Loco-regional radiosensitizing nanoparticles-in-gel augments head and neck cancer chemoradiotherapy.

The therapeutic gain in loco-regionally advanced unresectable head and neck squamous cell carcinoma (HNSCC) is limited with the traditional use of concurrent chemoradiotherapy (CRT) owing to dose-limiting toxicities of systemic clinical radiosensitizers. Delivery through regional platforms is challenging due to limited drug permeation but allows spatio-temporal control of combinatorial regimens locally to overcome drug resistance. We address these challenges by developing biodegradable gellan- and lipid-based dual nanocarriers-in-ion-triggered porous mucoadhesive hydrogels for enhanced site-specific delivery of clinically relevant radiosensitizers i.e. cisplatin and paclitaxel. Interestingly, the nanoparticle-in-gel prolonged the tumor bioaccumulation of both the chemotherapeutic drugs with reduced systemic absorption, thereby improving in vivo efficacy which was confirmed by PET-CT imaging and safety as compared to systemic commercial formulations approved for HNSCC chemoradiotherapy. The nanoparticles facilitated intracellular radiosensitizer uptake and cell arrest to synergistically enhance radiation-induced DNA nicks and apoptosis. Our findings suggest the clinical potential of the present platform in the loco-regional management of HNSCC requiring curative CRT.