Ph 2 Open Label Study of GC4419 to Reduce SOM Associated With Chemoradiotherapy for Head and Neck Cancer

Inclusion Criteria: 1. Pathologically-confirmed diagnosis of locally advanced squamous cell carcinoma of the head and neck that will be treated with cisplatin plus concurrent IMRT. 2. Treatment plan to receive a continuous course of IMRT delivered as single daily fractions of 2.0 to 2.2 Gy with a cumulative radiation dose of 60-72 Gy. 3. Patients who have had prior surgery may be eligible, 4. Treatment plan to receive standard cisplatin monotherapy administered either every three weeks (100 mg/m2 for 3 doses) or weekly (40 mg/m2 for 6-7 doses). 5. Age 18 years or older 6. ECOG performance status ≤ 2 7. Adequate hematologic function 8. Adequate renal and liver function Alkaline phosphatase ≤ 2.5 ULN Exclusion Criteria: 1. Metastatic disease 2. Prior radiotherapy to the region of the study cancer or adjacent anatomical sites 3. Prior induction chemotherapy or plans for chemotherapy to be administered only sequentially with IMRT 4. Planned concurrent chemotherapy other than single agent cisplatin 5. Receiving any approved or investigational anti-cancer agent 6. Concurrent participation in another interventional clinical study 7. Inability to eat soft solid food at baseline for reasons other than mouth soreness after surgery or dental procedures 8. Complete reliance on parenteral or gastrointestinal tube-delivered nutrition at baseline 9. Malignant tumors other than head and neck cancer (HNC) within the last 5 years 10. Active infectious disease excluding oral candidiasis 11. Presence of oral mucositis at baseline. 12. Known history of human immunodeficiency virus (HIV) or active hepatitis B/C 13. Female patients who are pregnant or breastfeeding 14. Known allergies or intolerance to cisplatin and similar platinum-containing compounds 15. Requirement for concurrent treatment with nitrates or other drugs that may, in the judgment of the treating Investigator, create a risk for a precipitous decrease in blood pressure.