Comparison of Myeloablative and Reduced Intensity Conditioning Regimens in Haploidentical Peripheral Blood Stem Cell Transplantation

Limited information is available on the impact of intensity of conditioning regimens in haploidentical peripheral blood stem cell transplant (haploPBSCT) with post-transplant cyclophosphamide (PTcy). We retrospectively compared outcomes of haplo-PBSCT between myeloablative (MAC) (n = 24) and reduced intensity conditioning (RIC) regimens (n = 65). Propensity score-based multivariable analyses were performed to adjust confounding effects of baseline characteristics between both groups. Eighty-nine patients underwent haplo-PBSCT between January 2012 and June 2019. For MAC and RIC, the cumulative incidences of grade III--IV acute GVHD were 4.2% and 3.1%, respectively (p = 0.92), and chronic GVHD were 18.9% and 36.5%, respectively (p = 0.08). Median follow-up for overall survival (OS) after MAC and RIC was 1.86 and 2.2 years, respectively. For MAC and RIC, one-year OS was 68.8% and 67.4%, respectively (p = 0.85); one-year relapse rate was 22.4% and 18.3%, respectively (p = 0.74); one-year relapse-free survival (RFS) was 56% and 59.7%, respectively (p = 0.87); and one-year non-relapse mortality (NRM) was 22% and 21.9%, respectively (p = 0.58). Using propensity score-based multivariable analyses, no difference in OS (HR 0.72, p = 0.51), relapse (SHR 0.63, p = 0.42), RFS (HR 0.74, p = 0.49) and NRM (SHR 1.11, p = 0.87) was noted between RIC and MAC. Our study shows no difference in outcomes between MAC and RIC regimens in haplo-PBSCT.