Access to Allogeneic Cell Transplantation Based on Donor Search Prognosis: BMT CTN 1702 Trial

Patients requiring allogeneic hematopoietic cell transplantation (HCT) have variable likelihoods of identifying an 8/8 HLA-matched unrelated donor (MUD). A Search Prognosis calculator can estimate the likelihood. This study (NCT#03904134; https://clinicaltrials.gov/study) evaluates if using a Search Prognosis algorithm results in similar incidence of transplant between patients Very Likely (>90%) versus Very Unlikely (<10%) to have a MUD. An additional objective included understanding barriers resulting in a delay or cancellation of a patient transplant. The national multicenter Blood and Marrow Transplant Clinical Trial Network (BMT CTN) 1702 interventional trial utilized Search Prognosis-based biologic assignment to guide donor selection. HCT eligible patients at participating transplant centers were invited to enroll. Patients assigned to the Very Likely arm were to proceed with MUD, while Very Unlikely were to utilize alternative donors. A third stratum, Less Likely (∼25%), were observed under standard center practices, but were not part of the primary objective. We report here the cumulative incidence of HCT by Search Prognosis group and barriers to HCT. Evaluable patients included 1751 of which 413 (24%) were from racial/ethnic minorities. Seach Prognosis was 958 (55%) Very Likely, 517 (30%) Less Likely, and 276 (16%) Very Unlikely. About 1171 (67%) received HCT, 384 (22%) died without HCT, and 196 (11%) remained alive without HCT. Among the 1234 patients (Very Likely versus Very Unlikely), the adjusted cumulative incidence (95% CI) of HCT at 6 months was 59.8% (56.7 to 62.8) in Very Likely versus 52.3% (46.1 to 58.5) in Very Unlikely (P = .113). Median time to HCT were similar in all Seach Prognosis groups. The predominant barriers resulting in a delay or cancellation of transplant were due to poor patient health (59%). Around 9% of delays and cancellations were attributed to excellent patient disease response, with only 14% of delays and 2% of cancellations due to donor reasons. A prospective Search Prognosis-based algorithm can be effectively implemented in a national multicenter clinical trial, with donor related barriers to transplant representing a small proportion of cases. This approach resulted in rapid alternative donor identification and no statistical difference in rates of HCT in patients Very Likely and Very Unlikely to find a MUD.