Background: A prior retrospective analysis of US patients (pts) with RRMM suggested that pts treated with belamaf, a BCMA-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 sourced from the US EHR-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 safety and treatment effectiveness. Data on ocular AEs were reported separately for all pts and pts with ≥4 months (mo) of follow-up to allow for sufficient follow-up to evaluate 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% patients, 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) mo. Among pts with ≥4 months of follow-up (n=94) 75% had ≥1 ocular AE, with keratopathy and blurred vision being the most frequent. Mean (SD) time to first ocular AE was 39 (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 mo, PFS 4.5 mo, and OS 7.9 mo, while the 6-month DoR rate was 57%, PFS rate was 46%, and OS rate was 58%. 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.

AE, adverse event.