To investigate the efficacy and safety of rebamipide liquid for chemoradiotherapy-induced oral mucositis in patients with head and neck cancer following administration of rebamipide and to determine the optimal dose of rebamipide.

Inclusion Criteria:

• Head and neck cancer patients scheduled for definitive or postoperative chemoradiotherapy.

• Patients with a histopathological diagnosis of head and neck cancer and primary tumor in one of the following regions.

  1. Definitive therapy: nasopharynx, oropharynx, hypopharynx, or larynx
  2. Postoperative therapy: oral cavity, oropharynx, hypopharynx, or larynx

• Patients with no history of chemotherapy, radiotherapy, or chemoradiotherapy for head and neck cancer

• Patients with an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1

• Patients who are able to hold fluid in the mouth

• Patients who are able to swallow the investigational medicinal product (IMP)

• Patients expected to survive for at least 3 months

• Patients who have given written informed consent in person

• Patients who can stay at or visit the hospital for scheduled examinations and observations

• Patients who are able to take contraceptive measures to avoid pregnancy of the patient or their partner from the time of informed consent until 4 weeks after completion of IMP administration

Exclusion Criteria:

• Patients with primary malignant tumors other than head and neck cancer.

• Patients with symptomatic viral, bacterial, or fungal infection

• Patients with serious renal impairment

• Patients with distant metastasis

• Patients with severe complications (uncontrolled cardiac disease, diabetes, hypertension, etc)

• Patients with any of the following laboratory test results:

  1. Neutrophil count: <1500 L
  2. Platelet count: <75000 L
  3. Hemoglobin: <10.0 g/L
  4. Aspartate aminotransferase (AST): >3 times the upper limit of the reference value at the trial site
  5. Alanine aminotransferase (ALT): >3 times the upper limit of the reference value at the trial site
  6. Serum bilirubin: >1.5 times the upper limit of the reference value at the trial site
  7. Serum albumin: <3.0 g/dL
  8. Serum creatinine: >1.5 the upper limit of the reference value at the trial site
  9. Creatinine clearance : <30 mL/min

• Patients complicated with autoimmune disease

• Patients requiring continuous systemic administration of glucocorticoid

• Female patients who are pregnant or lactating, who may possibly be pregnant, or who wish to become pregnant

• Patients who have participated in any other clinical trial within 4 weeks prior to initiation of chemoradiotherapy

• Patients who have a history of drug allergy to rebamipide, cisplatin, or other platinum compounds

• Patients who are otherwise judged by the investigator or sub-investigator to be inappropriate for inclusion in the trial