Allogeneic hematopoietic stem cell transplantation in myelofibrosis: the 20-year experience of the Gruppo Italiano Trapianto di Midollo Osseo (GITMO).

BACKGROUND: Allogeneic stem cell transplantation is a potentially curative treatment for myelofibrosis, although its use is limited by a high rate of transplant-related mortality. In this study, we evaluated the outcome of patients with myelofibrosis who underwent allogeneic stem cell transplantation, and the impact of prognostic factors. DESIGN AND METHODS: One hundred patients were transplanted in 26 Italian centers between 1986 and 2006. We analyzed the influence of the patients' characteristics and the clinical features of their disease before stem cell transplantation and of transplant procedures on transplant-related mortality, overall survival, and relapse-free survival by means of univariate and multivariate analyses.
RESULTS: The median age of the patients at the time of stem cell transplantation was 49 years (range, 21-68) and 90% of them had an intermediate or high Dupriez score. Forty-eight percent received a myeloablative conditioning regimen and 78% received stem cells from matched sibling donors. The cumulative incidence of engraftment at day 90 after transplant was 87% (95% CI, 0.87-0.97). The cumulative 1-year and 3-year incidences of transplant-related mortality were 35% and 43%, respectively. The estimated 3-year overall and relapse-free survival rates after stem cell transplantation were 42% and 35%, respectively. In multivariate analysis, negative predictors of transplant-related mortality were year of stem cell transplantation before 1995, unrelated donor, and a long interval between diagnosis and transplantation. There was a trend towards longer overall and relapse-free survival in patients receiving peripheral blood stem cells rather than bone marrow as the source of their graft (p=0.070 and p=0.077, respectively). The intensity of the conditioning regimen (myeloablative versus reduced intensity regimens) did not significantly influence the outcome.
CONCLUSIONS: We conclude that the outcome of myelofibrosis patients who underwent allogeneic stem cell transplantation significantly improved after 1996 due to the reduction in transplant-related mortality. We observed that a reduction in transplant-related mortality was associated with the choice of a matched sibling donor, whereas longer overall survival was associated with the use of peripheral blood as the source of stem cells.