Prospective feasibility analysis of reduced-intensity conditioning (RIC) regimens for hematopoietic stem cell transplantation (HSCT) in elderly patients with acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS)

To prospectively assess the applicability of reduced-intensity conditioning hematopoietic stem cell transplantation (RIC-HSCT), we wrote a protocol in which all untreated patients 50 years or older with acute myeloid leukemia (AML) and unfavorable cytogenetics would be evaluated during induction for a possible RIC-HSCT in first complete remission (CR1). Ninety-nine of 259 patients entered CR. Fifty-three of the 99 were seen by the Transplant Service with the remainder not seen because of illness, lack/unavailability of siblings, refusal, or, primarily, unclear reasons (21 patients). A donor was identified for 26 patients (21 sibling, 5 unrelated) with RIC-HSCT performed in 14 (13 sibling). Results in consulted patients suggested that 50% or fewer of the 85 patients who did not undergo transplantation were potential transplant candidates. We attempted to find one or more chemotherapy pair-mates for each patient who underwent transplantation based on cytogenetics, age, and a relapse-free survival (RFS) time that was more than or equal to the time from CR1 to RIC-HSCT in the patient who underwent transplantation. Thirty-two of the 39 matches favored (longer RFS) RIC-HSCT and 7, chemotherapy. The probability that the corresponding beta distribution was different than expected (ie, that RIC-HSCT was superior) was 0.99 (P = .004). Results were similar with respect to survival. While RIC-HSCT thus seems of interest, methods are needed to extend its applicability.