Peripheral blood stem cell for haploidentical transplantation with post-transplant high dose cyclophosphamide: detailed analysis of 181 consecutive patients

While bone marrow (BM) grafts were initially used for T-replete HLA-haploidentical related donors transplantation (Haplo-SCT) with post-transplantation cyclophosphamide (PT-Cy), the use of peripheral blood stem cell (PBSC) remains debated. We thus conducted a detailed analysis evaluating the incidence, risk factors, and prevalence of GVHD after PBSC Haplo-SCT with PT-Cy. One hundred and eighty-one patients with hematological diseases were included. Median time for neutrophil and platelet recovery was 21 and 30 days, respectively. The cumulative incidence of grade 3-4 acute GVHD and severe chronic GVHD were 8% and 4%, respectively, approaching what was observed after BM Haplo-SCT. NRM at 2 years was 21%, and 41% of the non-relapse deaths were caused by GVHD. The cumulative incidence of relapse at 2 years was 17% in the whole cohort, and 13% among AML patients (n = 54), suggesting a high GVL effect. As surrogate markers for good quality of life, we observed a 2-year GVHD-relapse-free survival probability of 50% and found that 6% and 2% of disease-free patients at 2 years were still living with GVHD and immunosuppressive treatments, respectively. Haplo-SCT with PT-Cy using PBSC grafts results in low incidence GVHD and promising disease control, making PBSCs a valuable alternative to BM graft in this setting.