SCT) is a potentially curative option and is increasingly considered in patients with severe symptomatic SCD. The use of SCT is limited by donor availability and treatment related complications. Several advancements in conditioning regimen and use of alternate donor source have favorably impacted the feasibility of this approach. We identified SCT performed for sickle cell disease in the Healthcare Cost and Utilization Project National Inpatient Sample (HCUP-NIS) from 2002-2014 in an attempt to identify hospitalization outcomes, factors affecting length of stay and healthcare utilization. Methods: HCUP-NIS is a 20% stratified sample of all discharges from hospitals across 46 states in the United States and incorporates weighting algorithms to predict nationwide estimates. We used International Classification of Diseases, Ninth Revision (ICD-9) procedure codes to identify HCT hospitalizations {Bone marrow (BM):41.02, 41.03, Peripheral blood (PB): 41.05, 41.08 and Cord blood (CB): 41.06} for sickle cell disease (282.5,282.6X -282.6X). We excluded patients who underwent SCT for indications other than SCD. Surveyfreq was used to calculate proportions and surveymeans was used to calculate median length of stay and hospital charges. Kruskal-Wallis test was used for non-parametric data. Chi-square for categorical data frequency, P value of < 0.05 was statistically significant. All analysis was performed using SAS 9.4. Results: Outcomes were analyzed from a total of 742 hospitalizations for SCT from 2002-2014 (table 1). Median age for stem cell transplant was 9 years. GVHD occurred in 14% of stem cell transplants. Overall, in-hospital mortality was low at 2.6% while mortality in patients who developed GVHD was 14%. Bacterial infections (including C.difficile) occurred more commonly than viral or fungal infections (table 2). Patients who developed graft vs host disease (GVHD) were also more likely to have bacterial, viral and fungal infections than those without. Pain crisis was noted in 9% of total admissions while stroke occurred in 6%. Median length of stay (LOS) was 35 days and median charges were $359,646. If GVHD developed, median LOS increased to 54 days while median charges increased to $712,324. Similarly, bacterial sepsis was associated with a longer median LOS of 63 days while median charges increased to $626,986 (table 3). Conclusions: The rate of inpatient mortality with SCT in sickle cell disease is lower than the overall inpatient mortality rate for allogeneic SCT (7%; Godara et al bbmt 2018), indicating a favorable outcome for these patients. Infections do occur commonly during the course of hospitalization, especially in association with GVHD. Length of stay is adversely impacted by occurrence of GVHD, bacterial sepsis, C.difficile infection and viral infections. While we are limited by duration of follow up in our study, these patterns suggest some essential modifiers for inpatient morbidity and mortality, therefore require validation in a large prospective study. Disclosures No relevant conflicts of interest to declare.

Background and objective: Blood loss associated with total lower-extremity joint arthroplasty (TJA) often results in postoperative anemia and need for red blood cell transfusions (RBCT). We report the results of a quality improvement initiative to improve blood management and decrease transfusions in patients undergoing TJA in one tertiary hospital. Methods: Pre and post analysis after the implementation of a multifaceted intervention which included preoperative assessment for anemia, use of tranexamic acid, discouragement of autologous pre-operative blood collection and institution of more restrictive RBCT protocols. The results were stratified into three periods: I - pre-interventional (01/01/2013 -09/30/2013); II - peri-interventional (10/01/2013 -04/30/2014); and III - post-interventional (05/01/2014 -12/31/2014). We used fractional logistic regression with robust standard errors and regression modeling was configured using a segmented, or "piecewise", approach in which slope coefficients in each period were estimated. Results: During the study period 2511 patients underwent surgery. Compared with the pre-intervention period, the total number of RBC units transfused decreased from a total of 587 in the pre- to 107 in the post-intervention period (81.8% decrease). The percentage of patients receiving transfusion declined from 36.7% in pre-implementation period to 8.8% to post-intervention period. Depending upon the costing methodology used, annualized savings in RBC expenditure between time period 1 and 3 ranged from a low of $108,000 using the acquisition cost per unit (~$225/unit) to $480,000 when using activity based costing (~$1000/unit). Mean length of stay (days) and 30-day readmission rates remained stable during the study period. Conclusions: A multidisciplinary approach with proactive involvement of all the interested parties can be successful and sustainable in reducing RBCT and its associated costs, in patients undergoing TJA. Disclosures No relevant conflicts of interest to declare.

Background: The use of social media is expanding in medicine. More and more healthcare professionals, patients and advocates are using social media as a common platform to enhance communication. Methods: Each year American Society of Hematology (ASH) creates a hashtag (#) followed by year of the annual meeting (e.g. ASH 2014 had this hashtag: #ASH14) on Twitter. We conducted a retrospective study of annual meeting's hashtag use on Twitter for past 4 annual meetings using data from Symplur, LLC. Symplur is an online forum offering analytics of the global Twitter based conversations. Following hashtags were used for analysis, #ASH11, #ASH12, #ASH13 and #ASH14. Results: Overall there is an increasing trend for use of annual meeting's hashtag (see table 1). Last year's meeting generated over 72 million impressions. Number of tweets being sent out is doubling every year. More twitter users are engaging in conversations than the year before using annual meeting's hashtag. Last year almost 4000 individual twitter accounts were used during the annual meeting. Number of tweets per participant has stayed relatively constant over past four years. @ash_hematology remains the most commonly mentioned twitter handle every year since 2011. In 2014 itself, @ash_hematology was mentioned over 2000 times. Conclusion: Twitter is a very powerful tool that amplifies the content of scientific meetings. Use of twitter using meeting's hashtag is increasing every year at annual ASH meetings. This analysis provides a snapshot of twitter activity at the conference. Avenues for further research are: trend identification, "influencer" identification, and qualitative analysis. Interdisciplinary research should focus on evaluation methods that can assess the quality, value, and impact of tweeting. Table 1. Year Impressions Tweets Participants Average tweet per participant 2011 12,255,646 3123 606 5 2012 18,153,786 5,094 870 6 2013 30,018,580 12,233 1942 6 2014 72,433,270 24,185 3977 6 Disclosures No relevant conflicts of interest to declare.

Abstract 5083 In this retrospective study, we sought to describe the demographics, diagnoses, management, and outcomes of elderly patients with primary CNS lymphoma (PCNSL) at a single institution. Patients and Methods After obtaining IRB approval, the Cleveland Clinic Brain Tumor and Neuro-Oncology Center's database was used to identify patients with newly diagnosed PCNSL who were older than 60 years between 1986 and 2010. We excluded patients who were HIV positive or had systemic lymphoma. During individual chart review, we confirmed the diagnosis and collected information of patients' demographics, disease presentation, diagnostic procedures, initial and salvage therapy, and clinical outcome. Results A total of 84 patients were older than 60 years of age when they were diagnosed with PCNSL at our institution from 1986 to 2010. The median age was 67. 9 years (range: 60. 3–89. 2 years). The median Karnofsky performance status (KPS) of these patients at the diagnosis was 70 (range: 20–90), which stayed the same at the subsequent disease relapses. The median duration of symptoms was 1. 5 months (range: 0. 1–13 months). The initial treatment regimens included whole brain radiation therapy (WBRT), chemotherapy with or without consolidation WBRT. Five patients (6%) received WBRT alone. 43 patients (51%) received chemotherapy alone. Six patients (7%) received chemotherapy followed by consolidation WBRT. Among the patients who received chemotherapy with or without WBRT, 40 of them (48%) received methotrexate-based therapy; 9 patients (11%) received non-methotrexate-based therapy. Among the patients who received initial treatment, 20 of them (37%) achieved complete response (CR), while 19 patients (35%) had disease progression during the treatment. The median progression free survival (PFS) was 8. 0 months (95% CI 2. 7–22 months). The median overall survival (OS) was 15. 5 months (95% CI 6. 6–38. 5 months). We also compared the benefit of individual initial treatment regimens although the reason of their allocation was not determined. It turned out that patients with chemotherapy followed by consolidation WBRT had significantly higher response rate and longer survival than patients with WBRT alone (Figure 1). Unfortunately, no patient who received WBRT alone achieved CR. In addition, the methotrexate-based chemotherapy offered significantly longer PFS than non-methotrexate-based chemotherapy (P = 0. 0008). In univariate analysis, we evaluated potential prognostic factors such as gender, age, KPS, symptom duration, prior malignancy, year of diagnosis, symptoms, and multiple site involvement for response rate, PFS, and OS. Recursive partitioning analysis identified 70 years as the cutoff point for age and 70 as the cutoff point for KPS. We found that no factors can predict response to therapy. However, younger age, higher KPS, more recent diagnosis, and the presence of ocular symptoms were favorable factors for longer OS. Age is the only favorable prognostic factor for PFS, although higher KPS has a trend (P = 0. 08) toward longer PFS. When these factors were subjected to multivariable analysis, age older than 70 years and KPS less than 70 were the only poor prognostic factors for both OS and PFS. With this information in hand, we divided the patients into three prognostic groups based on the number of poor prognostic factors (Table 1). The median OS and PFS for the group with no poor prognostic factors were 65 months and 24 months, respectively. The median OS and PFS for the group with all poor prognostic factors were 1. 0 month and 0. 6 month, respectively. Conclusions Chemotherapy followed by consolidation WBRT had significantly higher response rate and longer survival than patients with WBRT alone. Age and performance status were the only independent predictor of either PFS or OS. Disclosures: No relevant conflicts of interest to declare.