Using bispecific antibodies in a patient with peritoneal dialysis for relapsed multiple myeloma.

IntroductionBispecific antibodies (BsAbs) are a promising therapy for relapsed/refractory multiple myeloma (RRMM), but their efficacy in patients with end-stage renal disease (ESRD) on peritoneal dialysis (PD) remains unclear. Given the prevalence of renal impairment in MM, understanding BsAbs' use in this population is critical.Case ReportWe present a 72-year-old woman with ESRD on PD diagnosed with RRMM after developing a pathologic humeral fracture. Bone marrow biopsy confirmed lambda light chain multiple myeloma with extensive skeletal involvement.Management & OutcomeThe patient was treated with upfront radiation, and then received daratumumab, cyclophosphamide, bortezomib, and dexamethasone (Dara-CyBorD), followed by carfilzomib, lenalidomide, and dexamethasone (KRd) upon progression. Due to limited response, teclistamab was initiated, achieving a significant but transient response, prompting a switch to talquetamab. Following relapse, she was transitioned to elotuzumab, pomalidomide, and dexamethasone, then selinexor as a bridge to chimeric antigen receptor T-cell (CAR-T) therapy.DiscussionThis case demonstrates that BsAbs may be effective in RRMM patients on PD, though responses were transient. Further research is needed to explore BsAbs' pharmacokinetics, optimal dosing, and long-term outcomes in dialysis-dependent MM patients.