Clinical outcomes of T-cell acute lymphoblastic leukemia versus T-cell lymphoblastic lymphoma after allogeneic hematopoietic stem cell transplantation

Abstract Although T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) were historically regarded as different manifestations of a single disease entity driven by immature T-lymphoblast proliferation, recent advances in molecular diagnostics and cytogenetic testing have revealed inherent differences in their molecular signatures and chromosomal profiles. Despite these differences, comparative data on clinical outcomes following allogeneic hematopoietic stem cell transplantation (allo-HSCT) between the two subtypes remain limited. To address this gap, we retrospectively analyzed 106 consecutive patients, including 71 with T-ALL and 35 with T-LBL, who underwent allo-HSCT at our institution between January 2010 and January 2025. No statistically significant differences were observed in overall survival (OS), disease-free survival (DFS), graft-versus-host disease–free, relapse-free survival (GRFS), cumulative incidence of relapse (CIR), or cumulative incidence of non-relapse mortality (NRM) between patients with T-ALL and T-LBL. Diagnosis was not associated with these outcomes in multivariable analyses. However, the association between diagnosis and OS, DFS, CIR, and NRM varied over time. At 6 months, the multivariable analysis showed worse OS in T-LBL (hazard ratio at the specified time [HR(t)], 2.41; 95% confidence interval [CI], 1.10–5.28; P = 0.028). At 36 months, T-LBL was associated with lower risks of DFS failure (HR(t), 0.16; 95% CI, 0.03–0.91; P = 0.039) and NRM (subdistribution hazard ratio at the specified time [sHR(t)], 0.06; 95% CI, 0.01–0.72; P = 0.026). The 36-month restricted mean survival time (RMST) for OS was 5.79 months shorter in T-LBL (95% CI, − 11.38 to − 0.19; P = 0.043), whereas DFS and GRFS RMST did not differ significantly. Results for most outcomes did not differ significantly between groups in either the PSM cohorts or the first complete remission subgroup, although moderate to severe chronic graft-versus-host disease (cGVHD) was less frequent in T-LBL. Complete case analyses for white blood cell (WBC) and lactic dehydrogenase (LDH) and analyses restricted to patients in complete remission with evaluable measurable residual disease (MRD) did not materially alter the diagnosis estimates. Overall, OS, DFS, CIR, NRM, and GRFS did not differ significantly between patients with T-ALL and T-LBL, although the effects of diagnosis on OS, DFS, CIR, and NRM changed during follow-up. These findings should be interpreted cautiously and confirmed in larger multicenter studies.