This research study is a way of gaining new knowledge about the treatment for cGVHD that has not responded to steroids. This research study is evaluating a drug called Interleukin-2 (IL-2) as a possible treatment for cGVHD. In this Phase I study, the investigators are looking to see if 8- week individual patient dose- escalated IL-2 therapy for cGVHD is safe and its effects on your immune cells.