ABSTRACT
Background: First-line conventional chemoimmunotherapy in MCL can be improved. Promising results have been seen with Bruton tyrosine kinase inhibitors (BTKis) in combination with venetoclax (V) and an anti-CD20 monoclonal antibody in patients (pts) with relapsed/refractory or TN MCL. Acalabrutinib (A) is a next-generation, highly selective, covalent BTKi currently approved for relapsed/refractory MCL. We report initial safety and efficacy results of the ongoing, multicenter, open-label phase 1b study of A, V, and rituximab (R) (AVR) in TN MCL. Methods: TN MCL pts aged ≥18 y with ECOG PS ≤2 were eligible. Starting on cycle 1 day 1, A was administered at 100 mg BID until disease progression or discontinuation for other reasons. R was administered at 375 mg/m 2 on day 1 of each 28-day cycle for 6 cycles, followed by maintenance every other cycle for pts achieving complete response (CR) or partial response (PR), through cycle 24. Starting on cycle 2 day 1, V was administered via an initial 5-wk ramp-up schedule (20, 50, 100, 200, and 400 mg/d) to 400 mg/d, through cycle 25. Dose-limiting toxicity (DLT) was assessed from cycle 2 day 1 to cycle 3 day 28. Primary endpoint was AVR safety. Secondary endpoints were overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS) per Lugano criteria. Positron-emission tomography (PET)/computed tomography (CT) scans were performed after 3 and 6 cycles and to confirm CR at any time. CT scans were performed after 3, 6, 9, and 12 cycles, and then every 6 cycles. Longitudinal minimal residual disease (MRD) was assessed using the clonoSEQ assay in peripheral blood at PR, CR, every 6 cycles post-CR, and treatment end. Results: 21 pts were enrolled (median age 66 y [range 51-85];ECOG PS ≤1 20 [95%];Ann Arbor stage IV disease 19 [90%];bulky disease >5 cm 7 [33%];intermediate- and high-risk simplified MCL International Prognostic Index scores 11 [52%] and 4 [19%], respectively;blastoid variant 1 [5%];and Ki-67 proliferation index ≥50% 3 [14%]). Fifteen (71%) pts had bone marrow (BM) involvement at baseline. As of March 19, 2021, median time on study was 16 mo (range 8-26.2). Median (range) number of cycles administered was 15 (7-27) for A, 13.5 (5-23) for 400 mg daily V, and 12 (6-15) for R. Seventeen (81%) pts remain on study treatment and 4 (19%) have discontinued (progressive disease: n=1;COVID-19 infection: n=3). No DLTs were observed;V 400 mg daily after ramp-up was the dose chosen for triple therapy. Most common any-grade AEs in ≥20% of pts were diarrhea (13 [62%]), headache (11 [52%]), fatigue (10 [48%]), neutropenia (6 [29%]), paresthesia (6 [29%]), cough (6 [29%]), dyspnea (6 [29%]), myalgia (5 [24%]), dizziness (5 [24%]), and hypoesthesia (5 [24%]). Grade 3/4 AEs in ≥2 pts were neutropenia (5 [24%]) and pneumonia (2 [10%]). Serious any-grade AEs in ≥2 pts were COVID-19 infection (4 [19%]) and pneumonia (2 [10%]). In the 4 pts with COVID-19 infection, the events led to triple-drug discontinuation and death in 3 pts and to dose holds of A and V and event resolution in 1 pt (all considered unrelated to study treatment). Diarrhea led to V dose reduction in 1 pt. AEs led to dose holds in 12 (57%) pts and were associated with A, V, and R in 52%, 48%, and 14%, respectively. Events of clinical interest are shown in Table 1. At the end of cycle 6, ORR was 100%, with CR/PR in 90%/10% by PET/CT alone (11 of the 13 CRs by PET/CT lacked BM confirmation);the CR/PR rate by Lugano criteria with BM confirmation was 38%/62% (Table 2). Median DOR was 19 mo (95% CI 17-not estimable [NE]) overall, and not reached when the 3 pts with COVID-19 deaths were censored. Median PFS and OS were not reached. The 1-y PFS and OS rates were 89% (95% CI 62-97) and 95% (95% CI 71-99), respectively. Treating the 3 COVID-19 deaths as censored, the 1-y PFS rate was 93.8% (95% CI 63.2-99.1). Median time to initial response and best response was 2.8 mo. Twelve of 16 (75%) pts with available MRD results at cycle 6 achieved MRD negativity (10 -6), including 6 pts with
ABSTRACT
Background: Brexucabtagene autoleucel (brexu-cel) is the first CD19 chimeric antigen receptor T-cell (CAR T) therapy approved for use in patients (pts) with relapsed mantle cell lymphoma (MCL). The ZUMA-2 trial demonstrated that brexu-cel induces durable remissions in these pts with an ORR of 85% (59% CR), estimated 12-month PFS rate of 61%, and similar toxicity profile to other CAR T therapies (Wang et al, NEJM 2020). We conducted a multicenter, retrospective study of pts treated with commercial brexu-cel to evaluate its safety and efficacy in the non-trial setting. Methods: We reviewed records of pts with relapsed MCL across 12 US academic medical centers. Pts who underwent leukapheresis between July 2020 and June 2021 with the intent to proceed to commercial brexu-cel were included. Baseline demographic and clinical characteristics were summarized using descriptive statistics. Survival curves were generated using the Kaplan-Meier method, and univariate models were fit to identify predictors of post-CAR T outcomes. Results: Fifty-five pts underwent leukapheresis. There were 3 manufacturing failures. Baseline characteristics of the 52 pts who received brexu-cel are summarized in Table 1. Median age was 66 yrs (range: 47-79 yrs) and 82% were male. Twenty of 29 (69%) pts with known baseline MIPI were intermediate or high risk. Seven pts had a history of CNS involvement. The median number of prior therapies was 3 (range: 2-8), including prior autologous stem cell transplant (ASCT) in 21 (40%) and prior allogeneic transplant in 2 pts (1 with prior ASCT and 1 without). Fifty percent had relapsed within 24 months of their initial therapy. All pts had previously received a Bruton's tyrosine kinase inhibitor (BTKi), including 29 (56%) with disease progression on a BTKi. Forty (77%) pts received bridging therapy (17 BTKi, 10 BTKi + venetoclax, 6 chemo, 3 venetoclax, 2 XRT only, 1 steroids only, 1 lenalidomide + rituximab). The ORR was 88% (CR 69%) among patients who received brexu-cel. Two pts had PD on initial restaging and 3 died prior to first response assessment (without evidence of relapse). Seven pts have not completed restaging due to limited follow-up (< 3 months) and were not included in the response assessment. Five pts have progressed, including 2 with CR and 1 with PR on initial restaging. With a median follow-up of 4.2 months, the estimated 6-month PFS and OS rates were 82.7% and 89.0%, respectively. All 7 pts with prior CNS involvement were alive without relapse at last follow-up. The incidence of cytokine release syndrome (CRS) was 84% (10% grade ≥ 3) with a median time to max grade of 5 days (range: 0-10 days). There were no cases of grade 5 CRS. The incidence of neurotoxicity (NT) was 57% (31% grade ≥ 3) with a median time to onset of 7 days (range: 4-15 days). NT occurred in 4/7 pts with prior CNS involvement (3 grade 3, 1 grade 4). Grade 5 NT occurred in 1 pt who developed cerebral edema and died 8 days after infusion. Thirty-five pts received tocilizumab, 33 received steroids, 7 received anakinra, and 1 received siltuximab for management of CRS and/or NT. Post-CAR T infections occurred in 8 pts, including two grade 5 infectious AEs (covid19 on day +80 and septic shock on day +40 after infusion). Rates of grade ≥ 3 neutropenia and thrombocytopenia were 38% and 37%, respectively. Among pts with at least 100 days of follow-up and lab data available, 5/34 (15%) had persistent grade ≥ 3 neutropenia and 4/34 (12%) had persistent grade ≥ 3 thrombocytopenia at day +100. Five pts have died, with causes of death being disease progression (2), septic shock (1), NT (1), and covid19 (1). Univariate analysis did not reveal any significant associations between survival and baseline/pre-CAR T MIPI, tumor pathologic or cytogenetic features, prior therapies, receipt of steroids/tocilizumab, or pre-CAR T tumor bulk. Conclusions: This analysis of relapsed MCL pts treated with commercial brexu-cel reveals nearly identical response and toxicity rates compared to those reported on ZUMA-2. Longer follow-up is require to confirm durability of response, but these results corroborate the efficacy of brexu-cel in a population of older adults with high-risk disease features. While all 7 pts with prior CNS involvement are alive and in remission, strategies to mitigate the risk of NT in this setting need to be evaluated. Further studies to define the optimal timing of CAR T, bridging strategies, and salvage therapies for post-CAR T relapse in MCL are warranted. [Formula presented] Disclosures: Gerson: TG Therapeutics: Consultancy;Kite: Consultancy;Abbvie: Consultancy;Pharmacyclics: Consultancy. Sawalha: TG Therapeutics: Consultancy, Research Funding;Celgene/BMS: Research Funding;BeiGene: Research Funding;Epizyme: Consultancy. Bond: Kite/Gilead: Honoraria. Karmali: Janssen/Pharmacyclics: Consultancy;BeiGene: Consultancy, Speakers Bureau;Morphosys: Consultancy, Speakers Bureau;Takeda: Research Funding;Genentech: Consultancy;AstraZeneca: Speakers Bureau;Roche: Consultancy;Karyopharm: Consultancy;Epizyme: Consultancy;Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau;BMS/Celgene/Juno: Consultancy, Research Funding;EUSA: Consultancy. Torka: TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Chow: ADC Therapeutics: Current holder of individual stocks in a privately-held company, Research Funding;AstraZeneca: Research Funding. Shadman: Abbvie, Genentech, AstraZeneca, Sound Biologics, Pharmacyclics, Beigene, Bristol Myers Squibb, Morphosys, TG Therapeutics, Innate Pharma, Kite Pharma, Adaptive Biotechnologies, Epizyme, Eli Lilly, Adaptimmune, Mustang Bio and Atara Biotherapeutics: Consultancy;Mustang Bio, Celgene, Bristol Myers Squibb, Pharmacyclics, Gilead, Genentech, Abbvie, TG Therapeutics, Beigene, AstraZeneca, Sunesis, Atara Biotherapeutics, GenMab: Research Funding. Ghosh: Genentech: Research Funding;Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding, Speakers Bureau;Karyopharma: Consultancy, Honoraria;Seattle Genetics: Consultancy, Honoraria, Speakers Bureau;Janssen: Consultancy, Honoraria, Speakers Bureau;TG Therapeutics: Consultancy, Honoraria, Research Funding;Incyte: Consultancy, Honoraria;Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau;Genmab: Consultancy, Honoraria;Epizyme: Honoraria, Speakers Bureau;Bristol Myers Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau;AstraZeneca: Consultancy, Honoraria, Speakers Bureau;ADC Therapeutics: Consultancy, Honoraria;Adaptive Biotech: Consultancy, Honoraria;AbbVie: Honoraria, Speakers Bureau. Moyo: Seattle Genetics: Consultancy. Fenske: TG Therapeutics: Consultancy, Speakers Bureau;Servier Pharmaceuticals: Consultancy;Seattle Genetics: Speakers Bureau;Sanofi: Speakers Bureau;Pharmacyclics: Consultancy;MorphoSys: Consultancy;Kite (Gilead): Speakers Bureau;KaryoPharm: Consultancy;CSL Therapeutics: Consultancy;Bristol-Myers Squibb: Speakers Bureau;Biogen: Consultancy;Beigene: Consultancy;AstraZeneca: Speakers Bureau;ADC Therapeutics: Consultancy;Adaptive Biotechnologies: Consultancy;AbbVie: Consultancy. Grover: Genentech: Research Funding;Novartis: Consultancy;ADC: Other: Advisory Board;Kite: Other: Advisory Board;Tessa: Consultancy. Maddocks: Seattle Genetics: Divested equity in a private or publicly-traded company in the past 24 months;BMS: Divested equity in a private or publicly-traded company in the past 24 months;Pharmacyclics: Divested equity in a private or publicly-traded company in the past 24 months;Novatis: Divested equity in a private or publicly-traded company in the past 24 months;Janssen: Divested equity in a private or publicly-traded company in the past 24 months;Morphosys: Divested equity in a private or publicly-traded company in the past 24 months;ADC Therapeutics: Divested equity in a private or publicly-traded company in the past 24 months;Karyopharm: Divested equity in a private or publicly-traded company in the past 24 months;Beigene: Divested equity in a private or publicly-traded company in the past 24 months;Merck: Divested equity in a private or publicly-traded company in the past 24 months;KITE: Divested equity in a private or publicly-traded company in the past 24 months;Celgene: Divested equity in a private or publicly-traded company in the past 24 months. Jacobson: Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support;Humanigen: Consultancy, Honoraria, Other: Travel support;Celgene: Consultancy, Honoraria, Other: Travel support;Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding;Lonza: Consultancy, Honoraria, Other: Travel support;AbbVie: Consultancy, Honoraria;Precision Biosciences: Consultancy, Honoraria, Other: Travel support;Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support;Nkarta: Consultancy, Honoraria;Axis: Speakers Bureau;Clinical Care Options: Speakers Bureau. Cohen: Janssen, Adaptive, Aptitude Health, BeiGene, Cellectar, Adicet, Loxo/Lilly, AStra ZenecaKite/Gilead: Consultancy;Genentech, Takeda, BMS/Celgene, BioInvent, LAM, Astra Zeneca, Novartis, Loxo/Lilly: Research Funding.