Long‐term outcomes of antithymocyte globulin in patients with hematological malignancies undergoing myeloablative allogeneic hematopoietic cell transplantation: a systematic review and meta‐analysis

Antithymocyte globulin ( ATG ) has shown efficacy in preventing acute GVHD (a GVHD ) in allogeneic hematopoietic cell transplantation (allo‐ HCT ), but its efficacy in chronic GVHD ( cGVHD ) and long‐term outcomes remains controversial. We conducted a systematic review and meta‐analysis to evaluate potential benefit and risk of prophylactic ATG use in myeloablative HCT . We searched P ubmed, EMBASE , C ochrane databases, and included 10 trials (two RCT s and eight retrospective) comparing ATG use vs. control with a total of 1859 patients. The median follow‐ups were over two yr. Outcomes assessed included overall cGVHD , extensive cGVHD , overall survival ( OS ), disease‐free survival, relapse, and causes of death. Our results showed ATG significantly decreased overall cGVHD (RR = 0.59; 95% CI: 0.53–0.66, p < 0.00001), extensive cGVHD (RR = 0.34; 95% CI: 0.25–0.47, p < 0.00001). Pooled results also showed ATG use was associated with a marginal increased risk of relapse (RR = 1.28; 95% CI: 1.01–1.63, p = 0.04), and a non‐inferior OS (HR = 0.86; 95% CI: 0.74–1.01, p = 0.06). We conclude prophylactic use of ATG exerts a favorable effect in reducing cGVHD without survival impairment in a long term, although a higher relapse rate is a major threat.