Chlorophyllin for Reducing Oral Mucositis in Total Body Irradiation Prior to Transplant

The goal of this phase II, single-arm interventional clinical trial is to evaluate whether oral sodium copper chlorophyllin (CHL) can reduce the frequency and severity of oral mucositis in patients aged 12-65 years undergoing myeloablative total body irradiation (TBI) as part of conditioning before their first allogeneic Hematopoietic Stem Cell Transplantation (HSCT). The main questions it aims to answer are: Does oral chlorophyllin reduce the incidence of Grade III and IV oral mucositis by day +28 after HSCT? Does oral chlorophyllin reduce the duration of severe oral mucositis and the need for total parenteral nutrition (TPN), opioid analgesics, and other treatment-related toxicities, while maintaining acceptable safety? Participants will: Receive oral sodium copper chlorophyllin 750 mg once daily (tablet or oral suspension) starting 48 hours before TBI conditioning and continuing u