PRECISION MEDICINE FOR HEAD AND NECK CANCER Chemosensitivity guided therapy and emerging therapeutic agents

Head and neck squamous cell carcinoma (HNSCC) is the 6th common malignancy worldwide, and it is characterized by high recurrence and mortality rates. Despite advances in diagnosis and treatment, the five-year survival rate remains poor. Precision medicine approaches integrating functional assays, molecular profiling, and novel therapeutic agents represent a promising strategy to overcome treatment resistance and improve therapeutic decision-making. This thesis aimed to develop and evaluate an integrated precision-oncology framework for HNSCC combining functional chemosensitivity testing, transcriptomic profiling, and preclinical evaluation of bioactive compounds. Patient-derived tumor samples were used to establish primary cultures of bulk tumor cells and cancer stem cell (CSC)–enriched populations. For functional drug testing, biopsy specimens were divided into diagnostic and research samples. Primary cultures and CSC-enriched spheroids were generated using a rotating bioreactor and exposed to standard chemotherapeutic agents, with cell viability assessed to determine patient-specific drug sensitivity. Transcriptomic profiling was performed using bulk mRNA sequencing, followed by diNerential expression and pathway enrichment analyses to identify transcriptional programs associated with CSCs and therapeutic resistance. The therapeutic potential of two bioactive compounds was investigated. Polydatin was tested on HNSCC cells and healthy gingival cells to assess eNects on viability and oxidative stress. Benzyl Isothiocyanate (BITC) was evaluated as a chemosensitizing agent in therapy-resistant HNSCC cell lines treated with cisplatin and radiotherapy, with analyses of apoptosis, reactive oxygen species modulation, and mitochondrial function. Chemosensitivity assays revealed inter-patient variability within CSC populations. Transcriptomic analyses demonstrated diNerences between 2D and 3D cultures, with CSC- enriched models activating pathways related to stemness and aggressiveness. Polydatin selectively reduced tumor cell viability while sparing healthy cells, whereas BITC enhanced sensitivity to chemo-radiotherapy. Overall, these findings support the translational potential of precision medicine approaches for improving therapeutic eNicacy and reducing treatment- related toxicity in HNSCC.