CLINICAL TRIALS AND OBSERVATIONS 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 (RICHSCT), 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). Ninetynine of 259 patients entered CR. Fiftythree 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) RICHSCT 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. (Blood. 2007; 109:1395-1400)