Background and Rationale: Transformation of myelofibrosis (MF) to acute leukemia (>20% blasts) portends a grave prognosis. Allogeneic stem cell transplantation (ASCT) is a curative approach for patients with acute leukemia; however, the outcomes of ASCT in patients with MF transformed to acute leukemia are currently unknown.
Methods: Fifty-one consecutive patients with either primary (PMF) or secondary (SMF) were transplanted at UTMDACC after 1994. Thirteen patients who developed AML (25%), 10 arising from PMF and 3 with SMF, received an ASCT from a sibling or matched unrelated donor. Median age was 59 years. Five patients (38%) had prior splenectomy. JAK2V617F mutation analysis was performed in 7, and was present in 5 patients. Cytogenetics were intermediate in 10 and poor-risk in 3 patients. Seven patients (54%) were not in remission at the time of transplant. Eleven of 13 patients received induction chemotherapy; 6 achieved remission, while 7 had persistent disease at the time of transplant. One patient had a prior autologous transplant and 2 patients had prior allogeneic transplant for myelofibrosis. The donors were matched siblings (7 patients), matched unrelated (4 patients) and 1 antigen mismatched relatives (2 patients). The stem cell source was peripheral blood in 9 and bone marrow in 4 patients. Nine patients received a reduced-intensity conditioning regimen with a fludrabine-melphalan-based regimen, and 4 myeloablative conditioning (3 fludarabine-busulfan, 1 busulfan-cyclophosphamide).
Results: All patients engrafted, 75% achieved full donor chimerism, on day 30. Neutrophil and platelet engraftment occurred after a median of 13 and 21.5 days. Twelve evaluable patients achieved remission; 3 subsequently relapsed. JAK2V617F mutation became negative after transplant in all tested patients and reappeared in 1 patient who later relapsed. Grade 2–4 aGVHD developed in 3 patients (grade 3–4 in one) and cGVHD in 4/11 evaluable patients (extensive in two). After a median follow-up of 17.2 months (range 7.2–128.6 mo), OS and EFS were 49% (SE 15%) and 44% (SE 14%), respectively (Figure1). Six patients died, related to disease relapse (2), pneumonia (2), GVHD (1), and hepatic failure (1).
Conclusion: Patients with acute leukemia transformed from myelofibrosis with good performance status can achieve durable complete remissions with ASCT.
Disclosures: No relevant conflicts of interest to declare.