Nonmyeloablative Haploidentical BMT with Post-Transplant Cyclophosphamide for Pediatric and Young Adult Patients with High-Risk Hematologic Malignancies

Abstract

uCB-unit. The median follow-up was 42 (range 0.3-131) months. Seventeen patients (13%) did not receive ATG. Indications were equally distributed over the 3 ATG exposure groups. Lower AUC of active ATG after CBT (continuous variable) was the best predictor for successful IR (HR 0.97, p¼0.0001; In Fig 1a depicted in the 4 groups). In multivariate analyses, successful IR is associated with higher OS (HR 0.33, p¼0.0020; fig 1b), EFS (HR 0.38, p¼0.0016) and TRM (HR 0.31, p¼0.008). Low active-ATG exposure after CBT (continuous) predicted higher EFS (HR 1.005, p¼0.015), and showed a trend to higher OS (p¼0.08). High ATG exposure before CBT was a predictor for a lower incidence of acute GvHD 2-4 (HR 0.40, p¼0.031). Acute-GvHD 3-4 (12% @ 180d), extensive chronic-GvHD (6% @ 1yr) and GF (12% @ 1yr) were not associated with ATG exposure, possibly due to the low incidence. Low exposure of active-ATG after CBT is a predictor for IR and EFS, while presence of IR is associated with higher OS and EFS chances. Individualized dosing of ATG targeted to optimal exposures before and after CBT may result in better survival chances. A clinical trial investigating the influence of individualized dosing of ATG on IR is recruiting in the Netherlands.