The Use Of Anti-Thymocyte Globulin Is Associated With Decreased Risk Of Chronic Graft-Versus-Host Disease Without Impact On Survival After Allogeneic Peripheral Blood Stem Cell Transplantation For Adults With Philadelphia-Positive Acute Lymphoblastic Leukemia: An Analysis By The Acute Leukemia Working Party Of The Ebmt

BACKGROUND Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the standard of care for adults with Philadelphia-positive acute lymphoblastic leukemia (Ph-pos ALL). During the last decade mobilized peripheral blood stem cells (PBSCT) have become predominant source of graft for allo-SCT. However, as compared to bone marrow, PBSCT is associated with increased risk of chronic graft-versus-host disease (cGVHD). Attempts to reduce the cGVHD rate include the addition of anti-thymocyte globulin (ATG) to the conditioning regimen. The goal of this registry-based, retrospective study was to analyze the effect of ATG on results of allo-PBSCT in adults with Ph-pos ALL. PATIENTS AND METHODS 1055 patients, aged 18-76 years, with Ph-pos ALL, treated with unmanipulated allo-PBSCT in first complete remission between 1997-2014 were included in the analysis. Conditioning regimen was myeloablative in 769 (72%) cases and based on total body irradiation in 608 (58%) cases. Among 590 transplantations from matched sibling donors, ATG was used in 95 (16%) patients. While, in the 8/8 HLA-matched unrelated setting 304/465 (65%) patients were treated with ATG. RESULTS In a univariate analysis the use of ATG was associated with decreased incidence of the overall cGVHD (32% vs. 48%, p In a multivariate model adjusted for other potential risk factors, the use of ATG was associated with reduced risk of the overall cGVHD (HR=0.53, p CONCLUSIONS Patients with Ph-pos ALL treated with allo-PBSCT benefit from the use of ATG in terms of reduced risk of cGVHD without impact on survival. Increased risk of relapse, as shown in a multivariate model implicates the need for strict monitoring of minimal residual disease and either prophylactic or pre-emptive use of tyrosine kinase inhibitors after transplantation. Further studies are needed to explore potential role of the ATG brand and dose. Disclosures Mohty: Sanofi: Honoraria, Speakers Bureau.