Key Points: Over the last decade, allogeneic HCT has been increasingly administered in the United States to adults aged 70 and older with hematologic malignancies. Allogeneic transplant outcomes were reasonable; high comorbidity and ablative conditioning regimens were associated with inferior outcomes.

We examined the efficacy of reduced-intensity conditioning (RIC) and compared outcomes of 93 patients older than 16 years after RIC with 1428 patients receiving full-intensity conditioning for allografts using sibling and unrelated donors for Philadelphia-negative acute lymphoblastic leukemia (ALL) in first or second complete remission. RIC conditioning included busulfan 9 mg/kg or less (27), melphalan 150 mg/m2 or less (23), low-dose total body irradiation (TBI; 36), and others (7). The RIC group was older (median 45 vs 28 years, P < .001) and more received peripheral blood grafts (73% vs 43%, P < .001) but had similar other prognostic factors. The RIC versus full-intensity conditioning groups had slightly, but not significantly, less acute grade II-IV graft-versus-host disease (39% vs 46%) and chronic graft-versus-host disease (34% vs 42%), yet similar transplantation-related mortality. RIC led to slightly more relapse (35% vs 26%, P = .08) yet similar age-adjusted survival (38% vs 43%, P = .39). Multivariate analysis showed that conditioning intensity did not affect transplantation-related mortality (P = .92) or relapse risk (P = .14). Multivariate analysis demonstrated significantly improved overall survival with: Karnofsky performance status more than 80, first complete remission, lower white blood count, well-matched unrelated or sibling donors, transplantation since 2001, age younger than 30 years, and conditioning with TBI, but no independent impact of conditioning intensity. RIC merits further investigation in prospective trials of adult ALL.

Key Points: In combination with cyclophosphamide, intravenous busulfan is associated with better leukemia-free and overall survival in AML than TBI.

We compared the outcomes of unrelated donor (URD, n = 358) with human leukocyte antigen (HLA)–matched sibling donor (MSD, n = 226) transplantations in patients with acute myeloid leukemia (AML) in first complete remission (CR1) having unfavorable cytogenetics at diagnosis. Unfavorable cytogenetic abnormalities were: complex (≥ 3 abnormalities), 32%; and noncomplex involving chromosome 7, 25%; chromosome 5, 9%; 11q or MLL rearrangements, 18%; t(6;9), 5%; and other noncomplex, 10%. URDs were HLA-well-matched (n = 254; 71%) or partially-matched (n = 104; 29%). Three-year leukemia-free survival (LFS) for MSD was 42% (95% confidence interval [CI], 35%-48%) compared with 34% (95% CI, 28%-41%) for HLA-well-matched URD and 29% (95% CI, 20%-39%) for partially-matched URD (P = .08). In multivariate analysis, HLA-well-matched URD and MSD yielded similar LFS (relative risk [RR] = 1.1, 95% CI, 0.86-1.40, P = .44) and overall survival (OS; RR = 1.06, 95% CI, 0.83-1.37, P = .63). LFS and OS were significantly inferior for HLA-partially-matched URD recipients, those with prior myelodysplastic syndrome, and those older than 50 years. All cytogenetic cohorts had similar outcomes. Patients with chronic graft-versus-host disease had a significantly lower risk of relapse (RR = 0.68, 95% CI, 0.47-0.99, P = .05). Hematopoietic cell transplantation (HCT) using HLA-well-matched URD and MSD resulted in similar LFS and OS in AML patients in CR1 with unfavorable cytogenetics. Outcomes of HCT from HLA-partially- matched URD were inferior.