An open-label controlled randomized trial of low-dose (1 × 106 U/d) given for 2 weeks beginning on day 60 in allo-HSCT recipients showed that the IL-2 treated group had a significantly lower incidence of moderate-to-severe chronic GVHD (33% vs. 57%), accompanied by a significant increase in GVHD-free and GVHD progression-free survival at three years (47% vs. 31%) [161]. The gene discussed is IL2; the disease is chronic graft versus host disease.