Real-world analysis of belantamab mafodotin (belamaf): Care patterns in relapsed/refractory multiple myeloma.
Authors: Patel Mihir , Locke Susan C. , Falvey Caroline , Troy Jesse D. , Herring Kris W. , Bolgioni-Smith Amanda , Doherty Allison , Elcock Cherie Howard , Iadeluca Laura L. , LeBlanc Thomas William 
Published: June 2024

e19507

Background: Belamaf is an anti-B cell maturation antigen immunoconjugate for relapsed/refractory multiple myeloma that has shown efficacy and safety in the DREAMM clinical trials. Additional long-term real-world data on its use patterns, efficacy, and tolerability are needed. Methods: This retrospective review (NCT05986682) analyzed adults with multiple myeloma receiving ongoing care at Duke Cancer Institute who began belamaf monotherapy (not in a clinical trial) between 8/5/2020 and 11/22/2022. We abstracted data for 30 patients through 9/18/2023. We described baseline clinical characteristics, disease response (per International Myeloma Working Group [IMWG] criteria, as possible given available marrow biopsy data), belamaf use patterns, and ocular adverse events (AEs) (per the Keratopathy Visual Acuity [KVA] scale). Results: Our sample was 53% (n=16) female, 47% (14) White, and 47% (14) Black; median age was 68 years at the beginning of belamaf therapy. 67% (20) had ≥4 prior lines of therapy (median: 4, min-max: 2-19), 87% (26) were triple-/quad-/penta-refractory, and 23% (7) had high-risk cytogenetics (per IMWG). Overall response rate (ORR) was 67% (11 very good partial response, 9 partial response). Median (min-max) time to best response was 1.5 (0.7-9.9) months. Median (min-max) response duration was 9.8 (1.1-20.2) months. Progression occurred in 73% (22) of patients; median progression-free survival (PFS) was 8.4 months (95% CI 6.6-12.7). Median overall survival was not reached. Median (min-max) number of cycles was 6.5 (2-13). 63% of patients (19) had a dose reduction from 2.5 to 1.9 mg/kg; 65% (13) were due to corneal AEs and 30% (6) due to hematologic AEs. 93% (28) had ≥1 cycle delay, and the median (min-max) number of delays was 5 (1-14); 85% of delays (n=153) were due to corneal AEs. Cycle length changed for 33% (10) from every 3 weeks to every 4 (1) or 6 (9) weeks; 91% (n=10) of cases were due to corneal AEs. 93% (28) had keratopathy (any grade); among all events (n=323), 2% were grade ≥3. Median (min-max) time to resolution of grade ≥2 keratopathies was 6 (2-22) weeks. 90% (27) experienced a visual acuity change; among all events (n=244), 3.3% were grade ≥3. Median (min-max) time to resolution of grade ≥2 visual acuity events was 6 (2.9-53) weeks. The most common ocular symptoms were blurry vision (53% of symptoms), dry eyes (17%), and photophobia (14%). Belamaf was discontinued in 13% (4) due to ocular AEs and 20% (6) to patient/physician choice or other reason. Median (min-max) time to last dose/discontinuation was 9.3 (0.7-21.6) months. Conclusions: In our study, ORR and median PFS were greater than other real-world studies. Corneal AEs were also more common, but severity was consistent with these and DREAMM-3 findings. Despite a higher rate of dose reductions and delays than other real-world studies, our study adds promise to the benefit of belamaf over an extended time with dose modifications.