P-238: A Real-World Observational Study of Belantamab Mafodotin (Belamaf) as a Treatment for Relapsed/Refractory Multiple Myeloma (RRMM)

Introduction: Belamaf, a first-in-class B-cell maturation antigen-targeting antibody-drug conjugate approved in the EU for treatment of RRMM, has demonstrated deep and durable responses as monotherapy. This study explores real-world (RW) use, effectiveness, and safety of belamaf in Europe, including the monitoring and management of ocular events.

Methods: This ongoing non-interventional, retrospective and prospective study includes adult patients (pts) with RRMM receiving belamaf in routine clinical care, consistent with approved labelling. The primary objective is to characterize RW pt demographics and disease characteristics. The key secondary objective is to identify pts who experience belamaf-related ocular adverse events (AEs) of special interest (AESI). Secondary outcomes include incidence of ocular AESIs, dose modifications, treatment discontinuation, and treatment response.

Results: This first interim analysis (as of March 17, 2023) included 37 pts from Italy, Austria, Norway, Germany, Belgium, Spain, and Greece (34 received ≥1 belamaf dose). Mean age was 70.4 years (≥75 years, n=15; 44%); 68% were female. Median time since diagnosis was 86.4 months. Prior therapy data were available for 31 pts (91%): 25 (74%) had ≥4 prior lines of therapy; all 31 had prior exposure to proteasome inhibitors, anti-CD38 therapies (daratumumab 85%), and immunomodulatory therapies; and 91% were triple-class refractory. At baseline, 24 pts (71%) had ≥1 prior/ongoing comorbidity including cardiac disease (n=11; 32%), diabetes (n=10; 29%), eye disease (n=10; 29%), pulmonary disease (n=9; 27%), vascular disorders (n=9; 27%), endocrine disorders (n=7; 21%), and renal disease (n=7; 21%). Most pts (n=29, 85%) saw an ophthalmologist before initiating belamaf; 80%, 78%, and 90% visited an ophthalmologist prior to their 2nd, 3rd and 4th doses.

Median treatment time was 4.8 months, and 16 pts (47%) had ≥4 months of follow-up. Overall, 22 pts (65%) reported ocular AESIs including keratopathy (n=16; 47% [Grade ≥2, n=12]), best corrected visual acuity change (n=5; 15%), corneal erosion (n=2; 6%), and dry eye (n=1; 3%). AESIs led to dose reduction in 2 pts (6%) and dose delays in 10 pts (29%). Discontinuation was due to disease progression (n=7; 21%) or AESI (n=3; 9%); 9 pts experienced disease progression or died. Median RW progression-free survival was 3.9 months. Efficacy data are subject to additional follow-up and will be presented.

Conclusions: This study demonstrates that in Europe belamaf is used routinely in later lines of therapy, in line with the current approved indication in the EU, including in pts who are aged ≥75 years, have current or prior comorbidities, and/or are triple class refractory. Our data suggest that ocular AEs are being monitored appropriately with ophthalmologist visits and managed using dose modifications. Treatment discontinuations occurred primarily due to progressive disease. Updated RW clinical efficacy data will be forthcoming.