Chronic Graft Versus Host Disease (cGvHD) occurs in approximately 40% of patients who have received a transplant of hematopoietic stem cells sourced from the bone marrow or peripheral blood of a donor. These hematopoietic stem cell transplants are used to treat some blood or bone marrow cancers as well as other hematologic conditions, such as aplastic anemia, which are not related to cancer. The donated cells identify the recipient’s body as foreign and attack it as a result. While acute GVHD usually appears in the first 100 days after a transplant, and in specific body systems, chronic GvHD can occur at any time (even several years) after a transplant, and may manifest in many parts of the body such as: skin, mouth, eyes, liver, intestines, lungs and joints. Long term immunosuppression is given to try to prevent or treat chronic GvHD. Since this treatment suppresses the immune system for a very long time, patients are at high risk of infections, and are prescribed multiple medications to try to address this major risk.