Safety and Efficacy of RRx-001 in the Attenuation of Oral Mucositis in Patients Receiving Chemoradiation for the Treatment of Oral Cancers

Inclusion Criteria: 1. Pathologically confirmed diagnosis of squamous cell carcinoma (SCC) of the oral cavity and oropharynx Note: Patients with unknown primary tumors whose treatment plan matches the requirements specified in Inclusion Criterion #3 below are eligible for the trial 2. Treatment planned to include standard cisplatin monotherapy administered either every three weeks (100 mg/m2 for 3 doses) with concomitant radiation delivered as a continuous course of IMRT with single daily fractions of 2.0 to 2.2 Gy with a cumulative radiation dose between 60 Gy and 72 Gy. Planned radiation treatment fields must include at least two oral sites (buccal mucosa, floor of mouth, tongue, soft palate) that are each planned to receive a total of \> 55 Gy. Patients who have had prior surgery are eligible, provided they have fully recovered from surgery, and patients who may have surgery in the future are eligible. 3. ECOG performance status ≤ 2. 4. Participants must have adequate organ and marrow function as defined below: A. Absolute neutrophil count (ANC) \>1,500 / mm3 B. Platelets \> 100,000 / mm3 C. Hemoglobin ≥ 9.0 g/dL 5. Adequate renal and liver function as indicated by: A. Serum creatinine acceptable for treatment with cisplatin per institutional guidelines) B. Total bilirubin ≤ 1.5 x upper-normal limit (ULN) C. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 x ULN D. Alkaline phosphatase ≤ 2.5 x ULN 6. Human papilloma virus (HPV) status in tumor has been documented using tumor immunohistochemistry for HPV-p16 or other accepted test for patients with cancers of the oropharynx, base of tongue, or unknown primary. 7. Age 18 years or older 8. Patient must consent to the access, review and analysis of previous medical and cancer history, including imaging data by the sponsor or a third party nominated by the sponsor. 9. Ability to understand and sign a written informed consent document. 10. Women of child-bearing potential and men with partners of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Note: A woman of child-bearing potential is any female (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: * Has not undergone a hysterectomy or bilateral oophorectomy; or * Has not been postmenopausal for at least 12 consecutive months 11. Adequate visual access to permit examination of the following oral cavity sites: lips, buccal mucosa, floor of mouth, ventral and lateral tongue and soft palate. Exclusion Criteria: 1. Prior radiation to the head and neck 2. Tumor of the lips, nasopharynx, hypopharynx, larynx, or salivary glands 3. Patients with simultaneous primaries or bilateral tumors 4. Metastatic disease (M1) Stage IV 5. Malignant tumors other than HNC within the last 5 years, unless treated definitively and with low risk of recurrence in the judgment of the treating investigator 6. Presence of oral mucositis (WHO Score ≥ Grade 1) or other oral mucosal ulceration at study entry 7. Grade 3 or 4 dysphagia or odynophagia (National Cancer Institute Common Toxicity Criteria, version 5.0) or inability to eat a normal diet 8. Requirement at baseline for parenteral or gastrointestinal tube-delivered nutrition for any reason 9. Known history of HIV or active hepatitis B/C (patients who have been vaccinated for hepatitis B and do not have a history of infection are eligible) 10. Any significant medical diseases or conditions, as assessed by the investigators and sponsor that would substantially increase the medical risks of participating in this study (i.e., uncontrolled diabetes, NYHA II-IV congestive heart failure, myocardial infarction within 6 months of study, severe chronic pulmonary disease or active uncontrolled infection, uncontrolled or clinically relevant pulmonary edema). 11. Pregnant or nursing 12. Untreated active oral or dental infection, including severe tooth decay (caries) 13. Known allergies or intolerance to cisplatin and similar platinum-containing compounds 14. Evidence of immediate life-threatening disease or a life expectancy of less than 3 months 15. Receipt of unapproved or off-label medication within 30 days prior to start of study treatment 16. Sjogren syndrome