Photo by Chad McNeeley
Results of a phase 2 study suggest that reduced-intensity conditioning (RIC) may allow older patients with acute myeloid leukemia (AML) to remain in long-term remission after allogeneic hematopoietic stem cell transplant (HSCT).
The study included patients age 60 and older who were in their first complete remission (CR1) at transplant.
Two years later, the probability of overall survival was 48%, and the probability of disease-free survival was 42%.
“This new data offers strong support against using biological age as a limiting factor for stem cell transplantation in AML patients who are otherwise well positioned to tolerate and achieve long-term remission with this approach,” said Steven Devine, MD, of The Ohio State University in Columbus.
He and his colleagues shared the data in the Journal of Clinical Oncology.
The researchers wanted to determine whether RIC could improve long-term remission rates after HSCT for older patients with AML.
So the team studied 114 patients with a median age of 65 (range, 60-74) who were treated at 21 US hospitals between November 2004 and November 2011. Most patients were male (62%), and most had intermediate cytogenetics (70%).
All of the patients were in CR1 according to International Working Group criteria. The CR had to be achieved after no more than 2 cycles of induction chemotherapy, and patients were required to undergo HSCT within 6 months of the initial documentation of morphologic CR.
The median time from CR1 documentation to HSCT was 85 days (range, 9-184), and the median time from AML diagnosis to HSCT was 138 days (range, 61-265).
All patients received RIC (fludarabine followed by busulfan) prior to HSCT, which essentially cut treatment strength by half compared to traditional high-dose conditioning. The patients received tacrolimus and methotrexate as graft-versus-host disease (GVHD) prophylaxis.
Forty-eight percent of patients underwent HSCT from a matched, related donor, and 52% had a matched, unrelated donor.
At 2 years, disease-free survival was 42%, and overall survival was 48%. Among patients with unrelated donors, disease-free survival was 40%, and overall survival was 50%.
The cumulative incidence of relapse was 44%, and non-relapse mortality was 15%. Twenty-eight percent of patients had chronic GVHD, and 9.6% had grade 2-4 acute GVHD.
“Close to half of the patients treated in this study achieved long-term, cancer-free survival after 2 years,” Dr Devine noted. “These outcomes are similar to what we would expect to see in younger patients and appear to be better results than those that can be achieved with conventional chemotherapy-based approaches typically used in AML patients over 60.”
