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.