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BACKGROUND ELRA is a humanized, BCMA/CD3 bispecific antibody. In the phase 2 registrational MagnetisMM-3 (MM-3) trial, SC ELRA given as 2 step-up priming doses (12 mg on day 1 and 32 mg on day 4 of cycle 1) followed by 76 mg QW in patients (pts) with RRMM naive to BCMA-directed therapy resulted in an ORR of 61.0%. With a median follow-up of 28.4 mos, the median DOR, PFS, and OS were not reached (NR; 2-year rate, 66.9%), 17.2, and 24.6 mos, respectively. Overall, 56.3% of pts had CRS (grade 2, 14.3%; no grade ≥3). Most events occurred after doses 1 (44.5%), 2 (20.2%), and 3 (5.9%); 0.8% (1 pt) had CRS with doses ≥4. Recurrent CRS occurred in 15.1% of pts. The phase 1/2 MagnetisMM-9 (MM-9; NCT05014412) study is examining an alternative priming regimen and longer dosing intervals of ELRA. Here, we present updated MM-9 results. METHODS In MM-9, pts with RRMM and disease refractory to ≥1 IMiD drug, ≥1 PI, and ≥1 anti-CD38 antibody were given SC ELRA as step-up priming doses of 4 and 20 mg on Day 1 and Day 4 of Cycle 1, respectively. After the priming doses, ELRA 76 mg was given QW for the next 6 cycles (Part 1) or for 1 cycle followed by 116 (dose level 1 [DL1]) or 152 (dose level 2 [DL2]) mg Q2W for the next 5 cycles (Part 2A). After 6 cycles, the dosing frequency was decreased from QW to Q2W (Part 1) or from Q2W to Q4W (Part 2) in pts who achieved ≥PR lasting ≥2 months. The recommended phase 2 dose from Part 2A (152 mg, DL2) was evaluated in Part 2B (dose expansion). The primary endpoint for both parts is grade ≥2 CRS rate per ASTCT criteria during Cycle 1. Secondary endpoints include evaluation of efficacy and adverse events. Data cutoff: February 13, 2024. RESULTS Overall, 85 pts (median age, 64.0 y) were treated with ELRA. The majority (72.9%) of pts had R-ISS stage I/II disease (23.5% with R-ISS stage III); 31.8% had high-risk cytogenetics. Median number of prior lines of therapy was 5.0 (range, 1-12). The median treatment duration was 8.6, 2.9, 1.4, and 3.3 mos, in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, respectively. Median follow-up for pts overall (n=85), in Part 1 (n=33), Part 2A DL1 (n=12), Part 2A DL2 (n=11), and Part 2B (n=29) was 10.4, 23.3, 16.5, 15.2, and 9.3 mos, respectively. Overall, the ORR was 58.8%. For pts in Part 1, Part 2A DL1, Part 2A DL2, or Part 2B, ORR was 66.7%, 58.3%, 36.4%, and 58.6%, respectively; median DOR was NR (9-mo rate: 86.4%), 10.8 mos (9-mo rate: 80.0%), NR (9-mo rate: 100.0%), and NR (9-mo rate: 84.8%); median PFS was 17.1 (9-mo rate: 62.8%), 11.6 (9-mo rate: 50.9%), 1.6 mos (9-mo rate: 40.0%), and NR (9-mo rate: 57.1%); median OS was NR (9-mo rate: 75.8%), 17.4 mos (9-mo rate: 66.7%), NR (9-mo rate: 60.0%), and NR (9-mo rate: 72.4%), respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, grade ≥2 CRS rates during Cycle 1 were 15.2%, 16.7%, 27.3%, and 6.9%, respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, CRS rates were 30.3%, 33.3%, 36.4%, and 24.1% after dose 1, 27.3%, 25.0%, 36.4%, and 24.1% after dose 2, 15.2%, 33.3%, 27.3%, and 20.7% after dose 3, 6.1%, 8.3%, 0%, and 3.4% after dose 4, and 6.1%, 16.7%, 9.1%, and 0% after doses ≥5. Recurrent CRS occurred in 18.2%, 33.3%, 18.2%, and 17.2% of pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B. The most common (>60%) TEAEs (any grade/grade ≥3) were hematologic TEAEs (Part 1, 75.8%/75.8%; Part 2A DL1, 83.3%/83.3%; Part 2A DL2, 81.8%/81.8%; Part 2B, 79.3%/69.0%), infections (Part 1, 78.8%/48.5%; Part 2A DL1, 83.3%/66.7%; Part 2A DL2, 72.7%/63.6%; Part 2B, 62.1%/37.9%), and CRS (Part 1, 60.6%/0%; Part 2A DL1, 83.3%/0%; Part 2A DL2, 90.9%/9.1%; Part 2B, 48.3%/0%). Grade 5 TEAEs not including PD were infection (n=4), fall (n=1), subdural hematoma (n=1), and food poisoning (n=1). CONCLUSIONS The 4/20 mg step-up priming regimen and alternative dosing schedules in MM-9 resulted in similar efficacy vs the step-up regimen used in the registrational MM-3 study (12/32 mg). Responses were durable with encouraging PFS and OS with the alternative step up and longer dosing schedule. While the overall safety signals with the alternative step up regimen are similar to those seen with MM-3, the CRS profile differed with more CRS events after each subsequent dose and a higher prevalence of recurrent CRS. Thus, the optimal ELRA step-up regimen remains 12/32 mg from the original regimen in the MM-3 study. In addition, these early results suggest that reducing the dose frequency of ELRA may not compromise efficacy.

Abstract Outcomes are poor in triple-class–exposed (TCE) relapsed and refractory multiple myeloma (R/RMM). In the phase 3 KarMMa-3 trial, patients with TCE R/RMM and 2 to 4 prior regimens were randomized 2:1 to idecabtagene vicleucel (ide-cel) or standard regimens (SRs). An interim analysis (IA) demonstrated significantly longer median progression-free survival (PFS; primary end point; 13.3 vs 4.4 months; P < .0001) and higher overall response rate (ORR) with ide-cel vs SRs. At final PFS analysis (median follow-up, 30.9 months), ide-cel further improved median PFS vs SRs (13.8 vs 4.4 months; hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.38-0.63). PFS benefit with ide-cel vs SRs was observed regardless of number of prior lines of therapy, with greatest benefit after 2 prior lines (16.2 vs 4.8 months, respectively). ORR benefit was maintained with ide-cel vs SRs (71% vs 42%; complete response, 44% vs 5%). Patient-centric design allowed crossover from SRs (56%) to ide-cel upon progressive disease, confounding overall survival (OS) interpretation. At IA of OS, median was 41.4 (95% CI, 30.9 to not reached [NR]) vs 37.9 (95% CI, 23.4 to NR) months with ide-cel and SRs, respectively (HR, 1.01; 95% CI, 0.73-1.40); median OS in both arms was longer than historical data (9-22 months). Two prespecified analyses adjusting for crossover showed OS favoring ide-cel. This trial highlighted the importance of individualized bridging therapy to ensure adequate disease control during ide-cel manufacturing. Ide-cel improved patient-reported outcomes vs SRs. No new safety signals were reported. These results demonstrate the continued favorable benefit-risk profile of ide-cel in early-line and TCE R/RMM. This trial was registered at www.ClinicalTrials.gov as #NCT03651128.

7522 Background: Elranatamab (ELRA) is a humanized BCMA-CD3 bispecific antibody. In the phase 2 registrational MagnetisMM-3 (MM-3) trial, SC ELRA was given as 2 step-up priming doses (12 mg on C1D1 and 32 mg on C1D4) followed by 76 mg QW in patients (pts) with RRMM. Overall, 56.3% of pts had CRS (grade 2, 14.3%; no grade ≥3). Most events occurred after doses 1 (44.5%), 2 (20.2%), and 3 (5.9%); 0.8% (1 pt) had CRS with doses 4+. Recurrent CRS (>1 event) occurred in 15.1% of pts (Lesokhin Nat Med 2023). Methods: MagnetisMM-9 (MM-9; NCT05014412) is a phase 1/2, open-label, nonrandomized study of ELRA examining an alternative 2-dose step-up priming regimen (4 and 20 mg on C1D1 and C1D4, respectively). Eligible pts had RRMM and were refractory to ≥1 IMiD, ≥1 PI, and ≥1 anti-CD38 antibody. After the priming doses, ELRA 76 mg was given QW for 6 cycles (Part 1) or for 1 cycle followed by 116 or 152 mg Q2W for 5 cycles (Part 2A). The RP2D from Part 2A (152 mg) was evaluated in Part 2B (dose expansion). The rate of grade ≥2 CRS per ASTCT criteria during C1 is the primary endpoint for both parts. Secondary endpoints include evaluation of AEs and PK. Here, we report the overall safety and CRS profile associated with the 4/20 mg priming regimen. Results: For 85 treated pts, median age was 64.0 y; 49.4% were male; 23.5% had EMD; 31.8% had high-risk cytogenetics. Pts had a median of 5.0 (range, 1-12) prior LOTs; 85.9% had triple-class refractory disease. After a median follow-up of 7.4 mo, the most common (>50%) AEs were CRS (63.5%; grade ≥2, 15.3%) and neutropenia (54.1%; all grade ≥2). ICANS occurred in 4.7% of pts (all grade ≤2). The grade ≥2 CRS rate in C1 was 14.1% (90% CI, 8.4-21.9). CRS rates after the first 3 doses are in the the table. For doses 4+, any grade (grade ≥2) CRS was observed in 10.6% (3.5%) of pts overall, 12.1% (3.0%) of pts continuing to receive 76 mg (n=33), 25.0% (0%) of pts receiving 116 mg (n=12), and 5.0% (5.0%) of pts receiving 152 mg (RP2D; n=40). Overall, recurrent CRS was observed in 20.0% of pts. The geometric means (CV%) of free ELRA concentrations 24 h (Cmax-24h) after step-up doses 1 and 2 were 85.64 (48%) and 242.8 (55%). Conclusions: The 4/20 mg step-up priming regimen and alternative dosing schedules resulted in similar safety and incidence of overall and grade ≥2 CRS events vs the regimen used in MM-3 (12/32 mg), with no new safety signals identified. However, the CRS profile in this study differed, with more CRS after doses 2, 3, and 4+ and a higher prevalence of recurrent CRS. The Cmax-24h of free ELRA (CV%) after the priming doses were lower than those in MM-3 (107.4 [47%] and 405.1 [72%], respectively). Thus, the priming regimen used in MM-3 remains the optimal regimen for mitigating CRS. Future analyses of ongoing studies will be used to confirm these results. Clinical trial information: NCT05014412 . [Table: see text]

Introduction A single ide-cel infusion showed significantly longer median progression-free survival (PFS) vs std regimens (13.3 vs 4.4 months [mo], HR 0.49, 95% CI 0.38-0.65, P < 0.001) with deep, durable responses in heavily pretreated TCE RRMM at an interim analysis (IA) of KarMMa-3 (NCT03651128); safety data were consistent with prior studies (Rodríguez-Otero et al. NEJM 2023). Ide-cel benefits were consistent across pts in high-risk subgroups and across 2-4 prior lines of therapy (Tx). Results of the preplanned final PFS analysis of KarMMa-3 with 12.3 mo additional follow-up are reported. Methods In the phase 3 KarMMa-3 trial, pts with RRMM who received 2-4 prior regimens, including an immunomodulatory agent, proteasome inhibitor, and daratumumab, and were refractory to last regimen were randomized 2:1 to ide-cel or a std regimen (DPd, DVd, IRd, Kd, or EPd). In the ide-cel arm, pts could receive ≤ 1 cycle of optional bridging Tx for disease control. Pts in the std regimens arm could receive ide-cel after confirmed disease progression (PD). The primary endpoint was IRC-assessed PFS in the ITT population; final PFS was planned to be analyzed with ~289 events. Key secondary endpoints were IRC-assessed overall response rate (ORR) and overall survival (OS); other secondary endpoints included complete response rate (CRR), duration of response (DOR), minimal residual disease (MRD) status, time to next anti-myeloma Tx (TTNT; time from randomization to next anti-myeloma Tx [MTx]), event-free survival (EFS; time from randomization to first PD, next MTx or any-cause death, whichever is first), PFS2 (time from randomization to second objective PD or any-cause death, whichever is first), safety, and health-related quality of life (QOL). Results Of 386 randomized pts (ide-cel, n = 254; std regimens, n = 132), 225 received ide-cel and 126 received a std regimen. Baseline characteristics were generally balanced. Median follow-up from randomization to data cutoff (April 28, 2023) was 30.9 mo (range 12.7-47.8). Ide-cel significantly improved median PFS (95% CI) vs std regimens (13.8 [11.8-16.1] vs 4.4 [3.4-5.8] mo), representing a 51% reduced risk of PD or death (HR 0.49, 95% CI 0.38-0.63; Figure); 18 mo PFS rates were 41% vs 19%, respectively. Ide-cel significantly improved ORR vs std regimens (71% vs 42%) with deeper (CRR 44% vs 5%; ≥CR and MRD negative status [sensitivity level 10 -5], 22% vs 1%), more durable responses (median DOR 16.6 vs 9.7 mo; Table). PFS and ORR benefits of ide-cel vs std regimens were consistent with the IA. Interim OS will be included in the presentation. In pts who received ide-cel (n = 225) or a std regimen (n = 126), median PFS (95% CI) was 15.7 (12.5-18.9) vs 4.4 (3.4-5.8) mo, respectively. In the ITT population, median TTNT, EFS, and PFS2 were numerically longer with ide-cel vs std regimens. Median (range) TTNT was 20.9 (16.6-24.2) vs 7.0 (5.3-8.5) mo. Median (95% CI) EFS was 13.3 (11.3-15.7) vs 3.9 (3.0-5.3) mo. Median PFS2 (95% CI) was 23.5 (18.4-27.9) vs 16.7 (12.2-20.3) mo; ide-cel was next MTx in 70 (53%) pts in the std regimens arm. In the treated population, grade (gr) 3/4 infections occurred in 66/249 (27%) pts in the ide-cel arm vs 25/126 (20%) in the std regimens arm. In the ide-cel safety population, any gr cytokine release syndrome occurred in 197/225 (88%) pts, gr ≥ 3 in 11 (5%); median time to first onset was 1 d (1-14), median duration was 4 d (1-51). Any gr investigator-identified neurotoxicity occurred in 34/225 (15%) pts, gr ≥ 3 in 7 (3%); median time to onset was 3 d (range 1-317); median duration was 2.5 d (range 1-252). Ide-cel continued to demonstrate durable, clinically meaningful improvements in pt-reported outcomes, including symptoms, functioning, and QOL vs std regimens. Conclusions In this final PFS analysis of KarMMa-3, significantly longer PFS was maintained with ide-cel; PD or death risk reduced by 51%; responses were deeper and more durable vs std regimens. CRR with ide-cel increased since the IA, indicating a deepening response, but were unchanged with std regimens. A single ide-cel infusion vs continuous treatment with std regimens resulted in longer median TTNT and PFS2, indicating improved long-term disease control. The ide-cel safety profile was consistent with previous reports, with no parkinsonism or Guillain-Barré syndrome reported. These data continue to support use of ide-cel in pts with TCE RRMM. Study support 2seventy bio and Celgene, a Bristol-Myers Squibb Company.

Background Maintenance therapy improves PFS in NDMM pts. Additional active, well-tolerated treatment options that are suitable for long-term administration are required. The international, multicenter, double-blind, placebo-controlled, phase 3 TOURMALINE-MM4 trial (NCT02312258) of the oral PI ixazomib as maintenance therapy post-induction in non-transplant NDMM pts met its primary endpoint of PFS. Ixazomib demonstrated a significant and clinically meaningful benefit vs placebo, with a manageable and well-tolerated toxicity profile. Feasible, tolerable options for long-term therapy are particularly important in this setting, as pts are often elderly and/or frail. We report herein a subgroup analysis of TOURMALINE-MM4 according to age and frailty status. Methods Pts who achieved ≥partial response (PR) after 6-12 months of standard-of-care induction therapy were randomized 3:2 to ixazomib or placebo maintenance for up to 24 months. The sum of 4 components - age (<75 vs 75-80 vs >80 years; score 0 vs 1 vs 2), the Katz Index of Independence in Activities of Daily Living (ADL; >4 vs ≤4, score 0 vs 1), the Lawton Instrumental ADL Scale (>5 vs ≤5, score 0 vs 1), and the Charlson Comorbidity Index (≤1 vs ≥2, score 0 vs 1) - was used to classify pts as fit (total score: 0), unfit (score: 1), or frail (score: ≥2). Analyses of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 and MY20 modules were conducted to evaluate the effects of treatment on QoL within subgroups defined by frailty status and age. Results In the ixazomib (n=425) vs placebo (n=281) arms, there were similar proportions of pts aged <65, 65-74, and ≥75 years and of pts classified as fit, unfit, and frail (Table 1). Baseline disease and treatment characteristics were generally balanced in ixazomib vs placebo pts across the different age and frailty groups, with some numerical differences observed. In pts aged <65 years, higher rates of International Staging System (ISS) stage III disease and fit pts and a lower rate of complete (CR) or very good partial (VGPR) response post-induction were seen (Table 1). Across frailty groups, a higher rate of CR or VGPR was seen in fit pts, a lower rate of ISS stage III disease was seen in unfit pts, and a higher rate of ISS stage III disease and a lower rate of CR or VGPR were seen in frail pts (Table 1). PFS benefit with ixazomib vs placebo was seen across age groups, with hazard ratios (HRs) of 0.576 (95% confidence interval [CI] 0.299-1.108, p=0.095, median 11.0 vs 9.3 months) in pts aged <65 years, 0.615 (95% CI 0.467-0.810, p<0.001, median 17.9 vs 9.3 months) in pts aged 65-74, and 0.740 (95% CI 0.537-1.019, p=0.064, median 16.7 vs 10.2 months) in pts aged ≥75 years. HRs for time to progression (TTP) were similar to those for PFS. PFS benefit with ixazomib vs placebo was also seen across frailty groups (Figure), with similar HRs for TTP. Rates of grade ≥3 treatment-emergent adverse events (TEAEs), serious TEAEs, and discontinuation due to TEAEs were higher or similar with ixazomib vs placebo across age and frailty subgroups (Table 2). Rates were generally somewhat higher in older age groups and in unfit/frail pts in both arms; nevertheless, rates of discontinuation due to TEAEs across groups were <20%, even in pts aged ≥75 years and frail pts (Table 2). With ixazomib, rates of common gastrointestinal TEAEs were similar across age groups; rash and liver impairment appeared less common and peripheral neuropathy more common in older pts (Table 2). Covariate-adjusted changes in QoL subscales from baseline were estimated at each cycle using repeated measures linear mixed models stratified by frailty status. In all frailty groups, the mean changes in each treatment arm were small over time (<10 points on a 0-100 scale) and similar between arms, indicating that continued treatment with ixazomib vs placebo maintenance did not adversely affect pts' QoL. Analyses by age were generally consistent with the results by frailty. Conclusions Ixazomib as post-induction maintenance therapy in non-transplant NDMM pts results in PFS benefits vs placebo regardless of age or frailty status. Ixazomib appeared generally well tolerated across groups, with TEAE rates in both arms generally elevated in elderly/frail vs younger/fit pts. Ixazomib is a feasible and effective maintenance option for prolonging PFS across this heterogeneous pt population. Disclosures Bringhen: Takeda: Consultancy; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Vorog:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Labotka:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Wang:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Cherepanov:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Cain:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Manne:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Dimopoulos:Celgene: Honoraria; Janssen: Honoraria; Takeda: Honoraria; Bristol-Myers Squibb: Honoraria; Beigene: Honoraria; Amgen: Honoraria. OffLabel Disclosure: Use of the oral proteasome inhibitor ixazomib as maintenance therapy in patients with newly diagnosed multiple myeloma not undergoing stem cell transplantation