RecruitingProcedurePredicting the Quality of Response to Specific Treatments in Patients With cGVHD, PQRST StudyThis trial collects clinical data and blood samples to predict the quality of response to specific treatments in patients with chronic graft-versus-host disease (cGVHD) who are about to start a new therapy. Collecting and analyzing clinical data and blood samples from patients with cGVHD before and after treatment initiation may help doctors identify changes that may predict treatment response.