Explosive Disease Progression After Single-Agent B-cell Maturation Antigen-Targeted Treatment in Multiple Myeloma: A Report of Three Cases in Sheikh Shakhbout Medical City

Patients with “penta-refractory” multiple myeloma (MM) are challenging to treat given the limited treatment options available to them. Belantamab mafodotin is the first B-cell maturation antigen (BCMA)-targeting antibody-drug conjugate approved for the treatment of relapsed/refractory MM (RRMM). In this case report, we reviewed in detail three female patients who were diagnosed with MM international scoring system (ISS)-3 and were heavily pretreated, and refractory to CD38 monoclonal antibodies, two proteasome inhibitors, and two immunomodulatory agents. These patients were started on belantamab mafodotin and experienced rapid and explosive clinical, biochemical, and extramedullary disease progression within a short period of time. All three patients experienced worsening cytopenia, increased transfusion requirement, severe uncontrolled bony pain, recurrent infections, and frequent hospital admissions. Two of them passed away due to disease progression complications within a few months of starting belantamab mafodotin. Although belantamab mafodotin as a single agent was withdrawn from the market after the DREAMM-3 trial failed to achieve its primary endpoint in late RRMM, BCMA-targeted therapy may still be a promising treatment approach, and the role of belantamab mafodotin is yet to be revealed in combination therapy in early RRMM.