P-233: Retrospective, single-center, real-world experience of belantamab mafodotin in relapsed/refractory multiple myeloma

8060 Background: Belantamab mafodotin (belamaf) is a BCMA antibody drug conjugate approved for the treatment of relapsed refractory multiple myeloma (RRMM) patients (pts) based on the pivotal phase 2 DREAMM-2 study (Lonial et al, Lancet Oncology, 2019), which demonstrated an overall response rate (ORR) of 32%, median progression free survival (PFS) of 2.8 months, and overall survival (OS) of 13.7 months in triple class (proteasome inhibitor, IMiD, and anti-CD38) refractory (TCR) MM. In this single-center retrospective study, we report the efficacy and safety of belamaf in RRMM pts administered in a real-world, standard of care (SOC) setting. Methods: All MM pts who initiated therapy with SOC belamaf, either as monotherapy or in combination, between 11/1/2020 and 11/30/2021 at MD Anderson were included in this study. Response and progression were evaluated using International Myeloma Working Group standard criteria. Keratopathy and best corrected visual acuity (BCVA) adverse events (AEs) were graded per the Keratopathy and Visual Acuity (KVA) scale. The Kaplan-Meier method was used to estimate time to event endpoints. Results: A total of 39 consecutive pts with a median of 7 prior lines of therapy were included in the analysis, of whom 37 pts (95%) received single agent belamaf. Median age was 66 years (range 39-89), 14 of 37 (38%) pts with available FISH had high risk disease (del 17p, t(4;14, and/or t(14;16)), 14 pts (36%) had extramedullary disease, 37 (95%) pts were TCR, 32 (82%) pts were TCR and alkylator-refractory, and 8 pts (21%) were BCMA-refractory. Notably, the majority (69%) of pts in this analysis would have been ineligible for the DREAMM-2 trial based on key eligibility criteria. Median number of belamaf doses administered was 2 (range 1-9). Among 37 pts with measurable, response evaluable baseline disease, the best ORR (≥ PR) was 27% with ≥ VGPR of 3%. The clinical benefit rate (≥ MR) was 35%. Among 8 BCMA-refractory pts, there was 1 PR and 1 MR. Median PFS was 1.8 months and median OS was 9.2 months with a median follow-up of 10.1 months. Median duration of response has not been reached among 10 responding pts. Among 33 pts with a post-treatment ocular exam, 25 pts (76%) developed any grade keratopathy (Grade 1/2/3/4, 9%/55%/12%/0%, respectively) and BCVA changes (Grade 1/2/3/4, 42%/27%/6%/0%, respectively). Median time to first keratopathy or BCVA AE was 1.3 months. The most common reasons for treatment discontinuation were disease progression (75%) and AEs (9%). Conclusions: Our current study in heavily pretreated RRMM pts, of whom the majority would have been ineligible for the DREAMM-2 study, demonstrates an ORR, PFS, and ocular AE profile with SOC belamaf therapy comparable to outcomes reported in the pivotal registration study. Future studies are needed to further define the optimal use and sequencing of belamaf in MM pts, particularly in context of other BCMA-targeting modalities.