P-423: Salvage Autologous PBSC Transplantation for tMDS and AML Leads to Remission and Long-Term Disease Control

Introduction: Multiple myeloma patients are often treated with induction chemotherapy, autologous peripheral blood stem cell (PBSC) transplantation, then maintenance therapy with lenalidomide for disease control. This process improves progression-free and likely overall survival but can result in the development of a therapy related myeloid neoplasm (TMN) typically myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML). Survival for those with a TMN is short (~13 months). Over the past 7 years, 5 patients with a TMN who could not undergo allogeneic transplantation were treated with a salvage autologous PBSC transplant using banked stem cells collected prior to their initial transplant. Outcomes for these patients are reported.

Methods: Five patients with a history of multiple myeloma and a TMN were treated with melphalan 140-200 mg/m2 and the re-infusion of banked stem cells. All patients had either tMDS requiring transfusion support (3 patients) or AML (2 patients).

Results: All patients engrafted neutrophils and platelets within 21 days. No patient required further transfusion support after this time. One patient succumbed from relapsed multiple myeloma 14 months after transplantation without evidence of MDS. Two patients remain in CR from the TMN and multiple myeloma after 17 months and 7 years respectively. One patient has residual MDS 6 years later with a TMN that lost two adverse cytogenetic features but that no longer requires transfusion support. The final patient recovered normal hematopoiesis but is only 1 month post transplantation.

Conclusions: The development of a TMN is a devastating event in patients with multiple myeloma after a PBSC transplantation. A salvage second PBSC using stored autologous peripheral blood stem cells after melphalan conditioning has resulted in durable hematopoietic recovery, long-term disease-free outcomes, improved quality of life and in one case a cure of disease. This approach should be considered in these patients.