Characteristics and outcomes of therapy-related acute leukemia following autologous transplant (Auto-HCT) for multiple myeloma.

With a prolonging duration of survivorship, patients with multiple myeloma (MM) who receive high-dose chemotherapy and autologous hematopoietic stem cell transplantation (auto-HCT) have an increased risk of secondary malignancy, most concerning acute leukemia. We retrospectively reviewed the records of all patients with MM who underwent auto-HCT between January 1, 2010, and January 1, 2023, who later developed therapy-related acute leukemia (t-AL). Of 1770 patients with MM who underwent auto-HCT, 18 (1.01%) developed t-AL at a mean interval of 60.0 ± 41.3 months after auto-HCT. The patients with t-AL consisted of 9 (50%) with B-cell acute lymphoblastic leukemia (B-ALL), 8 (44.4%) with acute myeloid leukemia (AML), and 1 (5.6%) with acute promyelocytic leukemia (APML). All patients had received an alkylating agent as part of induction, and the majority received lenalidomide as maintenance therapy. Genetic abnormalities of t-AL were consistent with prior reports. Median overall survival from diagnosis of t-AL was 19.5 months. In patients with t-AL who entered CR, long term survival was common. Further research on predisposing conditions to developing t-AL in patients with MM undergoing auto-HCT is warranted.