Akkermansia Muciniphila (AKK) for Radiation-Induced Skin Injury

Inclusion Criteria: * Diagnosis of breast cancer, head and neck cancer (including nasopharyngeal carcinoma) receiving radiotherapy * Age ≥18 years and ≤75 years, any sex * Signed written informed consent * Radiation field skin area can be localized and skin inflammation can be assessed * ECOG performance status 0-1, life expectancy ≥3 months * Adequate major organ function * Fertile patients (both sexes) must use effective medical contraception during the study and for 6 months after the last dose * Willing to comply with follow-up and skin image collection Exclusion Criteria: * Cognitive impairment preventing understanding of the study * Use of antibiotics or antifungals within 1 month * Previous treatment with other bacterial preparations * Participation in other bacterial therapy trials * Any abnormality (e.g., scar, tattoo) in the radiation field that would interfere with assessment * Allergy to probiotics or any component of the study preparation; history of severe allergic reactions (e.g., anaphylaxis, angioedema, respiratory distress, allergic purpura, Arthus reaction) * Use of immunosuppressive drugs * Symptomatic or rapidly progressive central nervous system metastases, extensive lung metastases causing dyspnea, tumor invading major vessels or nerves * Poorly controlled cardiac disease (NYHA class ≥2 heart failure, unstable angina, myocardial infarction within 1 year, clinically significant arrhythmia requiring treatment) * Pregnancy or breastfeeding * Active tuberculosis, bacterial or fungal infection (grade ≥2 per CTCAE), or HIV infection * Substance abuse or psychiatric disorder * Active autoimmune disease or history thereof (exceptions: vitiligo, childhood asthma fully resolved with no intervention in adulthood) * History of alcohol or drug abuse * Planned pregnancy from screening until 12 months after last treatment * Any concomitant condition that, in the investigator's judgment, would compromise patient safety or study completion * Any other condition deemed unsuitable for enrollment by the investigator * Inability to provide written informed consent