A Study of Photobiomodulation (PBM) Therapy in People With Oral Graft-Versus-Host Disease (GVHD) After Stem Cell Transplant

Inclusion Criteria:

* Allo-HCT recipients
* Age ≥ 4 years-old
* Oral cGvHD with NIH-modified OMRS score ≥ 3 who have failed ≥ 1 line of therapy, including topical corticosteroids..
* No change in systemic immunosuppressive therapy (type or intensity level) within 2 weeks prior to enrollment.
* If a patient is currently using another oral topical treatment for mouth lesions/symptoms, patient must be stable on this treatment for ≥2 weeks prior to study enrollment. Patient may continue same topical dose/frequency during the study period.

Exclusion Criteria:

* Presence of an active uncontrolled infection. Subjects with a controlled infection receiving definitive therapy for 48 hours prior to enrollment are eligible.
* Personal history of mucosal head and neck cancer in the past 5 years.
* Pregnant or breastfeeding.
* The subject or guardian is unable to give informed consent or unable to comply with the treatment protocol including appropriate supportive care, follow-up, and research tests.
* Any serious medical or psychiatric illness that could, in the Investigator's opinion, potentially interfere with the completion of treatment according to this protocol.