Outcomes of Allogeneic Stem Cell Transplantation in a North American Adult T Cell Leukemia/Lymphoma Cohort.

BACKGROUND

Adult T-cell leukemia/lymphoma (ATLL) is an and aggressive mature T-cell neoplasm driven by human T-cell leukemia virus type 1 (HTLV-1) with dismal prognosis. North American ATLL (NA-ATLL) disproportionately impacts individuals of Afro-Caribbean and Latin American descent who face significant disparities in identifying conventional 8/8 HLA-matched donors in international registries. While allogeneic hematopoietic cell transplantation (HCT) is established in East Asian cohorts, outcomes data in Western populations remain limited. We aimed to evaluate post-HCT survival, toxicities, and prognostic risk factors in NA-ATLL.

OBJECTIVE

The objective of this study was to evaluate HCT clinical outcomes. Our primary outcome was overall survival (OS), and secondary outcomes included progression-free survival (PFS), non-relapse mortality (NRM), and graft-versus-host disease (GVHD). We tested the hypotheses that alternative donor HCT yields comparable survival to matched donor HCT and assessed variables that may dictate post-transplant survival.

STUDY

DESIGN

This was a multicenter retrospective registry study evaluating 46 adult patients with NA-ATLL who underwent allogeneic HCT across participating North American centers. Myeloablative conditioning regimens were myeloablative in 21.7%, and alternative donor HCT (without a matched donor) were used in 54.3%. Survival endpoints (OS, PFS) were estimated using the Kaplan-Meier method and compared via log-rank tests. Cumulative incidences of relapse, NRM, acute GVHD, and chronic GVHD were calculated considering competing risks. Independent prognostic variables were evaluated using Cox multivariable proportional hazards regression analysis.

RESULTS

There was no significant difference in OS or PFS between those who received matched versus alternative donor HCT (OS p = 0.601, PFS p = 0.376). Patients with acute disease subtype had worse OS compared to lymphomatous (logrank p = 0.043, 3-year OS 22.2% versus 52.3%, respectively). Acute GVHD yielded a 1-year cumulative incidence rate of 45.7% (95%CI; 30.7-59.5%) while that of chronic GVHD was 18.5% (95%CI; 8.5-31.5%). Twenty-seven patients were deceased at time of analysis, primarily due to relapse-related causes in 17 patients. In multivariable analysis, lymphomatous disease subtype (HR 0.3, 95%CI 0.1-0.88, p = 0.027) and Karnofsky performance score of ≥80 (HR 0.26, 95%CI 0.09-0.73, p = 0.01) were significant predictors of OS.

CONCLUSION

This is the largest cohort evaluating HCT outcomes in a NA-ATLL population. Alternative donor HCT may expand access to HCT without an apparent increase in non-relapse mortality in this selected cohort. Clinical acute disease subtype shows inferior outcomes compared to lymphomatous subtype. Baseline performance status is a predictor of improved prognosis post-transplant. These data suggest that fit patients should proceed to HCT expeditiously with any donor option available.