Durable Remission of Highly Refractory Multiple Myeloma and Therapy-Related MDS/AML After Allogeneic Hematopoietic Cell Transplantation: Reconsidering Its Role in the CAR-T Era.

Therapy-related myelodysplastic syndrome and acute myeloid leukemia (MDS/AML) are increasingly recognized as late complications of multiple myeloma (MM) treatment and are associated with a dismal prognosis. We report on a patient with highly refractory MM who developed therapy-related MDS/AML during the course of multiple lines of anti-myeloma therapy, including proteasome inhibitors, immunomodulatory drugs, anti-CD38 monoclonal antibodies, and repeated autologous stem cell transplantation. Progressive cytopenias led to bone marrow evaluation and the diagnosis of therapy-related MDS/AML. Allogeneic hematopoietic cell transplantation (allo-HCT) was performed primarily for therapy-related MDS/AML and resulted in durable disease control of both MDS/AML and MM. At the latest follow-up, approximately 3 years after allo-HCT, the patient remains in complete remission from therapy-related MDS/AML and in stringent complete response with sustained minimal residual disease negativity in MM, without any post-transplant maintenance therapy. Although chimeric antigen receptor T-cell therapies have demonstrated remarkable efficacy in relapsed and refractory MM, they are not currently regarded as curative. This case highlights that allo-HCT may still play a clinically meaningful role in selected and complex clinical settings, even in the era of cellular immunotherapy.