Recurrent Severe Infections During Teclistamab Therapy in a Kidney Transplant Recipient With Relapsed Multiple Myeloma: A Case Report.

Bispecific antibodies targeting B-cell maturation antigen (BCMA), such as teclistamab, have significantly improved outcomes in relapsed/refractory (R/R) multiple myeloma (MM) but are associated with an increased risk of infections and hypogammaglobulinemia. We report the case of an 82-year-old kidney transplant recipient with penta-refractory IgG kappa MM treated with teclistamab. Despite a rapid hematological response, the patient developed multiple severe infections, predominantly respiratory, in the context of profound hypogammaglobulinemia and pre-existing bronchiectasis. Immunoglobulin (Ig) replacement therapy and azithromycin prophylaxis were introduced, leading to a marked reduction in infectious episodes while maintaining myeloma control and stable graft function initially. Due to the recurrent occurrence of these respiratory infections, the administration of teclistamab was also spaced out, which led not only to a reduction in the occurrence of these infections but also to a relapse of MM. This case illustrates the challenges associated with managing solid organ transplant recipients receiving teclistamab for MM, particularly with regard to infectious complications and severe immunosuppression in these patients. The challenge lies in striking a balance between reducing the risk of infection and maintaining the best possible hematological response.