Indirect comparison of linvoseltamab versus elranatamab for triple-class exposed (TCE) relapsed/refractory multiple myeloma (RRMM).

7531 Background: In the absence of head-to-head trials comparing anti-BCMA×CD3 bispecific antibodies in TCE RRMM, this study used an unanchored matching-adjusted indirect comparison (MAIC) to compare the efficacy of linvoseltamab and elranatamab. Methods: Patient (pt)-level data from LINKER-MM1 (117 pts receiving linvoseltamab 200 mg, data cut-off [DCO] 7/2024, median follow-up [mFU] 21.3 months [mos]) and published data from MagnetisMM-3 Cohort A (123 elranatamab pts, DCO 9/2024, mFU 33.9 mos) were analyzed. Ten LINKER-MM1 pts with prior BCMA antibody–drug conjugate exposure were excluded to align with MagnetisMM-3. LINKER-MM1 pts were weighted to match MagnetisMM-3 pts on prespecified prognostic factors deemed most important by an international expert panel: cytogenetic risk, age, refractory status, R-ISS stage, ECOG PS, extramedullary and/or paramedullary disease. Objective response rate (ORR), very good partial response or better (≥VGPR) and complete response or better (≥CR) rates, duration of response (DOR), progression-free survival (PFS), and overall survival (OS) were compared. DOR and PFS in LINKER-MM1 were recalculated to match MagnetisMM-3 censoring rules. Additional MAICs matched all available prespecified prognostic factors, included all 117 LINKER-MM1 pts, or matched to a MagnetisMM-3 subgroup with ECOG PS 0/1. Results: After matching, linvoseltamab effective sample size (ESS) was 71.3 (range of patient weights: 0.04–2.90). Linvoseltamab demonstrated statistically significantly higher ORR and ≥CR rate, a numerically higher ≥VGPR rate, and longer DOR, PFS, and OS vs elranatamab (Table). The additional MAICs yielded directionally consistent findings. Conclusions: Linvoseltamab demonstrated significantly higher ORR and ≥CR rate, numerically better ≥ VGPR rate, DOR, PFS, and OS compared with elranatamab, though the follow-up was shorter. These results highlight the potential of linvoseltamab as a highly effective treatment option for TCE RRMM. Elranatamab Linvoseltamab Linvoseltamab Linvoseltamab vs elranatamab Linvoseltamab vs elranatamab N=123 Unadjusted N=107 Adjusted ESS= 71.3 Unadjusted Adjusted % % % OR (CI) OR (CI) ORR 61 71 71 1.57 (1.04–2.37)* 1.60 (1.00–2.57)* ≥VGPR 56 64 65 1.36 (0.93–2.00) 1.45 (0.94–2.24) ≥CR 37 52 50 1.84 (1.26–2.68)* 1.71 (1.12–2.61)* Median, mos (CI); 12-mo landmark % Median, mos (CI); 12-mo landmark % Median, mos (CI); 12-mo landmark % HR (CI) HR (CI) DOR NR (29.4–NE); 73.9 NR (NE–NE); 82.8 NR (NE–NE); 84.4 0.93 (0.53–1.66) 0.82 (0.43–1.55) PFS 17.2 (9.8–NE); 56.4 NR (15.7–NE); 65.5 NR (16.2–NE); 64.7 0.86 (0.59–1.27) 0.86 (0.55–1.34) OS 24.6 (13.4–NE); 62.3 31.4 (27.8–NE); 75.5 NR (27.8–NE); 74.6 0.70 (0.47–1.04) 0.67 (0.42–1.05) OR >1 or HR <1 favor linvoseltamab. *Statistically significant at p<0.05. CI: 95% confidence interval, HR: hazard ratio, NE: not estimable, NR: not reached, OR: odds ratio.