RecruitingPhase 2Device studyA Study of Photobiomodulation (PBM) Therapy in People With Oral Graft-Versus-Host Disease (GVHD) After Stem Cell TransplantThe purpose of this study is to find out whether photobiomodulation/PBM therapy using the Thor LX2.3 therapy system is a safe and effective treatment for oral Graft-Versus-Host Disease/GVHD.