Lower dose of ATG combined with post-transplant cyclophosphamide for HLA matched RIC alloHCT is associated with effective control of GVHD and less viral infections.

This study compares the outcomes before and after reducing the ATG dose from 4.5 to 2 mg/kg, in a combination of PTCy and CsA for GVHD prevention, in 250 patients treated with HLA matched RIC PB-alloHCT (70% received 4.5 mg/kg and 30% received 2 mg/kg). The incidences of grade II-IV and III-IV aGVHD at day +100, and moderate/severe cGVHD at 1-year were 12.6% vs. 20% ( p  = 0.431), 3.6% vs. 4.5% ( p  = 0.935), and 10.9% vs. 26.1% ( p  = 0.480), respectively. PTLD (9.1% vs. 1.3%, p  = 0.026) and viral infections (30.3% vs. 12%; p  = 0.001) were lower for those treated with 2 mg/kg of ATG. The reduction of the ATG dose resulted in a comparable OS (2-year: 64.7% vs. 64.7%), GRFS (2-year: 48.0% vs. 44.5%), RFS (2-year: 57.0% vs. 62.0%), and NRM (2-year: 17.8 vs. 14.9). The use of (2 mg/kg) ATG-PTCy-CsA for HLA matched RIC alloHCT results in lower viral infections, and incomparable GVHD preventive effect and survival rates.