A multi-center study of 1879 adults with acute myeloid leukemia (AML) undergoing allogeneic transplantation in second complete remission (CR2), has shown that the strength of the conditioning regimen has no significant effect on 2-year overall survival, leukemia-free survival, and graft-versus-host disease relapse-free survival.
The study found only one patient cohort experiencing a difference in outcome — patients 50 years and older — who experienced significantly higher non-relapse mortality (NRM) after myeloablative (MAC) vs. reduced-intensity (RIC) regimens than patients <50 years (p<0.001).
Patients in the study were all 18 years or older, received their first allogeneic transplant between 2007 and 2016, and had available cytogenetic profiles at diagnosis. Donors were matched related, unrelated with 9/10 or 10/10 HLA antigen match, or haploidentical.
MAC regimens were used in 1010 (54%) of transplants; 869 patients received a RIC regimen prior to HCT. Multivariate and univariate analyses were performed on all patients combined, and separately by patient age <50 years and those 50 years and older.
Two-year outcomes by conditioning regimen and age are shown in the table.
| HCT Outcomes | Myeloablative Conditioning | Reduced Intensity Conditioning | Myeloablative Conditioning | Reduced Intensity Conditioning |
| Age | <50 | <50 | >50 | >50 |
| Overall Survival | 61% | 62% | 58% | 55% |
| Leukemia-Free Survival | 54% | 54% | 52% | 49% |
| Non-Relapse Mortality | 18% | 15% | 27%* | 19%* |
*p=0.001
All outcomes in the table are comparable regarding MAC vs. RIC conditioning within each patient age cohort. The researchers noted that higher NRM after MAC transplantation in the >50 year cohort occurred despite worse chronic graft-versus-host disease (GVHD) after RIC transplantation 32% vs. 39%, respectively.
Results reported by cytogenetic risk group showed overall survival at 2 years after HCT was 67.4, 56.8 and 37.9 in good, intermediate and adverse risk respectively.
Researchers concluded that in considering HCT, patients age < 50 and > 50 who receive MAC or RIC conditioning regimen resulted in similar and improved 2-year overall survival, leukemia-free survival and incidence of relapse.
Gileese MH, et al., Leukemia