Outcomes following allo-HSCT in blast-phase MPN

Results from a single-center retrospective cohort study, evaluating post-allogeneic hematopoietic stem cell transplantation (allo-HSCT) outcomes in 51 adults (53 transplants) with blast-phase myeloproliferative neoplasms (MPN-BP), were published in Bone Marrow Transplantation by Barbullushi et al. The primary endpoint was overall survival (OS). Secondary endpoints included disease-free survival (DFS), relapse incidence (RI), non-relapse mortality (NRM), and cumulative incidence of neutrophil engraftment and acute (a) or chronic (c) graft-versus-host disease (GvHD).  

Key data: With a median follow-up of 4.7 years, the 1-year OS rate was 43.4% (95% confidence interval [CI], 31.9–59.0) and 5-year OS rates were 36.0% (95% CI, 22.6–57.2) for patients undergoing first allo-HSCT and 28.6% (95% CI, 12.5–65.3) for patients undergoing second allo-HSCT. The 1-year DFS rate was 37.7%. Neutrophil engraftment occurred in all but two patients, with a median time to engraftment of 12 days. At 1 year, the cumulative incidences of Grade II–IV aGvHD and moderate-to-severe cGvHD were 35.8% and 7.5%, respectively, and the incidence of NRM and RI were 25.8% and 44.3%, respectively. In multivariable analyses, TP53 mutations (p = 0.02) and higher peripheral blast burden (p = 0.03) adversely affected OS, while CALR mutations were associated with improved OS (p = 0.01). 

Key learning: Allo-HSCT remains the only potentially curative option for MPN-BP. TP53 status and peripheral blast burden may be actionable risk markers for guiding transplant strategies.