Treatment of Post-radiation Xerostomia With Allogeneic Mesenchymal Stromal Stem Cells

Inclusion Criteria: * squamous cell carcinoma of the oropharynx, Union for International Cancer Control TNM Classification of Malignant Tumors )8th ed.) clinical stage T1-2N+ or cT3-4cN0-3 M0, treated with curative intent radiotherapy (tumor dose 66-70 Gy, bilateral neck irradiation) with or without concurrent chemotherapy * 2 years or more post-treatment without signs of locoregional recurrence or systemic metastasis * non-smoker or former smoker (quit smoking ≥2 years ago) * mean radiation dose \>26 Gy to each of the parotid glands and \>35 Gy to each of the submandibular glands * xerostomia of grade 2 or 3, assessed according to the CTCAE v5.0 scale * Clinically reduced salivary flow and hyposalivation (unstimulated whole saliva flow rate 0.05-0.20 ml/min) * age between 18-75 years * both sexes * signed "Informed Consent Form" for participation in the study Exclusion Criteria: * newly diagnosed malignancy anywhere in the body within the past two years * active smoker * use of medications with potential to cause dry mouth (e.g., tricyclic antidepressants, antipsychotics, decongestants, bronchodilators, antihypertensives like beta-blockers and diuretics, antihistamines, hypnotic sedatives, opioids, and muscle relaxants) * other salivary gland diseases (e.g., Sjögren's syndrome, scleroderma, sialolithiasis, etc.) * patients on anticoagulant therapy that cannot be discontinued during the intervention * pregnancy or planned pregnancy within the next two years * breastfeeding…