P-272: Belantamab Mafodotin For Relapsed/Refractory Multiple Myeloma: A Real-World Observational Study Update

Introduction: Prior retrospective analysis of US patients (pts) with relapsed/refractory multiple myeloma (RRMM) suggested that pts treated with belantamab mafodotin (belamaf), a B-cell maturation antigen-targeting antibody-drug conjugate, experienced similar outcomes to those who received belamaf in the pivotal DREAMM-2 study. This updated analysis aimed to characterize pts, assess occurrence and management of ocular adverse events (AEs), and evaluate belamaf effectiveness in a real-world setting.

Methods: This retrospective, longitudinal, observational study used data from the US electronic health record-derived Flatiron Health de-identified database (01/01/2011–06/30/2022). Eligible pts had a confirmed MM diagnosis, initiated belamaf after FDA approval (08/05/2020; first administration=index date), were ≥18 years old at index, and had chart abstraction data for ocular AEs and treatment effectiveness. Data on ocular AEs were reported separately for all pts and pts with ≥4 months of follow-up to allow sufficient evaluation of the incidence of ocular AEs and their mitigations. Tumor response was assessed in all pts, along with Kaplan-Meier estimates of duration of response (DoR), overall survival (OS), and progression-free survival (PFS).

Results: Of the 184 pts included in the study, mean age was 68.7 years; 64% were White and 47% were female. Eastern Cooperative Oncology Group (ECOG) status was ≥2 in 28% pts, 62% had received ≥5 prior lines of therapy, and 82% were triple-class refractory. Median (IQR) follow-up was 4.1 (1.9–8.5) months. Ocular AEs (≥1) were reported in 50% of all pts (92/184) and 75% of those with ≥4 months of follow-up (70/94): the most frequent were keratopathy (83% and 83%), blurred vision (57% and 66%), dry eye (35% and 37%), and keratitis (20% and 23%). Among pts with ≥4 months of follow-up, mean time to first ocular AE was 39 (SD: 34) days. Most ocular AEs were managed by therapy hold (69%; of which 73% restarted belamaf) and/or AE treatment (63%). The median dose hold due to ocular AEs was 43 days (physician-reported keratopathy: mild, 21 days; moderate/severe, 56 days). In all pts, 39 (21%) had a derived tumor response based on serum free light chain levels, (partial response: 74%, very good partial response: 51%). For all pts, the estimated median DoR was 9.1 months, PFS 4.5 months, and OS 7.9 months. The 6-month DoR, PFS and OS rates were 57%, 46%, and 58%, respectively.

Conclusions: Overall, belamaf was effective in the real-world setting in heavily pre-treated pts with RRMM and limited therapy options. The AE profile was consistent with DREAMM-2. Ocular AEs were manageable and despite their occurrence, a high percentage of pts remained on treatment, suggesting belamaf may fill an unmet need for triple-class refractory pts with RRMM.