COMPARISON OF THREE STRATEGIES OF GVHD PROPHYLAXIS AFTER T-CELL REPLETE HAPLOIDENTICAL HEMATOPOIETIC TRANSPLANTATION: TACROLIMUS vs. CALCINEURIN INHIBITORS-MMF vs. SIROLIMUS-MMF

Since the introduction of post-transplant cyclophosphamide (PTCy), haploidentical HSCT (HaploSCT) has become a real alternative for patients who lack other eligible donors. The standard GvHD prophylaxis after PTCy has been a calcineurin inhibitor plus MMF (up to day+35), but promising results with sirolimus (+/- MMF) and single-agent tacrolimus have been recently published. The current multicenter retrospective study compared the outcomes of 372 adult HaploSCT recipients who received TBF conditioning; PTCY and additional GVHD prophylaxis with one of three strategies, cohort-A: single-agent tacrolimus (N 222), cohort-B: CNI-MMF (N 49) and cohort-C: sirolimus-MMF (N 101). No differences in terms of grade II-IV (20%, 25%, and 30%) and III-IV (9%, 6%, and 15%) aGvHD at 100 days were found. However, cohort A had the lowest incidence of overall cGvHD [24%, 47%, and 52%, respectively (p 0.001)] and moderate-severe cGvHD [13%, 35%, and 33%, respectively (p 0.001)]. There were no differences in the 3-year overall survival, progression-free survival, NRM nor relapse among the cohorts. In conclusion, our study suggests that single-agent tacrolimus, CNI+MMF and sirolimus+MMF GvHD prophylaxis lead to similar outcomes following HaploSCT with TBF and PTCy, with low incidence of grade III-IV aGvHD, albeit possible differences in cGVHD require further investigation.