P1306: impact of hla disparity on the risk of overall mortality in patients with extensive chronic gvhd

Topic: 22. Stem cell transplantation - Clinical Background: Chronic graft-versus-host disease (cGVHD) is a significant cause of morbidity and mortality in long-term survivors after allogeneic hematopoietic cell transplantation (allo-HCT). It is unclear whether stem cell source or HLA disparity significantly impact the overall survival (OS) after the development of extensive cGVHD. Aims: The aim of this study is to clarify the impact of HLA disparity on the clinical outcome after the development of extensive cGVHD. Methods: We performed a retrospective analysis using a database of the Japanese Society for Transplantation and Cellular Therapy. This retrospective study included patients who underwent their first allo-HCT between 2007 and 2016 and subsequently developed extensive cGVHD. The data was obtained from the Transplant Registry Unified Management Program of Japanese Society for Transplantation and Cellular Therapy. Results: We analyzed the clinical outcomes of 4,389 patients who developed extensive cGVHD. The median age of the patients was 48 years (IQR 34–58). The probability of 2-year OS after the onset of extensive cGVHD in the study cohort was 68.3% (95% CI 66.9–69.8). The multivariate analysis showed that the presence of HLA disparity ≥2 loci in the related HCT was associated with an inferior OS (HR 1.68, 95% CI 1.11–2.52, P=0.014, Figure), but there was no impact of HLA disparity in unrelated HCT and cord blood transplantation (CBT). The cumulative incidence of 2-year NRM after the onset of extensive cGVHD was 18.5% (95% CI, 17.2-19.8). In multivariate analysis, there was a trend toward a higher NRM rate in patients with HLA disparity ≥2 loci in related HCT, but there was no significant impact of HLA disparity in unrelated HCT and CBT.Summary/Conclusion: Our study suggests that HLA disparity could be a prognostic factor in the related HCT but not in the unrelated HCT or CBT in patients with extensive cGVHD. Further research using other databases is necessary to confirm our findings. Keywords: Graft-versus-host disease (GVHD), Allogeneic hematopoietic stem cell transplant