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548 Updated Clinical and Correlative Results from the Phase I CRB-402 Study of the BCMA-Targeted CAR T Cell Therapy bb21217 in Patients with Relapsed and Refractory Multiple Myeloma

Program: Oral and Poster Abstracts
Type: Oral
Session: 704. Cellular Immunotherapies: Cellular Therapies for Myeloma
Hematology Disease Topics & Pathways:
Clinical Trials, Biological, Clinical Research, Plasma Cell Disorders, Chimeric Antigen Receptor (CAR)-T Cell Therapies, Diseases, Therapies, Lymphoid Malignancies
Sunday, December 12, 2021: 4:45 PM

Noopur S. Raje, MD1, Nina Shah, MD2, Sundar Jagannath, MD3, Jonathan L. Kaufman, MD4, David S. Siegel, MD, PhD5, Nikhil C. Munshi, MD, PhD6, Jacalyn Rosenblatt, MD7, Yi Lin, MD, PhD8, Andrzej Jakubowiak9, Alison Timm, MA10*, Ashish Yeri, PhD10*, Nathan Martin, PhD11*, Timothy B. Campbell, MD, PhD11*, Olivia Finney, PhD10*, Anna Truppel-Hartmann, MD10*, Fabio Petrocca, MD10*, Jesús G. Berdeja12 and Melissa Alsina, MD13

1Division of Hematology and Oncology, Mass General Hospital Cancer Center, Boston, MA
2University of California San Francisco, San Francisco, CA
3Department of Medicine, Hematology and Medical Oncology, Mount Sinai Medical Center, New York, NY
4Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA
5Hackensack Univ. Med. Ctr., Hackensack, NJ
6Dana-Farber Cancer Institute, Harvard Medical School, Boston
7Beth Israel Deaconess Medical Center, Boston, MA
8Mayo Clinic, Rochester, MN
9University of Chicago, Chicago, IL
10bluebird bio, Cambridge, MA
11Bristol Myers Squibb, Princeton, NJ
12Sarah Cannon Research Institute, Nashville, TN
13Department of Blood & Marrow Transplant and Cellular Immunotherapy, H. Lee Moffitt Cancer Ctr. Hematologic Malignancies Program, Tampa, FL

Introduction: Idecabtagene vicleucel (ide-cel, bb2121) is the first chimeric antigen receptor (CAR) T cell therapy approved for the treatment of relapsed or refractory multiple myeloma after four or more prior lines of therapy, including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody. bb21217 is a B-cell maturation antigen (BCMA) directed CAR T cell therapy which uses the same CAR molecule as ide-cel, with the addition of a PI3K inhibitor (bb007) during ex vivo culture to enrich the drug product (DP) for memory-like T cells and decrease the proportion of highly differentiated or senescent T cells. We hypothesize that DPs enriched for memory like CAR T cells will persist and function longer than non-enriched DPs and this increased persistence will positively influence duration of response (DOR). We previously demonstrated patients with sustained response are more likely to have drug product enriched for naïve gene signatures and depleted of effector gene signatures compared to patients without a sustained response.

Methods: CRB-402 (NCT03274219) is a multi-center phase 1 trial of bb21217 in RRMM patients who received ≥3 prior lines of antimyeloma therapy, including a proteasome inhibitor and an immunomodulatory agent, or are double-refractory to both classes. In expansion, patients were required to have prior exposure to an anti-CD38 antibody and were required to be refractory to their last line of therapy. Patients underwent lymphodepletion with fludarabine (30 mg/m2) and cyclophosphamide (300 mg/m2) daily for 3 days, then received a single infusion of bb21217 at 150, 300 or 450 x 106 CAR+ T cells. The primary outcome measure is incidence of adverse events (AEs), including dose-limiting toxicities (DLTs). Additional outcome measures include overall response rate and DOR by IMWG Uniform Response Criteria. Exploratory analyses include correlation of outcome with the molecular characteristics of materials collected temporally through the treatment course, including PBMCs at apheresis, CAR+ T cells from drug product and CAR+ T cells collected from patients around the time of peak expansion.

Results: As of Feb 16, 2021, 72 patients received bb21217, 12 at 150, 14 at 300 and 46 at 450 x 106 CAR+ T cells; median follow up for all patients is 9.0 (<1-36) months (M). Patients had a median of 6 (3-17) prior lines of therapy with 49/72 (68%) triple refractory. Cytokine release syndrome (CRS) developed in 54/72 (75%) patients and was predominately G1/2 (51 pts), with 1 G3 event and 2 deaths (previously reported). Median time to first onset of CRS was 2 days (1-20); tocilizumab (38 pts) + corticosteroids (12 pts) was used to manage CRS. Eleven (15%) patients developed neurotoxicity [8 G1/G2, 2 G3, 1 G4] with median time to first onset of 7 (2-24) days. Response was assessed per investigator for 72 patients treated with bb21217 (Table). CAR+ T cells remained detectable in 30/37 (81%) patients and 9/15 (60%) patients at 6 and 12 M respectively, post bb21217 infusion. Of the 15 patients evaluable for MRD with ≥CR, 14 (93%) were MRD negative at 10-5 by NGS. Analysis of peripheral blood samples collected 15 days post bb21217 infusion demonstrated patients with higher than the median number of CD8+ CAR+ T cells expressing CD27 and CD28 had significantly longer DOR (p=0.0024), compared to patients with lower than the median values. This suggests less differentiated, more proliferative CAR+ T cells at peak expansion are associated with prolonged disease response (median DOR in high vs low: 27.2M (95% CI; 16.8, NE) vs 9.4M (95% CI; 5.1, NE).

Conclusions: Adverse events are consistent with known toxicities of CAR T cell therapies. Efficacy results are encouraging with a median DOR estimate of 17M, CR rate continues to mature. Patients with higher levels of proliferative, less differentiated memory like CAR+ T cells at peak expansion are more likely to experience prolonged DOR, continuing to support the hypothesis that the memory like T cell phenotype associated with bb21217 results in prolonged DOR.

Disclosures: Raje: Amgen: Other; bluebird bio: Other; Janssen: Other; Caribou: Other; BMS: Other; Celgene: Other. Shah: Poseida: Research Funding; Precision Biosciences: Research Funding; Sanofi: Consultancy; Sutro Biopharma: Research Funding; Karyopharm: Consultancy; Janssen: Research Funding; Oncopeptides: Consultancy; Kite: Consultancy; Nektar: Research Funding; Indapta Therapeutics: Consultancy; GSK: Consultancy; CSL Behring: Consultancy; CareDx: Consultancy; BMS/Celgene: Research Funding; Bluebird Bio: Research Funding; Amgen: Consultancy; Teneobio: Research Funding. Kaufman: Sutro, Takeda: Research Funding; Roche, BMS: Consultancy; BMS, Janssen, AbbVie, Novartis, Amgen: Research Funding. Siegel: Celularity: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Speakers Bureau; Takeda: Honoraria; Bristol Myers Squibb: Honoraria, Speakers Bureau; Amgen Inc.: Honoraria; Karyopharm: Honoraria; Janssen: Honoraria, Speakers Bureau. Munshi: Janssen: Consultancy; Bristol-Myers Squibb: Consultancy; Legend: Consultancy; Adaptive Biotechnology: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Abbvie: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Karyopharm: Consultancy; Pfizer: Consultancy. Rosenblatt: Karyopharm: Membership on an entity's Board of Directors or advisory committees; Parexel: Consultancy; Wolters Kluwer Health Inc: Consultancy, Patents & Royalties; BMS: Research Funding; Attivare: Consultancy; Imaging Endpoints: Consultancy; Sanofi: Research Funding. Lin: Sorrento: Consultancy; Takeda: Research Funding; Juno: Consultancy; Celgene: Consultancy, Research Funding; Merck: Research Funding; Vineti: Consultancy; Legend: Consultancy; Bluebird Bio: Consultancy, Research Funding; Novartis: Consultancy; Gamida Cell: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Jakubowiak: BMS: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Gracell: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees. Timm: bluebird bio: Current Employment. Yeri: bluebird bio: Current Employment. Martin: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Campbell: Bristol Myers Squibb: Current Employment, Current holder of individual stocks in a privately-held company. Finney: bluebird bio: Current Employment, Current equity holder in publicly-traded company. Truppel-Hartmann: bluebird bio: Current Employment. Petrocca: blue bird bio: Ended employment in the past 24 months. Berdeja: Abbvie, Acetylon, Amgen: Research Funding; Celularity, CRISPR Therapeutics: Research Funding; Bluebird bio, BMS, Celgene, CRISPR Therapeutics, Janssen, Kite Pharma, Legend Biotech, SecuraBio, Takeda: Consultancy; EMD Sorono, Genentech: Research Funding; GSK, Ichnos Sciences, Incyte: Research Funding; Lilly, Novartis: Research Funding; Poseida, Sanofi, Teva: Research Funding.

OffLabel Disclosure:

*signifies non-member of ASH