Randomized clinical trials offer the highest quality data for modifying clinical practice. Results of a phase III randomized trial of non-myeloablative transplantation for adults with high- risk hematologic malignancies with two umbilical cord blood (UCB) units (n=183) or HLA-haploidentical relative bone marrow (Haplo-BM) (n=154) revealed 2-year progression-free survival (PFS) of 41% and 35% after Haplo-BM and two-unit UCB transplantation, respectively (p=0.41); overall survival was 57% and 46%, respectively (p=0.04), BMT CTN 1101; NCT01597778.We sought to examine the generalizability of BMT CTN 1101 to a contemporaneous cohort beyond the trial's pre-specified 2-year outcomes. All transplantation occurred between June 2012 and June 2018 in the United States. We hypothesized that the results of a rigorous phase III randomized trial will be generalizable. Changes in graft selection for HLA-haploidentical relative transplantation during the trial period allowed comparison of outcomes after transplantation with Haplo-BM to those after haploidentical peripheral blood (Haplo-PB).The trial's broad eligibility criteria were applied to the data source of the Center for International Blood and Marrow Transplant Research to select non-trial subjects. Extended follow up of trial subjects was obtained from this data source. Three separate analyses were performed: 1) trial subjects beyond the trial's 2-year endpoint 2) comparison of trial subjects to a contemporaneous cohort of non-trial subjects (195 two-unit UCB, 358 Haplo-BM, 403 Haplo-PB) and 3) comparison of non-trial subjects by donor and graft type. Multivariate analyses were performed using Cox proportional hazards models for comparison of outcomes by treatment groups.With longer follow up of the trial cohorts, 5-year PFS (37% versus 29%, p=0.08) and overall survival (42% versus 36%, p=0.06) were not significantly different between treatment groups. We then compared the trial results to comparable real-world transplantations. Five-year overall survival after trial and non-trial two-unit UCB (36% versus 41%, p=0.48) and trial and non-trial Haplo-BM (42% versus 47%, p=0.80) transplantation were not different confirming generalizability. The randomized trial did not accrue as planned and therefore lacked the statistical power to detect a 15% difference in progression-free survival. With substantially larger numbers of non-trial Haplo-BM transplantations, 5-year survival was higher after non-trial Haplo-BM compared to trial two-unit UCB (47% versus 36%, p=0.012). Non-trial patients who received Haplo-PB transplantation had higher 5-year survival (54%) compared to trial (HR 0.76, p=0.044) and non-trial (HR 0.78, p=0.026) Haplo-BM. Similarly, survival was higher after Haplo-PB compared to trial (HR 0.57, p<0.0001) and non-trial UCB (HR 0.63, p=0.0002).When considering alternative donor low intensity conditioning regimen transplantation, a haploidentical relative is preferred. Further, PB is the preferred graft.
View details for DOI 10.1016/j.jtct.2021.11.002
View details for PubMedID 34775146