MM-392: Belantamab Mafodotin (Belamaf; GSK2857916) US Expanded Access Program (EAP) for Heavily Pre-Treated Patients with Relapsed/Refractory Multiple Myeloma (RRMM): Baseline Characteristics

Context The belamaf US EAP (NCT03763370) provided medicine access to patients unable to participate in a clinical trial prior to regulatory agency approval. Objective To obtain insight from the belamaf EAP on patient types potentially eligible for belamaf treatment in a real-world setting. Methods The EAP included patients with RRMM who received ≥3 prior lines of therapy and were refractory to proteasome inhibitors, immunomodulatory agents, and anti-CD38 monoclonal antibody. Patients received belamaf 2.5 mg/kg Q3W. Safety was closely monitored, and dose delays/reductions were permitted to manage adverse events. Treating physicians re-evaluated eligibility to continue belamaf at each treatment cycle; patients could withdraw at any time. The EAP closed following US FDA approval of belamaf. We report baseline characteristics from included patients. Results In this preliminary analysis (as of 3 Feb 2021), 263 patients were screened; 235 were treated with ≥1 dose of belamaf and were included in this analysis. The most common reasons for withdrawal were lack of continued clinical benefit (n=37) and death (n=21); 23 patients continued therapy beyond closure of the program. Of 235 treated patients, 137 (58.3%) were male. Median age was 66 years, with 106 patients (45.1%) aged 75 years. Two hundred eighteen patients had further medical history available; 61 (26.0%) had prior treatment-related toxicities, 10 (4.3%) had active renal disease, and 5 (2.1%) had undergone allogeneic stem cell transplant. Two hundred twenty-one patients had ocular baseline characteristics reported; these included prior glaucoma diagnosis (single-eye, n=16 [6.8%]), prior cataract diagnosis (single, n=124 [52.8%]), history of cataract surgery (single, n=66 [28.1%]), and prior dry eye diagnosis (n=46 [19.6%]). The most common prior anticancer therapies included bortezomib, lenalidomide, pomalidomide, and carfilzomib. Data cleaning is ongoing for this study. Conclusions This EAP provides insights from a real-world population of US belamaf-treated patients, which, in addition to data from the pivotal DREAMM-2 study, may help practitioners identify patients potentially eligible for belamaf treatment. Funding GlaxoSmithKline (213304). Drug linker technology licensed from Seagen Inc.; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa.