Low-dose melphalan in elderly patients with relapsed or refractory acute myeloid leukemia: A well-tolerated and effective treatment after hypomethylating-agent failure.

Relapsed or refractory (R/R) disease remains challenging in acute myeloid leukemia (AML), especially in elderly patients not considered eligible for intensive treatment options. We retrospectively evaluated the safety and efficacy of low-dose melphalan (LD-Mel) in a multicenter analysis in patients over 65 years with R/R AML, who previously had received ≥1 non-curative treatment line. The study included 31 patients (median age 77 years) with 1-4 previous treatment lines. Three patients (9.7%) achieved a complete remission. Two patients (6.5%) achieved a partial remission, nine patients (29.0%) had disease stabilization with reduction of peripheral or bone marrow blast burden, resulting in an overall response rate of 16.1% and 45.2% achieved clinical benefit. Responders showed a significantly longer median overall survival than non-responders (16.3 vs. 2.3 months, p < 0.001). Multivariate analysis identified complex karyotype as the only risk factor associated with inferior survival (p < 0.001), whereas prior treatment with hypomethylating agents (HMAs) in 25 of 31 patients was associated with superior OS, regardless of prior response to HMAs (p = 0.03). LD-Mel was well tolerated, with mild myelosuppressive side effects. Conclusively, LD-Mel is an effective treatment option in elderly patients with R/R AML, particularly after HMA therapy and in the absence of a complex karyotype.