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Multiple myeloma is the most common hematological malignancy in Gaucher disease type 1 (GD1). There is a lack of outcome data and consensus regarding screening of gammopathies. This study explores utility of screening in Porto Alegre, Brazil, and Cincinnati, Ohio. A retrospective analysis of clinical information and laboratory data from GD1 patients was performed. Over 19 years, 68 individuals with GD1 (31 males, 37 females) underwent screening, and 20 (29.4%) had abnormalities. Twelve (17.6%) had polyclonal gammopathy (mean age 24.2 years, p = .02), seven (10%) had monoclonal gammopathy of uncertain significance (MGUS; mean age 52.7 years, p = .009). One had multiple myeloma (age 61 years). Risk factors for MGUS included male gender (p = .05), p.N409S allele (p = .032). MGUS developed in six of 62 treated and two of four untreated individuals. Of those with MGUS receiving treatment, four were on enzyme replacement therapy (ERT) and one on substrate reduction therapy (SRT). Gammopathy normalized in 13 treated individuals (10 polyclonal, three MGUS) and remained abnormal in two treated individuals (two polyclonal, two MGUS). Gammopathy relapse was seen in one individual with MGUS and three with polyclonal gammopathy. This study describes screening for gammopathies and identifies risk factors in individuals with GD1.

Background: Patients with relapsed or refractory (R/R) DLBCL generally have a poor prognosis, particularly if they are not candidates for autologous stem cell transplantation (ASCT) or experience relapse following approved CAR-T therapies. The UNITY-NHL study systematically explored the efficacy and tolerability of the PI3K-d/CK1-e inhibitor, umbralisib, alone (umbra), and in combination with the glycoengineered anti-CD20 monoclonal antibody ublituximab (U2), followed by a cohort treated with U2 plus bendamustine (U2+benda). Herein we report on the experience in a large cohort of patients with R/R DLBCL. Methods: This study explored a sequential combination design as described above. Eligible patients had histologically confirmed R/R DLBCL and were ineligible for ASCT, with no limit on number or type of prior treatment. Umbra was given orally at 800 mg once daily in 28-day cycles (C) until disease progression or unacceptable tolerability. Ublituximab was administered intravenously (IV) on Days 1, 8, and 15 of C1, on Day 1 of C2-6, and on Day 1 every 3C through C24. Benda was administered IV (90 mg/m 2) on Days 1/2 of C1-6. Cell of origin, NGS, and c-myc (FISH) were analyzed centrally. The primary endpoint of the study was overall response rate (ORR) as assessed by an independent review committee. Secondary endpoints included duration of response, progression-free survival, time to response, and safety. Results: 226 patients with DLBCL were enrolled as follows: umbra monotherapy (n=30), U2 (n=66), and U2+benda (n=130). The population demographics included the following features: median age was 72 years (range 32-95); 59% were male; 64% of patients had stage III or IV disease; 58% were refractory to their immediate prior therapy; and the median number of prior therapies was 2 (range 1-8). There were no substantive differences in these characteristics across cohorts. Median follow-up for the umbra, U2, and U2+benda arms was 51 months (range 47-61), 46 months (range 41-57), and 40 months (range 35-47), respectively. Overall and complete response rates for the umbra mono, U2, and U2+benda arms were 13.3% (CR 3.3%), 31.8% (CR 10.6%), and 43.1% (CR 16.9%), respectively. Results pertaining to secondary endpoints are listed in Table 1. Correlation of response to cell of origin and mutation/c-myc status is ongoing and will be available at the time of presentation. Adverse events (AEs) were similar across the cohorts, with the exception of hematologic AEs which were increased in patients receiving benda. The most common all-grade AEs by treatment arm (umbra, U2, and U2+benda, respectively) were diarrhea (47%; 41%; and 48%), nausea (40%; 45%; and 45%), fatigue (33%; 30%; and 41%) and neutropenia (3.3%; 18%; and 32%). All-grade AEs of special interest included non-infectious colitis (3.3%, 1.5%, and 2.3%) and pneumonitis (3%, 1.5%, and 1.5%) in umbra, U2 and U2+benda treated patients respectively. Grade 3/4 AEs were uncommon, with the only events >10% being limited to neutropenia (11% for U2; 27% for U2+benda), and anemia (17% for U2+benda). Conclusions: In the DLBCL cohort of UNITY-NHL, the U2+benda triplet regimen was active and well tolerated in patients with R/R DLBCL who were unsuitable for transplant or who had relapsed following ASCT. Umbra monotherapy and U2 were also well tolerated but resulted in lower ORR than in the U2+benda cohort. Figure 1 Figure 1. Disclosures Burke: X4 Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; SeaGen: Consultancy, Speakers Bureau; Beigene: Consultancy, Speakers Bureau; Roche/Genentech: Consultancy; Epizyme: Consultancy; Adaptive Biotechnologies: Consultancy; Kura: Consultancy; MorphoSys: Consultancy; AstraZeneca: Consultancy; Kymera: Consultancy; AbbVie: Consultancy; Verastem: Consultancy. Fonseca: Amgen: Honoraria, Speakers Bureau; Celgene/BMS: Honoraria, Speakers Bureau; Dava Oncology: Honoraria; Epizyme: Honoraria; Karyopharm: Honoraria; Sanofi: Honoraria; Abbvie: Honoraria. Jurczak: Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Research Funding; Morphosys: Research Funding; Mei Pharma: Research Funding; Merck: Research Funding; Loxo Oncology: 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; Incyte: Research Funding; Epizyme: Research Funding; Debbiopharm: Research Funding; Celgene: Research Funding; Celtrion: Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Sandoz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; TG Therapeutics: Research Funding. Melear: TG Therapeutics: Speakers Bureau; Astrazeneca: Speakers Bureau; Janssen: Speakers Bureau. Islas-Ohlmayer: Seagen Inc.: Research Funding. Reeves: Apollomics, Inc.: Research Funding; Tarveda Therapeutics: Research Funding; Ascentage Pharmaceuticals: Research Funding; Clovis Oncology: Research Funding; Arvinas: Research Funding; Pfizer: Research Funding; Ellipses: Research Funding; ImmunoGen: Research Funding; Karyopharm Therapeutics: Honoraria, Research Funding; Moderna: Research Funding; Thrive: Research Funding; Genentech: Research Funding; Incyte Corporation: Research Funding; Astellas Pharma: Research Funding; IDEAYA Biosciences: Research Funding; Pharmacyclics: Research Funding; Loxo Oncology: Research Funding; AbbVie Inc.: Research Funding; Celgene: Research Funding; GSK: Research Funding; Jiangsu Hengrui Medicine Co.: Research Funding; Arcus Biosciences: Research Funding; Calithera: Research Funding; Amgen: Research Funding; Mirati Therapeutics, Inc.: Research Funding; Array BioPharma Inc.: Research Funding; Taiho Pharmaceutical: Research Funding; Boehringer Ingelheim: Research Funding; GI Therapeutics Inc.: Research Funding; Hutchison: Research Funding; MacroGenics: Research Funding; Ipsen: Research Funding; MedImmune, LLC.: Research Funding; BeiGene: Research Funding; TG Therapeutics: Research Funding; Acerta Pharma: Research Funding; Verastem: Research Funding; Janssen Pharmaceuticals: Research Funding, Speakers Bureau; Eisai Co.: Research Funding, Speakers Bureau; Roche Pharma: Research Funding; Novartis Pharmaceuticals: Research Funding; Daiichi Sankyo: Research Funding; Arvinas: Research Funding; CytomX: Research Funding; Sermonix Pharmaceutical: Research Funding; Seattle Genetics: Research Funding; AstraZeneca: Research Funding; Evelo Biosciences: Research Funding. Wróbel: Takeda: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; BMS: Honoraria; Roche: Honoraria, Research Funding, Speakers Bureau; BeiGene: Honoraria; Janssen: Honoraria, Speakers Bureau. Pagel: Incyte/MorphoSys: Consultancy; MEI Pharma: Consultancy; Pharmacyclics/AbbVie: Consultancy; AstraZeneca: Consultancy; Gilead: Consultancy; Actinium Pharmaceuticals: Consultancy; Kite, a Gilead Company: Consultancy; Epizyme: Consultancy; BeiGene: Consultancy. Goldschmidt: Ontada: Current Employment; Blue Ridge Cancer Care: Current Employment; Amgen: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; TG Therapeutics: Honoraria; G1 Therapeutics: Honoraria, Speakers Bureau. Miskin: TG Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Sportelli: TG Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. O'Connor: TG Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company; Nomocan: Consultancy; Dren: Consultancy, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Myeloid Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Kymera: Consultancy, Current equity holder in publicly-traded company; Mundipharma: Consultancy. Ghosh: Seattle Genetics: Consultancy, Honoraria, Speakers Bureau; Genmab: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy, Honoraria; Genentech: Research Funding; Karyopharma: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Adaptive Biotech: Consultancy, Honoraria; Epizyme: Honoraria, Speakers Bureau; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Honoraria, Speakers Bureau.

Background: Venetoclax (VEN), an oral B-cell lymphoma 2 inhibitor, is approved for use in adult patients (pts) with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). As a targeted and highly active antitumor agent, VEN induces rapid and profound tumor reduction. Inpatient monitoring for initial doses of VEN is recommended by US Prescribing Information for pts with medium tumor burden and reduced renal function or high tumor burden. Administration of debulking agents, such as obinutuzumab (G), help reduce tumor burden and, consequently, facilitate subsequent administration of VEN in the outpatient setting. However, tumor reduction data are needed to definitively establish the utility of a debulking strategy. This study performed disease restaging after every 2 cycles of debulking to evaluate the safety and efficacy of G ± bendamustine (B) as a debulking regimen before VEN treatment in the outpatient community setting. The safety and efficacy of subsequent VEN+G treatment after debulking was also evaluated. Methods: This open-label, Phase 3b study (NCT03406156) enrolled adult pts with previously untreated CLL/SLL (except those with 17p deletion) who had medium (any lymph node [LN] 5 to Results: Of 120 pts treated, 81 received G for debulking and 39 received G+B. As of 13 May 2021, 2 pts remained on study treatment, 108 were in posttreatment follow-up, and 10 had discontinued the study for reasons including death (n=7), withdrawn consent (n=2), and COVID-19 infection (n=1). At baseline, 82.5% of pts had ALC ≥25x10 9/L, 33.3% had LN ≥5 cm, and 24.2%/75.0%/0.8% had high/medium/low tumor burden, respectively. Low tumor burden was achieved in 91.6% (109/119) of evaluable pts receiving G±B debulking. In the all-treated population (N=120), the objective response rate (ORR) was 90.0% and the CR/CRi rate was 35.8%. Among pts receiving VEN with disease assessment at EoT (N=76), the ORR was 98.7% and the CR/CRi rate was 44.7% (Table). The best uMRD4 rates in peripheral blood were 89.2% (107/120) for all-treated and 98.2% (107/109) for evaluable pts. Among evaluable pts, the uMRD4 rates were 100% (100/100) and 97.1% (68/70) at EoCT and EoT, respectively. Among pts with MRD assessments at both timepoints (N=67), 19.4% had a deepening of their MRD response from EoCT to EoT, and 67.2% maintained the same MRD level (Figure). At a median follow-up of 24.0 mo, 7 deaths (6 related to COVID-19 infection and 1 from cardiac complication after pancreatic mass resection) and no incidences of disease progression were reported; the estimated 18-mo PFS was 94.1%. In pts treated with G vs G+B debulking, respectively, the incidences of Grade ≥3 TEAEs were 71.6% vs 84.6% (most common was neutropenia at 28.4% vs 41.0%) and serious AEs were 23.5% vs 17.9% (most common were pneumonia and COVID-19 pneumonia, each at 3.7% vs 2.6%). Conclusion: In this study, most (91.6%) pts achieved low tumor burden after debulking. The uMRD4 rate was 98.2% among MRD-evaluable pts (89.2% among all pts), with 100% and 97.1% uMRD4 rates at EoCT and EoT, respectively. Overall, these results highlight the utility of G±B as an effective debulking strategy that can facilitate VEN treatment initiation in the outpatient setting. The efficacy and safety results are consistent with other VEN+G trials. Preventive measures for COVID-19 should be continuously emphasized for pts with CLL. Figure 1 Figure 1. Disclosures Flinn: AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Andorsky: AbbVie: Research Funding; Celgene/Bristol Myers Squibb: Consultancy; Celgene/Bristol Myers Squibb: Research Funding; Epizyme: Research Funding; AstraZeneca: Other: served on steering committees; AbbVie: Consultancy. Melear: TG Therapeutics: Speakers Bureau; Astrazeneca: Speakers Bureau; Janssen: Speakers Bureau. Manda: Morphosys: Honoraria; Genmab: Current equity holder in publicly-traded company. Kolibaba: TG Therapeutics: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Atara Biotechm: Consultancy; McKesson Specialty Health: Consultancy; Sunitomo Dainippon Pharma: Consultancy; Tolero Pharma: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Yimer: GSK: Speakers Bureau; Beigene: Speakers Bureau; Janssen: Speakers Bureau; Astrazeneca: Speakers Bureau; Karyopharm: Current equity holder in publicly-traded company, Speakers Bureau; Sanofi: Speakers Bureau; Amgen: Speakers Bureau; Pharmacyclics: Speakers Bureau; Texas Oncology: Current Employment. Burke: Kura: Consultancy; Epizyme: Consultancy; Kymera: Consultancy; Adaptive Biotechnologies: Consultancy; Roche/Genentech: Consultancy; Beigene: Consultancy, Speakers Bureau; MorphoSys: Consultancy; Verastem: Consultancy; AstraZeneca: Consultancy; AbbVie: Consultancy; Bristol Myers Squibb: Consultancy; X4 Pharmaceuticals: Consultancy; SeaGen: Consultancy, Speakers Bureau. Fanning: BMS: Speakers Bureau; TG Pharma: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genmab: Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Sanofi: Speakers Bureau; Takeda: Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees. Islas-Ohlmayer: OHC/USON: Current Employment; AbbVie: Honoraria; Rigel: Honoraria, Speakers Bureau. Vizkelety: AbbVie: Current Employment, Current equity holder in publicly-traded company. Pesko: AbbVie: Current Employment, Current equity holder in publicly-traded company. Chyla: AbbVie: Current Employment, Current equity holder in publicly-traded company. Jiang: AbbVie: Current Employment, Current equity holder in publicly-traded company. Sharman: Pharmacyclics LLC, an AbbVie Company: Consultancy; BMS: Consultancy; Lilly: Consultancy; BeiGene: Consultancy; Centessa: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy; TG Therapeutics: Consultancy; AbbVie: Consultancy.

Introduction Brentuximab vedotin (BV) and nivolumab are both active and well tolerated in patients (pts) with classical Hodgkin lymphoma (cHL) and were previously studied in first salvage (overall response rate [ORR] 85%; complete response [CR] 67%) (Advani 2021) and as firstline therapy in older adults (ORR 95%; CR 79%) (Yasenchak 2019). BV is approved for the treatment of adults with treatment-naïve Stage III or IV cHL in combination with doxorubicin, vinblastine, and dacarbazine (AVD) (Connors 2017) and targets CD30, a receptor expressed on the Reed-Sternberg cells. Nivolumab is approved for treatment of adults with relapsed/refractory cHL and restores antitumor immunity by blocking the PD-1 receptor on activated T-cells. The combination of BV plus nivolumab demonstrated promising activity that supports this combination when evaluated as a frontline treatment option for pts over 60 years of age with cHL (Friedberg 2018). Additionally, in pts with non-bulky Stage I or II cHL, treatment with BV plus doxorubicin and dacarbazine (AD) resulted in a CR rate of 97% at end of treatment (EOT), as well as a promising 4-year progression-free survival (PFS) estimate of 91%. Importantly, there were no cases of ≥Grade 3 peripheral neuropathy and only 9% were Grade 2 (Abramson 2021). Herein, we present preliminary safety results from Part B of this phase 2 study, where combination treatment with AN+AD (BV, nivolumab, doxorubicin, and dacarbazine) was well tolerated without excessive dose modifications or discontinuations and is consistent with the known safety profiles of the individual components of this treatment regimen. Methods SGN35-027 (NCT03646123) is an open-label, multiple part, multicenter, phase 2 clinical trial. Part B of this study enrolled pts with Ann Arbor Stage I or II cHL with bulky mediastinal disease (defined as ≥ 10 cm) or Stage III or IV cHL. Pts received up to 6 cycles of AN+AD (consisting of BV 1.2 mg/kg, nivolumab 240 mg, doxorubicin 25 mg/m 2, and dacarbazine 375 mg/m 2). All study drugs were administered by IV infusion on Days 1 and 15 of each 28-day cycle. The primary endpoint was CR rate at EOT. Secondary endpoints included safety, tolerability, overall response rate, and PFS. Disease response and progression was assessed by investigators using the Lugano Classification Revised Staging System for nodal non-Hodgkin and Hodgkin Lymphomas (Cheson 2014) and Lymphoma Response to Immunomodulatory Therapy Criteria (LYRIC) (Cheson 2016) at Cycle 2 and EOT. Results In Part B, the majority of the 58 pts enrolled were white (86%), not of Hispanic or Latino/a or Spanish origins (79%), and less than 65 years old (95%). Median age was 35 years (range: 19-78 years). Twenty-nine percent of pts had Stage II cHL with bulky mediastinal disease, while the remainder had Stage III (17%) or Stage IV (50%) cHL. Of the 58 pts enrolled, 57 received at least one dose of study treatment. Of the 57 pts who received at least one dose of study treatment, 1 pt discontinued treatment (all study drugs) by the end of Cycle 2 due to treatment-emergent adverse events (TEAEs). By end of Cycle 2, the majority of TEAEs were Grades 1 and 2; 16% of pts experienced ≥Grade 3 TEAEs. Nausea, fatigue, and alopecia were the most frequently reported treatment-related TEAEs (51%, 33%, and 26% of pts, respectively). No febrile neutropenia was observed, and there were no Grade 5 adverse events. Two pts (4%) experienced treatment-related treatment-emergent serious adverse events; 1 pt (2%) experienced hypophysitis and aseptic meningitis, and discontinued treatment, and 1 pt (2%) experienced pneumonitis. Preliminary efficacy results are anticipated for presentation. Conclusions Preliminary results demonstrate that AN+AD is well-tolerated, and no new safety signals were observed. The omission of bleomycin and vinblastine may have contributed to the absence of certain AEs, such as febrile neutropenia. This study of AN+AD is ongoing, and updated safety and efficacy results will be presented at the meeting. Disclosures Lee: BMS: Honoraria, Research Funding; Aptitude Health: Honoraria; Century Therapeutics: Consultancy; Pharmacyclics: Research Funding; Guidepoint: Honoraria; Oncternal: Research Funding; Seagen: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Janssen: Honoraria. Flinn: Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Melear: Astrazeneca: Speakers Bureau; TG Therapeutics: Speakers Bureau; Janssen: Speakers Bureau. Ramchandren: curis: Research Funding; MERCK: Consultancy, Research Funding; pharmacyclics: Consultancy, Research Funding; seattle genetics: Consultancy, Research Funding; BMS: Consultancy; Trillium: Research Funding. Friedman: Seagen Inc.: Research Funding. Burke: MorphoSys: Consultancy; Beigene: Consultancy, Speakers Bureau; AbbVie: Consultancy; Epizyme: Consultancy; Adaptive Biotechnologies: Consultancy; Bristol Myers Squibb: Consultancy; Kymera: Consultancy; AstraZeneca: Consultancy; Verastem: Consultancy; Kura: Consultancy; X4 Pharmaceuticals: Consultancy; SeaGen: Consultancy, Speakers Bureau; Roche/Genentech: Consultancy. Linhares: Seagen Inc.: Research Funding. Peterson: Seagen Inc.: Research Funding. Raval: Abbvie Pharmaceuticals: Speakers Bureau; Adaptive Biotechnologies: Consultancy; ADCT Therapeutics: Consultancy, Speakers Bureau; Alexion Pharmaceuticals: Speakers Bureau; Amgen Biotechnology Company: Research Funding; Astellas Pharmaceuticals: Speakers Bureau; Astrazeneca Pharmaceuticals: Consultancy, Speakers Bureau; Beigene Pharmaceuticals: Speakers Bureau; Bristol Meyers Squibb Pharmaceuticals: Consultancy; Epizyme Pharmaceuticals: Consultancy, Speakers Bureau; Genetech Biotechnology Company: Research Funding; GlaxoSmithKline Pharmaceuticals: Consultancy; Incyte Pharmaceuticals Corporation: Speakers Bureau; Jazz Pharmaceuticals: Consultancy; Karyopharm Therapeutics: Consultancy; Morphosys Biotech Company: Speakers Bureau; Sanofi Genzyme: Consultancy; Seagen Biotechnology Company: Research Funding; Takeda Pharmaceuticals: Consultancy, Speakers Bureau. Chintapatla: Seagen Inc.: Research Funding. Feldman: Alexion, AstraZeneca Rare Disease: Honoraria, Other: Study investigator. Yimer: Janssen: Speakers Bureau; Beigene: Speakers Bureau; Astrazeneca: Speakers Bureau; Karyopharm: Current equity holder in publicly-traded company, Speakers Bureau; GSK: Speakers Bureau; Sanofi: Speakers Bureau; Amgen: Speakers Bureau; Pharmacyclics: Speakers Bureau; Texas Oncology: Current Employment. Islas-Ohlmayer: Seagen Inc.: Research Funding. Dean: Seagen Inc.: Research Funding. Rana: Seagen Inc.: Research Funding. Gandhi: GlaxoSmithKline: Honoraria; Karyopharm Therapeutics: Honoraria; TG Therapeutics: Honoraria. Renshaw: Amgen: Speakers Bureau; SeaGen: Consultancy; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Texas Oncology: Current Employment. Gillespie-Twardy: Seagen Inc.: Research Funding. Ho: Seagen Inc.: Current Employment, Current equity holder in publicly-traded company. Fanale: Seagen, Inc: Current Employment, Current equity holder in publicly-traded company. Guo: Seagen Inc.: Current Employment, Current equity holder in publicly-traded company. Yasenchak: Seagen Inc.: Research Funding.

Background: Venetoclax (VEN), a B-cell lymphoma 2 inhibitor, is an oral agent with demonstrated efficacy in patients (pts) with chronic lymphocytic leukemia (CLL). VEN treatment induces rapid tumor reduction, posing a risk for tumor lysis syndrome (TLS), particularly in pts with high tumor burden, and may require inpatient monitoring at the initiation of therapy. Agents such as obinutuzumab (G), ibrutinib, and bendamustine (B) have been used in clinical studies to debulk tumors prior to treatment with VEN. However, the benefits of these debulking regimens could not be established conclusively, as disease restaging was rarely performed. In the present study, disease restaging was performed every 2 cycles to evaluate the efficacy and safety of G, with or without B, as a debulking therapy in untreated pts with CLL, prior to VEN treatment in an outpatient community setting. Methods: This open-label, phase 3b trial (NCT03406156) enrolled adult pts with previously untreated CLL/small lymphocytic lymphoma (excluding those with 17p deletion) who had Eastern Cooperative Oncology Group performance status of ≤1 and medium (any lymph node [LN] 5 to 10 cm or with del(11q) and LN >5 cm. Restaging data were obtained after every 2 cycles of debulking therapy. When low tumor burden was achieved, VEN was administered (5-week ramp-up schedule) as combination therapy with G (VEN+G) for 5 months, and then as monotherapy (VEN mono) for a total of 1 year. Response assessments were scheduled at week 38 and week 65 post-VEN initiation. Adverse events (AEs) were monitored throughout the study. Primary endpoints were the reduction in tumor burden after debulking therapy and the complete remission (CR)/CR with incomplete marrow recovery (CRi) rates of pts subsequently treated with VEN. We report the results of a planned interim analysis when 50 pts had completed their week 38 disease assessment. Results: As of 3 Feb 2020, 117 pts were treated with study drug(s): 80 (68%) received G and 37 (32%) received G+B for debulking; 113 pts were active in study (7 in the debulking phase; 106 completed debulking therapy and initiated VEN, including 26 in posttreatment follow-up). Four pts discontinued study due to withdrawal by pt (n=2; 1 at debulking and 1 at VEN treatment phase) and physician decision (n=1; at VEN treatment phase) and other (n=1; at debulking). At baseline, 85% of pts had ALC ≥25 × 109/L, 9% had LN ≥10 cm, 23% had LN 5-10 cm; 74%/26% had medium/high TLS risk, respectively, per investigator assessment (1 pt with low TLS risk was enrolled and subsequently discontinued). After 2 cycles of debulking therapy, low tumor burden was achieved in 85% (89/105) of evaluable pts: 86% (63/73) with G and 81% (26/32) with G+B. Reductions by pt subgroups and genetic features are presented in Figure. For pts debulked with G, similar debulking efficacy was observed among the subgroups being explored (Figure). Of the 50 pts with a week 38 disease assessment, 17 pts had an initial response of partial remission and await confirmation per IWCLL criteria. Objective response rate was 96% (48/50) overall, with 95% (37/39) for those debulked with G and 100% (11/11) for those debulked with G+B. The rate of CR or CRi was 52% (26/50) overall, with 54% (21/39) achieving CR/CRi for those debulked with G and 45% (5/11) for those debulked with G+B (Figure). More grade ≥3 AEs were observed in pts receiving G+B than those receiving G: debulking, 62% vs 40%; VEN+G, 43% vs 34%; VEN mono, 41% vs 28%. Conclusions: Most pts (85%) achieved low tumor burden after 2 cycles of G±B. Similar debulking efficacy was observed across subgroups in pts debulked with G. In this early efficacy analysis, CR/CRi at week 38 was observed in 52% of pts treated with VEN after the debulking phase. Preliminary efficacy results from this study are consistent with other VEN studies in treatment-naive pts. Current study highlights the efficacy of the debulking strategy prior to treatment with VEN; this may allow more pts to have VEN ramp-up in outpatient setting. Figure Disclosures Flinn: Calithera Biosciences: Research Funding; Forma Therapeutics: Research Funding; F. Hoffmann-La Roche: Research Funding; Celgene: Research Funding; Merck: Research Funding; Curio Science: Consultancy; Pfizer: Research Funding; Seattle Genetics: Consultancy, Research Funding; Novartis: Research Funding; MorphoSys: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Trillium Therapeutics: Research Funding; Triphase Research & Development Corp.: Research Funding; Constellation Pharmaceuticals: Research Funding; Johnson & Johnson: Other; Teva: Research Funding; BeiGene: Consultancy, Research Funding; Curis: Research Funding; Nurix Therapeutics: Consultancy; Verastem: Consultancy, Research Funding; Yingli Pharmaceuticals ≠: Consultancy, Research Funding; Rhizen Pharmaceuticals: Research Funding; Roche: Consultancy, Research Funding; Vincera Pharma: Consultancy; Forty Seven: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Portola Pharmaceuticals: Research Funding; Takeda: Consultancy, Research Funding; Incyte: Research Funding; AstraZeneca: Consultancy, Research Funding; Karyopharm Therapeutics: Research Funding; Agios: Research Funding; ArQule: Research Funding; Kite Pharma: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; IGM Biosciences: Research Funding; Infinity Pharmaceuticals: Research Funding; Unum Therapeutics: Consultancy, Research Funding; Juno Therapeutics: Consultancy, Research Funding; Acerta Pharma: Research Funding; AbbVie: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Iksuda Therapeutics: Consultancy; Great Point Partners: Consultancy; Loxo: Research Funding; Genentech, Inc.: Research Funding. Andorsky:AstraZeneca: Research Funding; Celgene: Research Funding; AbbVie: Honoraria. Melear:Janssen: Speakers Bureau; AstraZeneca: Speakers Bureau. Manda:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials. Anz:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials. Kolibaba:Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Janssen: Research Funding; Novartis: Research Funding; Verastem: Honoraria; Cell Therapeutics: Research Funding; Celgene: Research Funding; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Atara Biotech: Membership on an entity's Board of Directors or advisory committees; AbbVie: Research Funding; Acerta: Research Funding; Compass Oncology: Ended employment in the past 24 months; McKesson Life Sciences: Consultancy; Sumitomo Dainippon Pharma Oncology: Consultancy, Other: travel, accommodations, expenses, . Yimer:Sanofi: Speakers Bureau; Janssen: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding, Speakers Bureau; TG Therapeutics: Consultancy; Celgene, a Bristol-Myers Squibb Company: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; BeiGene: Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding, Speakers Bureau; Texas Oncology: Current Employment; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Epizyme: Consultancy, Divested equity in a private or publicly-traded company in the past 24 months; Karyopharm: Consultancy, Divested equity in a private or publicly-traded company in the past 24 months, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau. Burke:Adaptive: Consultancy; Kura: Consultancy; Morphosys: Consultancy; Celgene: Consultancy; AbbVie: Consultancy; Bayer: Consultancy; Gilead: Consultancy; Seattle Genetics: Speakers Bureau; Roche: Consultancy; Bristol Myers Squibb: Consultancy; Verastem: Consultancy; Astra Zeneca: Consultancy; Epizyme: Consultancy; Adaptive Biotechnologies: Consultancy. Fanning:TG Therapeautics: Consultancy; Abbvie: Consultancy; Prisma Health: Current Employment; Sanofi Aventis: Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Bristol Myers Squibb: Consultancy, Speakers Bureau. Courtright:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials.. Islas-Ohlmayer:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials.. Kambhampati:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials.. Jiang:AbbVie: Current Employment, Other: may hold stock or options. Pesko:AbbVie, Inc.: Current Employment, Other: may hold stock or other options. Vizkelety:AbbVie: Current Employment, Other: may hold stock or stock options.. Sharmokh:AbbVie: Current Employment, Current equity holder in publicly-traded company. Sharman:AbbVie: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Bristol Meyers Squibb: Consultancy, Research Funding; BeiGene: Research Funding; Acerta: Consultancy, Research Funding; Roche: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding.

Background/Aims Bcl-2 inhibitor venetoclax (VEN) has demonstrated efficacy in patients with chronic lymphocytic leukemia (CLL). As VEN induces rapid cell death, patients with medium- to high tumor burden (TB) are at greater risk for tumor lysis syndrome (TLS). We explore tumor debulking prior to outpatient VEN initiation. Methods This phase 3b trial enrolled untreated adults with CLL/SLL without 17p deletion, having medium-to high TB. Patients received at least 2 cycles (C), or a maximum of 6 cycles of debulking therapy (Obinutuzumab [G] ± bendamustine [B]). Once achieved low TB, VEN was started with VEN+G initially, then VEN monotherapy. Primary endpoints were reduction in TB after every 2 C of debulking, and IWCLL response rates. Results As of 12/2/2019, 110 patients were included; 76 received G and 34 G+B for debulking. Majority were Conclusions Most patients achieved low TB at C2 of debulking with G±B prior to VEN ramp-up. AE of TLS was reported in 1 patient during VEN phase. Similar Gr ≥3 AEs were observed during VEN phases regardless of debulking agents. Debulking reduced TB and may facilitate outpatient VEN initiation. Abstract was previously published at EHA25.

BACKGROUND: Based on the encouraging activity and manageable safety profile observed in a phase 1 study, the ECHELON-2 trial was initiated to compare the efficacy and safety of brentuximab vedotin, cyclophosphamide, doxorubicin, and prednisone (A+CHP) versus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) for the treatment of CD30-positive peripheral T-cell lymphomas.METHODS: ECHELON-2 is a double-blind, double-dummy, randomised, placebo-controlled, active-comparator phase 3 study. Eligible adults from 132 sites in 17 countries with previously untreated CD30-positive peripheral T-cell lymphomas (targeting 75% with systemic anaplastic large cell lymphoma) were randomly assigned 1:1 to receive either A+CHP or CHOP for six or eight 21-day cycles. Randomisation was stratified by histological subtype according to local pathology assessment and by international prognostic index score. All patients received cyclophosphamide 750 mg/m2 and doxorubicin 50 mg/m2 on day 1 of each cycle intravenously and prednisone 100 mg once daily on days 1 to 5 of each cycle orally, followed by either brentuximab vedotin 1·8 mg/kg and a placebo form of vincristine intravenously (A+CHP group) or vincristine 1·4 mg/m2 and a placebo form of brentuximab vedotin intravenously (CHOP group) on day 1 of each cycle. The primary endpoint, progression-free survival according to blinded independent central review, was analysed by intent-to-treat. This trial is registered with ClinicalTrials.gov, number NCT01777152.FINDINGS: Between Jan 24, 2013, and Nov 7, 2016, 601 patients assessed for eligibility, of whom 452 patients were enrolled and 226 were randomly assigned to both the A+CHP group and the CHOP group. Median progression-free survival was 48·2 months (95% CI 35·2-not evaluable) in the A+CHP group and 20·8 months (12·7-47·6) in the CHOP group (hazard ratio 0·71 [95% CI 0·54-0·93], p=0·0110). Adverse events, including incidence and severity of febrile neutropenia (41 [18%] patients in the A+CHP group and 33 [15%] in the CHOP group) and peripheral neuropathy (117 [52%] in the A+CHP group and 124 [55%] in the CHOP group), were similar between groups. Fatal adverse events occurred in seven (3%) patients in the A+CHP group and nine (4%) in the CHOP group.INTERPRETATION: Front-line treatment with A+CHP is superior to CHOP for patients with CD30-positive peripheral T-cell lymphomas as shown by a significant improvement in progression-free survival and overall survival with a manageable safety profile.FUNDING: Seattle Genetics Inc, Millennium Pharmaceuticals Inc, a wholly owned subsidiary of Takeda Pharmacuetical Company Limited, and National Institutes of Health National Cancer Institute Cancer Center.

BACKGROUND: Venetoclax is an effective oral agent for frontline treatment of patients with chronic lymphocytic leukemia (CLL). Due to the rapid induction of cell death caused by the targeted activity of venetoclax, some patients require inpatient monitoring for tumor lysis syndrome (TLS) at initiation of therapy. In the recent CLL14 study, 64% and 22% of venetoclax-treated patients were medium and high risk for TLS, respectively. This study used disease re-staging every two cycles to explore the efficacy of using of obinutuzumab, with or without bendamustine prior to initiation of venetoclax, to reduce tumor burden and thus eliminate the need for hospitalizations, as well as reduce the risk for TLS at the initiation of venetoclax therapy. METHODS: This is a single arm open-label, phase 3b trial (NCT03406156). Patients had previously untreated CLL/SLL (excluding those with 17p deletion), an Eastern Cooperative Oncology Group (ECOG) performance score of ≤1, and a medium (any lymph node 5 - RESULTS: A majority of patients were 10 cm were debulked to 30%) were infusion-related reactions (71%; all grade 1-2), nausea (39%), headache (35%) and fatigue (32%). Neutropenia (28%) and thrombocytopenia (10%) were the most frequently reported Grade 3+ AEs. AEs of TLS were reported in the debulking phase in 7% (5/69) of patients. A retrospective analysis using Howard criteria for TLS identified three additional patients with laboratory TLS: two occurred during the debulking phase and one during the venetoclax phase, all driven by phosphate and uric acid. Uric acid levels were below the institutional upper limit of normal for the patient with TLS during venetoclax treatment and did not require management. No patients were hospitalized during venetoclax ramp up. CONCLUSIONS: Two cycles of obinutuzumab prior to initiation of venetoclax was an effective debulking strategy for patients with ALC >25 × 109 /L and lymph nodes 5 cm treated with obinutuzumab or >10 cm treated with obinutuzumab plus bendamustine may need >2 cycles to achieve low tumor burden. Debulking via obinutuzumab, with or without bendamustine, may allow more patients to be administered venetoclax in the outpatient setting, eliminating the need for hospitalization during venetoclax initiation. Figure Disclosures Sharman: AstraZeneca: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Research Funding; Genentech: Consultancy, Honoraria, Research Funding; TG Therapeutics: Consultancy, Honoraria, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding; Acerta: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Andorsky:Genetech: Research Funding; Gilead: Research Funding; Celgene: Research Funding; AstraZeneca: Consultancy; CTI: Research Funding. Melear:Texas Oncology: Employment; DARA: Speakers Bureau. Kolibaba:Atara Bio: Consultancy; AbbVie, Acerta, Celgene, Genentech, Gilead, Janssen, Novartis, Pharmacyclics, Seattle Genetics, TG Therapeutics: Research Funding; Verastem: Honoraria. Yimer:Clovis Oncology: Equity Ownership; Celgene: Honoraria; Seattle Genetics: Honoraria; Janssen: Speakers Bureau; AstraZeneca: Speakers Bureau; Amgen: Consultancy; Puma Biotechnology: Equity Ownership. Burke:Celgene: Consultancy; Roche/Genentech: Consultancy; Gilead: Consultancy. Fanning:Celgene: Speakers Bureau; Takeda: Speakers Bureau. Masud:AbbVie: Employment, Other: Stock/stock options. Zimmerman:AbbVie: Employment, Other: stock or options. Nielsen:AbbVie: Employment, Other: and may hold stock or stock options. Vizkelety:AbbVie: Employment, Other: stock or options. Jiang:AbbVie: Employment, Other: stock or options. Flinn:AbbVie, Seattle Genetics, TG Therapeutics, Verastem: Consultancy; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; Acerta Pharma, Agios, Calithera Biosciences, Celgene, Constellation Pharmaceuticals, Genentech, Gilead Sciences, Incyte, Infinity Pharmaceuticals, Janssen, Karyopharm Therapeutics, Kite Pharma, Novartis, Pharmacyclics, Portola Pharmaceuticals: Research Funding; F. Hoffmann-La Roche Ltd: Research Funding.

Autologous stem cell transplantation (ASCT) is standard of care for patients with Hodgkin lymphoma (HL) who have relapsed/refractory disease after frontline chemotherapy. Achievement of complete remission (CR) with pre-ASCT salvage chemotherapy predicts favorable outcomes post-ASCT. This phase 1/2 study evaluated the combination of brentuximab vedotin (BV) plus bendamustine as a first salvage regimen in relapsed/refractory HL. A total of 55 patients (28 primary refractory and 27 relapsed) were enrolled. Patients received BV (1.8 mg/kg) on day 1 and bendamustine (90 mg/m 2 ) on days 1 and 2 of a 21-day cycle for up to 6 cycles. Patients could undergo ASCT any time after cycle 2. Following ASCT or completion of combination therapy if not proceeding to ASCT, patients could receive BV monotherapy for up to 16 cycles of total therapy. After a median of 2 cycles of combination therapy (range, 1-6), the objective response rate among 53 efficacy-evaluable patients was 92.5%, with 39 patients (73.6%) achieving CR. Forty patients underwent ASCT. Thirty-one patients (25 of whom underwent ASCT) received BV monotherapy (median, 10 cycles; range, 1-14). After a median of 20.9 months of follow-up, the estimated 2-year progression-free survival was 69.8% and 62.6% for patients who received ASCT and all patients, respectively. Thirty-one patients (56.4%) experienced infusion-related reactions (IRRs), with a majority occurring during cycle 2 of combination therapy. A protocol amendment requiring premedication reduced IRR severity. BV plus bendamustine as first salvage therapy in relapsed/refractory HL is highly active with a manageable toxicity profile. This trial was registered at www.clinicaltrials.gov as #NCT01874054.

Plerixafor plus granulocyte-colony stimulating factor (G-CSF) has been shown to mobilize more CD34(+) cells than G-CSF alone for autologous hematopoietic stem cell transplantation (HSCT). However, many centers use chemotherapy followed by G-CSF to mobilize CD34(+) cells prior to HSCT. We performed a retrospective study of patients who participated in the expanded access program (EAP) of plerixafor and G-CSF for initial mobilization of CD34(+) cells, and compared outcomes to matched historic controls mobilized with cyclophosphamide 3-5 g/m(2) and G-CSF at 2 centers that participated in the EAP Control patients were matched for age, sex, disease, disease stage, and number of prior therapies. Mobilization costs were defined to be the costs of medical procedures, resource utilization, and medications. Median national CMS reimbursement rates were used to establish the costs of procedures, hospitalization, provider visits, apheresis, CD34(+) cell processing and cryopreservation. Average sale price was used for G-CSF, plerixafor, cyclophosphamide, MESNA, antiemetics, and antimicrobials. A total of 33 patients from the EAP and 33 matched controls were studied. Two patients in the control group were hospitalized for neutropenic fever during the mobilization period. Apheresis started on the scheduled day in 33 (100%) study patients and in 29 (88%) control patients (P = 0.04). Sixteen (48%) control patients required weekend apheresis. There was no difference in number of CD34(+) cells collected between the groups, and all patients proceeded to HSCT with no difference in engraftment outcomes. Median total cost of mobilization was not different between the plerixafor/G-CSF and control groups ($14,224 versus $18,824; P = .45). In conclusion, plerixafor/G-CSF and cyclophosphamide/G-CSF for upfront mobilization of CD34(-) cells resulted in similar numbers of cells collected, costs of mobilization, and clinical outcomes. Additionally, plerixafor/G-CSF mobilization resulted in more predictable days of collection, no weekend apheresis procedures, and no unscheduled hospital admissions.

Epstein-Barr virus (EBV)-induced lymphoproliferative disease is an important complication in the context of immune deficiency. Impaired T-cell immunity allows the outgrowth of transformed cells with the subsequent production of predominantly B-cell lymphomas. Currently there is no in vivo model that can adequately recapitulate EBV infection and its association with B-cell lymphomas. NOD/SCID mice engrafted with human CD34 + cells and reconstituted mainly with human B lymphocytes may serve as a useful xenograft model to study EBV infection and pathogenesis. We therefore infected reconstituted mice with EBV. High levels of viral DNA were detected in the peripheral blood of all infected mice. All infected mice lost weight and showed decreased activity levels. Infected mice presented large visible tumors in multiple organs, most prominently in the spleen. These tumors stained positive for human CD79a, CD20, CD30, and EBV-encoded RNAs and were light chain restricted. Their characterization is consistent with that of large cell immunoblastic lymphoma. In addition, tumor cells expressed EBNA1, LMP1, and LMP2a mRNAs, which is consistent with a type II latency program. EBV + lymphoblastoid cell lines expressing human CD45, CD19, CD21, CD23, CD5, and CD30 were readily established from the bone marrow and spleens of infected animals. Finally, we also demonstrate that infection with an enhanced green fluorescent protein (EGFP)-tagged virus can be monitored by the detection of infected EGFP + cells and EGFP + tumors. These data demonstrate that NOD/SCID mice that are reconstituted with human CD34 + cells are susceptible to infection by EBV and accurately recapitulate important aspects of EBV pathogenesis.

Introduction:Thrombocytopenia is a common problem in hospitalized patients, which has a diverse etiology. One of the infrequent causes is heparin-induced thrombocytopenia (HIT), a complex immune disorder in which heparin leads to the production of IgG antibodies, targeting platelet factor 4 (PF4). HIT diagnosis is based on a decrease in the platelet count of more than 50% beginning 5 to 10 days after starting heparin, in association with platelet-activating HIT antibodies (screening test), positive functional tests (confirmatory tests), in patients with no alternative causes for thrombocytopenia, necrosis or thrombosis (Figure 1). Most patients admitted to our institution receive unfractionated or low molecular weight heparin for venous thromboembolism prophylaxis. The risk of HIT depends on the type of heparin the patient receives. Even though HIT is rare, we tend to have a high suspicion and low threshold to order laboratory workup for this condition, occasionally without using the 4T«s score (Table 1). The 4T«s score is a validated system with a very high negative predictive value (NPV) of up to 99%, when the score is ²3. The aim of this study is to determine if the 4T«s score has been used appropriately in our institution. It is a very useful tool with a high negative likelihood ratio and using it systematically may decrease unnecessary laboratory testing, consequently decreasing costs and potentially length of stay. Methods:This is a retrospective descriptive study from a single teaching community hospital. Between January and December of 2015, 57 HIT screening tests (PF4 ELISA) were ordered in our institution. We reviewed all of the patient charts to determine their 4T«s score. The patients were divided into low, moderate and high pretest probability based on their score (low probability if ²3, intermediate 4-5, and high if ³6). The data analysis was completed with SPSS software. Results:57 tests were ordered, 5 patient charts did not have enough information to calculate 4T«s score and were excluded. 52 charts were reviewed, 28 patients were male and 24 were female (53 and 46% respectively), and they were between 25 and 89 years of age. 7 (13.4%) did not receive heparin (during current hospitalization or within 100 days), 11 (21.1%) received therapeutic doses of unfractionated heparin, 11 (21.1%) received prophylactic doses of unfractionated heparin, and 23 (44.2%) received prophylactic low molecular weight heparin (enoxaparin). The 4T«s score was calculated for each patient; 40 were low risk, 10 intermediate risk and 2 high risk (76.9, 19.2, 3.8% respectively). All the patients had HIT screening antibodies ordered; only 10 (19.2%) were positive and from those only 1 (1.9%) was confirmed by the serotonin release assay. This confirmed patient had a 4T«s score of 6. Of the 7 tested patients who did not receive heparin, none had a positive screening test (all had 4T«s score of 1 or 2). 35 of the screening tests were ordered by internal medicine residents, 5 by surgical residents, 12 by attending physicians (67.3, 9.6 and 23% respectively). Previous studies validated that a 4T«s score of ²3 can predict negative results for the confirmatory tests. By using theMcNemar«stest for matched pairs, we attempted to determine a cut off for the 4T«s score that would predict a negativeHIT screeningtest. We found that a 4T«s score ²2 predicted a negativeHIT screeningtest, with aNPVof 75% (p=0.0018). Since our study included a small patient cohort and due to the possibility of laboratory work up not being ordered in patients with a low 4T«s score, we suspect theNPVis actually lower than our current finding. A prospective study with a larger cohort of patients would be necessary to confirm these findings. Conclusions:Only 12% of the patients had a 4T«s score ³4 that would warrant laboratory work up, therefore we concluded that PF4 ELISA screening tests have been over utilized in our institution, increasing false positive results, length of stay and cost of hospitalization in patients without a significant risk for HIT. This could be avoided by calculating the 4T«s score before obtaining any further laboratory tests. The 4T«s scoring system has been validated by multiple studies with large cohorts in the past. We will continue to work with our staff, especially the residents, to improve education on HIT and adequate diagnosis, based on current guidelines. Disclosures No relevant conflicts of interest to declare.

Background Long-term outcomes from autologous stem cell transplant (ASCT) in patients (pts) with relapsed/refractory (R/R) Hodgkin lymphoma (HL) are significantly better in patients who achieve a complete remission (CR) from salvage chemotherapy prior to ASCT. However, standard salvage therapy produces variable CR rates (19%-60%) and is associated with significant toxicity. Brentuximab vedotin and bendamustine are highly active when administered as single agents to pts with R/R HL (34% and 33% CR rates, respectively) and have manageable safety profiles. This phase 1/2, single-arm, 2-stage, open-label study was designed to evaluate the safety and efficacy of brentuximab vedotin in combination with bendamustine for the treatment of pts with primary refractory disease or in first relapse (ClinicalTrials.gov #NCT01874054). Methods Pts received an outpatient IV infusion of 1.8 mg/kg brentuximab vedotin on Day 1 with bendamustine on Days 1 and 2 of 3-week cycles for up to 6 cycles. Pts could undergo ASCT any time after Cycle 2 and post-transplant resume treatment with brentuximab vedotin as monotherapy for up to 16 total doses. Phase 1 was designed to determine the recommended dose of bendamustine, with an initial dose of 90 mg/m2 and a de-escalation scheme to be implemented if it exceeded the maximum tolerated dose. During phase 2, bendamustine was administered at the recommended dose in order to assess the CR rate of the combination. Response was assessed by the investigator per Cheson 2007. Enrollment is complete and long-term follow-up for PFS and OS continues. Results Fifty-five pts (56% female) with a median age of 36 yrs (range, 19-79) were enrolled. Fifty-one percent of pts had relapsed disease and 49% of pts had primary refractory disease after frontline therapy. A median of 13.8 mos (range, 3-98) had elapsed since initial diagnosis. No dose-limiting toxicities were observed in the safety cohort, thus the recommended dose of bendamustine in combination with brentuximab vedotin was 90 mg/m2. Pts received a median of 2 cycles (range, 1-6) of the combination and a median of 9 cycles (range, 1-14) of single-agent brentuximab vedotin. The main toxicity observed with the combination was infusion-related reactions (56% overall). The most common symptoms (≥10%) were pyrexia (26%), chills (20%), dyspnea and nausea (15% each), flushing (13%), and hypotension (11%). Premedication with corticosteroids and antihistamines was instituted with a protocol amendment and appeared effective. Before the amendment, 6 pts (24% of treated pts) discontinued treatment prematurely because of IRRs; post-amendment, IRRs led to treatment discontinuation for 2 pts (7%). The CR rate of the combination was 74% (39/53 pts evaluable for response) and the overall objective response rate (CR and partial remission) was 93% (49/53 pts). The CR rate was 64% and 84% for refractory and relapsed pts, respectively. Stem cell collection after first-line mobilization (G-CSF± plerixafor) was successful in 93% of pts (37/40). Median number of CD34+ cells collected was 4.1 x106 (Q1, Q3: 3.0, 5.4) in a median of 2 (range, 1-5) apheresis sessions. Median time to neutrophil and platelet engraftment was 11 days (range, 9-21) and 13 days (range, 9-39), respectively. Pts have been followed for a median of approximately 1 year from first dose (median = 418 days; range, 118-635) and approximately 10 mos (314 days; range, 13-553) from ASCT. To date, 12 progression events have been observed: 7 in the 40 pts who underwent transplant and 5 in the 13 pts who did not undergo transplant. The estimated 12-mos PFS is 80% for both the transplanted population (95% CI: 70%, 90%) and the overall population (95% CI: 60%, 90%). Three of the 12 progression events were deaths; 2 pts died from progression of their HL and 1 pt died from septic shock after transplant. Conclusions The outpatient regimen of brentuximab vedotin 1.8 mg/kg on Day 1 in combination with bendamustine 90 mg/m2 on Days 1 and 2 of 3-week cycles induced a very high CR rate that compares favorably with historical data. The regimen has a manageable safety profile, with the most significant side effect being IRRs that can be successfully managed by premedication. The estimated 12-mos PFS rate of 80% demonstrates response durability, making the combination a promising salvage regimen for pts with HL in the first relapse setting. Progression-Free Survival Figure 1. Figure 1. Disclosures Off Label Use: Brentuximab vedotin is indicated in the US for treatment of patients with Hodgkin lymphoma after failure of autologous stem cell transplant or after failure of at least two prior multi-agent chemotherapy regimens in patients who are not ASCT candidates and for the treatment of patients with systemic anaplastic large cell lymphoma after failure of at least one prior multi-agent chemotherapy regimen. This study evaluates brentuximab vedotin in HL patients with primary refractory disease or in first relapse. . Sawas:Seattle Genetics, Inc.: Research Funding. Agura:Seattle Genetics, Inc.: Research Funding. Matous:Takeda Pharmaceuticals International Co.: Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Seattle Genetics, Inc.: Research Funding, Speakers Bureau. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding. Crosswell:KIYATEC (employment); Gilead (common stock ownership and research funding): Employment, Equity Ownership, Research Funding. Islas-Ohlmayer:Seattle Genetics, Inc.: Research Funding. Behler:Seattle Genetics, Inc.: Research Funding; Onyx Pharmaceuticals: Speakers Bureau. Cheung:Seattle Genetics, Inc.: Research Funding. Forero-Torres:Seattle Genetics, Inc.: Research Funding. Vose:Seattle Genetics, Inc.: Honoraria, Research Funding. Josephson:Seattle Genetics, Inc.: Employment, Equity Ownership. Advani:Seattle Genetics, Inc.: Research Funding; Genetech: Consultancy.

Background Patients (pts) with Hodgkin lymphoma (HL) who have relapsed/refractory disease after frontline therapy typically undergo salvage chemotherapy followed by high-dose conditioning and autologous stem cell transplant (ASCT). Improved outcomes have been reported for pts who achieve complete remission (CR) with salvage chemotherapy prior to ASCT. Variable CR rates (19%-60%) and significant toxicities are associated with standard salvage therapy in the first relapse setting. Brentuximab vedotin and bendamustine have independent mechanisms of action and are highly active with manageable safety profiles when administered as single agents to pts with HL who relapse after ASCT (brentuximab vedotin: 34% CR [Younes, 2012]; bendamustine: 33% CR [Moskowitz, 2013]). This phase 1/2, single-arm, 2-stage, open-label study was designed to evaluate the safety and efficacy of brentuximab vedotin in combination with bendamustine for the treatment of pts with HL in first relapse (ClinicalTrials.gov #NCT01874054). Methods Pts received an outpatient IV infusion of 1.8 mg/kg brentuximab vedotin on Day 1 with 90 mg/m2 bendamustine on Days 1 and 2 of 3-week cycles for up to 6 cycles. Pts could undergo ASCT any time after Cycle (C) 2 and post-transplant resume treatment with brentuximab vedotin as monotherapy for up to16 total doses. Phase 1 was designed to determine the recommended dose of bendamustine in combination with brentuximab vedotin. During this phase, the dose of bendamustine was to be de-escalated if ≥4/10 pts experienced dose-limiting toxicity (DLT), defined as any C1 toxicity requiring a dose delay of ≥14 days. During phase 2, bendamustine was administered at the recommended dose in order to assess the CR rate of the combination. Response was assessed by the investigator per Cheson 2007. Results Forty-five pts (58% female) with a median age of 35 yrs (range, 19-79) have been enrolled. Fifty-eight percent of pts had relapsed disease and 42% of pts primary refractory disease after frontline therapy. A median of 13.1 mos (range, 3- 98) had elapsed since initial diagnosis. No DLTs were observed in the safety cohort, thus the recommended dose of bendamustine in combination with brentuximab vedotin was 90 mg/m2. Pts received a median of 2 cycles (range, 1-6) of the combination. The main toxicity observed with the combination was infusion-related reactions. The most common symptoms (≥10%) were dyspnea (13%), flushing (13%), and chills (11%). The majority of reactions occurred within 24 hours of C2 infusion and were considered related to both agents. Premedication with corticosteroids and antihistamines was instituted with a protocol amendment and appeared effective. Prior to the amendment, 36% (9/25 unique pts) of treated pts had reactions that were either serious adverse events (SAEs) (n=6), Grade 3 in severity (n=8), and/or led to treatment discontinuation (n=6). Following premedication implementation, 15% (3/20 unique pts) of treated pts had such events (0 SAEs, 1 treatment discontinuation, and 2 Grade 3 toxicities). The CR rate of the combination was 82% (28/34 pts evaluable for response) and the overall objective response rate (CR and partial remission) 94% (32/34 pts). The majority of CRs (24/28 pts) were achieved after 2 cycles of combination therapy. Stem cell mobilization and collection was considered adequate in all 24 pts who underwent the procedure. The median number of CD34+ cells collected was 4.3 x106 (range, 1.7- 16.0 x106) in a median of 2 apheresis sessions (range, 1-5). To date, 20 pts have undergone ASCT, the majority after C2 (12 pts) or C3 (6 pts), and 13 pts have resumed brentuximab vedotin as monotherapy. One patient with CR developed progressive disease 3 cycles post-transplant. The median duration of remission for pts who obtained a CR has not been reached (95% CI: 8.7,– [range, 0.03+-10.4+ months]). Conclusions The outpatient regimen of brentuximab vedotin 1.8 mg/kg on Day 1 in combination with bendamustine 90 mg/m2 on Days 1 and 2 of 3-week cycles has a manageable safety profile with premedication. The very high CR rate observed on combination treatment compares favorably with historical data. The durability of responses observed to date and the success of stem cell mobilization and collection suggest that the regimen may represent a promising approach for maximizing responses prior to ASCT in pts with HL who are either relapsed or are refractory after frontline therapy. Disclosures LaCasce: Seattle Genetics, Inc.: Research Funding. Off Label Use: Brentuximab vedotin is indicated in the US for treatment of patients with Hodgkin lymphoma after failure of autologous stem cell transplant or after failure of at least two prior multi-agent chemotherapy regimens in patients who are not ASCT candidates and for the treatment of patients with systemic anaplastic large cell lymphoma after failure of at least one prior multi-agent chemotherapy regimen. Bociek:Seattle Genetics, Inc.: Research Funding. Matous:Celgene: Consultancy, Speakers Bureau; Onyx: Speakers Bureau; Takeda Pharmaceuticals International Co.: Speakers Bureau; Seattle Genetics, Inc.: Research Funding, Speakers Bureau. Sawas:Seattle Genetics, Inc.: Research Funding. Caimi:Seattle Genetics, Inc.: Equity Ownership, Research Funding. Ansell:Seattle Genetics, Inc.: Research Funding. Islas-Ohlmayer:Seattle Genetics, Inc.: Research Funding. Cheung:Seattle Genetics, Inc.: Research Funding. Agura:Seattle Genetics, Inc.: Research Funding. Behler:Onyx Pharmaceuticals: Speakers Bureau; Seattle Genetics, Inc.: Research Funding. Crosswell:Seattle Genetics, Inc.: Consultancy, Equity Ownership, Research Funding, Travel expenses Other. Vose:Seattle Genetics, Inc.: Honoraria, Research Funding. Josephson:Seattle Genetics, Inc.: Employment, Equity Ownership. Advani:Janssen Pharmaceuticals: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Takeda International Pharmaceuticals Co.: Research Funding; Seattle Genetics, Inc.: Research Funding, Travel expenses Other.

Dendritic cells (DCs) are derived from CD34+ progenitors and play a central role in the development of immune responses and in tolerance. Their therapeutic potential underscores the need for in vivo models that accurately recapitulate human DC development and function to provide a better understanding of DC biology in health and disease. Using nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice transplanted with human CD34+ cells as a model of human hematopoiesis, we examined DC ontogeny. Progenitors of both myeloid (m) and plasmacytoid (p) DCs were identified in the bone marrow of mice up to 24 weeks after transplant, indicating ongoing and sustained production of DCs after initial engraftment. To determine whether human DCs derived from transplanted stem cells were functional, their response to acute inflammation using lipopolysaccharide (LPS) was examined. Eighteen hours after LPS administration, a dramatic increase in the plasma levels of the human inflammatory cytokines interleukin (IL)-8, IL-10, tumor necrosis factor-alpha, and IL-12p70 was observed. Only mDCs and not pDCs responded in vivo to LPS by upregulating CD86 and CD83. In vivo activation of human mDCs resulted in a substantial increase in the ability of mDCs to induce the proliferation of naive human T cells. Taken together, these data indicate that human CD34+ cells seem to have differentiated appropriately within the NOD/SCID microenvironment into DCs that are developmentally, phenotypically, and functionally similar to the DC subsets found in humans.

Distinct human dendritic cell (DC) subsets differentially control immunity. Thus, insights into their in vivo functions are important to understand the launching and modulation of immune responses. We show that nonobese diabetic/LtSz-scid/scid (NOD/SCID) mice engrafted with human CD34+ hematopoietic progenitors develop human myeloid and plasmacytoid DCs. The skin displays immature DCs expressing Langerin, while other tissues display interstitial DCs. Myeloid DCs from these mice induce proliferation of allogeneic CD4 T cells in vitro, and bone marrow human cells containing plasmacytoid DCs release interferon-α (IFN-α) upon influenza virus exposure. Injection of influenza virus into reconstituted mice triggers IFN-α release and maturation of mDCs. Thus, these mice may provide a model to study the pathophysiology of human DC subsets.

Abstract 2277 Poster Board II-254 Background: Plerixafor plus G-CSF has been shown to mobilize more CD34+ cells than G-CSF alone for autologous (auto) hematopoietic stem cell transplant (HSCT). However, many centers use chemotherapy followed by G-CSF to mobilize CD34+ cells prior to HSCT. Comparing the effectiveness of CD34+ cell mobilization, cost, logistical issues, and clinical outcomes between plerixafor/G-CSF and chemotherapy/G-CSF mobilized pts may help better define optimal mobilization regimens. Patients and Methods: We performed a retrospective study of pts who participated in the expanded access program (EAP) of plerixafor/G-CSF for upfront mobilization of CD34+ cells, and compared the costs of mobilization and clinical outcomes to matched historical controls mobilized with chemotherapy/G-CSF at two centers that participated in the study. Control pts were matched for age, sex, disease stage, and number of prior therapies. Control pts received cyclophosphamide 3-5 gm/m2 followed by daily G-CSF. Study pts received G-CSF 10 mcg/kg daily for 5 days and plerixafor 0.24 mg/kg was given on the evening of day 4, twelve hours before a 3 blood volume apheresis on day 5, and the same plerixafor and G-CSF dosing was given for each subsequent day of apheresis. Apheresis was scheduled for 5 days after starting G-CSF in the study pts and 10 days after starting G-CSF in the control pts, but the actual start of apheresis was based on the peripheral blood (PB) CD34+ cell counts of 10/ul or greater. Mobilization costs were considered to be the costs of medical procedures, resource utilization and medications. Median national CMS national reimbursement rates were used to evaluate the costs of mobilization procedures, hospitalization, provider visits, apheresis, CD34+ cell processing and cryopreservation. Average sale price was used for medications related to mobilization including G-CSF, plerixafor, cyclophosphamide, mesna, antiemetics and antimicrobials. Results: A total of 34 patients from EAP and 34 matched controls were studied (Rocky Mountain BMT:25 study pts and 25 controls, Texas Transplant Institute:9 study pts and 9 controls). Study pts had a median age of 58 years, 18 (53%) were male, and had myeloma (n=20, 59%), or NHL (n=14, 41%). Control pts had a median age of 58 years, 18 (53%) were male and had myeloma (n=20, 59%), NHL (n=13, 38%), or Hodgkins disease (n=1, 3%). Comparison of the G-CSF dose, the number of doses of G-CSF, number of apheresis, total CD34+ cells collected, and cost is given in the table. All pts proceeded to auto HSCT with no difference in median time to ANC or platelet engraftment. The median costs of mobilization were similar between the groups. Two pts in the control group were hospitalized for neutropenic fever during the mobilization period after receiving cyclophosphamide. Apheresis started on the scheduled day in 27 (79%) of study pts and in 18 (53%) of control pts (p=0.021). Unplanned starts of apheresis resulted in 17 (50%) of control pts undergoing weekend apheresis. CMS national reimbursement data does not differentiate the costs of weekend or weekday apheresis or flow cytometry, and thus no cost difference for weekend procedures is reflected in the cost data. Study pts received a median of 1 dose of plerixafor (median 16.9 mg), and the average sale price for plerixafor in this analysis was set at $6,250 per 24 mg/vial. Adding this cost to the study pts resulted in a non-significant difference in total cost of mobilization for the two groups. Conclusion: In conclusion, plerixafor/G-CSF compared to cyclophosphamide/G-CSF for upfront mobilization of CD34+ cells for auto HSCT results in similar number of cells collected, cost of mobilization, and clinical outcomes. However, plerixafor/G-CSF mobilization resulted in more predictable days of collection, no weekend apheresis procedures, and no unscheduled hospital admissions. Higher acquisition cost of plerixafor was offset by less G-CSF use and less resource utilization compared to cyclophosphamide based mobilization. Disclosures: Shaughnessy: Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Silva:Genzyme: Consultancy. Steinberg:Genzyme: Consultancy. Selvey:Genzyme: Consultancy. Maris:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. McSweeney:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.