Characteristics and Outcomes of Patients With Multiple Myeloma Who Developed Therapy-Related Acute Myeloid Leukemia and Myelodysplastic Syndrome After Autologous Cell Transplantation.

Patients with multiple myeloma (MM) who undergo high-dose chemotherapy and autologous hematopoietic cell transplantation (Auto-HCT) have an increased risk of developing therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML). We retrospectively reviewed the medical records of all MM patients who underwent an Auto-HCT at our institution between 1 January and 31 December 2018 and later developed t-MDS/AML. Among the 2982 patients who underwent at least 1 Auto-HCT, 55 (2%) developed t-MDS/AML (MDS, n = 52; AML, n = 3). The median age at t-MDS/AML diagnosis was 66 years (range 43-83 years), and the median time from Auto-HCT to t-MDS/AML diagnosis was 58.5 months (range 6-206 months). At diagnosis, all 3 patients with tAML and 65% of those with therapy-related myelodysplastic syndrome (tMDS) had high-risk disease, per 2022 European LeukemiaNet and R-IPSS, respectively, and 62% had TP53 gene mutations. Patients who developed tMDS/AML were older at MM diagnosis (median 61 versus 59 years; P = .06), more often were male (73% versus 58%; P = .029), received more than 2 years of lenalidomide maintenance (57% versus 39%; P = .014), and experienced complete remission more frequently after Auto-HCT compared to those who did not develop t-MDS/AML (56% versus 40%; P = .012). In a multivariable model, male gender, advanced age at MM diagnosis, experiencing complete remission after Auto-HCT, and lenalidomide maintenance were independent predictors of developing t-MDS/AML. Among the patients who developed t-MDS/AML, 14 (25%) underwent allogeneic hematopoietic stem transplantation (Allo-HCT). After a median follow-up of 9.9 months from t-MDS/AML diagnosis, the median overall survival (OS) after t-MDS/AML diagnosis was 11.8 months for all patients, and 18.2 months versus 11.1 months for Allo-HCT recipients versus nonrecipients, respectively (P = .25). On univariate analysis, receiving an alkylator as induction for MM (hazard ratio [95% confidence interval]: 2.9 [1.3-6.3]; P = .009), age > 60 years (3.1 [1.2-8.2]; P = .025), and higher-risk R-IPSS (2.7 [1.3-6.0]; P=0.011) predicted worse OS after t-MDS/AML diagnosis. None of these retained significance in the multivariable analysis. T-MDS/AML after Auto-HCT for MM is associated with aggressive disease characteristics, including high-risk cytogenetics and TP53 mutations. The outcomes of patients remain poor, even with Allo-HCT. A better understanding of disease biology and novel therapeutic approaches is warranted.