"Life-saving cancer treatments can occasionally cause distressing or uncomfortable side effects that patients can find difficult to cope with. Extracorporeal photopheresis (ECP) is a relatively new treatment that’s helping to improve the quality of life for dozens of cancer patients every year ... ECP is most commonly used to treat two conditions - Cutaneous T cell Lymphoma (CTCL) and Chronic Graft versus Host Disease (GvHD)."
Graft-versus-host disease is a challenging, & life-threatening condition occurring when the newly transplanted cells identify & treat the patient’s normal cells as foreign invaders. The new immune cells then attack the recipient’s own cells, and begin to damage the patient’s organs. GVHD is the most serious complication from transplant therapy that seriously limits the ability to offer transplants more broadly: http://www.lgmpharma.com/blog/tag/gvhd/