Radiation therapy is the main treatment for nasopharyngeal carcinoma (NPC), and standard care for advanced NPC often includes combination chemotherapy and radiation (CCRT). However, many patients experience serious side effects, such as painful mouth sores (Radiation-Induced Oral Mucositis, RTOM). These side effects can be so severe that they lower a patient's ability to adhere to treatment, potentially making the CCRT less effective. Studies have shown that a significant number of patients stop treatment early due to this toxicity.

Current clinical guidelines from organizations like MASCC/ISOO and ESMO agree that preventing RTOM is crucial, but there is currently no specific drug that works for everyone.

This study aims to investigate a new approach: using Sapylin, a biological immune regulator, delivered through an atomized inhaler. Preliminary research suggests Sapylin delivered this way may enhance the effectiveness of chemotherapy and boost the body's immunity.

The main purpose of this study is to determine the effect of Sapylin inhalation on the incidence and severity of RTOM, and to evaluate its safety and impact on the overall success of CCRT.

By participating, you will help researchers find a high-efficiency, low-toxicity method to improve CCRT outcomes and manage RTOM for future NPC patients and specialists.

1. Inclusion Criteria:

   • Stage III-IVa NPC (AJCC 8th edition) diagnosed via pathology in a tertiary hospital;
   • No previous radiotherapy, chemotherapy, surgery, immunization, or targeted therapy;
   • Karnofsky Performance Status score ≥80;
   • Intact and normal oral mucosa before treatment;
   • Age 18-75 years;
   • Voluntary participation and provision of informed consent in person;
   • Routine blood examination: white blood cell count ≥4.0×109/L, hemoglobin ≥100g/L, neutrophil count ≥1.5×10^9/L, and platelet count ≥100×10^9/L;
   • Biochemical examination: total bilirubin ≤1.5×the upper limit of the normal range (ULN), alanine aminotransferase and aspartate aminotransferase ≤2×ULN, and estimated glomerular filtration rate ≥60 mL/min.

2. Exclusion Criteria:

   • With other malignant tumors in the past or present and/or distant metastasis during treatment;
   • Who have undergone surgery, chemoradiotherapy, and targeted immunotherapy;
   • With a history of asthma, rash, urticaria, and other allergic diseases;
   • With a history of autoimmune diseases, connective tissue diseases, and diabetes mellitus that significantly affect the healing of the oral mucosa;
   • With concomitant diseases, such as heart disease, kidney disease, and acute infectious diseases, which are judged by the investigator to seriously endanger the safety of patients or affect the completion of the study;
   • Who are breastfeeding, pregnant, or planning to become pregnant during the study;
   • With known allergies to the therapeutic agents and penicillin used in the trial;
   • Mental or nervous system diseases or poor compliance.

Individual participant data that underlie the results will be shared after study completion and publication.Data will be de-identified to protect participant privacy.

Starting 6 months after the study publication, extending for 3 years.

Any investigator who submits a methodologically sound proposal will be granted access. The data will be de-identified individual participant data, and the purpose must be for scientific research.