P-301: Real-world outcomes of belantamab mafodotin monotherapy in triple class refractory patients with multiple myeloma

Introduction: BCMA is a promising therapeutic target in multiple myeloma, as it is an antigen expressed specifically on plasma cells, with a higher expression in myeloma cells. The aim of this study was to assess the effectiveness and tolerability of monotherapy with the conjugated anti-BCMA monoclonal antibody belantamab mafodotin in triple-class refractory MM patients in the real-world practice.

Methods: The patients were administered belantamab mafodotin at 2.5 mg/kg intravenously once every 3 weeks. The drug is indicated as monotherapy for the treatment of multiple myeloma in adult patients, who have received at least four prior therapies and whose disease is refractory to at least one PI, one IMiD, and an anti-CD38 monoclonal antibody, and who have demonstrated disease progression on the last therapy.

Results: Overall, 27 patients were included in this analysis. Regarding the previous lines of treatment, all patients had received lenalidomide, bortezomib and anti-CD38 treatment, whereas 70% had received pomalidomide, and 89% had received carfilzomib. 59% of the patients had LDH above normal limits at the time of the initiation of the treatment. The patients had a median age of 65 years old (range 41-81), 52% were male and the median number of prior lines of treatment was 5 (4-10). 19% of the patients were ISS 3 and 14% RISS 3 at diagnosis. One patient is still receiving therapy, whereas the median number of lines post treatment with belantamab mafodotin is 1 (range 0-8) and 26% of patients are currently alive. The ORR (overall response rate, PR or better) in this cohort was 52%, whereas the DCR (disease control rate, SD or better) was 89%. The median PFS for the entire group was 2 months (95%CI: 0-7), whereas the median PFS among the responders was 12 months (95%CI: 6-18). Interestingly, the median PFS was 10 months (95%CI: 0-22) for patients who started belantamab mafodotin due to biochemical relapse, as compared to a median PFS of only 0.9 months (95%CI: 0.5-1.2) for patients with symptomatic myeloma relapse. The median OS was 89 months (95%CI: 48-129) from MM diagnosis, whereas the landmark median OS was 16 months (95%CI: 2-30) from belantamab mafodotin initiation. The landmark median OS for the responders was 40 months (95%CI: 24-56). Regarding the toxicity profile, the most common toxicity was eye toxicity in 44% of the patients. More specifically, keratopathy grade 2-3 was reported in 33.3% of the patients. Keratopathy was resolved in all patients, however one patient had to discontinue treatment due to corneal ulcer. Reduction in visual acuity was reported in 26% of the patients. Other toxicities included infections gr 2-3 in five patients, thrombocytopenia gr 3 in two patients and fatigue gr 2 in four patients.

Conclusions: Belantamab mafodotin showed a safety and efficacy profile consistent with the results of the DREAMM-2 study in triple-class refractory patients with MM in terms of survival benefit and tolerability in the real-world practice.