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We hypothesized that combining adoptively transferred autologous T cells with a cancer vaccine strategy would enhance therapeutic efficacy by adding antimyeloma idiotype (Id)–keyhole limpet hemocyanin (KLH) vaccine to vaccine-specific costimulated T cells. In this randomized phase 2 trial, patients received either control (KLH only) or Id-KLH vaccine, autologous transplantation, vaccine-specific costimulated T cells expanded ex vivo, and 2 booster doses of assigned vaccine. In 36 patients (KLH, n = 20; Id-KLH, n = 16), no dose-limiting toxicity was seen. At last evaluation, 6 (30%) and 8 patients (50%) had achieved complete remission in KLH-only and Id-KLH arms, respectively (P = .22), and no difference in 3-year progression-free survival was observed (59% and 56%, respectively; P = .32). In a 594 Nanostring nCounter gene panel analyzed for immune reconstitution (IR), compared with patients receiving KLH only, there was a greater change in IR genes in T cells in those receiving Id-KLH relative to baseline. Specifically, upregulation of genes associated with activation, effector function induction, and memory CD8+ T-cell generation after Id-KLH but not after KLH control vaccination was observed. Similarly, in responding patients across both arms, upregulation of genes associated with T-cell activation was seen. At baseline, all patients had greater expression of CD8+ T-cell exhaustion markers. These changes were associated with functional Id-specific immune responses in a subset of patients receiving Id-KLH. In conclusion, in this combination immunotherapy approach, we observed significantly more robust IR in CD4+ and CD8+ T cells in the Id-KLH arm, supporting further investigation of vaccine and adoptive immunotherapy strategies. This trial was registered at www.clinicaltrials.gov as #NCT01426828.

Clinical Practice Points • Carfilzomib (CFZ) has rarely been associated with atypical hemolytic uremic syndrome (aHUS). • Patients with heterozygous complement factor H related protein 3 (CFHR)/CFHR1 deletions may be predisposed to CFZ-induced aHUS. • The benefit of eculizumab in the treatment of CFZ-induced aHUS that fails to improve with drug withdrawal and supportive care remains uncertain.

Background High-sensitivity severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen assays are desirable to mitigate false negative results. Limited data are available to quantify and track SARS-CoV-2 antigen burden in respiratory samples from different populations. Methods We developed the Microbubbling SARS-CoV-2 Antigen Assay (MSAA) with smartphone readout, with a limit of detection of 0.5 pg/mL (10.6 fmol/L) nucleocapsid antigen or 4000 copies/mL inactivated SARS-CoV-2 virus in nasopharyngeal (NP) swabs. We developed a computer vision and machine learning–based automatic microbubble image classifier to accurately identify positives and negatives and quantified and tracked antigen dynamics in intensive care unit coronavirus disease 2019 (COVID-19) inpatients and immunocompromised COVID-19 patients. Results Compared to qualitative reverse transcription−polymerase chain reaction methods, the MSAA demonstrated a positive percentage agreement of 97% (95% CI 92%–99%) and a negative percentage agreement of 97% (95% CI 94%–100%) in a clinical validation study with 372 residual clinical NP swabs. In immunocompetent individuals, the antigen positivity rate in swabs decreased as days-after-symptom-onset increased, despite persistent nucleic acid positivity. Antigen was detected for longer and variable periods of time in immunocompromised patients with hematologic malignancies. Total microbubble volume, a quantitative marker of antigen burden, correlated inversely with cycle threshold values and days-after-symptom-onset. Viral sequence variations were detected in patients with long duration of high antigen burden. Conclusions The MSAA enables sensitive and specific detection of acute infections and quantification and tracking of antigen burden and may serve as a screening method in longitudinal studies to identify patients who are likely experiencing active rounds of ongoing replication and warrant close viral sequence monitoring.

Background There is a need for novel therapies for relapsed or refractory multiple myeloma, and B-cell maturation antigen (BCMA) is a validated target. Teclistamab is a bispecific antibody that binds BCMA and CD3 to redirect T cells to multiple myeloma cells. The aim of the MajesTEC-1 study was to evaluate the safety, tolerability, and preliminary efficacy of teclistamab in patients with relapsed or refractory multiple myeloma. Methods This open-label, single-arm, phase 1 study enrolled patients with multiple myeloma who were relapsed, refractory, or intolerant to established therapies. Teclistamab was administered intravenously (range 0.3-19.2 mu g/kg [once every 2 weeks] or 19.2-720 mu g/kg [once per week]) or subcutaneously (range 80-3000 mu g/kg [once per week]) in different cohorts, with step-up dosing for 38.4 mu g/kg or higher doses. The primary objectives were to identify the recommended phase 2 dose (part one) and characterise teclistamab safety and tolerability at the recommended phase 2 dose (part two). Safety was assessed in all patients treated with at least one dose of teclistamab. Efficacy was analysed in response-evaluable patients (ie, patients who received at least one dose of teclistamab and had at least one post-baseline response evaluation). This ongoing trial is registered with ClinicalTrials.gov, NCT03145181. Findings Between June 8, 2017, and March 29, 2021, 219 patients were screened for study inclusion, and 157 patients (median six previous therapy lines) were enrolled and received at least one dose of teclistamab (intravenous n=84; subcutaneous n=73). 40 patients were administered the recommended phase 2 dose, identified as once per week subcutaneous administration of teclistamab at 1500 mu g/kg, after 60 mu g/kg and 300 mu g/kg step-up doses (median follow-up 6.1 months, IQR 3.6-8.2). There were no dose-limiting toxicities at the recommended phase 2 dose in part one. In the 40 patients treated at the recommended phase 2 dose, the most common treatment-emergent adverse events were cytokine release syndrome in 28 (70%; all grade 1 or 2 events) and neutropenia in 26 (65%) patients (grade 3 or 4 in 16 [40%]). The overall response rate in response-evaluable patients treated at the recommended phase 2 dose (n=40) was 65% (95% CI 48-79); 58% achieved a very good partial response or better. At the recommended phase 2 dose, the median duration of response was not reached. 22 (85%) of 26 responders were alive and continuing treatment after 7.1 months' median follow-up (IQR 5.1-9.1). At the recommended phase 2 dose, teclistamab exposure was maintained above target exposure levels, and consistent T-cell activation was reported. Interpretation Teclistamab is a novel treatment approach for relapsed or refractory multiple myeloma. At the recommended phase 2 dose, teclistamab showed promising efficacy, with durable responses that deepened over time, and was well tolerated, supporting further clinical development. Copyright (C) 2021 Elsevier Ltd. All rights reserved.

Patients with cancer have high mortality from coronavirus disease 2019 (COVID-19), and the immune parameters that dictate clinical outcomes remain unknown. In a cohort of 100 patients with cancer who were hospitalized for COVID-19, patients with hematologic cancer had higher mortality relative to patients with solid cancer. In two additional cohorts, flow cytometric and serologic analyses demonstrated that patients with solid cancer and patients without cancer had a similar immune phenotype during acute COVID-19, whereas patients with hematologic cancer had impairment of B cells and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody responses. Despite the impaired humoral immunity and high mortality in patients with hematologic cancer who also have COVID-19, those with a greater number of CD8 T cells had improved survival, including those treated with anti-CD20 therapy. Furthermore, 77% of patients with hematologic cancer had detectable SARS-CoV-2-specific T cell responses. Thus, CD8 T cells might influence recovery from COVID-19 when humoral immunity is deficient. These observations suggest that CD8 T cell responses to vaccination might provide protection in patients with hematologic cancer even in the setting of limited humoral responses.

Key points T cells from patients early in myeloma therapy exhibit better fitness for CAR T manufacturing than those from relapsed/refractory patients. CAR T cells may be more effective if manufactured from patients before onset of relapsed/refractory disease.

Key Points Myeloma patients progressing on BCMA-targeted therapy can maintain BCMA expression and still respond to different BCMA-targeted therapy. These observations suggest this patient population could be included in ongoing BCMA-targeted therapy trials.

Multiple myeloma (MM) is a malignant plasma cell disorder that remains incurable for most patients despite significant improvements achieved with modern therapy. Tumor evasion is a key process in the pathogenesis of MM and a compromised immune system is associated with more aggressive forms of the disease. In contrast, the emergence of myeloma-specific immune responses after both autologous and allogeneic stem cell transplantation is associated with better prognosis. Adoptive T cell therapies may improve specific anti-myeloma immunity resulting in long-lasting remissions. CAR T cell therapies for MM are at an early stage of clinical development. To date, anti-BCMA CAR T cells have shown the greatest results in early-phase clinical trials. Toxicities have included cytokine release syndrome (CRS) and neurotoxicity. Current areas of research in CAR T cell therapies include the use of gene-editing to enhance their effectiveness and safety, the integration of CAR T cells with other therapies (immunomodulatory drugs, checkpoint inhibitors) and CAR T cells to target multiple antigens.

BackgroundLittle is known about the dynamics of SARS-CoV-2 antigen burden in respiratory samples in different patient populations at different stages of infection. Current rapid antigen tests cannot quantitate and track antigen dynamics with high sensitivity and specificity in respiratory samples.MethodsWe developed and validated an ultra-sensitive SARS-CoV-2 antigen assay with smartphone readout using the Microbubbling Digital Assay previously developed by our group, which is a platform that enables highly sensitive detection and quantitation of protein biomarkers. A computer vision-based algorithm was developed for microbubble smartphone image recognition and quantitation. A machine learning-based classifier was developed to classify the smartphone images based on detected microbubbles. Using this assay, we tracked antigen dynamics in serial swab samples from COVID patients hospitalized in ICU and immunocompromised COVID patients.ResultsThe limit of detection (LOD) of the Microbubbling SARS-CoV-2 Antigen Assay was 0.5 pg/mL (10.6 fM) recombinant nucleocapsid (N) antigen or 4000 copies/mL inactivated SARS-CoV-2 virus in nasopharyngeal (NP) swabs, comparable to many rRT-PCR methods. The assay had high analytical specificity towards SARS-CoV-2. Compared to EUA-approved rRT-PCR methods, the Microbubbling Antigen Assay demonstrated a positive percent agreement (PPA) of 97% (95% confidence interval (CI), 92-99%) in symptomatic individuals within 7 days of symptom onset and positive SARS-CoV-2 nucleic acid results, and a negative percent agreement (NPA) of 97% (95% CI, 94-100%) in symptomatic and asymptomatic individuals with negative nucleic acid results. Antigen positivity rate in NP swabs gradually decreased as days-after-symptom-onset increased, despite persistent nucleic acid positivity of the same samples. The computer vision and machine learning-based automatic microbubble image classifier could accurately identify positives and negatives, based on microbubble counts and sizes. Total microbubble volume, a potential marker of antigen burden, correlated inversely with Ct values and days-after-symptom-onset. Antigen was detected for longer periods of time in immunocompromised patients with hematologic malignancies, compared to immunocompetent individuals. Simultaneous detectable antigens and nucleic acids may indicate the presence of replicating viruses in patients with persistent infections.ConclusionsThe Microbubbling SARS-CoV-2 Antigen Assay enables sensitive and specific detection of acute infections, and quantitation and tracking of antigen dynamics in different patient populations at various stages of infection. With smartphone compatibility and automated image processing, the assay is well-positioned to be adapted for point-of-care diagnosis and to explore the clinical implications of antigen dynamics in future studies.

Cancer patients have increased morbidity and mortality from Coronavirus Disease 2019 (COVID-19), but the underlying immune mechanisms are unknown. In a cohort of 100 cancer patients hospitalized for COVID-19 at the University of Pennsylvania Health System, we found that patients with hematologic cancers had a significantly higher mortality relative to patients with solid cancers after accounting for confounders including ECOG performance status and active cancer status. We performed flow cytometric and serologic analyses of 106 cancer patients and 113 non-cancer controls from two additional cohorts at Penn and Memorial Sloan Kettering Cancer Center. Patients with solid cancers exhibited an immune phenotype similar to non-cancer patients during acute COVID-19 whereas patients with hematologic cancers had significant impairment of B cells and SARS-CoV-2-specific antibody responses. High dimensional analysis of flow cytometric data revealed 5 distinct immune phenotypes. An immune phenotype characterized by CD8 T cell depletion was associated with a high viral load and the highest mortality of 71%, among all cancer patients. In contrast, despite impaired B cell responses, patients with hematologic cancers and preserved CD8 T cells had a lower viral load and mortality. These data highlight the importance of CD8 T cells in acute COVID-19, particularly in the setting of impaired humoral immunity. Further, depletion of B cells with anti-CD20 therapy resulted in almost complete abrogation of SARS-CoV-2-specific IgG and IgM antibodies, but was not associated with increased mortality compared to other hematologic cancers, when adequate CD8 T cells were present. Finally, higher CD8 T cell counts were associated with improved overall survival in patients with hematologic cancers. Thus, CD8 T cells likely compensate for deficient humoral immunity and influence clinical recovery of COVID-19. These observations have important implications for cancer and COVID-19-directed treatments, immunosuppressive therapies, and for understanding the role of B and T cells in acute COVID-19.

Purpose: B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor (CAR) T cells (CART-BCMA) are a promising treatment for relapsed/refractory multiple myeloma (r/rMM). We evaluated the safety and feasibility of bridging radiation (RT) in subjects treated on a phase I trial of CART-BCMA. Experimental Design: Twenty-five r/rMM subjects were treated in three cohorts with two doses of CART-BCMA cells ± cyclophosphamide. We retrospectively analyzed toxicity, response, and CART manufacturing data based on RT receipt. Results: Thirteen subjects received no RT Conclusions: Bridging-RT appeared safe and feasible with CART-BCMA therapy in our r/rMM patients, though larger future studies are needed to draw definitive conclusions.

Multiple myeloma is a malignant neoplasm of plasma cells that accumulate in bone marrow, leading to bone destruction and marrow failure. This manuscript discusses the management of patients with solitary plasmacytoma, smoldering multiple myeloma, and newly diagnosed multiple myeloma.

Introduction: Novel agents are needed for multiple myeloma (MM), which remains incurable with most patients (pts) relapsing or becoming refractory to standard therapies. Talquetamab (Tal) is a bispecific antibody that binds to G protein-coupled receptor family C group 5 member D (GPRC5D), a receptor highly expressed on plasma cells with limited expression in healthy tissue, and CD3 to redirect T cells to GPRC5D-expressing MM cells. Tal monotherapy at the recommended phase 2 dose (RP2D) was well tolerated and yielded an overall response rate of 70% after 6.3 months of follow-up in pts with relapsed/refractory MM (RRMM) in the phase 1 MonumenTAL-1 study; responses were durable and continued to deepen over time. Daratumumab (Dara) is a monoclonal antibody approved for MM treatment that targets CD38 on MM cells, resulting in direct cytotoxicity of MM cells. Dara also impacts immune cell populations, ie, increasing helper and cytotoxic T cells and decreasing suppressive CD38+ immunoregulatory cells. Preclinical studies showed addition of Dara enhanced Tal-mediated lysis of MM cells, suggesting the combination may also increase clinical activity in pts with RRMM. We report initial findings for pts with RRMM who received Tal + Dara in a phase 1b multicohort study (TRIMM-2; NCT04108195). Methods: Eligible pts (aged ≥18 years) were diagnosed with MM and had received ≥3 prior lines of therapy (including a proteasome inhibitor [PI] and immunomodulatory drug [IMiD]) or were double refractory to a PI and an IMiD. Pts were excluded if they had received an anti-CD38 therapy ≤90 days. Subcutaneous (SC) Tal and Dara were administered in 28-day cycles in different dosing cohorts (with step-up dosing for Tal). The primary objectives were to identify the RP2D of Tal in combination with Dara and to characterize the safety of Tal + Dara at the RP2D. Responses were assessed by IMWG criteria. Adverse events (AEs) were graded per CTCAE v5.0 (cytokine release syndrome [CRS] and immune effector cell-associated neurotoxicity syndrome [ICANS] graded per ASTCT guidelines). Results: As of Jul 23, 2021, 23 pts were administered SC Tal + Dara in separate cohorts: Dara 1800 mg + Tal 400 µg/kg weekly (n=8), + Tal 400 µg/kg biweekly (n=5), and + Tal 800 µg/kg biweekly (n=10). Median follow-up across the Tal + Dara cohorts was 2.9 months (range 0.3-11.2). Median age of pts treated with Tal + Dara was 68 years (range 44-81), and 52.2% were male. Pts had received a median of 6 prior lines of therapy (range 3-18); 82.6% were triple-class exposed (82.6% received prior Dara and 8.7% received prior isatuximab) and 73.9% were penta-drug exposed. Any grade AEs were reported in 95.7% of pts and grade 3/4 AEs in 78.3%. The most frequently reported AEs (≥30% across Tal + Dara cohorts) were dysgeusia (52.2%; all grade 1/2), neutropenia (39.1%; grade 3/4 30.4%), thrombocytopenia (39.1%; grade 3/4 21.7%), anemia (34.8%; grade 3/4 21.7%), CRS (34.8%; all grade 1/2), and skin exfoliation (30.4%; all grade 1/2). The median time to CRS onset was 2.5 days (range 2-4), and the median duration was 2 days (range 1-3). Infections occurred in 34.8% of pts (grade 3/4 17.4%). Skin disorders were reported in 65.2% of pts (grade 3/4 13.0%), including nail disorders in 17.4% (all grade 1/2); these events were manageable and did not lead to treatment discontinuation. Two events of ICANS were reported (a grade 1 event [concurrent with CRS] and a grade 3 event), both of which resolved and did not recur. One pt in the Dara 1800 mg + Tal 400 μg/kg biweekly cohort died due to disease progression. Responses in different dosing cohorts are shown in the Table. The median time to first response across Tal + Dara cohorts was 1.0 month (range 0.9-2.4), and median duration of response was not reached. The pharmacokinetic profile of Tal was similar to that observed in the phase 1 monotherapy study. Tal + Dara treatment resulted in proinflammatory cytokine production and T-cell activation, evidenced by interferon-γ and tumor necrosis factor-α induction and PD-1 and CD38 upregulation on peripheral T cells, respectively. Updated data with longer follow-up will be presented at the congress. Conclusions: Tal in combination with Dara was well tolerated, with a safety profile comparable to the monotherapies, and showed promising efficacy in pts with RRMM. These findings support further clinical development of Tal + Dara combination therapy. Figure 1 Figure 1. Disclosures Chari: BMS/Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Secura Bio: Consultancy, Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Antengene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millenium/Takeda: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi Genzyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Research Funding; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees. Hari: Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Karyopharm: Consultancy; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Adaptive Biotech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene-BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau. Bahlis: Janssen: Consultancy, Honoraria; Genentech: Consultancy; BMS/Celgene: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Mateos: Sea-Gen: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene - Bristol Myers Squibb: 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; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bluebird bio: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria; Oncopeptides: Honoraria. van de Donk: Janssen Pharmaceuticals: 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; Bristol Myers Squibb: 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; Amgen: 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; Roche: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Cellectis: Research Funding. Dholaria: Janssen: Research Funding; Takeda: Research Funding; Jazz: Speakers Bureau; MEI: Research Funding; Angiocrine: Research Funding; Poseida: Research Funding; Celgene: Speakers Bureau; Pfizer: Research Funding. Garfall: Janssen: Honoraria, Research Funding; GSK: Honoraria; Novartis: Research Funding; Tmunity Therapeutics: Research Funding; Amgen: Honoraria. Goldschmidt: Novartis: Honoraria, Research Funding; Dietmar-Hopp-Foundation: Other: Grant; Sanofi: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Takeda: Consultancy, Research Funding; MSD: Research Funding; Mundipharma: Research Funding; Molecular Partners: Research Funding; Johns Hopkins University: Other: Grant; Janssen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Incyte: Research Funding; GSK: Honoraria; Chugai: Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; BMS: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Celgene: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Adaptive Biotechnology: Consultancy; Amgen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding. Krishnan: City of Hope Cancer Center: Current Employment; JANSSEN: Consultancy, Research Funding; BMS: Consultancy, Current equity holder in publicly-traded company, Speakers Bureau; MAGENTA: Consultancy; REGENERON: Consultancy; SANOFI: Consultancy; GSK: Consultancy; Amgen: Speakers Bureau. Martin: Janssen: Research Funding; Amgen: Research Funding; Oncopeptides: Consultancy; Sanofi: Research Funding; GlaxoSmithKline: Consultancy. Morillo Giles: Janssen: Honoraria; Takeda: Honoraria; Abbvie: Honoraria. Oriol: Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Reece: BMS: Honoraria, Research Funding; GSK: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Millennium: Research Funding; Karyopharm: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Sanofi: Honoraria. Rodriguez: Takeda: Consultancy, Speakers Bureau; Karyopharm: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Oncopeptides: Consultancy, Honoraria; BMS: Consultancy, Speakers Bureau. Rodriguez-Otero: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Regeneron: Honoraria; Clínica Universidad de Navarra: Current Employment. San-Miguel: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, GlaxoSmithKline, Janssen, Karyopharm, Merck Sharpe & Dohme, Novartis, Regeneron, Roche, Sanofi, SecuraBio, Takeda: Consultancy, Other: Advisory board. Usmani: Array BioPharma: Consultancy, Research Funding; GSK: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding, Speakers Bureau; Abbvie: Consultancy; Amgen: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; EdoPharma: Consultancy; Merck: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; SkylineDX: Consultancy, Research Funding; Janssen Oncology: Consultancy, Research Funding; Takeda: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Research Funding. Verona: Janssen: Current Employment. Wang Lin: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Prior: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Wade: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Weiss: Janssen: Current holder of individual stocks in a privately-held company, Ended employment in the past 24 months. Goldberg: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Askari: Janssen: Research Funding.

Background . Anti-CD19 chimeric antigen receptor T cells (CART19) are now a standard treatment for patients (pts) with relapsed/refractory (r/r) large B-cell lymphomas (LBCL). Lymphodepleting chemotherapy (LD) is administered before CART19 to optimize CAR T cell engraftment, expansion, and function. The most widely used LD regimen is the combination of fludarabine (25-30mg/m 2) and cyclophosphamide (250-500mg/m 2) administered daily over 3 days (Flu/Cy). However, Flu/Cy is associated with a significant risk of hematologic toxicity that may preclude administration or result in prolonged cytopenias in pts with pre-existing cytopenias. Bendamustine (Benda) combines both alkylating-agent and purine-analog activities, and has potent anti-tumor efficacy in lymphoid malignancies. Importantly, compared to Flu/Cy, Benda typically has less hematologic toxicity, which may reduce the risk of infections. Therefore, because of its safety profile and lymphocytotoxic activity, Benda has been used as an alternative LD regimen for some pts receiving tisagenlecleucel (tisa-cel). In this study, we compare outcomes for Benda 90mg/m 2 for 2 days with Flu/Cy as the LD regimen before tisa-cel in pts with r/rLBCL treated at 3 different institutions. Methods : We retrospectively evaluated the outcomes of 133 consecutive r/r LBCL pts treated with commercial tisa-cel at the Hospital of the University of Pennsylvania, Oregon Health and Science University, and the Medical University of Vienna between 2018 and 2021. Patients with complete response (CR) at the time of infusion (n=20) were excluded from this analysis as this study aimed at evaluating the role of the LD regimen not only as related to the LD ability but also its effect against the tumor. Therefore, the analysis included 113 adult r/rLBCL pts treated with Flu/Cy or Benda as LD and with measurable disease on the last PET/CT scan before tisa-cel infusion. LD choice was based on physician's preference. Pts were evaluated for response (Lugano criteria), progression (PFS) and overall survival (OS), as well as hematological and CART-specific toxicities (ASTCT criteria). Pts demographics, response rates, and adverse events were compared using chi-squared and t-student tests as appropriate; log rank test was used for survival analysis. Results: Of 113 pts, 68 (60%) had diffuse large BCL not otherwise specified (NOS), 3 (3%) high-grade BCL NOS, 32 (28%) transformed follicular lymphoma, 9 (8%) high-grade BCL with MYC and BCL2 and/or BCL6 translocations, and 1 (1%) primary mediastinal BCL. Forty-one pts (36%) received Flu/Cy and 72 (64%) received Benda LD. Characteristics of Flu/Cy pts were comparable to Benda in terms of sex (female: 37% vs. 32%, p=0.616), age (68 vs. 65 years, p=0.143), performance status (ECOG ≤1: 93% vs. 94%, p=0.709), number of previous lines of therapy (3 vs. 3, p=0.707), previous autologous hematopoietic cell transplant (27% vs. 14%, p=0.089), bridging therapy (73% vs 85% p=0.136), LDH at infusion (elevated: 54% vs. 51%, p=0.708), and bulky disease (>10 cm) (15% vs. 10%, p=0.431). In whole cohort, no difference in obtaining a CR at any point after CART was observed between groups (Flu/Cy: 22% vs. Benda: 33%, p=0.201) (Fig 1A). At a median follow-up of 20.4 months, no difference in PFS was observed between Flu/Cy and Benda pts with 12-month PFS of 22% and 27%, respectively (p=0.512, Fig 1B). OS was also similar between Flu/Cy and Benda groups (2-year OS 41% vs. 49%, respectively, p=0.108). Both cytokine-release syndrome (CRS) and neurotoxicity (ICANS) were more frequent in the Flu/Cy group compared to Benda (any grade CRS: 68% vs. 40%, respectively, p=0.004; any grade ICANS: 22% vs. 7%, respectively, p=0.020). Of note, pts receiving Flu/Cy developed more severe cytopenias compared to Benda. In particular, the median absolute neutrophil count nadir 30 days after tisa-cel was significantly lower in Flu/Cy group (0.20x10 9/L) compared to Benda (2.15x10 9/L) (p Conclusions: This retrospective study of r/r LBCL pts receiving tisagenlecleucel suggests that Benda is as effective as Flu/Cy and validates a safer adverse event profile with reduced CRS, ICANS, and hematological toxicities. Figure 1 Figure 1. Disclosures Svoboda: Pharmacyclics: Consultancy, Research Funding; TG: Research Funding; Seattle Genetics: Consultancy, Research Funding; Imbrium: Consultancy; Merck: Research Funding; Incyte: Research Funding; Genmab: Consultancy; Atara: Consultancy; BMS: Consultancy, Research Funding; Astra Zeneca: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding. Dwivedy Nasta: Merck: Other: Data safety monitoring board; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; ATARA: Research Funding; Millenium: Research Funding; Pharmacyclics: Research Funding; Roche: Research Funding; Rafael: Research Funding; Debiopharm: Research Funding. Landsburg: Incyte: Membership on an entity's Board of Directors or advisory committees; ADCT: Membership on an entity's Board of Directors or advisory committees; Curis: Research Funding; Takeda: Research Funding; Triphase: Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: DSMB member; Morphosys: Membership on an entity's Board of Directors or advisory committees. Gerson: Kite: Consultancy; TG Therapeutics: Consultancy; Abbvie: Consultancy; Pharmacyclics: Consultancy. Barta: Daiichi Sankyo: Honoraria; Seagen: Honoraria; Acrotech: Honoraria; Kyowa Kirin: Honoraria. Garfall: Amgen: Honoraria; Tmunity Therapeutics: Research Funding; Janssen: Honoraria, Research Funding; GSK: Honoraria; Novartis: Research Funding. Porter: National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Genentech: Current equity holder in publicly-traded company, Ended employment in the past 24 months; American Society for Transplantation and Cellular Therapy: Honoraria; Incyte: Membership on an entity's Board of Directors or advisory committees; DeCart: Membership on an entity's Board of Directors or advisory committees; ASH: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Tmunity: Patents & Royalties; Wiley and Sons Publishing: Honoraria. Jaeger: BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Norvartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Maziarz: Novartis: Consultancy, Other: Data and Safety Monitoring board, Research Funding; Bristol-Myers, Squibb/Celgene,, Intellia, Kite: Honoraria; Incyte Corporation: Consultancy, Honoraria; Allovir: Consultancy, Research Funding; Artiva Therapeutics: Consultancy; CRISPR Therapeutics: Consultancy; Intellia: Honoraria; Omeros: Research Funding; Athersys: Other: Data and Safety Monitoring Board, Patents & Royalties; Vor Pharma: Other: Data and Safety Monitoring Board. Ruella: AbClon: Consultancy, Research Funding; viTToria biotherapeutics: Research Funding; Tmunity: Patents & Royalties; BMS, BAYER, GSK: Consultancy; Novartis: Patents & Royalties. Schuster: Abbvie: Consultancy, Research Funding; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; Adaptive Biotechnologies: Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; DTRM: Research Funding; Genetech: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Incyte: Research Funding; Juno Theraputics: Consultancy, Research Funding; Loxo Oncology: Consultancy; Merck: Research Funding; Nordic Nanovector: Consultancy; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Pharmaclcyclics: Research Funding; Tessa Theraputics: Consultancy; TG Theraputics: Research Funding.

Abstract Background: The two FDA approved mRNA-based SARS-CoV2 vaccines have shown >90% efficacy at preventing COVID and eliciting protective immunity in nearly all healthy individuals. However, the extent of vaccine induced antibody and T cell immunity in immunocompromised patients is not well known. Our study objective is to determine if patients with hematologic malignancies treated with B-cell targeting chimeric antigen receptor (CAR) T cell therapies can mount antibody and T cell immune responses to SARS-CoV2 vaccines. A prospective single-center study to evaluate the SARS-CoV2 immune responses in immunocompromised individuals (COVAX Study) was initiated at University of Pennsylvania following the IRB guidelines. The study enrolled 8 healthy adults,12 patients are in remission after treatment (average of 40.6 months) with CART cells targeting either CD19 or CD19+CD22 and received both doses of SARS-CoV2 vaccine. Methods and Results: Serology to SARS-CoV2 spike-receptor binding domain (RBD) IgG, RBD-IgA, RBD-IgM and spike-specific T cell responses were measured prior to vaccination and serially up to 28 days after booster vaccination. RBD-IgG and RBD-IgA were detected in 8/8 and 7/8 healthy subjects compared to 5/12 and 2/12 CART patients, respectively (Figure A). In the CART cohort, several patients who demonstrated an induction of RBD-IgG (57.2/uL +/- 20.2) compared to those who were RBD-IgG-negative (9/uL +/- 10.1, ANOVA with multiple comparisons test p=0.017) have higher level of circulating B cells. No association was found with time since CART infusion, age, disease type, or vaccine manufacturer. All 8 healthy subjects demonstrated induction of SARS-Cov2 spike-specific CD4 + T cell immunity compared to 7 out of 11 CART patients (Figure B). RBD-IgG responses were not correlated with CD4 + T cell activation (Pearson correlation, R=0.21, p=0.53). Indeed, 3 CART patients demonstrated robust CD4 + T cell activation despite absence of antibody induction. Overall, 8/12 CART patients demonstrated induction of either or both humoral and T cell immune responses. Conclusions: We show that immune responses to SARS-CoV2 mRNA vaccines are induced in majority of patients who have been treated with CART therapies targeting B-cell lineage antigens. Induction of vaccine-specific antibody was strongly associated with the level of circulating B cells. However, in CART cohort patients despite severe humoral immune deficiency, strong CD4 + T cell responses were observed suggestive of a sufficient protective immunity. Figure 1 Figure 1. Disclosures Frey: Novartis: Research Funding; Sana Biotechnology: Consultancy; Kite Pharma: Consultancy; Syndax Pharmaceuticals: Consultancy. Garfall: Amgen: Honoraria; CRISPR Therapeutics: Research Funding; GlaxoSmithKline: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Research Funding; Tmunity: Research Funding. Porter: American Society for Transplantation and Cellular Therapy: Honoraria; Genentech: Current equity holder in publicly-traded company, Ended employment in the past 24 months; ASH: Membership on an entity's Board of Directors or advisory committees; DeCart: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Tmunity: Patents & Royalties; Wiley and Sons Publishing: Honoraria. June: AC Immune, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Consultancy; Tmunity, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Current equity holder in publicly-traded company; Novartis: Patents & Royalties.

Introduction: Cellular immunotherapy with CD19-targeted chimeric antigen receptor (CAR) T cells has provided new therapeutic options for patients with high-risk hematologic malignancies. Following this therapy, patients may experience disease relapse or CAR-mediated toxicity due to cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS). Recent studies have confirmed that the intestinal microbiome can modulate the anti-tumor immune response to chemotherapy, immune checkpoint blockade, graft-versus-host disease after allogeneic hematopoietic cell transplantation, and adoptive cellular therapy. The contribution of the intestinal microbiome on the function of CAR T cells in vivo both with respect to their anti-tumor function and their propensity to induce toxicities is not known. Hence, in a multi-center study we analyzed the association between clinical outcomes and (1) antibiotic exposure prior to CAR T cell infusion and (2) the composition and diversity of the fecal microbiome. Methods and Results: We retrospectively collected clinical data and antibiotic exposures from patients with acute lymphoblastic leukemia (ALL, n=91) and non-Hodgkin lymphoma (NHL, n=137) treated with investigational or commercial CD19 CAR T cells at Memorial Sloan Kettering Cancer Center (MSK) and the University of Pennsylvania (Penn). We considered any antibiotic exposure between day -30 and the day of CAR T cell infusion. We focused our analysis on anaerobe-targeting antibiotics used in the setting of neutropenic fever: piperacillin-tazobactam, imipenem-cilastatin, and meropenem (here referred to as "P-I-M"). We found that forty-seven (20.6%) of 228 patients were exposed to P-I-M in the four weeks before CAR T cell infusion. Patient characteristics at the time of CAR T cell infusion were similar between the P-I-M-exposed and not-exposed groups, although a worse performance status was observed in patients with NHL treated with P-I-M. We found that overall survival (OS) was significantly decreased following CAR T cell infusion in patients exposed to P-I-M (Fig 1A; OS HR, 2.58; 95% CI, 1.68 - 3.98; p= We also prospectively collected baseline fecal samples prior to cell infusion from CD19 CAR T cells recipients (n=48) at MSK and Penn. Samples were submitted for 16S RNA sequencing of the V4-V5 region on the Illumina MiSeq platform and the amplicon sequence variants (ASVs) were annotated according to the NCBI 16S database using BLAST. In comparison to healthy controls (n=30), we found that alpha-diversity was significantly lower in fecal samples from CAR T cell patients (p= 0.0023, Fig 1B) and the composition of fecal samples was significantly different (p= Conclusion: Our results suggest that exposure to antibiotics, in particular P-I-M, in the four weeks before therapy was associated with worse survival. Profiling of the baseline fecal microbiome samples by 16S revealed that CD19 CAR T cell patients presented with evidence of an altered fecal microbiome as measured by lower alpha-diversity and a composition that is distinct from that of healthy controls. Finally, we identified bacterial taxa that were associated with Day 100 CR and CAR-mediated toxicity. Our findings indicate that the intestinal microbiome can affect the efficacy of CD19 CAR T cell therapy and provides a rationale to target the intestinal microbiome to improve clinical outcomes of patients treated with cellular therapies. Figure 1 Figure 1. Disclosures Smith: Janssen: Consultancy, Honoraria. Gomes: Xbiome: Current Employment. Schluter: Postbiotics Plus LLC: Other: cofounder. Park: Kura Oncology: Consultancy; BMS: Consultancy; Servier: Consultancy; Autolus: Consultancy; Curocel: Consultancy; Artiva: Consultancy; Kite Pharma: Consultancy; Amgen: Consultancy; Novartis: Consultancy; Affyimmune: Consultancy; Intellia: Consultancy; Innate Pharma: Consultancy; Minerva: Consultancy; PrecisionBio: Consultancy. Palomba: Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Kite Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Jain: Targeted Healthcare Communications: Consultancy; Bristol Myers Squibb: Other: for advisory board participation; CareDx: Other: for advisory board participation; CTI Biopharma: Research Funding; Syneos Health: Research Funding. Pennisi: Gilead Sciences: Consultancy. Perales: Miltenyi Biotec: Honoraria, Other; Novartis: Honoraria, Other; Omeros: Honoraria; NexImmune: Honoraria; Bristol-Myers Squibb: Honoraria; Merck: Honoraria; Celgene: Honoraria; Takeda: Honoraria; Kite/Gilead: Honoraria, Other; Medigene: Honoraria; Nektar Therapeutics: Honoraria, Other; Cidara: Honoraria; Servier: Honoraria; Sellas Life Sciences: Honoraria; Karyopharm: Honoraria; MorphoSys: Honoraria; Equilium: Honoraria; Incyte: Honoraria, Other. Garfall: Amgen: Honoraria; CRISPR Therapeutics: Research Funding; GlaxoSmithKline: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Research Funding; Tmunity: Research Funding. Landsburg: Triphase: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: DSMB member; Incyte: Membership on an entity's Board of Directors or advisory committees; ADCT: Membership on an entity's Board of Directors or advisory committees; Curis: Research Funding; Takeda: Research Funding. Gerson: Kite: Consultancy; Pharmacyclics: Consultancy; Abbvie: Consultancy; TG Therapeutics: Consultancy. Svoboda: Imbrium: Consultancy; Genmab: Consultancy; Astra Zeneca: Consultancy, Research Funding; Atara: Consultancy; BMS: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding; Incyte: Research Funding; Merck: Research Funding; Pharmacyclics: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; TG: Research Funding. Giralt: AMGEN: Membership on an entity's Board of Directors or advisory committees; PFIZER: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; SANOFI: Membership on an entity's Board of Directors or advisory committees; CELGENE: Membership on an entity's Board of Directors or advisory committees; JAZZ: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; JENSENN: Membership on an entity's Board of Directors or advisory committees; Actinnum: Membership on an entity's Board of Directors or advisory committees. Gill: Interius Biotherapeutics: Current holder of stock options in a privately-held company, Research Funding; Novartis: Other: licensed intellectual property, Research Funding; Carisma Therapeutics: Current holder of stock options in a privately-held company, Research Funding. Rivière: FloDesign Sonics: Other: Provision of Services; Centre for Commercialization of Cancer Immunotherapy: Other: Provision of Services; Fate Therapeutics: Other: Provision of Services, Patents & Royalties; The Georgia Tech Research Corporation (GTRC): Other: Provision of Services (uncompensated); Juno Therapeutics: Patents & Royalties. Porter: Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; Wiley and Sons Publishing: Honoraria; Tmunity: Patents & Royalties; Novartis: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; ASH: Membership on an entity's Board of Directors or advisory committees; DeCart: Membership on an entity's Board of Directors or advisory committees; Genentech: Current equity holder in publicly-traded company, Ended employment in the past 24 months; American Society for Transplantation and Cellular Therapy: Honoraria; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees. Schuster: Abbvie: Consultancy, Research Funding; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; Adaptive Biotechnologies: Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; DTRM: Research Funding; Genetech: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Incyte: Research Funding; Juno Theraputics: Consultancy, Research Funding; Loxo Oncology: Consultancy; Merck: Research Funding; Nordic Nanovector: Consultancy; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Pharmaclcyclics: Research Funding; Tessa Theraputics: Consultancy; TG Theraputics: Research Funding. Sadelain: NHLBI Gene Therapy Resource Program: Other: Provision of Services (uncompensated); Fate Therapeutics: Other: Provision of Services (uncompensated), Patents & Royalties; Atara Biotherapeutics: Patents & Royalties; Ceramedix: Patents & Royalties; Mnemo Therapeutics: Patents & Royalties; Takeda Pharmaceuticals: Other: Provision of Services, Patents & Royalties; St. Jude Children's Research Hospital: Other: Provision of Services; Juno Therapeutics: Patents & Royalties; Minerva Biotechnologies: Patents & Royalties. Frey: Novartis: Research Funding; Kite Pharma: Consultancy; Sana Biotechnology: Consultancy; Syndax Pharmaceuticals: Consultancy. Brentjens: Gracell Biotechnologies, Inc: Consultancy, Ended employment in the past 24 months; BMS: Consultancy, Patents & Royalties, Research Funding; sanofi: Patents & Royalties; Caribou: Patents & Royalties. June: AC Immune, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Consultancy; Novartis: Patents & Royalties; Tmunity, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Current equity holder in publicly-traded company. Pamer: Diversigen: Other: Advisory board; Bristol Myers Squibb, Celgene, Seres Therapeutics, MedImmune, Novartis and Ferring Pharmaceuticals: Honoraria. Peled: DaVolterra: Consultancy; MaaT Pharma: Consultancy; CSL Behring: Consultancy; Seres Therapeutics: Research Funding. Ruella: BMS, BAYER, GSK: Consultancy; Novartis: Patents & Royalties; AbClon: Consultancy, Research Funding; Tmunity: Patents & Royalties; viTToria biotherapeutics: Research Funding. van den Brink: WindMILTherapeutics: Honoraria; Pluto Therapeutics: Current holder of stock options in a privately-held company, Other: has consulted, received honorarium from or participated in advisory boards ; Priothera: Research Funding; Forty-Seven, Inc.: Honoraria; MagentaTherapeutics: Honoraria; GlaskoSmithKline: Other: has consulted, received honorarium from or participated in advisory boards; Ceramedix: Other: has consulted, received honorarium from or participated in advisory boards ; Merck & Co, Inc: Honoraria; Synthekine (Spouse): Other: has consulted, received honorarium from or participated in advisory boards; Kite Pharmaceuticals: Other; Amgen: Honoraria; Frazier Healthcare Partners: Honoraria; Seres: Other: Honorarium, Intellectual Property Rights, Research Fundingand Stock Options; Rheos: Honoraria; Therakos: Honoraria; Jazz Pharmaceuticals: Honoraria; Notch Therapeutics: Honoraria; Nektar Therapeutics: Honoraria; Wolters Kluwer: Patents & Royalties; Juno Therapeutics: Other; DKMS (nonprofit): Other; Pharmacyclics: Other; Da Volterra: Other: has consulted, received honorarium from or participated in advisory boards; Novartis (Spouse): Other: has consulted, received honorarium from or participated in advisory boards; Lygenesis: Other: has consulted, received honorarium from or participated in advisory boards .

We studied the effect of HLA-C matching in 515 patients after double umbilical cord blood (UCB) transplantation. After HLA matching HLA-A, -B, and -DRB1 at the allele level, we scored patients according to number of donor-recipient HLA-C matches at 4 possible loci: 2 from each donor unit, at the allele level. Given a direct interaction between HLA-A, -B, and -DRB1 matching and HLA-C score, we analyzed HLA-C matching in those receiving at least 1 2/6 to 4/6 HLA–matched unit (n = 389) versus those receiving only 5/6 or 6/6–matched units (n = 126). In those with at least 1 2/6 to 4/6 HLA–matched unit, a better HLA-C matching score was associated with significantly lower risk of death of any cause and nonrelapse mortality and better disease-free survival. There was no association with the risk of relapse, acute and chronic graft-versus-host disease, and hematopoietic recovery. In contrast, among patients receiving only allele-level 5/6 or 6/6 HLA–matched UCB units, HLA-C match had no demonstrable effect on any outcome. For patients receiving at least 1 allele-level 2/6 to 4/6 HLA–matched UCB unit, matching at HLA-C reduces nonrelapse mortality and improves survival.

Introduction: High-grade B cell lymphoma (HGBCL) with rearrangements of MYC in addition to either BCL2 or BCL6 (DHL) generally has a poor prognosis for response to conventional therapies. Nevertheless, current studies of responses to anti-CD19 CAR-T cell therapies (CAR-T) have not demonstrated poorer overall response rates (ORR) in patients with DHL (Locke Lancet Oncol 2019, Schuster NEJM 2019). Double expressor diffuse large B-cell lymphoma (DEL), which lacks the chromosomal rearrangements of DHL but overexpresses MYC and BCL2 proteins by immunohistochemistry, has been similarly associated with poor outcomes, including after autologous and allogeneic stem cell transplantation (Herrera JCO 2017; Kawashima Biol Blood Marrow Transplant, 2018). DEL and DHL each have a different cell of origin and biology; DEL is typically activated B cell-like phenotype, whereas DHL typically have germinal center-like phenotype. To our knowledge, the association of DEL and outcomes with CAR-T has not been assessed. We aimed to assess whether DEL is associated with outcome after CAR-T. Methods: We retrospectively reviewed the records of 75 consecutive patients with aggressive B-cell lymphomas treated with commercial CAR-T therapy at the University of Pennsylvania between April 2018 and October 2019. We included all patients with either diffuse large B cell lymphoma or HGBCL who had both: a) fluorescence in situ hybridization testing for MYC, BCL2 and BCL6 chromosomal rearrangements, and b) immunohistochemical staining (IHC) for MYC and BCL2. Patients who had both MYC and BCL2 and/or BCL6 chromosomal rearrangements were classified as DHL; patients with IHC expression of both MYC in > 40% and BCL2 in > 50% of tumor cells without meeting criteria for DHL were classified as DEL. Patient characteristics were collected. Fisher's exact test was used to compare overall response rate (ORR) and log-rank test was used for comparison of progression-free survival (PFS). Results: Seventy-five eligible cases of aggressive B-cell lymphoma were identified; 9 were excluded due to non-DLBCL or HGBCL subtype and 16 were excluded due to insufficient characterization of tissue to assess DHL and DEL status. Fifty patients were eligible for analysis; 18 patients (36%) met criteria for DEL, 10 patients (20%) met criteria for DHL, and the remaining 44% of patients had neither DEL nor DHL (non-DEL/DHL). Tisagenlecleucel was administered to 39 patients, whereas axicabtagene ciloleucel was administered to 11 patients. Median age at leukapheresis was 65 years (range: 35-81). LDH, administration of bridging therapy, and ECOG performance status (PS) did not significantly differ between the three groups. Median follow-up for the entire cohort was 15.9 months. For all patients, best ORR was 54% (27/50 patients), median PFS was 3.7 months (95%CI: 2.8-NE), and median OS was not reached. Best ORR was 56% (10/18) for DEL patients, 50% (5/10) for DHL patients, and 55% (12/22) for patients with non-DEL/DHL. ORR did not differ between these groups (p=1.0). There was no difference in PFS (see Figure, p=0.90), OS (p=0.61), or RD (p=0.38) between the three groups. At 16 months, 69% of responding DEL continue in CR (95%CI: 30-89%), 72% of non-DEL/DHL (95%CI: 35-90%) continue in CR, and 100% of DHL (95%CI: NE) continue in CR. Conclusions: The proportion of patients with DEL in our study was similar to that reported for patients with diffuse large B-cell lymphoma in the literature. There were no significant differences between DEL, DHL, and non-DEL/DHL groups with regard to the proportion of patients with elevated LDH, bridging therapy, or ECOG PS. Although DHL and DEL have a negative prognostic impact on response to salvage therapies and hematopoietic stem cell transplant, neither DHL nor DEL status was associated with inferior response to anti-CD19 commercial CAR-T products. We demonstrate that patients with DEL can achieve prolonged responses after CAR-T. Moreover, neither DEL nor DHL status appeared to impact PFS, OS, or RD outcomes after commercial CAR-T. Figure Disclosures Chong: BMS: Membership on an entity's Board of Directors or advisory committees; Tessa: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; KITE Pharma: Membership on an entity's Board of Directors or advisory committees. Landsburg:Curis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Triphase: Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Speakers Bureau; Takeda: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees. Gerson:Loxo: Research Funding; Genentech: Consultancy; Pharmacyclics: Consultancy; Abbvie: Consultancy. Svoboda:Atara: Consultancy; Genmab: Consultancy; TG: Research Funding; Adaptive: Consultancy; Astra-Zeneca: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Imbrium: Consultancy; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Merck: Research Funding; Incyte: Research Funding. Dwivedy Nasta:Merck: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; Debiopharm: Research Funding; Forty Seven: Research Funding; Incyte: Research Funding; Atara: Research Funding; Rafael Pharmaceuticals: Research Funding. Barta:Atara: Honoraria; Pfizer: Honoraria; Janssen: Honoraria; Seattle Genetics: Honoraria, Research Funding; Monsanto: Consultancy. Garfall:Novartis: Research Funding; Tmunity: Consultancy, Other: Personal fees, Research Funding; Amgen: Research Funding; Kite Pharma: Other: Personal fees; Janssen: Consultancy, Research Funding; GSK: Consultancy; Surface Oncology: Consultancy. Ruella:UPenn/Novartis: Patents & Royalties; Abclon, BMS, NanoString: Consultancy; Abclon: Consultancy, Research Funding. Frey:Amgen: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria; Syntax: Consultancy, Honoraria. Porter:Incyte: Other: Advisory board; Novartis: Honoraria, Other: Advisory board, Patents & Royalties: CAR T cells for CD19+ malignancies, Research Funding; Janssen: Other: Advisory board; Genentech/Roche: Current equity holder in publicly-traded company, Other: Spouse employment (ended Sept 2020); her salary includes stock/options; Glenmark: Other: Advisory board; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; American Board of Internal Medicine: Other: Member, exam writing committee (end date Oct 2019); Tmunity: Patents & Royalties; Adicet bio: Other: Advisory board; Kite/Gilead: Other: Advisory board. Schuster:AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria; Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding.

Allogeneic hematopoietic cell transplantation and donor lymphocyte infusion for multiple myeloma (MM) can induce graft-versus-myeloma immunity and long-term survivorship, but limited efficacy and associated toxicities have prevented its widespread use. Cellular immunotherapies and vaccines seek to induce more specific, reliable, and potent antimyeloma immune responses with less treatment-related risk than is possible with allogeneic transplantation. Advances in molecular biology, and basic and applied immunology, have led to promising approaches such as genetically engineered T cells with chimeric antigen receptors and T-cell receptors targeting myeloma-specific epitopes, vaccine primed ex vivo expanded autologous T cells, expanded marrow-infiltrating lymphocytes, and plasma cell/dendritic cell fusion vaccines. The addition of these emerging therapies to immunomodulatory drugs and inhibitors of programmed death-1 T-cell regulatory pathways are poised to improve outcome for our patients with myeloma.

PURPOSE Cardiovascular adverse events (CVAEs) can occur during proteasome inhibitor (PI) therapy. We conducted a prospective, observational, multi-institutional study to define risk factors and outcomes in patients with multiple myeloma (MM) receiving PIs. PATIENTS AND METHODS Patients with relapsed MM initiating carfilzomib- or bortezomib-based therapy underwent baseline assessments and repeated assessments at regular intervals over 6 months, including cardiac biomarkers (troponin I or T, brain natriuretic peptide [BNP], and N-terminal proBNP), ECG, and echocardiography. Monitoring occurred over 18 months for development of CVAEs. RESULTS Of 95 patients enrolled, 65 received carfilzomib and 30 received bortezomib, with median 25 months of follow-up. Sixty-four CVAEs occurred, with 55% grade 3 or greater in severity. CVAEs occurred in 51% of patients treated with carfilzomib and 17% of those treated with bortezomib ( P = .002). Median time to first CVAE from treatment start was 31 days, and 86% occurred within the first 3 months. Patients receiving carfilzomib-based therapy with a baseline elevated BNP level higher than 100 pg/mL or N-terminal proBNP level higher than 125 pg/mL had increased risk for CVAE (odds ratio, 10.8; P < .001). Elevated natriuretic peptides occurring mid–first cycle of treatment with carfilzomib were associated with a substantially higher risk of CVAEs (odds ratio, 36.0; P < .001). Patients who experienced a CVAE had inferior progression-free survival (log-rank P = .01) and overall survival (log-rank P < .001). PI therapy was safely resumed in 89% of patients, although 41% required chemotherapy modifications. CONCLUSION CVAEs are common during PI therapy for relapsed MM, especially with carfilzomib, particularly within the first 3 months of therapy. CVAEs were associated with worse overall outcomes, but usually, discontinuation of therapy was not required. Natriuretic peptides were highly predictive of CVAEs; however, validation of this finding is necessary before uniform incorporation into the routine management of patients receiving carfilzomib.

BACKGROUND. CAR T cells are a promising therapy for hematologic malignancies. B cell maturation antigen (BCMA) is a rational target in multiple myeloma (MM). METHODS. We conducted a phase I study of autologous T cells lentivirally transduced with a fully human, BCMA-specific CAR containing CD3ζ and 4-1BB signaling domains (CART-BCMA), in subjects with relapsed/refractory MM. Twenty-five subjects were treated in 3 cohorts as follows: cohort 1, 1 × 108 to 5 × 108 CART-BCMA cells alone; cohort 2, cyclophosphamide (Cy) 1.5 g/m2 plus 1 × 107 to 5 × 107 CART-BCMA cells; cohort 3, Cy 1.5 g/m2 plus 1 × 108 to 5 × 108 CART-BCMA cells. No prespecified BCMA expression level was required. RESULTS. CART-BCMA cells were manufactured and expanded in all subjects. Toxicities included cytokine release syndrome and neurotoxicity, which were grade 3–4 in 8 (32%) and 3 (12%) subjects, respectively, and reversible. One subject died at day 24 from candidemia and progressive myeloma, following treatment for severe cytokine release syndrome and encephalopathy. Responses (based on treated subjects) were seen in 4 of 9 (44%) in cohort 1, 1 of 5 (20%) in cohort 2, and 7 of 11 (64%) in cohort 3, including 5 partial, 5 very good partial, and 2 complete responses, 3 of which were ongoing at 11, 14, and 32 months. Decreased BCMA expression on residual MM cells was noted in responders; expression increased at progression in most. Responses and CART-BCMA expansion were associated with CD4/CD8 T cell ratio and frequency of CD45RO–CD27+CD8+ T cells in the premanufacturing leukapheresis product. CONCLUSION. CART-BCMA infusions with or without lymphodepleting chemotherapy are clinically active in heavily pretreated patients with MM. TRIAL REGISTRATION. {"type":"clinical-trial","attrs":{"text":"NCT02546167","term_id":"NCT02546167"}}NCT02546167. FUNDING. University of Pennsylvania-Novartis Alliance and NIH.

Background Multiple myeloma is usually fatal due to serial relapses that become progressively refractory to therapy. CD19 is typically absent on the dominant multiple myeloma cell population but may be present on minor subsets with unique myeloma-propagating properties. To target myeloma-propagating cells, we clinically evaluated autologous T cells transduced with a chimeric antigen receptor (CAR) against CD19 (CTL019). Methods Subjects received CTL019 following salvage high-dose melphalan and autologous stem cell transplantation (ASCT). All subjects had relapsed/refractory multiple myeloma and had previously undergone ASCT with less than 1 year progression-free survival (PFS). Results ASCT + CTL019 was safe and feasible, with most toxicity attributable to ASCT and no severe cytokine release syndrome. Two of 10 subjects exhibited significantly longer PFS after ASCT + CTL019 compared with prior ASCT (479 vs. 181 days; 249 vs. 127 days). Correlates of favorable clinical outcome included peak CTL019 frequency in bone marrow and emergence of humoral and cellular immune responses against the stem-cell antigen Sox2. Ex vivo treatment of primary myeloma samples with a combination of CTL019 and CAR T cells against the plasma cell antigen BCMA reliably inhibited myeloma colony formation in vitro, whereas treatment with either CAR alone inhibited colony formation inconsistently. Conclusion CTL019 may improve duration of response to standard multiple myeloma therapies by targeting and precipitating secondary immune responses against myeloma-propagating cells. Trial registration Clinicaltrials.gov identifier NCT02135406. Funding Novartis, NIH, Conquer Cancer Foundation.

e14513 Background: MUC1 is a glycoprotein that is expressed in healthy tissues on the luminal surface of simple and glandular epithelium. In tumors that arise from these cells, an alternate form with aberrant glycosylation is frequently over expressed and distinguishes tumor associated TnMUC1 from normal MUC1. We have generated a novel chimeric antigen receptor (CAR) targeting the TnMUC antigen comprised of a mouse anti-human scFv derived from the monoclonal antibody 5E5 which recognizes the epitope comprising Tn glycan of MUC1, a CD8a transmembrane region and dual CD2 and CD3z intracellular signaling domains. CD2 signaling in T-cells has been demonstrated to result in delayed exhaustion. The novel incorporation of this co-stimulatory domain may lead to enhanced persistence of the CART cells which is believed to be critical for efficacy in solid-tumors. Methods: This is a multi-center first in human Phase I study to evaluate the safety and preliminary efficacy of CART-TnMUC1-Cells for the treatment of solid-tumors. Solid-tumors included in the dose-escalation phase include metastatic treatment-resistant ovarian cancer (OC), pancreatic adenocarcinoma (PC), triple-negative breast cancer (TNBC) or non-small lung cancer (NSCLC). All patients must have TnMUC1 expression as determined by immunohistochemistry. Results: As of January 2021, a total of six patients were treated. Three in Cohort 1 (no lymphodepletion; dose = 1-2 x 107 TDN CART cells; tumors = 1 OC, 1 TNBC and 1 PC) and 3 in Cohort 2 (flu/cy lymphodepletion; dose = 1-2 x 107 TDN CART cells; tumors = 1 NSCLC and 2 OC). None of the patients treated experienced DLT’s. The trial is currently enrolling to Cohort 3 (flu/cy lymphodepletion, 5-6 x 107 TDN). No CRS, neurotoxicity, serious adverse reactions and no on-target/off-tumor toxicity was observed at these dose levels. The most common AE’s were low-grade GI symptoms (e.g., nausea, abdominal pain) in 5/6 patients (83.3%), generalized disorders (e.g., chills, fatigue) in 5/6 (83.3%) and hematologic disorders (e.g., anemia, neutropenia) in 3/6 (50%) of patients. CAR expansion was demonstrated in all patients and was improved in Cohort 2 following LD chemotherapy. Preliminary efficacy assessed by RECIST v1.1 at Day +28 demonstrate SD in all patients in Cohort 2. Conclusions: This is the first report of a novel CART-TnMUC1 construct containing a CD2 co-stimulatory domain that has been used in clinical trials for the treatment of refractory solid-tumor malignancies. While the study is still early in dose-escalation having completed only 2 of 6 planned dose levels there is no evidence of safety concerns or on-target/off-tumor toxicity. Additional safety, efficacy and biomarker data is currently being reviewed and will be presented. Clinical trial information: NCT04025216.

8007 Background: BCMA-targeted immunotherapies offer considerable promise for relapsed/refractory MM. Teclistamab (JNJ-64007957) is a BCMA × CD3 bispecific IgG4 antibody that redirects CD3+ T cells to BCMA-expressing MM cells. We present updated results of patients (pts) treated at the recommended phase 2 dose (RP2D) in the first-in-human phase 1 study of teclistamab. Methods: Eligible pts had MM and were relapsed, refractory or intolerant to established therapies. Primary objectives were to identify the RP2D (part 1) and characterize safety and tolerability of teclistamab at the RP2D (part 2). Teclistamab was given intravenously (IV; range 0.3–19.2 µg/kg [biweekly]; range 19.2–720 µg/kg [weekly]) or subcutaneously (SC; range 80.0–3000 µg/kg weekly) in different cohorts, with step-up dosing used for ≥38.4 µg/kg doses. Adverse events (AEs) were graded by CTCAE v4.03 (cytokine release syndrome [CRS] by Lee et al 2014). Response was assessed per IMWG criteria. Results: As of Feb 4, 2021, 156 pts received teclistamab (IV n = 84; SC n = 72). The RP2D, identified as weekly SC 1500 µg/kg teclistamab with 60.0 and 300 µg/kg step-up doses, was given to 40 pts (median follow-up 4.3 mo [range 1.1–10.4+]). Pts dosed at the RP2D (median age, 62.5 y [range, 39–84]; 65% male) had received a median of 5 prior lines of therapy (range 2–11; 100% triple-class exposed; 65% penta-drug exposed; 83% triple-class refractory; 35% penta-drug refractory; 85% refractory to their last line of therapy). There were no dose-limiting toxicities at the RP2D in part 1. The most common AEs at the RP2D were CRS (70%; grade 3/4 0) and neutropenia (60%; grade 3/4 40%); grade 1 neurotoxicity was reported in 1 (3%) pt. Median time to CRS onset was later with SC vs IV dosing (day after SC injection vs day of IV infusion). The overall response rate in response-evaluable pts treated at the RP2D (n = 40) was 65%; 58% achieved a very good partial response or better and 30% achieved a complete response (CR) or better; median time to first confirmed response was 1.0 mo (range 0.2–3.1). At the RP2D, median duration of response was not reached; 23 of 26 responders (88%), after median follow-up of 5.3 mo (range 1.2–10.4+), were alive and continuing on treatment with responses deepening over time. Of 14 evaluable pts across all cohorts, 9 with CR were minimal residual disease–negative at 10-6. At the RP2D, teclistamab exposure was sustained across the dosing interval and exceeded target levels, and consistent T cell activation was observed. Conclusions: Teclistamab at the RP2D (weekly 1500 µg/kg SC) was well-tolerated and showed encouraging efficacy with durable, deepening responses, supporting further investigation as monotherapy and in combination with other agents. With the extended exposure profile at the RP2D and delayed and low-grade CRS observed with SC administration, alternative SC dosing strategies are being explored. Clinical trial information: NCT03145181.

Background: MM inevitably relapses and becomes refractory to treatment, representing a patient (pt) population with unmet needs. Teclistamab (JNJ-64007957) is a bispecific BCMA x CD3 antibody that induces T cell-mediated cytotoxicity against BCMA-expressing MM cells. Previously presented results from an ongoing study of teclistamab in RRMM (NCT03145181) included a 67% objective response rate [ORR] for the 270 µg/kg dose administered intravenously (iv) (Usmani et al, ASCO 2020 Oral Presentation #100). Here we present updated results and newly available data for subcutaneous (sc) administration. Methods: Pts have MM that is RR to established therapies. The primary objective is to identify a recommended phase 2 dose(s) (RP2D). Multiple sc and iv doses ± step-up doses were explored. Adverse events (AEs) were graded per CTCAE v4.03 and cytokine release syndrome (CRS) per Lee et al 2014. Response was investigator-assessed using IMWG criteria; minimal residual disease (MRD) in bone marrow was assessed by next generation sequencing. Results: As of 20 Jul 2020, iv teclistamab (0.3-720 µg/kg) and sc teclistamab (20-3000 µg/kg) were received by 84 and 44 pts, respectively. Overall, median age was 64 y (24-82), median number of prior lines of therapies (LOT) was 6 (2-14), 95%/79% triple-class exposed/refractory, 70%/38% penta-drug exposed/refractory, and 91% refractory to last LOT. AEs in >20% of pts (both iv and sc combined) included anemia (55%), neutropenia (55%), thrombocytopenia (41%), and leukopenia (26%), as well as non-hematologic events of CRS (53%), pyrexia (28%), diarrhea (24%), cough (23%), fatigue (23%), nausea (22%), back pain (20%), and headache (20%). 39% of pts had treatment-related grade ≥3 AEs; neutropenia (23%) and anemia (9%) were most frequent. CRS occurred in 55% and 50% of pts with iv and sc dosing, respectively, tending to occur later (relative to the most recent dose) with sc administration (median time to onset of 1.0 day iv and 2.0 days sc). CRS events were all gr 1 (n=51) or 2 (n=17) and generally confined to initial doses. 5% of pts (all iv) had neurotoxicity (2% gr ≥3), and 12% had treatment-related infusion/injection related reaction (including 4 infusion reactions [all iv, 5%] and 11 injection related reactions [all sc, 25%], all gr 1/2). Gr 3 or higher infection-related AEs were reported in 15% of pts (3% treatment related). Four gr 5 AEs were reported (all iv and considered unrelated to treatment by investigator except for 1 case of pneumonia). Pharmacokinetic results showed that the half-life of teclistamab supports weekly iv dosing. Exposure increased in an approximately dose-proportional manner following weekly iv or sc treatment dosing. 1500 µg/kg sc dose had comparable Cmax to that of 270 µg/kg iv and higher trough levels than that of 720 µg/kg iv. Individual time to reach Cmax following sc dosing ranged from Day 3 - Day 8. Teclistamab treatment in both iv and sc cohorts led to pharmacodynamic changes supporting mechanism of action, including increases in T cell activation and circulating cytokine levels, such as IL-10, IL-2Ra and IL-6. 120 pts were evaluable for response, with the highest and most active dose levels of 270 µg/kg and 720 µg/kg weekly for iv and 720 µg/kg and 1500 µg/kg weekly for sc (of note, response data for 3000 µg/kg sc is not yet mature). Combining these 4 iv and sc dose levels, ORR was 30/47 (63.8%, including n=24 with very good partial response [VGPR] or better and n=9 with complete response [CR] or better). 1500 µg/kg sc was selected as a RP2D, and currently at this dose, 6 of 6 pts are in response (3 PR, 1 VGPR, 2 stringent CR) with progressive deepening of responses over time. Among 48 pts with responses across all iv and sc cohorts, median time to first response was 1 mo (range, 0.3-4.2) and median duration of response has not been reached, with 38 responding pts remaining on therapy 1.6 to 21.3+ months. Of MRD-evaluable pts who had a CR, 4/5 pts treated in the iv cohorts and 2/2 pts in the sc cohorts are MRD negative at 10-6. Conclusions: Teclistamab has a manageable safety profile, which includes low-grade CRS (with no gr ≥3 events) and low severe infection and neurotoxicity rates with both iv and sc administration. Deep and durable responses were observed with both iv and sc administration. The encouraging tolerability and efficacy of teclistamab support the planned phase 2 monotherapy (at 1500 µg/kg sc) trial and future combination studies. Disclosures Garfall: Tmunity: Consultancy, Other: Personal fees, Research Funding; Kite Pharma: Other: Personal fees; Amgen: Research Funding; Novartis: Research Funding; GSK: Consultancy; Janssen: Consultancy, Research Funding; Surface Oncology: Consultancy. Usmani:Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Incyte: Research Funding; SkylineDX: Consultancy, Research Funding; GSK: Consultancy, Research Funding; Celgene: Other; Amgen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Array Biopharma: Research Funding; Abbvie: Consultancy; BMS, Celgene: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Takeda: Consultancy, Honoraria, Other: Speaking Fees, Research Funding. Mateos:Adaptive: Consultancy; Amgen: Consultancy; GlaxoSmithKline: Consultancy; Pharmamar: Consultancy; Janssen: Consultancy; Celgene: Consultancy; EDOMundipharma: Consultancy; AbbVie: Consultancy; Takeda: Consultancy. van de Donk:Bayer: Membership on an entity's Board of Directors or advisory committees; Amgen: 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; Novartis: Membership on an entity's Board of Directors or advisory committees; Ferrer: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding. San-Miguel:Amgen, BMS, Celgene, Janssen, MSD, Novartis, Takeda, Sanofi, Roche, Abbvie, GlaxoSmithKline and Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees. Oriol Rocafiguera:Amgen: Consultancy, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Chari:Seattle Genetics: Consultancy, Research Funding; Karyopharm: Consultancy; Bristol Myers Squibb: Consultancy; Pharmacyclics: Research Funding; Array BioPharma: Honoraria; The Binding Site: Honoraria; Sanofi Genzyme: Consultancy; Adaptive Biotechnology: Honoraria; Novartis: Honoraria; Takeda: Consultancy, Research Funding; Antengene: Consultancy; Amgen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Secura Bio: Consultancy; Glaxo Smith Kline: Consultancy; Oncopeptides: Consultancy. Bhutani:Prothena: Other: Clinical Trial Funding to Institute; Janssen: Other: Clinical Trial Funding to Institute; Takeda: Other: Clinical trial funding to institute, Speakers Bureau; Amgen: Speakers Bureau; BMS: Other: Clinical trial funding to institute, Speakers Bureau; Sanofi Genzyme: Consultancy; MedImmune: Other: Clinical Trial Funding to Institute. Pei:J&J: Current Employment, Current equity holder in publicly-traded company. Verona:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Girgis:Johnson & Johnson: Current Employment, Current equity holder in private company. Stephenson:Johnson & Johnson: Current Employment, Current equity holder in private company. Goldberg:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Banerjee:Janssen: Current Employment. Krishnan:BMS/Celgene: Consultancy, Other: Stock BMS, Speakers Bureau; Janssen: Consultancy; Takeda: Speakers Bureau; Z Predicta: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; Sanofi: Consultancy; Sutro: Membership on an entity's Board of Directors or advisory committees; Regeneron: Consultancy.

OBJECTIVES/GOALS: We aim to identify and characterize anti-Sox2-specific CD8+ T cell responses in stable MUGS patients expressing HLA class I alleles-A*02:01 and /or -B*07:02. METHODS/STUDY POPULATION: Cross sectional study of patients with stable MGUS defined as stable serum paraprotein for ≥ 12 months from the MM Research Clinic at the Abramson Cancer Institute. Sox2 T cell reactivity will be assessed by IFN-γ ELISPOT assays. Rested PBMC will be pulsed with candidate Sox2-derived peptides predicted to display high affinity to HLA class I alleles and known to be processed and presented as determined by “targeted MS/MS” (mass spectrometry). The presence of anti-Sox2-specific CD8+ T cells will be confirmed in peptide/HLA multimer assays using flow cytometry. Anti-Sox2-specific CD8+ T cells will be characterized for HLA restriction and TCR αβ composition. RESULTS/ANTICIPATED RESULTS: Our work is still in progress. From Aug to Dec 2019, 22 MGUS subjects have been analyzed, 11 of which were found to have the HLA of interest. Positive Sox-2 reactivity by ELISpot was found in 3 subjects. DISCUSSION/SIGNIFICANCE OF IMPACT: Anti-Sox2 immune responses may maintain MGUS in a clinical indolent state by eliminating Sox2-expressing clonogenic MM cells. A detailed characterization of anti-Sox2 T cells followed by in-vivo assessment of their anti-myeloma activity could provide the foundation for a Sox2 based immunotherapy approach in MM.

100 Background: Teclistamab (JNJ-64007957) is a bispecific BCMA x CD3 antibody that induces T cell-mediated cytotoxicity against BCMA-expressing myeloma cells. Initial results from an ongoing study of teclistamab in RRMM (NCT03145181) are presented. Methods: Pts have MM and are RR to standard therapies. Primary objective for part 1 is to identify a recommended phase 2 dose(s). Multiple intravenous (iv) doses ± priming doses were explored. Adverse events (AEs) were graded per CTCAE v4.03 and cytokine release syndrome (CRS) per Lee et al 2014. Response was investigator-assessed using IMWG criteria; minimal residual disease (MRD) in bone marrow was assessed by next generation sequencing. Results: As of 31 Jan 2020, 66 pts had received iv teclistamab (0.3–270 µg/kg). Median age was 64 y (24–82), median prior therapies was 6 (2–14), 97% triple-class exposed, 83% triple-class refractory, and 38% penta-drug refractory. Most common treatment-related AEs (all grade) were CRS (56%), neutropenia (26%), and anemia (23%). CRS events were all grade 1–2 and generally confined to initial doses. 8% of pts had treatment-related neurotoxicity (3% grade ≥3), and 9% had infusion related reaction. Infection-related AEs were reported in 61% of pts (21% grade ≥3). 2 dose-limiting toxicities were reported: grade 4 delirium (resolved after 16 days) and grade 4 thrombocytopenia (resolved after 1 day). 36% of pts had treatment-related grade ≥3 AEs; neutropenia (20%) and anemia (14%) were most frequent. Only 1 grade 5 AE was reported (respiratory failure in the setting of pneumonia deemed unrelated by the investigator). PK results indicate that the half-life of teclistamab supports weekly dosing. On-target pharmacodynamic activity (T cell redistribution and activation along with transient release of cytokines) was observed at doses ≥9.6 µg/kg. Cytokine production was modulated with step-up dosing while T cell activation was maintained. 65 pts were evaluable for response. Activity was observed starting at treatment doses ≥38.4 µg/kg, with 20/52 (38%) pts achieving a response. At the highest dose, 7/9 (78%) pts responded (1 response pending confirmation). Of MRD-evaluable pts who had complete response, 2/2 were MRD negative at 10−6 with treatment ongoing > 12 mo. Conclusions: Teclistamab has manageable safety across all doses explored. A 78% overall response rate was observed at the highest weekly treatment dose in pts with advanced RRMM, supporting further evaluation of teclistamab in expansion cohorts. Clinical trial information: NCT03145181.

Multiple myeloma (MM) is a plasma cell malignancy characterized by impaired immune surveillance mechanisms, such as altered antibody production, dysregulation of T cell and natural killer cell proliferation and activation, disruption of antigen presentation processes, and upregulation of checkpoint and immunosuppressive mediators. New and emerging immunotherapeutic agents, such as chimeric antigen receptor (CAR)-engineered T-cell therapies, vaccines, antibody-based therapy, and checkpoint inhibitors, have been developed as a means to target evasion tactics of MM. Herein we summarize the proceedings of "Immunotherapy in Multiple Myeloma: Accelerating on the Path to the Patient," a workshop held in Havana, Cuba, with contributions from 18 expert hematologic oncologists from the United States, European Union, and Cuba, as well as patient advocacy and industry representatives. The goal of the workshop was to evaluate and discuss key topics and issues regarding development and use of immunotherapies in MM and to collaborate on improving patient outcomes. Clinical significance of recent advances in immunotherapies in MM were discussed, in addition to their current status and therapeutic potential, key issues from various regional perspectives, and opportunities for collaboration to improve MM patient outcomes. In this review we summarize expert presentations on cellular (CAR T cell, allogeneic stem cell transplantation, and vaccine) therapies, antibody-based (daratumumab, elotuzumab, checkpoint inhibitor, anti-cluster of differentiation 28 antibody) therapies, genomics and immunotherapy, and biomarkers of response.

Immunotherapy approaches seek to boost immune responses against cancer. A single antibody engineered to recognize three targets shows promise, when tested in animals, in improving the ability of T cells to target cancer. Trispecific antibody boosts T-cell responses targeting myeloma.

Importance Cardiovascular adverse events (CVAE) with carfilzomib in patients with multiple myeloma can be potentially life-threatening and remain incompletely characterized. We performed the first systematic review and meta-analysis of carfilzomib-associated CVAE. Objective To determine the incidence of carfilzomib-associated CVAE and to compare the rates of carfilzomib CVAE among different doses and companion therapies. Data Sources PubMed, EMBASE, Web of Science, and clinicaltrials.gov were queried for the keywords “carfilzomib,” “Kyprolis,” and “PX-171” through January 1, 2017. Study Selection Phase 1 to 3 prospective clinical trials of carfilzomib in patients with multiple myeloma with evaluable toxic effects data were eligible for meta-analysis. Data Extraction and Synthesis Data were independently extracted by 2 reviewers following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Pooled incidence rates and relative risks (for randomized trials) and 95% confidence intervals were calculated using a random effects model. Subgroup analyses were performed to assess study-level characteristics associated with CVAE. Main Outcomes and Measures Cardiovascular adverse events were defined as heart failure, hypertension, ischemia, and arrhythmia. All-grade and grades 3 or higher AEs and study characteristics were recorded. Results A total of 514 studies were assessed for eligibility. Of those, 24 studies were eligible, including a total of 2594 patients with multiple myeloma. All-grade and grades 3 and higher CVAE were seen in 617 (18.1%) and 274 (8.2%), respectively. Phase 2 or 3 studies and carfilzomib doses of 45 mg/m2or higher were associated with high-grade CVAE. Median age older than 65 years, prior myeloma therapies, and concurrent myeloma therapies were not associated with CVAE. For the 3 randomized clinical trials, the summary relative risk of all-grade and grade 3 or higher CVAE for patients receiving carfilzomib compared with noncarfilzomib-receiving control patients were 1.8 and 2.2, respectively. Conclusions and Relevance Carfilzomib was associated with a significant incidence of CVAE, with higher rates seen with higher doses of carfilzomib. Phase 1 studies may be underdetecting CVAE. Future studies are needed to identify patients at high risk for CVAE, develop optimal monitoring strategies, and explore strategies to mitigate these risks.

A patient with refractory multiple myeloma received an infusion of CTL019 cells, a cellular therapy consisting of autologous T cells transduced with an anti-CD19 chimeric antigen receptor, after myeloablative chemotherapy (melphalan, 140 mg per square meter of body-surface area) and autologous stem-cell transplantation. Four years earlier, autologous transplantation with a higher melphalan dose (200 mg per square meter) had induced only a partial, transient response. Autologous transplantation followed by treatment with CTL019 cells led to a complete response with no evidence of progression and no measurable serum or urine monoclonal protein at the most recent evaluation, 12 months after treatment. This response was achieved despite the absence of CD19 expression in 99.95% of the patient's neoplastic plasma cells. (Funded by Novartis and others; ClinicalTrials.gov number, NCT02135406.).

CD19-specific chimeric antigen receptor (CAR) T cell therapies have been highly effective against B cell malignancies. We previously demonstrated that differential responses to anti-CD19 CAR T cell therapy in chronic lymphocytic leukemia (CLL) are associated with early memory T cell signature in apheresed, pre-manufacturing T-cells (CAR T-cell precursors). We tested the hypothesis that the composition of CAR-T precursor cells determines clinical efficacy in adult and pediatric Acute Lymphoblastic Leukemia (ALL), Non-Hodgkin's Lymphoma (NHL), Multiple Myeloma (MM), and CLL. Apheresed T cells were engineered to express 4-1BB plus CD3-zeta-signaling CARs targeting CD19, or B cell maturation antigen (BCMA). The same 9-day manufacturing process was used for all trials. CAR T cell kinetics were monitored using a CAR gene-specific quantitative PCR assay and standard clinical response assessments were performed. Apheresed T cells from 36 CLL, 30 adult ALL, 58 pediatric ALL, 33 NHL, and 25 MM patients were immunophenotyped by flow cytometry. The CLL cohort was used to discover phenotypically distinct subpopulations associated with the two main response groups; these associations were validated in the remaining patient cohorts. Eight CD8+ T cell populations or clusters were identified using the shared-nearest-neighbor clustering method (PMID: 31178118) in the CLL cohort. T cell subsets exhibiting naive (cluster 6) or early memory (cluster 4) features were significantly enriched in responding patients, whereas an effector memory CD8 subpopulation (cluster 2) marked the non-responding patients. Mapping these clusters onto apheresed CD8+ T cells from the other four diseases showed that cluster 4 predicted response to CAR T cell therapy in NHL and myeloma but not in adult and pediatric ALL. We also examined the expression of activation-regulated molecules including HLA-DR, Ki67, and exhaustion-related molecules PD1, CTLA4, TIM3, and LAG3. A CD27+ CD8+ population expressing low level CTLA4 but none of the activation or negative regulatory molecules was significantly enriched in responding CLL patients; this cluster validated in NHL and myeloma. A similar analysis on apheresed CD4+ T cells identified an early memory population (cluster 6) enriched in CLL responders, which expresses CCR7 and CD27 but not CD45RO, CD127, CD28, or other late memory/effector molecules. However, this population did not validate in any of the other diseases. Though not statistically significant, the CD4+ clusters with the largest effect size for enrichment in responders from NHL and myeloma trials exhibited early memory T cell features and lack of HLA-DR expression, suggesting that quiescent early memory state in CD4 may also be associated with clinical responses. A separate analysis of checkpoint inhibitory receptors and activation markers in memory CD4 T cell subsets confirmed the early memory, non-activated state of this population in CLL and was validated in myeloma but none of the other diseases. In vivo activation was a shared theme in CD4+ T cells for non-responding patients as well, though these CLL-defined CD4+ apheresed T cells clusters did not significantly validate in other diseases. In summary, our data confirm and extend our predictive biomarker profile in CLL to mature B cell and plasma cell malignancies by showing that a non-cycling, non-activated early memory CD8+ T cell population in pre-manufacturing cells was validated as a biomarker in myeloma, and NHL. We also showed that responder-associated apheresed CD4+ T cells with early memory features identified in CLL after CD19 CAR T infusions are validated in myeloma after BCMA CAR T. Thus, differentiation state and in vivo activation, and potentially exhaustion, separate response groups. Our findings inform next-generation CAR T-cell manufacturing using the populations identified herein as a starting population. Disclosures Pruteanu: Novartis: Employment. Cohen:Poseida Therapeutics, Inc.: Research Funding. Garfall:Surface Oncology: Consultancy; Novartis: Research Funding; Janssen: Research Funding; Amgen: Research Funding; Tmunity: Research Funding. Milone:Novartis: Patents & Royalties: patents related to tisagenlecleucel (CTL019) and CART-BCMA; Novartis: Research Funding. Gill:Novartis: Research Funding; Tmunity: Research Funding; Carisma: Equity Ownership, Research Funding; Sensei: Consultancy; Aro: Consultancy; Fate: Consultancy. Frey:Novartis: Research Funding. Ruella:Nanostring: Consultancy, Speakers Bureau; Novartis: Patents & Royalties: CART for cancer; AbClon: Membership on an entity's Board of Directors or advisory committees. Lacey:Novartis: Patents & Royalties: Patents related to CAR T cell biomarkers; Tmunity: Research Funding; Novartis: Research Funding. Svoboda:Merck: Research Funding; BMS: Consultancy, Research Funding; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; Celgene: Research Funding; Kite: Consultancy; Seattle Genetics: Consultancy, Research Funding; Kyowa: Consultancy; AstraZeneca: Consultancy. Chong:Tessa: Consultancy; Novartis: Consultancy; Merck: Research Funding. Fraietta:LEK Consulting: Consultancy; Cabaletta: Research Funding; Tmunity: Research Funding. Davis:Cabaletta: Research Funding; Tmunity: Research Funding. Nasta:Rafael: Research Funding; Aileron: Research Funding; Takeda/Millennium: Research Funding; Incyte: Research Funding; Roche/Genentech: Research Funding; Merck: Consultancy; Atara: Research Funding; Debiopharm: Research Funding. Levine:CRC Oncology: Consultancy; Vycellix: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership; Novartis: Consultancy, Patents & Royalties, Research Funding; Cure Genetics: Consultancy; Avectas: Membership on an entity's Board of Directors or advisory committees; Brammer Bio: Membership on an entity's Board of Directors or advisory committees; Incysus: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy. Maude:Kite: Consultancy; Novartis: Consultancy. Schuster:Nordic Nanovector: Honoraria; Pfizer: Honoraria; AstraZeneca: Honoraria; Pharmacyclics: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Loxo Oncology: Honoraria; Merck: Honoraria, Research Funding; Acerta: Honoraria, Research Funding; Novartis: Honoraria, Patents & Royalties: Combination Therapies of CAR and PD-1 Inhibitors with royalties paid to Novartis, Research Funding; AbbVie: Honoraria, Research Funding; Gilead: Honoraria, Research Funding. Stadtmauer:Celgene: Consultancy; Tmunity: Research Funding; Novartis: Consultancy, Research Funding; Takeda: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Abbvie: Research Funding. Grupp:Novartis: Consultancy, Research Funding; Roche: Consultancy; GSK: Consultancy; Cure Genetics: Consultancy; Humanigen: Consultancy; CBMG: Consultancy; Novartis: Research Funding; Kite: Research Funding; Servier: Research Funding; Jazz: Other: study steering committees or scientific advisory boards; Adaptimmune: Other: study steering committees or scientific advisory boards. Porter:Incyte: Membership on an entity's Board of Directors or advisory committees; American Board of Internal Medicine: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Glenmark Pharm: Membership on an entity's Board of Directors or advisory committees; Immunovative: Membership on an entity's Board of Directors or advisory committees; Genentech: Employment; Wiley and Sons: Honoraria; Novartis: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. June:Novartis: Research Funding; Tmunity: Other: scientific founder, for which he has founders stock but no income, Patents & Royalties. Melenhorst:Novartis: Research Funding, Speakers Bureau; Parker Institute for Cancer Immunotherapy: Research Funding; Stand Up to Cancer: Research Funding; Incyte: Research Funding; IASO Biotherapeutics, Co: Consultancy; Simcere of America, Inc: Consultancy; Shanghai Unicar Therapy, Co: Consultancy; Colorado Clinical and Translational Sciences Institute: Membership on an entity's Board of Directors or advisory committees; Genentech: Speakers Bureau; National Institutes of Health: Research Funding.

BACKGROUND: Anti-BCMA CAR T cells are effective in relapsed/refractory multiple myeloma (RRMM), but most patients eventually progress. Extensive prior therapy and high disease burden in RRMM pts may compromise CAR T cell safety, feasibility, and efficacy, and rare BCMA-neg/CD19+ MM cells with enhanced clonogenic potential may mediate relapse after anti-BCMA CARs. We therefore initiated a trial of anti-BCMA CAR T cells (CART-BCMA) as consolidation of response to prior MM therapy, including high-risk (HR) pts responding to first-line therapy, and combined CART-BCMA with anti-CD19 CAR T cells (CTL119). Both CART-BCMA and CTL119 are 4-1BB/CD3z-based CARs transduced via lentiviral vector. CART-BCMA was previously reported (Cohen et al JCI 2019) and exhibited 64% response rate at 5x108 cell dose following cyclophosphamide (cy) alone as lymphodepleting chemo in RRMM. CTL119 is a humanized version of tisagenlecleucel. METHODS: To assess safety/feasibility of CART-BCMA + CTL119, Phase A (PhA) is evaluating the combination in pts responding (≥MR) to ≥3rd line therapy (or ≥2nd line if exposed to all major agents). After early PhA results showed no excessive toxicity, Phase B (PhB) began enrolling HR pts (R-ISS 3, complex karyotype, PC leukemia, or RESULTS: 6/7 enrolled PhA pts were infused; 1 pt died due to CNS progression before infusion. 4/4 enrolled PhB pts were infused (2 CART-BCMA alone, 2 CART-BCMA + CTL119). See table for age & prior # therapies; 9/10 had HR cytogenetics or were R-ISS 3. Regarding mfg feasibility, 2 PhA pts (05, 07) failed to meet full target doses; all 4 PhB pts achieved full dose. Two subjects (01, 03) had the 3rd (60%) dose held due to early fevers. CRS was gr 0-2 by ASTCT criteria and was observed in pts with both high and low disease burden (table). No neurologic toxicity was observed. Gr 3-4 toxicities were mainly hematologic; 3/6 PhA pts had either ANC CONCLUSIONS: Preliminary results support safety and high initial response-rate of CART-BCMA + CTL119 after cy/flu in MM. In pts with low disease burden responding to prior therapy, including first-line therapy, CAR T cells expanded in vivo and generated clinical responses with low-grade CRS and no neurotoxicity. Preliminarily, hematologic toxicity and feasibility of maint seem more favorable in first-line setting. Addition of CTL119 did not clearly prevent progression after CART-BCMA in the PhA population (3-9 prior lines); data from PhB with randomization +/- CTL119 are immature. Accrual is ongoing, and updated results will be presented at the meeting. Table. Disclosures Garfall: Surface Oncology: Consultancy; Novartis: Patents & Royalties: inventor on patents related to tisagenlecleucel (CTL019) and CART-BCMA, Research Funding; Janssen: Research Funding; Amgen: Research Funding; Tmunity: Honoraria, Research Funding. Cohen:Poseida Therapeutics, Inc.: Research Funding. Lacey:Novartis: Research Funding; Tmunity: Research Funding; Novartis: Patents & Royalties: Patents related to CAR T cell biomarkers. Tian:Novartis: Research Funding. Hwang:Novartis: Research Funding; Tmunity: Research Funding. Vogl:Active Biotech: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Karyopharm Therapeutics: Consultancy; Takeda: Consultancy; Celgene: Consultancy. Lancaster:novartis: Research Funding. Nelson:Novartis: Research Funding. Ferthio:Novartis: Research Funding. Fesnak:Novartis: Research Funding. Melenhorst:National Institutes of Health: Research Funding; IASO Biotherapeutics, Co: Consultancy; Simcere of America, Inc: Consultancy; Incyte: Research Funding; Shanghai Unicar Therapy, Co: Consultancy; Colorado Clinical and Translational Sciences Institute: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding, Speakers Bureau; Stand Up to Cancer: Research Funding; Parker Institute for Cancer Immunotherapy: Research Funding; Genentech: Speakers Bureau. Young:novartis: Research Funding. Levine:Brammer Bio: Membership on an entity's Board of Directors or advisory committees; Vycellix: Membership on an entity's Board of Directors or advisory committees; Incysus: Membership on an entity's Board of Directors or advisory committees; Cure Genetics: Consultancy; Novartis: Consultancy; Novartis: Consultancy, Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership; CRC Oncology: Consultancy; Avectas: Membership on an entity's Board of Directors or advisory committees. Brogdon:Novartis: Employment. Isaacs:Novartis: Employment. June:Tmunity: Other: scientific founder, for which he has founders stock but no income, Patents & Royalties; Novartis: Research Funding. Milone:Novartis: Patents & Royalties, Research Funding. Stadtmauer:Amgen: Consultancy; Novartis: Consultancy, Research Funding; Tmunity: Research Funding; Abbvie: Research Funding; Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy.

Despite intense efforts, multiple myeloma remains incurable in most patients with the standard of care therapies. The plasma cell surface receptor B cell maturation antigen (BMCA) is highly expressed by myeloma cells and we recently demonstrated that 12 out of 25 heavily pretreated myeloma patients achieved a partial response or better after anti-BCMA CAR T cell treatment (VGPR, n=5; CR, n=1; sCR, n=1; Cohen et al., 2019, JCI 129(6):2210). To better understand the biological basis of this therapy, we identified key correlates of response using the pre-manufacturing apheresed T cells, the infusion product, and post-infusion T cells from the 25 patients in this cohort. As reported before, the disease characteristics, tumor burden, and CAR transduction efficiency did not correlate with therapy response. CAR T cell expansion, measured by the area under the curve of CAR qPCR in the first 21 days (AUC[0-21]), was highest in responding, lowest in non-responding patients (Jonckheere-Terpstra test, JT = 38, p=1.8x10^-6)(Fig.1A,B). Soluble BCMA, a biomarker of disease burden, shows a similar trend with response (Jonckheere-Terpstra test, JT = 54, p=1.2x10^-4). Furthermore, AUC[0-21] for CAR T cell expansion and soluble BCMA decline also strongly correlated (Spearman's rank correlation test, rho=0.82; p=2.41x10^-6), underscoring the quantitative relationship between CAR T cell expansion and tumor reduction. We have previously shown that response to CAR T cell therapy in CLL is largely determined by T cell memory function. To find if this extends to myeloma, we immunophenotyped apheresed T cells (or CAR-T precursor cells) and infusion product from the 25 patients. Phenotypically distinct T cell subpopulations were identified using shared-nearest-neighbor clustering method (PMID: 31178118) and their correlation with response to CAR T cell treatment was evaluated. This analysis revealed that among CD4+ and CD8+ CAR-T precursor cells, subpopulations representing naive and central memory T cells were enriched in T cells from responding patients, while non-responders displayed a distinctly activated effector phenotype at baseline. Additional analyses showed that apheresed CD8+ and CD4+ T cells from responder patients were non-cycling, granzyme B-negative, CTLA4[low] but otherwise largely immune checkpoint inhibitor-negative. CD8+ CAR-T precursor cells isolated from non-responders exhibited high expression levels of TIM3 or LAG3, and/or granzyme B, but not PD1, CTLA4, CD45RO or CD27. These data confirm the high activation, potential exhaustion and end-stage differentiation state of CAR-T precursor cells in this group. Similar analyses of infusion product CAR T cells did not reveal subpopulations associated with response. Clustering analysis of CD8+ CAR T cells within 20 days after infusion revealed a BCMA CAR-expressing cluster enriched in responding patients: a non-cycling, negatively regulated, Eomes-expressing central memory subset (cluster 0; Fig. 1E). Non-responding patients CAR-T cells displayed high levels of granzyme B and PD1 expression but were otherwise devoid of signs of activation (cluster 8; Fig. 1F). Furthermore, the abundance of CD8+ CAR-T cells with cluster 0 and 8 phenotype correlated significantly with in vivo expansion (AUC[0-21]; Fig. 1C). Four patients with a sufficiently high proportion of CAR expressing cells were phenotyped up to 125 days post-infusion. This analysis showed that the highly activated CAR T cell clusters 2 and 5 dominated at early phases post infusion but was rapidly replaced by non-cycling CAR T cells with downregulated CTLA4 and LAG3 but maintained expression of PD1 and TIM3 (cluster 0; Fig. 1D). Patient 27 with VGPR had a prominent effector population four months after infusion. BCMA-redirected CD4+ CAR T cells showed an enrichment of central memory phenotype CAR T cells in responding patients early after infusion, with high expression of Eomes, TIM3, and other immune checkpoint inhibitor molecules. This cluster also dominated the CD4 T cell repertoire in the first four months after infusion in the four responding patients. In conclusion, our data suggest that strategies to promote expression of Eomes and central memory function and reduce exhaustion in BCMA CAR T cells will enhance clinical activity. Further, these results underscore the "self-sustaining" feature of successful CAR T cell therapies in myeloma. Disclosures Pruteanu: Novartis: Employment. Cohen:Poseida Therapeutics, Inc.: Research Funding. Garfall:Tmunity: Honoraria, Research Funding; Amgen: Research Funding; Novartis: Patents & Royalties: inventor on patents related to tisagenlecleucel (CTL019) and CART-BCMA, Research Funding; Janssen: Research Funding; Surface Oncology: Consultancy. Lacey:Novartis: Patents & Royalties: Patents related to CAR T cell biomarkers; Tmunity: Research Funding; Novartis: Research Funding. Fraietta:Tmunity: Research Funding; Cabaletta: Research Funding; LEK Consulting: Consultancy. Brogdon:Novartis: Employment. Davis:Tmunity: Research Funding; Cabaletta: Research Funding. Levine:Tmunity Therapeutics: Equity Ownership; Avectas: Membership on an entity's Board of Directors or advisory committees; Vycellix: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Novartis: Consultancy, Patents & Royalties, Research Funding; Cure Genetics: Consultancy; Incysus: Membership on an entity's Board of Directors or advisory committees; Brammer Bio: Membership on an entity's Board of Directors or advisory committees; CRC Oncology: Consultancy. Milone:Novartis: Research Funding; Novartis: Patents & Royalties: patents related to tisagenlecleucel (CTL019) and CART-BCMA. Stadtmauer:Janssen: Consultancy; Tmunity: Research Funding; Amgen: Consultancy; Abbvie: Research Funding; Novartis: Consultancy, Research Funding; Takeda: Consultancy; Celgene: Consultancy. June:Novartis: Research Funding; Tmunity: Other: scientific founder, for which he has founders stock but no income, Patents & Royalties. Melenhorst:National Institutes of Health: Research Funding; Parker Institute for Cancer Immunotherapy: Research Funding; Novartis: Research Funding, Speakers Bureau; Colorado Clinical and Translational Sciences Institute: Membership on an entity's Board of Directors or advisory committees; Stand Up to Cancer: Research Funding; Incyte: Research Funding; IASO Biotherapeutics, Co: Consultancy; Simcere of America, Inc: Consultancy; Shanghai Unicar Therapy, Co: Consultancy; Genentech: Speakers Bureau.

Introduction: Venetoclax is an oral BCL2 inhibitor, effective in CLL and under investigation in multiple clinical trials to treat relapsed or refractory multiple myeloma (RRMM) in combination with a proteasome inhibitor (VPI) - either carfilzomib or bortezomib (Moreau P, 2017; Kumar S, 2017). VPI has shown promising initial results in a phase 2 trial with an overall response rate of 78% and a very good partial response or better (≥VGPR) rate of 56% (Costa L J, 2018; Terpos E, 2019). However, a separate phase 3 trial evaluating bortezomib given with venetoclax or placebo found improved response rates and progression free survival but a decrease in overall survival rate in the venetoclax arm of the study (data not published). The primary association with increased mortality was infection. Better characterizing infections in patients treated with VPI may give insight into the pathophysiology and suggest strategies for safe and effective use of this therapy in RRMM. Methods: We retrospectively reviewed charts of patients treated with VPI for infectious complications from initiation of treatment until one month after progression treated at the Hospital of the University of Pennsylvania. Infections were classified by site, pathogen and severity of infection. Additional data collected included demographics, blood cell counts, quantitative immunoglobulins, SPEP M-spike, light chain analysis, cytogenetics, prior lines of therapy, prophylactic antibiotics and IVIG use. We determined non-monoclonal IgG (NM-IgG) via the difference between serum M-spike and IgG for IgG patients. The two-sample Wilcoxon rank-sum was used to compare different subgroups within our study population. Results: We identified 18 patients treated with a VPI combination regimen of which 78% were male. The median age was 64.5 years (range 47-76) and a median of 3 (1-10) prior regimens. 14 were treated with carfilzomib and 4 with bortezomib combinations. 4 patients progressed by the time of data collection. 8 patients were positive for t(11;14). 11 patients experienced 35 discrete infectious episodes resulting in 4 hospitalizations. Respiratory infections predominated (29/35) with 24 upper respiratory infections or sinusitis. 4 were lower respiratory infections and comprised all the hospitalizations. Among respiratory infections, viruses were the only pathogens identified, including influenza, rhinovirus, coronavirus and RSV. Other sites of infection were gastrointestinal (including recurrent C. difficile) and urinary tract. No CNS, blood, or intra-abdominal infections were identified. Reductions in lymphocyte counts and non-monoclonal IgG were near universal but significant reductions in neutrophil counts were not observed. A greater proportional reduction of NM-IgG was noted in good-responders, defined as CR and VGPR (≥VGPR, n=9), with a mean of 78% decrease compared to 47% in poor-responders (PR/MR/SD/PD, n=4, p=0.045). Importantly, treatment of those with t(11;14) positive status demonstrated no significant difference in NM-IgG. Additionally, there was a relative risk ratio favoring a reduction in infections among those with t(11;14). Conclusion: Patients with RRMM treated with VPI experience frequent infectious complications, some severe, with sustained reductions in serum IgG and lymphocyte counts, but without neutropenia. Reduction in NM-IgG is associated with improved response depth. This phenomenon could explain the paradoxical improvement of response rate and progression free survival with concomitant reduction in overall survival due to infections noted by other reports. Interestingly, the presence of t(11;14) in this analysis was not associated with as great a drop in NM-IgG, as was seen in responders as whole, indicating a more differential effect. The absence of significant reduction in NM-IgG is a potential mechanism for relative reduction of infections in this subgroup. Suggestions of survival benefit among t(11;14) positive subgroups in other reports may be related to this preservation of NM-IgG. Replenishing NM-IgG with IVIG is a hypothetical mitigating strategy that could be of benefit in other subgroups treated with this combination of therapy. Disclosures Cohen: Poseida Therapeutics, Inc.: Research Funding. Garfall:Surface Oncology: Consultancy; Novartis: Patents & Royalties: inventor on patents related to tisagenlecleucel (CTL019) and CART-BCMA, Research Funding; Janssen: Research Funding; Amgen: Research Funding; Tmunity: Honoraria, Research Funding. Vogl:Karyopharm Therapeutics: Consultancy; Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Active Biotech: Consultancy. Mangan:janssen: Speakers Bureau; celgene: Speakers Bureau; takeda: Speakers Bureau; amgen: Speakers Bureau. Stadtmauer:Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Novartis: Consultancy, Research Funding; Tmunity: Research Funding; Abbvie: Research Funding. OffLabel Disclosure: venetoclax for myeloma

e19534 Background: Cardiovascular adverse events (CVAE) are common in patients with multiple myeloma (MM). Recent evidence suggests higher rates of CVAE occur among patients receiving carfilzomib (CFZ) compared to other MM therapies. We sought to determine the real-world relative incidence of CVAE in patients receiving CFZ and bortezomib (BTZ). Methods: We conducted a retrospective cohort study using the Optum Clinformatics Datamart. Patients with MM were included if they received BTZ or CFZ from 2012 to 2016. Exposure periods were defined as 90 days following infusion of either drug. Cardiac hospitalizations were identified using validated ICD-9 or ICD-10 code algorithms for heart failure, arrhythmia, myocardial infarction, and hypertensive urgency. Incidence rate ratios (IRR) were calculated using Poisson regression. Results: We identified 922 patients receiving CFZ and 4092 patients receiving BTZ (median age 70 and 72; median treatment duration 99 and 107 days; concurrent immunomodulatory drugs received in 28% and 25%, respectively). Unadjusted CVAE rates are summarized below. A multivariable regression model showed age (IRR 1.43, 95% CI 1.33-1.55) and male gender (IRR 1.22, 95% CI 1.07-1.40) were independent risk factors for CVAE while concurrent IMiD prescription was associated with lower risk (IRR 0.70, 95% CI 0.58-0.85). Adjusted CVAE rates were similar for patients treated with CFZ and BTZ (IRR 1.06, 95% CI 0.89-1.27). Conclusions: We found higher rates of CVAE hospitalizations than described in clinical trials. This may reflect differences in real-world treatment, patient selection patterns, or later identification of CVAE. Further study is need to identify patients at high-risk of CVAE and to develop risk reduction strategies. [Table: see text]

Allogeneic hematopoietic cell transplantation for plasma cell myeloma can lead to graft-vs-myeloma immunity and long-term survivorship, but limited efficacy and associated toxicities have prevented its widespread use. Cellular immunotherapies seek to induce more specific, reliable and potent antimyeloma immune responses with less treatment-related risk than is possible with allogeneic transplantation. Strategies under development include infusion of vaccine-primed and ex vivo expanded/costimulated autologous T cells after high-dose melphalan, genetic engineering of autologous T cells with receptors for myeloma-specific epitopes, administration of DC/plasma cell fusions and administration expanded marrow-infiltrating lymphocytes. In addition, novel immunomodulatory drugs such as inhibitors of the programmed death-1 T cell regulatory pathway may synergize with cellular immunotherapies.

Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) are important regulators of immune responses in cancer and have been directly implicated in promotion of tumor progression. However, the heterogeneity of these cells and lack of distinct markers hampers the progress in understanding of the biology and clinical importance of these cells. Using partial enrichment of PMN-MDSC with gradient centrifugation we determined that low density PMN-MDSC and high density neutrophils from the same cancer patients had a distinct gene profile. Most prominent changes were observed in the expression of genes associated with endoplasmic reticulum (ER) stress. Surprisingly, low-density lipoprotein (LDL) was one of the most increased regulators and its receptor oxidized LDL receptor 1 OLR1 was one of the most overexpressed genes in PMN-MDSC. Lectin-type oxidized LDL receptor 1 (LOX-1) encoded by OLR1 was practically undetectable in neutrophils in peripheral blood of healthy donors, whereas 5–15% of total neutrophils in cancer patients and 15–50% of neutrophils in tumor tissues were LOX-1+. In contrast to their LOX-1− counterparts, LOX-1+ neutrophils had gene signature, potent immune suppressive activity, up-regulation of ER stress, and other biochemical characteristics of PMN-MDSC. Moreover, induction of ER stress in neutrophils from healthy donors up-regulated LOX-1 expression and converted these cells to suppressive PMN-MDSC. Thus, we identified a specific marker of human PMN-MDSC associated with ER stress and lipid metabolism, which provides new insight to the biology and potential therapeutic targeting of these cells.

Relapsed and refractory hematologic malignancies have a very poor prognosis. Chimeric antigen receptor (CAR) T cells are emerging as a powerful therapy in this setting. Early clinical trials of genetically modified T cells for the treatment of non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL) have shown high complete response rates in patients with few therapeutic options. Exploration is ongoing for other hematologic malignancies including multiple myeloma (MM), acute myeloid leukemia (AML) and Hodgkin lymphoma (HL). At the same time, the design and production of CAR T cells is being advanced so that this therapy can be more widely utilized. Cytokine release syndrome (CRS) and neurotoxicity are common, but they are treatable and fully reversible. This review will review currently available data as well as future developments and challenges in the field.

Background: Despite major advances in the treatment of multiple myeloma (MM) only a minority of patients achieve long-term disease control. Immunotherapy combined with autologous hematopoietic stem cell transplantation (auto-HCT) may reduce relapse rates. Vaccination with Ig idiotype (Id) conjugated with a carrier protein, keyhole limpet hemocyanin (KLH), was associated with superior disease-free survival in a randomized trial in follicular lymphoma (Schuster S. et al. JCO 2011), and Id is also a tumor-specific antigen in MM. In addition, anti-CD3/-CD28 costimulated adoptive T-cell transfer augmented immune responses to pneumococcal vaccination despite cytotoxic therapy (Rapoport A et al. Nat Med 2005). We therefore hypothesized that Id-KLH vaccine + the vaccine-primed costimulated T cells will result in a robust Id-specific humoral and cellular response, compared with control vaccine (KLH only). Methods: In this randomized, phase II trial, eligible patients were randomized 1:1 to receive either KLH-only or Id-KLH vaccine, followed by auto-HCT, and then vaccine- primed costimulated T cells followed by two booster doses of the vaccine to which they were randomized. Immune response (IR) was evaluated by gene expression profiling (GEP) using NanoString nCounter. Results: A total of 36 patients were enrolled between 1/2013 and 5/2015, 20 to KLH-only and 16 to Id-KLH arm, and completed their assigned treatments. There were no significant differences between the groups in age, gender, stage, cytogenetic risk, induction regimen or response to induction (Table). Nineteen (95%) and 16 (100%) patients received maintenance therapy after protocol treatment in KLH-only and Id-KLH, respectively (p=0.42). No infusion reactions or dose-limiting toxicity was seen in either arm. There was no non-relapse mortality at 100-day and 1-year in either arm. At last evaluation, 5 (25%) and 7 (44%) had achieved CR in KLH-only and Id-KLH, respectively (p=0.29). Six (30%) and 9 (56%) achieved at least nCR in KLH-only and Id-KLH, respectively (p=0.17), and 12 (60%) and 12 (75%) achieved at least a VGPR in KLH-only and Id-KLH, respectively (0.48). Ten (50%) and 8 (50%) patients, for whom there were sufficient samples available underwent IR analysis in KLH-only and Id-KLH, respectively at baseline and at 30, 90 and 180 days after activated T cell infusion. In an initial 568 gene panel analyzed for IR, compared with KLH-only, there was a greater change in IR genes in CD8+ T cells in Id-KLH at days 30, 90 and 180 (Figure 1A). In a 30-gene panel of the most upregulated IR genes in CD8+ cells, there was a significantly higher expression of these genes in Id-KLH at all post-treatment time points (Figure 1B). Specifically, at day 180 post-treatment, there was higher expression of immune co-stimulatory genes in Id-KLH in both CD8+ and CD4+ T cell subsets. This increased co-stimulatory gene expression in Id-KLH vaccinated CD4+ (Figure 1C) and CD8+ T cells (not shown) was most marked in patients who had achieved a CR. After a median follow up of 38.3 months, 3-year PFS in KLH-only and Id-KLH was 64% and 53%, respectively (p=0.25). Conclusion: Id-KLH vaccine and vaccine-primed costimulated T cells can be safely administered in the setting of auto-HCT. In this randomized trial we detected a trend towards a deeper clinical response in the Id-KLH arm. There were significantly more robust IR in CD4+ and CD8+ T cells in the Id-KLH arm,which also correlated withdepth of clinical response. Future trials should focus on selection of patients most likely to mount a robust IR to Id vaccines. Download : Download high-res image (185KB) Download : Download full-size image Disclosures Shah: TeneoBio, Inc.: Honoraria; Indapta Therapeutics: Other: Stock Ownership; Celgene: Research Funding; Celgene, Indapta Therapeutics, Takeda: Consultancy. Patel: Juno: Consultancy; Celgene: Consultancy; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding. Thomas: Bristol Myers Squibb: Research Funding; Celgene: Research Funding. Orlowski: BioTheryX: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cohen: Celgene: Consultancy; Bristol Meyers Squibb: Consultancy, Research Funding; GlaxoSmithKline: Consultancy; Janssen: Consultancy. Vogl: Constellation: Research Funding; Karyopharm: Consultancy; GSK: Research Funding; Calithera: Research Funding; Takeda: Consultancy, Research Funding; Teva: Consultancy; Amgen: Consultancy; Celgene: Consultancy. June: Immune Design: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Novartis: Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership, Research Funding; WIRB/Copernicus Group: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celldex: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kwak: Celltrion, Inc: Consultancy; InnoLifes: Consultancy, Equity Ownership; Pepromene Bio: Consultancy, Equity Ownership.

Background: Autologous T cells expressing a chimeric antigen receptor (CAR) specific for B-cell maturation antigen (CART-BCMA cells) show activity in refractory MM, but relapses remain common. Anti-PD-1 antibodies (Abs) augment CAR T cell activity pre-clinically, and induced CAR T cell re-expansion and responses in DLBCL patients progressing after CD19-specific CAR T cells (Chong et al, Blood 2017). The IMiDs lenalidomide (len) and pomalidomide (pom) may enhance efficacy, but also toxicity, of both CAR T cells and PD-1 inhibitors in MM. Elotuzumab (elo) has clinical anti-MM activity in combination with IMiDs and dexamethasone (dex), and synergizes with anti-PD-1 Ab in pre-clinical models. Methods: We previously described outcomes of 25 subjects enrolled on our phase 1 study of CART-BCMA cells in relapsed/refractory MM (Cohen et al, ASH 2017, #505). We identified and retrospectively reviewed 5 subjects who progressed after CART-BCMA and received a PD-1 inhibitor (pembrolizumab (pembro)) combination as their next therapy. Responses were assessed by IMWG criteria. CART-BCMA levels were assessed by flow cytometry and qPCR pre-treatment, 2-4 weeks after first pembro dose, then q4 weeks until progression. Pembro dosing was 200mg every 3 weeks; dex dosing was 20-40mg/week. Results: Characteristics of the 5 subjects are in the Table. Median prior lines was 9; all had high-risk cytogenetics. All were refractory to pom, 2 to pembro/pom/dex, and 1 to elo. Best response to CART-BCMA was PR in 2, MR in 2, and PD in 1. Median time from CART-BCMA to pembro-based therapy was 117 days. All patients still had CART-BCMA cells detectable by qPCR, with 2 (pts. 07 and 21) still detectable by flow, at initiation of salvage therapy. The first pt. (02) received pembro/pom/dex and had MR but progressed at 2 months, with no detectable CART-BCMA re-expansion. The second pt. (07) had rapidly-progressing kappa light chain MM 2 months post-CART-BCMA and had previously progressed on pembro/pom/dex. He started elo/pembro/pom/dex and had MR at day 12 (free kappa 1446 to 937 mg/L), associated with robust expansion of CART-BCMA cells (875.64 to 20505.07 copies/µg DNA by qPCR; 0.7% to 6.4% of peripheral CD3+ cells by flow). Re-expanded CART-BCMA cells were predominantly CD8+ and highly activated (89% HLA-DR+, up from 18% pre-therapy). This response was short-lived, however, with progression 1 week later, and return of CART-BCMA levels to baseline at week 5. Three subsequent subjects then received elo/pembro/dex with either len or pom; with 2 MR and 1 SD, and PFS of 3 to 4 months. None had re-expansion of CART-BCMA cells. Non-specific immune modulation was observed and included altered CD4:CD8 T cell ratio (n=5), increased NK cell/decreased T cell frequency (n=4), and HLA-DR upregulation on CAR-negative T cells (n=2). More detailed phenotyping of CART and other immune cells, including PD-1 expression, is ongoing. With regard to toxicity, pt. 02 had self-limiting low-grade fevers and myalgias 4 weeks after pembro/pom/dex, associated with mild elevation in ferritin/CRP, suggestive of mild CRS. No other CRS was noted, including pt. 07 despite CART-BCMA re-expansion. One patient (17) developed recurrent expressive aphasia starting 2 months after elo/pembro/pom/dex, without signs of CRS and no observed expansion of CART-BCMA cells in blood or CSF. This resolved with stopping therapy and brief steroid taper. Conclusions: This study demonstrates that a PD1-inhibitor combination can induce CAR T cell re-expansion and anti-MM response in a MM patient progressing after CART-BCMA therapy. Since this patient previously progressed on pembro/pom/dex, the observed clinical activity was likely related to the CAR T cells, with elotuzumab also possibly contributing. However, this effect was very transient; re-expansion occurred infrequently (1/5 patients); and neurotoxicity was observed (though its relationship to the CAR T cells is unclear). This makes it difficult to endorse this specific salvage regimen. Nonetheless, this proof-of-principle observation suggests that a subset of patients may respond to checkpoint blockade or other immune-modulating approaches following BCMA CAR T cell therapy, meriting further study. Table. Table. Disclosures Garfall: Kite Pharma: Consultancy; Novartis: Research Funding; Amgen: Research Funding; Bioinvent: Research Funding. Melenhorst:novartis: Patents & Royalties, Research Funding; Incyte: Research Funding; Shanghai UNICAR Therapy, Inc: Consultancy; Casi Pharmaceuticals: Consultancy; Parker Institute for Cancer Immunotherapy: Research Funding. Lacey:Parker Foundation: Research Funding; Tmunity: Research Funding; Novartis Pharmaceuticals Corporation: Patents & Royalties; Novartis Pharmaceuticals Corporation: Research Funding. Stadtmauer:Janssen: Consultancy; AbbVie, Inc: Research Funding; Amgen: Consultancy; Takeda: Consultancy; Celgene: Consultancy. Vogl:Karyopharm Therapeutics: Consultancy. Plesa:Novartis: Research Funding. Young:Novartis: Patents & Royalties, Research Funding. Levine:Novartis: Consultancy, Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership, Research Funding; Incysus: Consultancy; Cure Genetics: Consultancy; CRC Oncology: Consultancy; Brammer Bio: Consultancy. June:Immune Design: Membership on an entity's Board of Directors or advisory committees; Immune Design: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Celldex: Consultancy, Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding; Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding. Milone:Novartis: Patents & Royalties. Cohen:Bristol Meyers Squibb: Consultancy, Research Funding; Celgene: Consultancy; Novartis: Research Funding; Poseida Therapeutics, Inc.: Research Funding; Kite Pharma: Consultancy; GlaxoSmithKline: Consultancy, Research Funding; Seattle Genetics: Consultancy; Janssen: Consultancy; Oncopeptides: Consultancy.

Background: Relapsed/refractory (rel/ref) MM is associated with progressive immune dysfunction, including reversal of CD4:CD8 T cell ratio and acquisition of terminally-differentiated T cell phenotypes. BCMA-directed CAR T cells have promising activity in MM, but the factors that predict for robust in vivo expansion and responses are not known. In a phase 1 study of CART-BCMA (autologous T cells expressing a human BCMA-specific CAR with CD3ζ/4-1BB signaling domains) in refractory MM patients (median 7 priors, 96% high-risk cytogenetics), we observed partial response (PR) or better in 12/25 (47%) (Cohen et al, ASH 2017, #505). Recently, we demonstrated in CLL pts receiving CD19-directed CAR T cells that certain T cell phenotypes prior to generation of the CAR T product were associated with improved in vivo expansion and clinical outcomes (Fraietta et al, Nat Med 2018). We thus sought to identify pre-treatment clinical or immunological features associated with CART-BCMA expansion and/or response. Methods: Three cohorts were enrolled: 1) 1-5 x 108 CART cells alone; 2) cyclophosphamide (Cy) 1.5 g/m2 + 1-5 x 107 CART cells; and 3) Cy 1.5 g/m2 + 1-5 x 108 CART cells. Phenotypic analysis of peripheral blood (PB) and bone marrow (BM) mononuclear cells, frozen leukapheresis aliquots, and phenotype and in vitro kinetics of CART-BCMA growth during manufacturing were performed by flow cytometry. CART-BCMA in vivo expansion was assessed by flow cytometry and qPCR. Responses were assessed by IMWG criteria. Results: Responses (≥PR) were seen in 4/9 pts (44%, 1 sCR, 2 VPGR, 1 PR) in cohort 1; 1/5 (20%, 1 PR) in cohort 2; and 7/11 (64%, 1 CR, 3 VGPR, 3 PR) in cohort 3. As of 7/9/18, 3/25 (12%) remain progression-free at 11, 14, and 32 months post-infusions. As previously described, responses were associated with both peak in vivo CART-BCMA expansion (p=0.002) as well as expansion over first month post-infusion (AUC-28, p=0.002). No baseline clinical or MM-related characteristic was significantly associated with expansion or response, including age, isotype, time from diagnosis, # prior therapies, being quad- or penta-refractory, presence of del 17p or TP53 mutation, serum hemoglobin, BM MM cell percentage, MM cell BCMA intensity, or soluble BCMA concentration. Treatment regimen given before leukapheresis or CART-BCMA infusions also had no predictive value. We did find, however, that higher CD4:CD8 T cell ratios within the leukapheresis product were associated with greater in vivo CART-BCMA expansion (Spearman's r=0.56, p=0.005) and clinical response (PR or better; p=0.014, Mann-Whitney). In addition, and similar to our CLL data, we found that a higher frequency of CD8 T cells within the leukapheresis product with an "early-memory" phenotype of CD45RO-CD27+ was also associated with improved expansion (Spearman's r=0.48, p=0.018) and response (p=0.047); Analysis of manufacturing data confirmed that higher CD4:CD8 ratio at culture start was associated with greater expansion (r=0.41, p=0.044) and, to a lesser degree, responses (p=0.074), whereas absolute T cell numbers or CD4:CD8 ratio in final CART-BCMA product was not (p=NS). In vitro expansion during manufacturing did associate with in vivo expansion (r=0.48, p=0.017), but was not directly predictive of response. At the time of CART-BCMA infusion, the frequency of total T cells, CD8+ T cells, NK cells, B cells, and CD3+CD56+ cells within the PB or BM was not associated with subsequent CART-BCMA expansion or clinical response; higher PB and BM CD4:CD8 ratio pre-infusion correlated with expansion (r=0.58, p=0.004 and r=0.64, p=0.003, respectively), but not with response. Conclusions: In this study, we found that CART-BCMA expansion and responses in heavily-pretreated MM patients were not associated with tumor burden or other clinical characteristics, but did correlate with certain immunological features prior to T cell collection and manufacturing, namely preservation of normal CD4:CD8 ratio and increased frequency of CD8 T cells with a CD45RO-CD27+ phenotype. This suggests that patients with less dysregulated immune systems may generate more effective CAR T cell products in MM, and has implications for optimizing patient selection, timing of T cell collection, and manufacturing techniques to try to overcome these limitations in MM patients. Disclosures Cohen: Celgene: Consultancy; Novartis: Research Funding; Oncopeptides: Consultancy; Janssen: Consultancy; Poseida Therapeutics, Inc.: Research Funding; Bristol Meyers Squibb: Consultancy, Research Funding; Kite Pharma: Consultancy; GlaxoSmithKline: Consultancy, Research Funding; Seattle Genetics: Consultancy. Melenhorst:Parker Institute for Cancer Immunotherapy: Research Funding; novartis: Patents & Royalties, Research Funding; Casi Pharmaceuticals: Consultancy; Incyte: Research Funding; Shanghai UNICAR Therapy, Inc: Consultancy. Garfall:Amgen: Research Funding; Kite Pharma: Consultancy; Bioinvent: Research Funding; Novartis: Research Funding. Lacey:Novartis Pharmaceuticals Corporation: Patents & Royalties; Parker Foundation: Research Funding; Tmunity: Research Funding; Novartis Pharmaceuticals Corporation: Research Funding. Davis:Novartis Institutes for Biomedical Research, Inc.: Patents & Royalties. Vogl:Karyopharm Therapeutics: Consultancy. Pruteanu:Novartis: Employment. Plesa:Novartis: Research Funding. Young:Novartis: Patents & Royalties, Research Funding. Levine:Novartis: Consultancy, Patents & Royalties, Research Funding; CRC Oncology: Consultancy; Incysus: Consultancy; Tmunity Therapeutics: Equity Ownership, Research Funding; Brammer Bio: Consultancy; Cure Genetics: Consultancy. June:Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding; Immune Design: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding; Immune Design: Membership on an entity's Board of Directors or advisory committees; Celldex: Consultancy, Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Stadtmauer:Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AbbVie, Inc: Research Funding; Janssen: Consultancy. Milone:Novartis: Patents & Royalties.