Treatment response. Per study design, 27 patients were enrolled with biopsy-proven lower GI aGVHD and monitored for their response to treatment with F-652 (rhIL-22) and systemic corticosteroids. The study was powered to indicate a promising treatment response if at least 60% of patients responded with an improvement in GVHD staging at day 28 after F-652 initiation. (A) The primary efficacy endpoint was achieved with an overall day-28 treatment response of 70%. (B) The majority of patients remained responders by day 56.