Allogeneic marrow transplantation for primary myelofibrosis and myelofibrosis secondary to polycythaemia vera or essential thrombocytosis.

Primary myelofibrosis is a clonal haemopoietic disorder, incurable with conventional therapy, and associated with a median survival of 4-5 years. Patients with polycythaemia vera and essential thrombocytosis who progress into a myelofibrotic picture also have a poor prognosis. Between 1980 and 1996, 13 patients with myelofibrosis due to one of these three myeloproliferative disorders (primary myelofibrosis [n=8], essential thrombocytosis [n=3], polycythaemia vera [n=2]) underwent allogeneic marrow transplantation in Seattle. The median age was 40 years (range 18-49). The median time from myeloproliferative diagnosis to transplantation was 39 months (range 5-192). Three patients received preparative regimens containing total body irradiation and 10 received busulphan-cyclophosphamide regimens. Nine patients received marrow from HLA-matched related donors, one from a one antigen mismatched related donor, and three from HLA-matched unrelated donors. The median time to both granulocyte and platelet engraftment was 21 d. Nine patients survive between 1.2 and 7.1 years post-transplant. Two patients relapsed at 1 year post-transplant, both of whom survive in a chronic myeloproliferative state. Four patients died of transplant-related complications between 43 d and 2.2 years post-transplant. At 1 year post-transplant the majority of the disease-free survivors have normal peripheral blood counts and none-to-minimal marrow fibrosis. These preliminary results are encouraging, and suggest that stem cell transplantation can be curative therapy for selected patients with myelofibrosis.