Platelet recovery delay and survival in patients with myelofibrosis undergoing allogeneic hemopoietic stem cell transplantation

Abstract

We studied platelet recovery in 93 patients with myelofibrosis, following an allogeneic hemopoietic stem cell transplant (HSCT). The primary end point of the study was achieving a platelet count of 50x10^9/L within day +100, which occurred in 62 patients (67%) and predicted 5 year non relapse mortality (5% vs 55%; p=0.0009) and 5 year actuarial survival (85% vs 38%; p=<0.00001). Relapse was unaffected. The cumulative incidence of strong platelet recovery was predicted by a matched sibling donor (MSD), compared to alternative donors (90% vs 60%, p=.001), by the dose of CD34+ cells (cut off 8.68x10^6/kg) (83% vs 61%, p=0.01), recipient age (cut off 63 years) (72% vs 48%, p=0.01), and splenectomy (86% vs 63%, p=0.04). In multivariate Cox analysis, significant predictors were a MSD (p=0.003), a high CD34 cell dose (p=0.02), splenectomy (p=0.003) and younger patients (p=0.02). Patients with slow platelet recovery, have significantly lower platelet counts long term, combined with chronic graft versus host disease. In conclusion strong post-HSCT platelet recovery in MF patients, is mainly predicted by donor type, together with CD34 cell dose, patients age, and is strongly associated with NRM and survival.