Reduced Intensity Versus Myeloablative Allogeneic Hematopoietic Cell Transplant for Myelofibrosis: A Single Institution Experience

Background Allogeneic hematopoietic cell transplant (alloHCT) is the only potentially curative therapy for myelofibrosis (MF). Outcomes after alloHCT for MF remain dismal, with 5-year overall survival (OS) of 30-40%. Given age, comorbidities, and often advanced disease, the decision of if and when to transplant can be a challenge. We undertook this analysis to investigate our institutional experience with alloHCT for MF. Methods We conducted a retrospective analysis was performed patients who received alloHCT at the Cleveland Clinic between January 1, 2010 and April 1, 2023. Patients with a diagnosis of MF (both primary and secondary) were included. All donor types (matched sibling, haploidentical, matched unrelated, and mismatch unrelated) and graft sources (peripheral blood stem cells, bone marrow, cord blood) were included. Results A total of 59 patients were identified. Median age at the time of transplant was 62 (range 56-67), with 22 (37.3%) patients being ≥65 years old (yo). Males represented 55.9% (n=33) of our cohort. Median time from diagnosis to transplant was 1.0 years (range, 0.53-4.77). The majority of transplants performed were reduced intensity (RIC; n=41, 69.5%), and Bu/Flu/ATG was used most frequently (n=26, 44.1%). Stem cell source was primarily peripheral blood (n=54, 91%), with a minority using cord blood for (n=3, 5.1%) and bone marrow for (n=2, 3.4%). Incidence of any-grade acute and chronic graft-versus-host disease (GVHD) was 39% and 32.2%, respectively. At median follow-up time of 1.26 years, 36/59 (61.0%) of patients were alive (Figure 1). Median OS from time of transplant for all patients and for those ≥65 was 3.1 years and 1.33 years, respectively. Median OS from transplant was not reached (NR) for patients who received myeloablative conditioning regimens, versus 1.97 years for reduced intensity (p=0.23) (Figure 2). Twenty-six patients died during the study period; 4 (15.4%) from relapse, and the remaining from treatment related causes, most frequently bacterial infections and GVHD. Discussion Our institutional 5-year post-alloHCT survival of 52.6% is superior to rates reported in the literature. Elderly patients (≥65) and those who received a reduced intensity conditioning regimen had inferior survival rates. This analysis will serve as the basis for our center to optimize conditioning regimen and patient selection, in particular those ≥65 yo. Analysis against matched controls who did not undergo transplant, of additional risk factors and disease characteristics, and investigation of molecular mutational status of the patients, is planned.