Allogeneic hematopoietic stem cell transplantation in T-cell acute lymphoblastic leukemia adults in complete remission: A systematic review and meta-analysis.

6559 Background: There is limited data on the outcomes of allogeneic hematopoietic stem cell transplantation (allo-HCT) in T-cell acute Lymphoblastic Leukemia (T-ALL) patients. This study aims to assess complications, recurrence rates, and survival outcomes in T-ALL patients in clinical remission receiving allo-HCT. Methods: Following PRISMA guidelines, a comprehensive literature search was conducted across PubMed, Embase, Cochrane, and the clinicaltrials.gov registry from inception to December 2024 using keywords related to T-ALL and allo-HCT. Out of 1161 identified search results, 8 studies were included in this meta-analysis. Data was analyzed for outcomes including overall survival (OS), leukemia-free survival (LFS), relapse rates, non-relapse mortality (NRM), and graft-versus-host disease (GVHD) of Allo-HSCT in adult T-ALL patients in clinical remission. R version 4.4.2 was used to conduct a proportional meta-analysis using an inverse variance, random effects model. Results: This study included eight retrospective studies involving 3,280 T-ALL patients undergoing allo-HCT, with a median age of 32 years (range: 17–49) and a median follow-up of 37 months (range: 28–44). Seventy-one percent of the patients were male. Donor types included matched sibling (48.3%), matched unrelated (33.7%), haploidentical (10.2%), and mismatched unrelated (7%). Most grafts were from peripheral blood (75.8%), with the remainder from bone marrow. A myeloablative conditioning regimen was used in 86% of patients. At the time of HSCT, 92.16% of patients were in clinical remission. The pooled 2-year overall survival (OS) for patients in clinical remission was 63.2% (95% CI: 47.2–79.2; p<0.0001; I² = 89.4%), and 53.5% at 5 years (95% CI: 25.9–81.1; p<0.0001; I² = 93.7%). Similarly, the pooled leukemia-free survival (LFS) was 64.5% at 2 years (95% CI: 51.9–77.1; p<0.0213; I² = 74%) and 62.7% at 5 years (95% CI: 26.9–99.4; p<0.0003; I² = 92.5%). The pooled relapse rate was 23.4% at 2 years (95% CI: 9.6–37.2; p<0.0001; I² = 89.4%) and 53.3% at 4 years (95% CI: 0.0–100; p<0.0001; I² = 98.5%). The pooled non-relapse mortality (NRM) rate was 14.5% at 1 year (95% CI: 9.1–19.6; p = 0.0695; I² = 69.6%), 20.8% at 4 years (95% CI: 17.9–23.8; p = 0.4907; I² = 0%), and 26% at 5 years (95% CI: 18.6–29.9; I² = 0%). The pooled incidence of chronic graft-versus-host disease (cGVHD) was 34.3% (95% CI: 27.0–41.5; p = 0.6564; I² = 75.8%). Conclusions: T-ALL patients in clinical remission at allo-HCT showed favorable survival outcomes, though relapse remains a significant concern, particularly over time. Non-relapse mortality stabilizes after the first year but continues to pose a challenge. Chronic graft-versus-host disease prevalence remains high, underscoring the importance of long-term management strategies.