Platelet Engraftment in Patients with Hematologic Malignancies following Unmanipulated Haploidentical Blood and Marrow Transplantation: Effects of CD34+ Cell Dose and Disease Status

Unmanipulated haploidentical blood and marrow transplantation has been developed as an alternative transplantation strategy for patients without an HLA-matched related or unrelated donor. In this transplantation setting, factors associated with hematopoietic recovery have not been defined completely. The aim of this study was to investigate the effects of donor and recipient characteristics on neutrophil and platelet engraftment after unmanipulated HSCT. The study group comprised 348 patients who underwent unmanipulated haploidentical blood and marrow transplantation to treat hematologic malignancy at a single institution between 2002 and 2007. Factors correlating with neutrophil and platelet engraftment posttransplantation were analyzed retrospectively. All patients achieved an absolute neutrophil count ANC of 500/μL in a median of 13 days (range, 9 to 49 days). Of the 348 patients, 331 (95.11%) achieved an untransfused platelet count of > 20,000/μL in a median of 16 days (range, 7 to 356 days). Multivariate analysis showed that the amount of CD34⁺ cells infused (CD34⁺ cells ≥ 2.19 × 10⁶/kg recipient weight vs < 2.19 ×10⁶/kg recipient weight; hazard ratio [HR] = 1.695; 95% confidence interval [CI] = 1.361 to 2.112; P < .0001), and disease stage (advanced vs early; HR = 0.724; 95% CI = 0.577 to 0.907; P = .005) were independently associated with increased risk of platelet engraftment. Our results suggest that low numbers of CD34⁺ cells in allografts and advanced-stage disease may be critical factors associated with delayed platelet engraftment after unmanipulated haploidentical transplantation.