Intratumoral Injectable Click-Crosslinked Hyaluronic Acid Depot for Sustained Gemcitabine Delivery

Gemcitabine (GE) is a widely used chemotherapeutic agent for solid tumors; however, its therapeutic efficacy is often compromised by rapid diffusion from the tumor site and insufficient intratumoral retention following local administration. Injectable hydrogel-based drug depots offer a promising strategy to prolong local drug availability and enhance antitumor efficacy while minimizing systemic toxicity.

An intratumoral injectable, gemcitabine-loaded, click-crosslinked hyaluronic acid hydrogel (GE + Cx-HA) was developed using a bioorthogonal click reaction to enable rapid in situ gelation. Physicochemical properties, gelation behavior, viscoelasticity, and injectability through a fine-gauge needle were characterized. In vitro gemcitabine release profiles and anticancer activity against B16F10 melanoma cells were evaluated. Antitumor efficacy, angiogenesis inhibition, and systemic toxicity were assessed in a murine melanoma model following a single intratumoral injection.

GE + Cx-HA remained in a low-viscosity solution state prior to injection and rapidly formed a stable hydrogel depot upon click crosslinking without needle clogging. The crosslinked network significantly suppressed burst release and enabled sustained gemcitabine release in vitro. Compared with free gemcitabine, GE + Cx-HA exhibited prolonged anticancer activity against B16F10 melanoma cells. In vivo, a single intratumoral administration of GE + Cx-HA markedly inhibited tumor growth and angiogenesis for up to 18 days, without observable systemic toxicity.

These results demonstrate that GE + Cx-HA functions as an effective intratumoral drug depot, providing sustained local chemotherapy and enhanced antitumor efficacy, highlighting its potential as a localized therapeutic platform for solid tumor treatment.