Castro, Januario E

Ibrutinib-based therapies are costly and require continuous administration. We hypothesized combining BTK inhibition with anti-CD20 monoclonal antibodies would yield deep remissions allowing discontinuation. We enrolled 32 therapy-naïve CLL patients to receive ibrutinib plus obinutuzumab, followed by single-agent ibrutinib. Patients could discontinue ibrutinib after 36 months with sustained complete response (CR). We evaluated treatment safety, efficacy, and outcomes after ibrutinib discontinuation. The overall response rate was 100%, 28% achieved a CR, and 12.5% achieved bone marrow undetectable minimal residual disease. At a three-year median follow-up, 91% remain in remission with 100% overall survival. Five patients in sustained CR stopped ibrutinib and have not progressed. Eight non-CR patients discontinued for other reasons, with only two progressing. The treatment was safe, with a lower IRR rate. All patients responded to treatment with longer time-to-progression after discontinuation of ibrutinib. Our data support the evaluation of ibrutinib discontinuation strategies in more extensive clinical trials (https://Clinicaltrials.gov Identifier https://clinicaltrials.gov/ct2/show/NCT02315768).

Abstract Background :COVID-19 adversely affects individuals with cancer. Several studies have found that seroconversion rates among patients with hematologic malignancies are suboptimal when compared to patients without cancer. Among patients with hematologic malignancies, seroconversion rates also appear to be influenced by recent treatment and the type of treatment they have received. Patients with non-Hodgkin lymphoma (NHL) and multiple myeloma (MM) are immunocompromised due to impaired humoral and cellular immunity in addition to prescribed immunosuppressive therapy. Chimeric antigen receptor T-cell (CAR T) therapy is now widely used for NHL and MM, but little is known about seroconversion rates after COVID-19 vaccination among these populations. Current national guidelines recommend COVID-19 vaccination to be offered to CAR T recipients as early as three months thereafter. We retrospectively evaluated SARS-CoV-2 spike-binding IgG antibody levels following COVID-19 vaccination among NHL and MM CAR T therapy recipients. Methods:This retrospective study was conducted at three Mayo Clinic sites on NHL and MM patients that received CAR T infusions from Sept 2016 to June 2021. Baseline characteristics were ascertained from medical records. All NHL and MM patients who had received CAR T at any point and were alive at the time that the COVID-19 vaccine first became available were eligible for inclusion for antibody response evaluation. For antibody response to vaccination, antibody spike values > 0.80 U/mL were considered positive. Results: Out of 104 CAR T infusions, 73 patients are alive at the time of this submission. We have had 7 patients with known COVID-19 pre-CAR T and all 7 are currently alive (5 have antibody titers and 2 have not been tested yet). Nineteen patients developed known COVID infection post-CAR T (13 alive and 6 deceased). The mortality of COVID post-CAR T in our sample was 31.5%. Furthermore, of the 13 patients that survived COVID-19, they received CAR T an average of 416 days prior to COVID-19 infection (median = 337, range = 54 - 1406); the 6 patients who died from COVID-19 had received CAR T an average of 250 days prior to COVID-19 infection (median = 164, range = 7 - 846). All 6 deceased patients did not receive COVID-19 vaccination pre-CAR T. Out of 17 CAR T patients tested for antibody spike titers post COVID-19 vaccination, 76.4% were able to mount an antibody response. More patients with MM had a higher titer response to the vaccine (>250 U/mL) compared to the NHL counterparts (0.80-249 U/mL). All patients that received the vaccine, regardless of antibody response, were alive at the time of this submission. Conclusions:The majority of CAR T recipients with NHL and MM are able to mount an antibody response following COVID-19 vaccination in our relatively small sample. The frequency of seroconversion among CAR T recipients seems to be similar to patients with hematologic malignancy who had received a hematopoietic cell transplant reported elsewhere. These findings are limited by our small sample size and may be influenced by the timing of vaccination relative to CAR T. Furthermore, almost half of our patients received IVIG post CAR T which could potentially cause false positive antibody results as pooled immunoglobulin preparations may contain COVID-19 antibodies from vaccinated healthy donors. To better understand the characteristics of the immunologic response against SARS-CoV-2 in patients post-CAR T, larger multicenter studies exploring both humoral and cellular immunity will be needed. JEWN, MI and JM are co-first authors and PV, HM and AR are co-senior authors. Figure 1 Figure 1. Disclosures Munoz: Physicians' Education Resource: Honoraria; Seattle Genetics: Honoraria; Bayer: Research Funding; Gilead/Kite Pharma: Research Funding; Celgene: Research Funding; Merck: Research Funding; Portola: Research Funding; Incyte: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Janssen: Research Funding; Millennium: Research Funding; Gilead/Kite Pharma, Kyowa, Bayer, Pharmacyclics/Janssen, Seattle Genetics, Acrotech/Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/BMS, Genentech/Roche.: Speakers Bureau; Pharmacyclics/Abbvie, Bayer, Gilead/Kite Pharma, Pfizer, Janssen, Juno/Celgene, BMS, Kyowa, Alexion, Beigene, Fosunkite, Innovent, Seattle Genetics, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, Servier: Consultancy; Targeted Oncology: Honoraria; OncView: Honoraria; Kyowa: Honoraria. Bergsagel: Oncopeptides: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties: human CRBN mouse; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Genetech: Consultancy, Honoraria; GSK: Consultancy, Honoraria. Wang: Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; InnoCare: Research Funding; Novartis: Research Funding; MorphoSys: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Fonseca: Juno: Consultancy; Kite: Consultancy; Aduro: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; AbbVie: Consultancy; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy; Amgen: Consultancy; Sanofi: Consultancy; Merck: Consultancy; Mayo Clinic in Arizona: Current Employment; Celgene: Consultancy; Takeda: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy. Palmer: Sierra Oncology: Consultancy, Research Funding; CTI BioPharma: Consultancy, Research Funding; Protagonist: Consultancy, Research Funding; Incyte: Research Funding; PharmaEssentia: Research Funding. Dingli: Novartis: Research Funding; GSK: Consultancy; Apellis: Consultancy; Alexion: Consultancy; Sanofi: Consultancy; Janssen: Consultancy. Kapoor: Sanofi: Research Funding; AbbVie: Research Funding; Takeda: Research Funding; Karyopharm: Consultancy; Cellectar: Consultancy; BeiGene: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Amgen: Research Funding; Ichnos Sciences: Research Funding; Regeneron Pharmaceuticals: Research Funding; Glaxo SmithKline: Research Funding; Karyopharm: Research Funding. Kumar: Roche-Genentech: Consultancy, Research Funding; Oncopeptides: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Research Funding; Beigene: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Tenebio: Research Funding; Merck: Research Funding; Carsgen: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Bluebird Bio: Consultancy; Antengene: Consultancy, Honoraria; Sanofi: Research Funding. Paludo: Karyopharm: Research Funding. Bennani: Kymera: Other: Advisory Board; Vividion: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Verastem: Other: Advisory Board. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Lin: Kite, a Gilead Company: Consultancy, Research Funding; Merck: Research Funding; Gamida Cell: Consultancy; Takeda: Research Funding; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Sorrento: Consultancy; Legend: Consultancy; Vineti: Consultancy. Murthy: CRISPR Therapeutics: Research Funding.

Abstract Introduction: CAR T-cell therapy has revolutionized the treatment of patients with relapsed/refractory (R/R) acute leukemia, NHL, and multiple myeloma. However, there are still areas of improvement in their clinical activity, source of the effector cells, prevention, and management of adverse events that require particular attention. Because of those reasons, NK cells appear as a viable effector cell alternative that can help address these challenges. NK cells offer a profile of activation, expansion, persistence, and cytotoxicity that is different from T cells and, when modified to bear CAR constructs, may provide significant advantages. However, the preclinical development of NK-CARs is challenging mainly because of the difficulty of generating large quantities of cells for testing and well-established pathways for CAR optimization before in vivo evaluation. Therefore, we developed a CAR optimization platform using the NK-92 cell line. NK-92 cells conserve their cytotoxic ability and can be easily expanded in vitro and used for functional and phenotypical evaluations of novel CAR-NK constructs. Here we present a rechallenge cytotoxic assay that mimics repetitive in vivo effector interactions with the target cells and its use for optimization, comparison, and development of NK-based cellular therapies. Methods: We generated lentivirus transduced CD19 CARs (FMC63-41BB-z) using T cells from healthy donors and NK-92 cells for comparison.T cells were expanded for 12 days, and a 41.9% CAR+ expression was achieved (CART19). Transduced NK-92 cells were sorted by FACS to obtain a population of 98.3 % CAR+ cells (CARNK19) and subsequently expanded for 12 days. JeKo-1 cells were used as CD19+ targets and BxPC3 cells as CD19 neg control (both cell types were GFP-Luc-PuroR). We developed a Luciferase-based rechallenge cytotoxicity assay. For this, we diluted the effector to target (E/T) ratio to obtain a logarithmic trendline of the cells' cytotoxicity. E/T ratio to get viability of 50% (IC50) measured at 4h (for CARNK19) and 24h (for CART19) was used as a proxy of the product's potency. Both CAR Immune Effector Cells (IECs) were co-cultured with their targets at an E/T ratio to obtain 70% cytotoxicity. After 24 hours with the target, we estimated the remaining IEC amount in the culture using GFP exclusion in flow analysis (IEC cells/mL = total cells/mL x GFP neg%). We repeated the plating of E/T ratio dilutions to perform daily IC50 curves using this rechallenge strategy for a total of 5 days. CAR and PD1 expression were measured on Day 0 and Day 5 by flow cytometry. Results: CART19 showed a higher IC50 than CARNK19 at baseline, 1.7 vs. 0.19 (Figure 1A). The IC50 trend of both IECs over time showed an uptrend that suggests progressive functional exhaustion (Figure 1B). At 5 days of rechallenge, it was 29 times higher in T cells than in NK-92 (12.07 vs. 0.42) and with a slope 265 times higher (10.6 vs. 0.04). Furthermore, we observed that when comparing the levels of CAR expression on Day 0 vs. Day 5, CART19 showed a decrease in CAR expression that was not present in CARNK19 (41.9 to 10.9% vs. 98.3 to 95.5%) (Figure 1C). In addition, there was a higher increase in PD1 expression in CART19 cells than CARNK19 cells from Day 0 to Day 5 of the in vitro rechallenge (9.9 to 46.8% vs. 0.88 to 8.88%) (Figure 1D). Conclusion: Our data shows the use of NK-92 cells as a tool for optimization and preclinical development of NK cell-based cellular therapies. We demonstrated that it is feasible to set up repetitive cytotoxic challenges that mimic closer in vivo E/T engagement. Moreover, using the cytotoxic IC50 calculated with this platform, we show increased cytotoxicity, less functional exhaustion, and less expression of PD1 in CARNK19 than in its T cell counterpart. Overall, the NK-92 rechallenge cytotoxicity assay platform constitutes a helpful tool for research, development, and optimization of cellular therapies based on NK cell effector function. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Chimeric Antigen Receptor (CAR) T cell therapy is arguably one of the most significant breakthroughs in cancer treatment. There are currently five FDA-approved products that are commercially available. However, despite their success, these CAR T-cell therapies cannot induce long-term durable responses in approximately 50% of leukemia or lymphoma-treated patients. Similarly, the results of CAR T-cells in solid tumors have been somewhat disappointing. Therefore, there is an urgent need to design and develop novel CAR T cells with improved efficacy in hematologic malignancies and solid tumors. ROR1 is a carcinoembryonic antigen expressed in different cancers and is associated with tumor stemness, proliferation, metastatic transformation, and treatment resistance. In this project, we optimize an anti-ROR1 CAR using a humanized single-chain variable fragment (scFv) with second (2G) or third-generation (3G) costimulatory domains. Methods: Several optimization steps in silico were performed using a selected scFv binding domain that targets ROR1. Those included codon optimizations, positional arrangement of heavy-light chains, evaluation of the ideal length of linkers based on tridimensional modeling of the docking between the antibody-like paratope with the target antigen (Figure 1A). After this initial scFv optimization process, we constructed a lentiviral vector that encodes CARs using the selected scFv linked to a transmembrane domain CD28 and different signaling endodomains for 2G and 3G variants (CD28, 41BB, ICOS, OX40), each linked to the T cell receptor CD3z domain. The cytotoxic activity of these constructs was evaluated using an in vitro rechallenge luciferase assay in ROR1 expressing JeKo-1 cells and ROR1(negative) controls. Results: The 2G 41BB-z construct with V H-V L scFv orientation and a long linker (V H-L-V L) showed optimal cytotoxicity with a CAR expression level in T cells of 36% (Range 28-49% for other constructs, Figure 1B-C). The V H-L-V L 41BB-z construct was evaluated comparatively using a rechallenge cytotoxic assay with 3G constructs that expressed CD28, ICOS, or OX40 signaling domains using JeKo-1 and ROR1(negative) target cells as controls. All the tested constructs showed specific ROR1 medicated cytotoxicity. CD28-41BB-z and ICOS-41BB-z showed the lowest cytotoxicity levels during the Day 1 of the repetitive rechallenge. However, the cytotoxicity levels of those constructs gradually increased during the 7 days of rechallenge and were closed to the levels induced by the 2G- 41BB-z construct (>80% of cytotoxicity). There were no significant differences in CAR T cells subsets generated by the different constructs during the 7 days of rechallenge with a predominance of effector memory phenotype (CCR7-, CD45RA-) and no difference in PD1 expression. Conclusions: Our results demonstrate that optimization of the CAR constructs enhances T-cell effector function and cytotoxicity against ROR1+ target cells. In previous studies, 3G CARs have shown longer persistence of the transduced T cells in peripheral blood, sustained and regulated cellular activation, improved solid tumor infiltration, and positive modulation of the tumor microenvironment. Our preclinical in vitro optimization demonstrates strategies to generate 3G constructs with a progressive and modulated cytotoxic profile that may confer benefits when tested in vivo in terms of enhanced persistence and lower adverse events profile. Additional experiments in vivo will be presented during the meeting to corroborate our findings. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Background Patients (pts) with aggressive B-cell non-Hodgkin lymphoma (NHL) progressing after anti-CD19 chimeric antigen receptor T (CART) cell therapy have poor prognosis and may benefit from new therapy options through clinical trials. However, in a single center report, only 12% of such pts were treated in trials (Chow et al. Am J Hematol, 2019). Identifying the reasons for this low enrollment is needed to design future studies for this population. Here, we evaluated the eligibility criteria for recent landmark trials for relapsed/refractory aggressive B-cell NHL to learn what eligibility barriers are present. Methods Pts with aggressive B-cell NHL who received FDA-approved CART cell therapy at Mayo Clinic (Rochester, Arizona, Florida) since 2018 and progressed after CART cell therapy were identified. The potential eligibility for the following key trials was evaluated: a) polatuzumab + bendamustine + rituximab, b) tafasitamab + lenalidomide, c) selinexor and d) loncastuximab. The eligibility for each trial was retrospectively assessed at the time of disease progression after CART cell therapy based on hemoglobin (Hb), absolute neutrophils count (ANC), platelet count (Plt), renal and liver function tests, ECOG performance status (PS), and central nervous system (CNS) involvement. Results Seventy-five pts had disease progression to axicabtagene ciloleucel (N=73, 97%) or tisagenlecleucel (N=2, 3%) and are included in this analysis. Median time to progression after CART was 2.1 months (IQR: 1.0 - 3.1). Thirteen (17%) pts were treated in clinical trials after progression following CART cell therapy, while 46 (61%) were treated off trials, and 16 (22%) pts never received any treatment after progression. At a median follow-up of 13.6 months (IQR: 9.1 - 26.7) from CART progression, the median overall survival (mOS) from CART progression was 5.8 months (95% CI 3.5 - 10.1) and 53 (71%) pts died. Thirty-eight pts (51%) did not meet eligibility criteria for any of the 4 recent landmark trials. Hematologic impairment was the most common barrier to inclusion of these patients in clinical trials: Hb < 9 g/dL n=23 (31%) or Hb < 10 g/dL n=36 (48%), ANC < 1.0 x 10 9/L n=19 (25%) or ANC < 1.5 x 10 9/L n=32 (43%), and Plt < 75 x 10 9/L n=30 (40%) or Plt < 90 x 10 9/L n=34 (45%). Renal (n=11, 15%) or liver dysfunction (n=5, 7%), CNS involvement (n=8, 11%) and ECOG PS > 2 (n=3, 4%) were less common reasons leading to exclusion from trials. Post CART trial ineligible pts had significantly shorter time to progression (median 1.7 months, IQR: 1.0 - 2.6 vs. 3.0 months IQR: 1.9 - 3.4, p < 0.01) and inferior overall response to CART (45% vs 67%, p = 0.06) compared to pts who met trial eligibility post CART. Baseline Hb (median Hb 9.5 g/dL, IQR: 8.5 - 10.5 vs. 10.9 g/dL, IQR: 9.7 - 12.2, p < 0.01) and Plt (median Plt 106 x 10 9/L IQR: 54 - 165 vs. 201 x 10 9/L IQR: 141 - 243, p < 0.01) were also significantly lower in pts ineligible for trials post CART. There were no significant differences between pts eligible or ineligible for trials with regards to age (median 59 vs. 60 years), number of prior therapies (median 3 vs. 3), prior autologous stem cell transplant (41% vs. 37%), bridging therapy (65% vs. 63%), baseline ANC (median 4,1 vs. 3,0 x10 9/L), or high-grade (grade ≥ 2) cytokine release syndrome (19% vs. 21%) or neurotoxicity (32%, vs. 42%), respectively. Survival after CART progression was significantly shorter (mOS 2.5 months, 95% CI: 1.6 - 5.1) for the 38 pts ineligible for trials compared to pts eligible for trials (mOS 10.6 months, 95% CI: 8.9 - NA), (p < 0.01). In the 59 pts who received therapy post CART progression, the mOS of pts treated on (n = 13) or off (n = 46) trials was 13.8 months (95% CI: 9.2 - NA) vs. 6.6 months (4.9 - 10.7), respectively (p = 0.047). Conclusion Approximately half of the pts (51%) with aggressive B-cell NHL progressing after CART cell therapy would have be excluded from landmark clinical trials. The current hematologic exclusion criteria are a major barrier to enrollment in clinical trials, which would exclude many pts who have disease progression within 3 months of CART cell therapy (ie, primary refractory disease), in whom cytopenia as a toxicity from therapy is prevalent. Given the known delayed hematologic recovery after CART cell therapy and the unmet need of pts progressing to CART cell therapy, the hematologic exclusion criteria should be adjusted to increase trial participation of this population, especially of those with primary refractory disease. Figure 1 Figure 1. Disclosures Munoz: Gilead/Kite Pharma, Kyowa, Bayer, Pharmacyclics/Janssen, Seattle Genetics, Acrotech/Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/BMS, Genentech/Roche.: Speakers Bureau; Janssen: Research Funding; Pharmacyclics/Abbvie, Bayer, Gilead/Kite Pharma, Pfizer, Janssen, Juno/Celgene, BMS, Kyowa, Alexion, Beigene, Fosunkite, Innovent, Seattle Genetics, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, Servier: Consultancy; Seattle Genetics: Research Funding; Millennium: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Incyte: Research Funding; Portola: Research Funding; Merck: Research Funding; Celgene: Research Funding; Gilead/Kite Pharma: Research Funding; Bayer: Research Funding; Seattle Genetics: Honoraria; Physicians' Education Resource: Honoraria; Targeted Oncology: Honoraria; OncView: Honoraria; Kyowa: Honoraria. Murthy: CRISPR Therapeutics: Research Funding. Maurer: Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Nanostring: Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Genentech: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bennani: Purdue Pharma: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Vividion: Other: Advisory Board; Kymera: Other: Advisory Board; Verastem: Other: Advisory Board. Paludo: Karyopharm: Research Funding. Wang: Genentech: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; MorphoSys: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; InnoCare: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lin: Vineti: Consultancy; Takeda: Research Funding; Sorrento: Consultancy; Novartis: Consultancy; Juno: Consultancy; Legend: Consultancy; Janssen: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Merck: Research Funding; Gamida Cell: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding.

Objective/background: Despite the success of chimeric antigen receptor (CAR) T-cell therapy in patients with aggressive non-Hodgkin lymphoma (aNHL), some patients still fail treatment, and their prognosis is dismal. Methods: We performed a retrospective study of aNHL patients treated with axicabtagene ciloleucel (axi-cel) at two Mayo Clinic centers between 2018 and 2020. We evaluated predictive factors, toxicities, and responses to salvage regimens after CAR T-cell therapy. Results: Thirty-four patients received axi-cel with a median length of hospitalization of 14 days. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome of any grade occurred in 91% and 41% of patients, respectively. Furthermore, 71% of patients responded to therapy, with 53% achieving a complete response (CR). The CRS grade and absolute lymphocyte count at leukapheresis (ALC Leuk ) correlated with CR and overall survival (OS), respectively. After a median follow-up of 6.8 months (interquartile range [IQR] 4.6–14.9), 15 patients (44%) showed progressive disease (PD). Most patients (60%) progressed during the first 3 months and had persistent CD19 tumor expression. Elevated C-reactive protein at baseline increased the risk of PD, whereas elevated ferritin increased PD and mortality risk. Twelve patients received salvage therapy, but only three responded. Median OS of relapsed/refractory patients to axi-cel was 3 months (IQR 1.3–5.1). Conclusion: The grade of CRS and ALC Leuk correlated with better outcomes to axi-cel therapy. In addition, elevated inflammatory markers at baseline were associated with PD and shorter survival. Relapses after treatment frequently occur within months after axi-cel infusion; they confer a poor prognosis and create an urgent need for novel and effective treatment options in this patient population.

e14516 Background: IEC are arguably the most promising therapy in oncology, and FDA approvals for CAR T cells are a testament to their real potential. This has led to a great growth of clinical trials (CT), making the evaluation of their associated data increasingly challenging. To facilitate this process, we performed a systematic review of ClinicalTrials.gov focused on IEC therapies in oncology. We performed an analysis of the CT data and forecast trends for 2025. Methods: CT registries were retrieved from ClinicalTrials.gov with a systematic search query. We included CT registered between 1993-2020, which used IEC-based therapies in oncology. Statistical analysis using descriptive and inferential methods allowed us to identify trends and establish forecasts. Results: We identified 938 registrations of IEC-CTs in oncology, and 51% of those were active. The most common IEC type was CAR T (51%), followed by NK (15%), TCR T (8%), TIL (8%), and CIK (3%). 69% of IEC-CTs were aimed at a specific target vs. 31% that lack that specificity. The number of annual CAR T-CTs continue to increase, and we forecast 320 registrations during 2025. Since 2018, the number of CTs using unmodified T cells and TIL has increased (largely due to metastatic melanoma studies). NK cells CTs represent 8% of all registrations, and by 2025 we anticipate that >150 NK-based CTs will be registered per year, a number similar to CAR T-CTs registered during 2020. IEC-CTs based on allogeneic sources represent 18% of all registrations and are expected to grow 2.5 fold in the next 5 years. In solid tumors, the most common IEC-CTs are based on Non-CAR studies, while in hem-malignancies 76% of CTs are CAR T. Only one solid tumor, CAR T-CT, has reached phase 2/3, while 7 CIK-CTs were used to target various organ tumors. Conclusions: IEC-CTs continue to grow exponentially and represent an active field of clinical research in oncology. Allogeneic and NK-CTs increase rapidly and are among the most promising IEC-CTs. A rising proportion of CTs in solid tumors are using CIK and TIL rather than CAR T-cells, which are more popular for treating hem-malignancies. This is a direct reflection of the challenges associated with CAR T infiltration and persistence in solid tumors. Our analyses indicate that annual IEC-CTs registrations will double by 2025. We anticipate the increase in cellular therapy options will demand an organized response, including adequate logistical planning and policy implementation in response to the landscape changes in clinical oncology during the upcoming years.[Table: see text]

7541 Background: FT516 is an investigational, NK cell cancer immunotherapy derived from a clonal master iPSC line. FT516 is engineered with a novel hnCD16 Fc receptor, demonstrated preclinically to maximize antibody-dependent cellular cytotoxicity (Zhu et al. Blood 2020). FT516 can be mass produced and made available off-the-shelf for broad pt access and multi-dose administration. Methods: This is a Phase I trial of FT516 combined with rituximab (R) in pts with R/R BCL. Treatment consists of 2 cycles, each with 3 days lympho-conditioning (fludarabine 30 mg/m 2 and cyclophosphamide 500 mg/m 2 ) and 1 dose of R followed by 3 weekly infusions of FT516 (planned doses 30-900 million/dose) with IL-2 (6 MIU after each FT516 dose). The primary objective is to identify the incidence of dose-limiting toxicity (DLT)/dose cohort and the recommended Phase II dose using a standard 3+3 design. Additional objectives include safety, tolerability, preliminary activity, pharmacokinetics, and immunogenicity. Results: Six pts (5 DLBCL, 1 FL, median age 65.5 y) have completed (5) or discontinued (1) study treatment after the DLT period (data cutoff 9 Dec 2020): 2 received 30 million cells/dose, 3 received 90 million cells/dose, and 1 received 300 million cells/dose. All pts received > 1 prior R-containing regimen, and median number of prior therapies was 3 (range 2-6), including CAR-T in 3 pts. FT516 was primarily administered in the outpatient setting. No FT516-related Grade ≥3 adverse events (AEs) or serious AEs, and no events of cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), or graft-versus-host disease (GvHD) of any grade were reported. DLT (Grade 4 neutrophil count decreased, not recovered to baseline by D29) was reported in the first pt at 30 million cells/dose and R dosing of 375 mg/m 2 weekly x 4/cycle, resulting in modification of R dosing to once/cycle; no DLTs were observed with modified R dosing. Most common all grade AEs in ≥3 pts: fatigue (4 pts) and decreased appetite, nausea, neutrophil count decreased, and headache (3 pts each). Grade ≥3 AEs in ≥2 pts: neutrophil count decreased (3 pts) and febrile neutropenia and platelet count decreased (2 pts each); none considered related to FT516. Host anti-product B- or T-cell immunogenicity was not observed. Three of 4 pts treated at ≥90 million cells/dose achieved objective response (2 complete responses [CRs] and 1 partial response). Conclusions: Administration of up to 6 doses of FT516 cells, including up to 300 million cells/dose, appears to be safe and tolerable, without CRS, ICANS, or GvHD. Activity was observed, including CRs, in heavily pretreated pts. Dose escalation is ongoing. Updated clinical and translational data will be presented. Clinical trial information: NCT04023071.

Abstract ZUMA-3 is a phase 1/2 study evaluating KTE-X19, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in adult relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We report the phase 1 results. After fludarabine-cyclophosphamide lymphodepletion, patients received a single infusion of KTE-X19 at 2 × 106, 1 × 106, or 0.5 × 106 cells per kg. The rate of dose-limiting toxicities (DLTs) within 28 days after KTE-X19 infusion was the primary end point. KTE-X19 was manufactured for 54 enrolled patients and administered to 45 (median age, 46 years; range, 18-77 years). No DLTs occurred in the DLT-evaluable cohort. Grade ≥3 cytokine release syndrome (CRS) and neurologic events (NEs) occurred in 31% and 38% of patients, respectively. To optimize the risk-benefit ratio, revised adverse event (AE) management for CRS and NEs (earlier steroid use for NEs and tocilizumab only for CRS) was evaluated at 1 × 106 cells per kg KTE-X19. In the 9 patients treated under revised AE management, 33% had grade 3 CRS and 11% had grade 3 NEs, with no grade 4 or 5 NEs. The overall complete remission rate correlated with CAR T-cell expansion and was 83% in patients treated with 1 × 106 cells per kg and 69% in all patients. Minimal residual disease was undetectable in all responding patients. At a median follow-up of 22.1 months (range, 7.1-36.1 months), the median duration of remission was 17.6 months (95% confidence interval [CI], 5.8-17.6 months) in patients treated with 1 × 106 cells per kg and 14.5 months (95% CI, 5.8-18.1 months) in all patients. KTE-X19 treatment provided a high response rate and tolerable safety in adults with R/R B-ALL. Phase 2 is ongoing at 1 × 106 cells per kg with revised AE management. This trial is registered at www.clinicaltrials.gov as #NCT02614066.

AbstractIntroductionHypoalbuminemia is a known adverse prognostic factor in lymphomas. Yet, it is unknown if axicabtagene ciloleucel (axi‐cel) overcomes the adverse prognostic impact of hypoalbuminemia in relapsed/refractory large B‐cell lymphoma.MethodsWe conducted a retrospective analysis across three Mayo Clinic centers to assess the relationship of hypoalbuminemia (defined as a serum albumin (SA) levels ≤ 3.5 g/dL) on outcomes of patients treated with axi‐cel.ResultsThis analysis included 81 patients. Two patients had no available SA levels preceding axi‐cel infusion. Eighteen patients (22.8%) had hypoalbuminemia with a median SA of 3.3 g/dL. Patients with normal SA had a statistically higher ORR than those without hypoalbuminemia (P = .018). There was no difference in 1‐year PFS and OS between the group with hypoalbuminemia and the group with normal SA levels (48% vs 49%, P = .81) and (74% vs 73%, P = .97), respectively. There was no difference in the severity or median duration of cytokine release syndrome or neurotoxicity between the two groups.ConclusionNotwithstanding the limitations related to the relatively small sample size, axi‐cel therapy appears to overcome the adverse effect of hypoalbuminemia on OS and PFS. Large multicenter clinical studies are certainly needed to validate these findings.