A study compared the effectiveness of post-transplantation cyclophosphamide (PTCy) and rabbit anti-thymocyte globulin (rATG) in preventing graft-versus-host disease (GVHD) in patients undergoing allogeneic stem cell transplantation (alloSCT) from mismatched unrelated donors (MMUD). The study analyzed data from 2123 patients with hematologic malignancies who received their first peripheral blood alloSCT from a 9/10 antigen-matched MMUD between 2018 and 2021. The results showed that patients receiving PTCy had significantly lower non-relapse mortality (NRM) compared to those receiving rATG, with 18% vs. 24.9% at two years. Overall survival was also higher in the PTCy group (65.7% vs. 55.7%), and progression-free survival was better (59.1% vs. 48.8%). The incidence and severity of both acute and chronic GVHD were not significantly different between the two groups. The study suggests that PTCy may be a more effective option for GVHD prophylaxis in MMUD alloSCT compared to rATG. However, the study also notes that the available evidence is still limited, and further research is needed to confirm these findings. The study highlights the importance of continued research into the optimal GVHD prophylaxis strategies for MMUD alloSCT.A study compared the effectiveness of post-transplantation cyclophosphamide (PTCy) and rabbit anti-thymocyte globulin (rATG) in preventing graft-versus-host disease (GVHD) in patients undergoing allogeneic stem cell transplantation (alloSCT) from mismatched unrelated donors (MMUD). The study analyzed data from 2123 patients with hematologic malignancies who received their first peripheral blood alloSCT from a 9/10 antigen-matched MMUD between 2018 and 2021. The results showed that patients receiving PTCy had significantly lower non-relapse mortality (NRM) compared to those receiving rATG, with 18% vs. 24.9% at two years. Overall survival was also higher in the PTCy group (65.7% vs. 55.7%), and progression-free survival was better (59.1% vs. 48.8%). The incidence and severity of both acute and chronic GVHD were not significantly different between the two groups. The study suggests that PTCy may be a more effective option for GVHD prophylaxis in MMUD alloSCT compared to rATG. However, the study also notes that the available evidence is still limited, and further research is needed to confirm these findings. The study highlights the importance of continued research into the optimal GVHD prophylaxis strategies for MMUD alloSCT.