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Martin, Nathan

https://orcid.org/0000-0002-2899-7610

Mayo Clinic

Bristol-Myers Squibb (United States)

Citations 7

Cross-Cohort Correlative Analysis of Clinically High-Risk Patients (pts) Treated with Idecabtagene Vicleucel (ide-cel) in KarMMa-2: Association between Progression-Free Survival (PFS) and Tumor Burden and Immune Status at Apheresis
Basudhar, Debashree, Descalzi‐Montoya, Dante B. , Wang, Minshi , Leleu, Xavier , Hosseyni, Daniela , Chaudhry, Maria, Martin, Nathan , Thompson, Ethan, Tang, Hao , Wu, Fan, Bergsagel, P. Leif

Blood | December 6, 2024 | Volume: 144 | Issue: Supplement 1 | Pages: 3382-3382

10.1182/blood-2024-198740 Get It

Introduction Despite improvements in outcomes with triplet and quadruplet combination regimens in front-line (1L) multiple myeloma (MM) treatment (Tx), pts with disease that relapses early after 1L Tx or responds inadequately to 1L autologous stem cell transplantation (ASCT) have poor prognosis. Therefore, Txs with novel mechanisms of action are needed. Ide-cel, a BCMA-directed CAR T cell therapy, resulted in deep and durable responses in pts with functional high-risk MM. KarMMa-2 (NCT03601078) is a phase 2, multicenter, multicohort trial of ide-cel: cohort 2a includes pts who progressed ≤ 18 mo of starting 1L therapy with ASCT, cohort 2b includes pts who progressed ≤ 18 mo of starting 1L therapy without ASCT, and cohort 2c includes pts who achieved less than very good partial response ~100 d after 1L ASCT. With a median follow-up of 21.5, 30.1, and 39.4 mo, respectively, median PFS (95% CI) for cohorts 2a, 2b, and 2c was 11.4 mo (5.6-19.6), not reached (NR; 12.2-NR), and NR (38.0-NR). Previous correlative analyses of ide-cel in relapsed and refractory MM have shown that pts with lower pre-Tx tumor burden and lower pre-Tx indicators of basal inflammation had better responses. This cross-cohort analysis evaluated tumor burden, baseline inflammatory status, and T-cell quality differences to develop hypotheses for biologic features underpinning robust PFS previously observed with ide-cel. Methods Levels of soluble BCMA (sBCMA) and 25 exploratory cytokines at infusion and post-Tx were measured by immunoassay. Apheresis and drug product material were characterized by high-parameter flow cytometry and immunoassay. Pharmacokinetics (PK) were evaluated by droplet digital polymerase chain reaction. These analyses were exploratory and post hoc in nature; statistical tests were utilized to identify relationships of interest to develop working hypotheses of the underlying biology. Results Baseline tumor burden, evaluated by median sBCMA (interquartile range [IQR]), was highest in cohort 2b at 156 ng/mL (83-300) compared with 2a at 91 ng/mL (41-169) and 2c at 27 ng/mL (19-48). Pts in cohort 2b had the lowest baseline levels of a subset of inflammatory cytokines, including interferon [IFN]-γ and interleukin-4. Phenotypic data from apheresis material showed that, among the 3 cohorts, pts in cohort 2b also had the lowest amount of effector memory T cells positive for CD45RA (TEMRA; terminally differentiated T cells) and CD57+ T cells (senescent T cells), and the highest amount of CCR7+CD27+ T cells (early memory T cells). Cohorts 2a and 2c had similar phenotypic profiles in the apheresis material. Median time from ASCT to infusion (IQR) was 12.1 mo (9.7-14.3) in cohort 2a and 5.8 mo (5.2-6.2) in cohort 2c. Pts in cohort 2b also had a higher CD4:CD8 ratio in the apheresis material vs the other 2 cohorts. Profiling the drug products from pts in cohort 2b showed higher CAR+ T cell frequency and CAR-specific IFN-γ, and tumor necrosis factor-α and granzyme secretion upon stimulation vs 2a and 2c, with a consistent and comparable potency profile among all cohorts. While sBCMA level at infusion was lower in cohort 2c vs 2a, the similarity in inflammatory state and T-cell quality may reflect impacts from recent melphalan use before ASCT and bone marrow recovery after ASCT, as most pts in both cohorts were < 18 mo from ASCT. Robust cell expansion was observed across cohorts. Conclusions The encouraging median PFS outcome previously observed in cohort 2b relative to existing therapies in this high-risk pt population may be driven by the higher T-cell quality and better inflammatory state pre-Tx despite high baseline tumor burden (sBCMA). Pts in cohorts 2c and 2a had comparatively less optimal baseline immune status vs cohort 2b. The promising PFS observed in cohort 2c may be reflective of sufficient T-cell quality to drive optimal responses in the context of relatively low tumor burden at study entry. The median PFS in cohort 2a may reflect the combination of high tumor burden and less optimal baseline inflammatory status. These observations suggest a working model in which ide-cel may demonstrate robust PFS in pts with early-line, high-risk MM and high tumor burden with good baseline immune status and T-cell quality, and in pts with less favorable baseline immune status and T-cell quality when tumor burden is relatively low and stable.
Validation of prototype biomarkers to identify risk factors of inflammatory adverse events (iAEs) following idecabtagene vicleucel (ide-cel) infusion in patients with relapsed and refractory multiple myeloma (RRMM) in KarMMa-3.
Sengupta, Sanhita , Amorosi, Clara J. , Takhar, Mandeep, Manier, Salomon , Juluri, Krishna R. , Kaeding, Allison, Piasecki, Julia , Campbell, Timothy , Kaiser, Shari M. , Shamsuzzaman, Md, Martin, Nathan , Lin, Yi , Baz, Rachid , Mashadi-Hossein, Afshin , Rytlewski, Julie

Journal of Clinical Oncology | June 10, 2024 | Volume: 42 | Issue: 16_suppl | Pages: 7529-7529

10.1200/jco.2024.42.16_suppl.7529 Get It

7529 Background: iAEs, such as cytokine release syndrome (CRS) and macrophage activation syndrome (MAS), can occur after infusion of chimeric antigen receptor T cell therapies such as ide-cel, but are typically low-grade and manageable with tocilizumab and corticosteroids. Although high-grade iAEs are rare with ide-cel, identification of patients at increased risk may improve management and remains an unmet need. Three composite biomarkers (multivariate models) of iAE risk were previously developed in a discovery cohort from the KarMMa and KarMMa-2 studies of ide-cel in RRMM (Mashadi-Hossein A, et al. J Clin Oncol 2023;41(16_suppl):e20005). Here, we validate these 3 prototype models for risk of developing high-grade iAEs after ide-cel infusion. Methods: Two models used pretreatment patient and routine clinical laboratory parameters; the third model also included change in 6 exploratory cytokines from baseline to 1 day following ide-cel infusion. To validate, each model was retrospectively applied to KarMMa-3 (NCT03651128) data in a blinded fashion, and sensitivity and specificity to identify grade ≥3 CRS and any-grade MAS were determined. Model performance thresholds used for sensitivity and specificity were 90% and 50%, respectively. Performance for identifying grade 2 CRS was also analyzed post hoc. Results: The first and simplest model comprised a manual algorithm with 7 features; it identified patients with grade ≥3 CRS or MAS with 85% sensitivity and 60% specificity. The second model comprised 19 routinely measured pretreatment features; it identified grade ≥3 CRS with 91% sensitivity and 59% specificity, and any-grade MAS with 60% sensitivity and 88% specificity. The third and most complex model comprised 7 pretreatment clinical features and 6 exploratory cytokines; it identified grade ≥3 CRS with 100% sensitivity and 51% specificity, and any-grade MAS with 100% sensitivity and 81% specificity. None of the models identified grade ≥2 CRS with passable sensitivity or specificity. Clustering analyses across all features showed that only a subset of grade 2 CRS cases was within the previously identified high-risk iAE cluster while the remaining grade 2 CRS cases were spread across other clusters. Conclusions: Two of the 3 composite biomarkers met validation criteria for grade ≥3 CRS risk. Criteria were not met for grade 2 CRS, suggesting these models are specific to higher-grade events and that grade 2 CRS represents a more heterogeneous group of patients. While high-grade iAEs are rare with ide-cel, these models may further optimize the robust benefit–risk profile that ide-cel has demonstrated by helping identify, prior to or shortly after infusion, patients most at risk for severe events. Clinical trial information: NCT03651128 .
P809: BASELINE CHARACTERISTICS IDENTIFYING PATIENTS WITH MULTIPLE MYELOMA TREATED WITH IDECABTAGENE VICELEUCEL (IDE-CEL; BB2121) WHO ARE AT RISK FOR SEVERE/REFRACTORY INFLAMMATORY ADVERSE EVENTS
Shamsuzzaman, Md, Basudhar, Debashree, Takhar, Mandeep, Kostić, Ana , Campbell, Timothy , Manier, Salomon , Lin, Yi, Martin, Nathan , Mashadi-Hossein, Afshin , Rytlewski, Julie

HemaSphere | August 22, 2023 | Volume: 7 | Issue: S3 | Pages: e1004207

10.1097/01.hs9.0000970140.10042.07 Get It

Baseline characteristics identifying patients (pts) with multiple myeloma (MM) treated with idecabtagene vicleucel (ide-cel; bb2121) who are at risk for severe/refractory inflammatory adverse events (iAEs).
Shamsuzzaman, Md, Basudhar, Debashree, Takhar, Mandeep, Kostić, Ana , Campbell, Timothy , Manier, Salomon , Martin, Nathan , Mashadi-Hossein, Afshin , Rytlewski, Julie , Lin, Yi

Journal of Clinical Oncology | June 9, 2023 | Volume: 41 | Issue: 16_suppl | Pages: e20005-e20005

10.1200/jco.2023.41.16_suppl.e20005 Get It

e20005 Background: iAEs such as cytokine release syndrome (CRS) and neurotoxicity (NT) are common with CAR T cell therapies such as ide-cel; CRS and NT observed with ide-cel are generally low grade and manageable with tocilizumab (toci) and corticosteroids. Identifying iAE risk with sensitivity and specificity is challenging, suggesting multifactorial etiology and limitations evaluating dynamic processes at specific timepoints. Macrophage activation syndrome (MAS; per CTCAE) has a specific molecular profile representing a homogeneous subgroup within CRS, tending to be more severe/refractory to front-line management. Using longitudinal data on post-infusion soluble factors we aimed to develop a candidate post-infusion inflammatory risk score based on MAS molecular signature and determine associations with pt baseline characteristics. Methods: Statistical learning tools were applied to the longitudinal profile of 34 factors measured over 28 d after ide-cel infusion in 291 pts from KarMMa (NCT03361748) and KarMMa-2 (NCT03601078) to extract features describing the profiles. Unsupervised machine learning-based clustering was applied to these features and enrichment for MAS cases within each cluster was assessed. A metric describing membership in a cluster of interest was used as a candidate post-infusion inflammatory risk score for further correlative analyses. Results: Pts with MAS had cytokine profiles consistent with high levels of pro-inflammatory signalling across multiple inflammatory cell types. Cytokine profiles of MAS were qualitatively similar to those of CRS/NT; however, unsupervised clustering showed a distinct group of pts with MAS. A metric of similarity to the MAS-enriched cluster was defined as a candidate post-infusion inflammatory risk score, posited to identify pts more likely to have more severe/refractory iAEs. This inflammatory risk score positively correlated with CRS and NT grades and frequency of toci usage (Kruskal-Wallis test; all P < 0.001). A prototype predictive model based on baseline pt and clinical characteristics strongly correlated with post-infusion inflammatory risk score (Pearson; ρ = 0.88). Low blood counts, higher tumor burden, and elevated levels of inflammatory markers on the day of ide-cel infusion were associated with a higher inflammatory risk score. Conclusions: A molecular profile of severe/refractory iAEs was preliminarily identified in ide-cel treated pts with MM. This profile enabled derivation of a candidate post-infusion inflammatory risk score and a prototype predictive model of this risk score based on pt baseline characteristics was developed. These results may help identify pts at risk for severe/refractory iAEs, who may be potential candidates for closer monitoring or novel interventions, and warrant further study. Clinical trial information: NCT03361748 , NCT03601078 .
Early and Sustained Undetectable Measurable Residual Disease (MRD) after Idecabtagene Vicleucel (ide-cel) Defines a Subset of Multiple Myeloma (MM) Patients in Karmma Achieving Prolonged Survival
Manrique, Irene , Campbell, Timothy , Kazanecki, Christian C. , Martin, Nathan , Kaiser, Shari M. , Anderson, Larry D. , Lin, Yi , Munshi, Nikhil C. , Anderson, Larry D , Paiva, Bruno , Rytlewski, Julie , Berdeja, Jesús G. , Lonial, Sagar , Raje, Noopur , Moreau, Philippe , Miguel, Jesús F. San

Blood | November 28, 2022 | Volume: 140 | Issue: Supplement 1 | Pages: 2104-2105

10.1182/blood-2022-166658 Get It

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
Shah, Nina , Munshi, Nikhil C. , Timm, Alison, Yeri, Ashish, Martin, Nathan , Campbell, Timothy , Finney, Olivia , Truppel-Hartmann, Anna, Alsina, Melissa , Raje, Noopur , Jagannath, Sundar , Kaufman, Jonathan L. , Siegel, David S. , Rosenblatt, Jacalyn , Lin, Yi , Jakubowiak, Andrzej , Petrocca, Fabio , Berdeja, Jesús G.

Blood | November 23, 2021 | Volume: 138 | Issue: Supplement 1 | Pages: 548-548

10.1182/blood-2021-146518 Get It

Abstract 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/m 2) and cyclophosphamide (300 mg/m 2) daily for 3 days, then received a single infusion of bb21217 at 150, 300 or 450 x 10 6 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: Asof Feb 16, 2021, 72 patients received bb21217, 12 at 150, 14 at 300 and 46 at 450 x 10 6 CAR+ T cells; median follow up for all patients is 9.0 (&lt;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. Figure 1 Figure 1. Disclosures Raje: Caribou: Other; Janssen: Other; bluebird bio: Other; Amgen: Other; Celgene: Other; BMS: 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: BMS: Consultancy, Research Funding; Tecnofarma SAS, AbbVie: Honoraria; Incyte, celgene: Consultancy; Janssen: Honoraria; Incyte, TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Heidelberg Pharma: Research Funding; Amgen: Research Funding; Fortis Therapeutics: Research Funding; Novartis: Research Funding; Roche/Genetech, Tecnopharma: Consultancy, Honoraria; Sutro, Takeda: Research Funding; Genentech, AbbVie, Janssen: Consultancy, 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: Parexel: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Imaging Endpoints: Consultancy; Attivare: Consultancy; Wolters Kluwer Health Inc: Consultancy, Patents & Royalties. 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.
Updated Results from the Phase I CRB-402 Study of Anti-Bcma CAR-T Cell Therapy bb21217 in Patients with Relapsed and Refractory Multiple Myeloma: Correlation of Expansion and Duration of Response with T Cell Phenotypes
Alsina, Melissa , Shah, Nina , Munshi, Nikhil C. , Jasielec, Jagoda, Timm, Alison, Turka, Ashley, Mao, Pingping, Martin, Nathan , Campbell, Timothy , Hege, Kristen , Raje, Noopur , Jagannath, Sundar , Madduri, Deepu , Kaufman, Jonathan L. , Siegel, David S. , Rosenblatt, Jacalyn , Lin, Yi , Jakubowiak, Andrzej , Bitter, Hans , Petrocca, Fabio , Berdeja, Jesús G.

Blood | November 4, 2020 | Volume: 136 | Issue: Supplement 1 | Pages: 25-26

10.1182/blood-2020-140410 Get It

Introduction: Chimeric antigen receptor (CAR) T cell therapy directed against B-cell maturation antigen (BCMA) has shown promising results for the treatment of relapsed refractory multiple myeloma (RRMM). bb21217 is an anti-BCMA CAR T cell therapy that uses the same CAR molecule as idecabtagene vicleucel (bb2121), but adds the PI3K inhibitor bb007 during ex vivo culture to enrich the drug product (DP) for memory-like T cells, thereby reducing the proportion of highly differentiated or senescent T cells. To investigate whether DP properties correlate with clinical outcomes including duration of response (DOR), we conducted extensive molecular characterization of patient DPs. Methods: CRB-402 (NCT03274219) is an ongoing, multi-center phase 1 dose escalation trial of bb21217 in RRMM patients who received ≥3 prior regimens, including proteasome inhibitor and immunomodulatory agent, or are double-refractory to both classes. In the expansion cohort, patients additionally required prior exposure to an anti-CD38 antibody and were required to be refractory to last line. Planned enrollment is 74 patients, including 50 in the expansion cohort. Patients undergo lymphodepletion with fludarabine (30 mg/m2) and cyclophosphamide (300 mg/m2) daily for 3 days, then receive 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. We profiled DP and apheresis starting material (PBMC) by RNAseq and cyTOF and correlated expression of memory/senescence markers from apheresis to DP with clinical outcomes, including DOR. Results: Asof March 1, 2020, 46 patients (median age 62 [33-74]) received bb21217, 24 in escalation (12 at 150, 6 at 300 and 6 at 450) and 22 in expansion (8 at 300 and 14 at 450); median follow up for all patients is 8.5 (&lt;1-29) months. Patients had a median of 6 (3-17) prior lines of therapy with 26/46 (57%) triple refractory. Cytokine release syndrome (CRS) developed in 31/46 (67%) patients and included one death (14 G1, 15 G2, 1 G3 and 1 G5). Median time to first onset was 3 days (1-20); tocilizumab (18 pts) +/- corticosteroids (6 pts) was used to manage CRS. Ten (22%) patients developed neurotoxicity [5 G1, 2 G2, 2 G3, 1 G4] with median time to first onset of 7 (3-24) days. Response was assessed per investigator for 44 patients with ≥ 2 months of follow up or PD/death within 2 months. Twenty-four (55%) patients had confirmed response per IMWG criteria including 8 (18%) with ≥CR and 13 (30%) with VGPR. Median time to CR was 2.5 (1-24) months. The median DOR was 11.9 (95% CI: 8.1-17.0) months across target dose levels of 150-450 x106 CAR+ T cells. The 450 target dose was selected as the RP2D and dose expansion is ongoing. bb21217 DPs from 44 patients were characterized. Paired analysis of T cells from PBMC and DP showed bb21217 DP is significantly enriched for memory-like T cells (LEF1+, CD27+, CCR7+) and depleted of highly differentiated or senescent CD57+ T cells. Patients with DPs most enriched for early memory markers (LEF1+, CCR7+ and CD27+) and with low expression of effector/exhaustion markers (EOMES+, GZMA+, CD57+) were more likely to have higher peak CAR+ T cell expansion. To evaluate the association of these DP markers with DOR, we split the 24 responders (≥PR) on median marker expression (high vs low) and analyzed DOR in these exploratory subgroups. High CD127 expression, associated with long-lasting memory T cell formation, was positively correlated with DOR, while multiple markers associated with differentiated T cells (e.g. EOMES+, TBET+) were negatively correlated with DOR. Conclusions: The adverse events observed are consistent with known toxicities of CAR T cell therapies. Initial efficacy results with bb21217 are encouraging, with 48% of patients treated across target dose levels of 150-450 obtaining ≥VGPR. The presence of T cell markers associated with memory and the absence of T cells markers associated with differentiation/senescence in DP correlated positively with peak expansion and DOR. These preliminary correlative data support the mechanistic hypothesis that enrichment for memory like T cells in bb21217 DP may result in improved clinical outcomes. Data for approximately 14 additional patients at the 450 target dose will be presented. Disclosures Alsina: Janssen: Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria; Amgen: Honoraria, Speakers Bureau; BMS: Consultancy, Research Funding. Shah:GSK, Amgen, Indapta Therapeutics, Sanofi, BMS, CareDx, Kite, Karyopharm: Consultancy; BMS, Janssen, Bluebird Bio, Sutro Biopharma, Teneobio, Poseida, Nektar: Research Funding. Raje:Janssen: Consultancy; Celgene: Consultancy; Immuneel: Membership on an entity's Board of Directors or advisory committees; Caribou: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Astrazeneca: Consultancy; Bluebird, Bio: Consultancy, Research Funding; Karyopharm: Consultancy; BMS: Consultancy; Amgen: Consultancy. Jagannath:Karyopharm: Consultancy, Honoraria; Legend Biotech: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Madduri:Janssen: Consultancy; BMS: Consultancy; Takeda: Consultancy; Legend: Consultancy; Sanofi: Consultancy; GSK: Consultancy; Kinevant: Consultancy; Foundation Medicine: Consultancy. Kaufman:Janssen: Consultancy, Honoraria; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Tecnopharma: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; AbbVie: Consultancy; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi/Genyzme: Consultancy, Honoraria. Siegel:Amgen: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Speakers Bureau; Karyopharma: Consultancy, Honoraria; Celulatiry: Consultancy. Munshi:BMS: Consultancy; OncoPep: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; C4: Current equity holder in private company; Janssen: Consultancy; Adaptive: Consultancy; Legend: Consultancy; Amgen: Consultancy; AbbVie: Consultancy; Karyopharm: Consultancy; Takeda: Consultancy. Lin:Novartis: Consultancy; Celgene: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy; Legend BioTech: Consultancy; Merck: Research Funding; Takeda: Research Funding; Gamida Cells: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Vineti: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Jakubowiak:AbbVie, Amgen, BMS/Celgene, GSK, Janssen, Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive, Juno: Consultancy, Honoraria. Timm:bluebird bio: Current Employment, Current equity holder in publicly-traded company. Turka:bluebird bio: Current Employment. Mao:bluebird bio: Current Employment, Current equity holder in publicly-traded company. Martin:BMS: Current Employment, Current equity holder in publicly-traded company. Campbell:BMS: Current Employment, Current equity holder in publicly-traded company. Hege:Arcus Biosciences: Divested equity in a private or publicly-traded company in the past 24 months; Mersana Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BMS: Current Employment, Current equity holder in publicly-traded company, Other: Travel, accommodations, expenses, Patents & Royalties: Numerous, Research Funding. Bitter:Novartis AG, Predicant Biosciences, Biospect, F Hofmann-La Roche: Ended employment in the past 24 months; bluebird bio: Current Employment, Current equity holder in publicly-traded company; Novartis: Ended employment in the past 24 months, Patents & Royalties. Petrocca:bluebird, bio: Current Employment, Current equity holder in publicly-traded company. Berdeja:Celgene: Consultancy, Research Funding; Cellularity: Research Funding; Constellation: Research Funding; CRISPR Therapeutics: Consultancy, Research Funding; CURIS: Research Funding; EMD Sorono: Research Funding; Takeda: Consultancy, Research Funding; Servier: Consultancy; Teva: Research Funding; Prothena: Consultancy; Poseida: Research Funding; Novartis: Research Funding; Lilly: Research Funding; Legend: Consultancy; Kite Pharma: Consultancy; Kesios: Research Funding; Karyopharm: Consultancy; Janssen: Consultancy, Research Funding; Glenmark: Research Funding; Genentech, Inc.: Research Funding; BMS: Consultancy, Research Funding; Bioclinica: Consultancy; Bluebird: Research Funding; Acetylon: Research Funding; Amgen: Consultancy, Research Funding; Abbvie: Research Funding; Vivolux: Research Funding.