A Phase II Trial of Low-Dose Interleukin-2 (IL-2) Added to Extra-Corporeal Photopheresis for Steroid-Refractory cGVHD

Inclusion Criteria: Participants must meet the following criteria on screening examination to be eligible to participate in the study: * Recipients of 7-8/8 HLA matched adult donor allogeneic stem cell transplantation with myeloablative or non-myeloablative conditioning regimens. * Participants must have steroid-refractory cGVHD. Steroid-refractory cGVHD is defined as having persistent signs and symptoms of cGVHD (Appendix D; section 17.4) despite the use of prednisone at ≥ 0.25 mg/kg/day (or 0.5 mg/kg every other day) for at least 4 weeks (or equivalent dosing of alternate corticosteroids) without complete resolution of signs and symptoms. Patients with either extensive chronic GVHD or limited chronic GVHD requiring systemic therapy are eligible. * Stable dose of corticosteroids for 4 weeks prior to enrollment * No addition or subtraction of other immunosuppressive medications (e.g., calcineurin-inhibitors, sirolimus, mycophenolate-mofetil) for 4 weeks prior to enrollment. The dose of immunosuppressive medicines may be adjusted based on the therapeutic range of that drug * Patient age ≥18 years old. Because no dosing or adverse event data are currently available on the use of IL-2 in participants \<18 years of age, children are excluded from this study. * Estimated life expectancy greater than 3 months. * ECOG performance status 0-2 (Appendix A; section 17.1). * Participants must have adequate organ function as defined below: * Hepatic: Adequate hepatic function (total …