Fludarabine and busulfan plus low-dose TBI as reduced intensity conditioning in older patients undergoing allogeneic hematopoietic cell transplant for myeloid malignancies.

We have been using a combination of fludarabine/busulfan plus low-dose total body irradiation (TBI) as the reduced-intensity conditioning (RIC) regimen for patients age ≥ 60 years undergoing allogeneic hematopoietic cell transplantation (HCT) for myeloid malignancies. We retrospectively analyzed outcomes of 116 older patients (median age 64 years) who underwent HCT from 2006 to 2015 for myeloid malignancies, including acute myeloid leukemia (AML) in first complete remission (CR1). On univariate analysis, overall survival (OS) for the cohort at 3 years was 33% (95% CI 25-42). Cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) at 3 years were 24% (95% CI 16-32) and 43% (95% CI 34-52), respectively. Multivariable analysis for OS demonstrated AML patients to have superior outcome (HR 1.60 for other myeloid, 95% CI 1.01-2.54, p = 0.045), as well as related donors (HR 1.92 for unrelated, 95% CI 1.22-3.03, p = 0.005). For NRM, AML patients had superior outcome (HR 1.76 for other myeloid, 95% CI 1.03-3.01, p = 0.038), as well as patients with related donors (HR 1.81 for unrelated, 95% CI 1.07-3.07, p = 0.028). We then demonstrated that AML patients with related donors (n = 45) had superior 3-year OS of 51% (95% CI 36-65), compared to 21% (95% CI 12-32) for all other patients (p = 0.0003). We conclude that the RIC regimen used is effective for older patients, particularly AML patients in CR1 with matched related donors.