A Phase 2 Trial of Rebamipide Liquid to Determine the Effective Dose for Prevention of Chemoradiotherapy-induced Oral Mucositis in Patients With Head and Neck Cancer

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