Therapeutic effects of boronate ester cross-linked injectable hydrogels for the treatment of hepatocellular carcinoma.

Hepatocellular carcinoma is the most common malignancy with a high incidence rate and is the leading cause of cancer-related deaths. Herein, we developed a thermo-responsive hydrogel comprising poly(ε-caprolactone--lactide)--poly(ethylene glycol)--poly(ε-caprolactone--lactide (PCLA) that exhibits acidity-accelerated delivery of the tumor-targeting glucuronic acid-bearing doxorubicin (DOX-pH-GA) conjugate into tumor tissues. The PCLA copolymer was post-modified with boronic acid (BA-PCLA) to covalently cross-link with the pH-responsive DOX-pH-GA conjugate. The BA-PCLA copolymer effectively coordinated with the DOX-pH-GA conjugate through the boronate ester formation and showed a lower critical gelation temperature. The DOX conjugated boronate ester exhibited a sustained release . Subcutaneous administration of PCLA copolymers formed gels in the subcutaneous layers of Sprague-Dawley rats and degraded after 6 weeks. Similarly, BA-PCLA copolymers coordinated with DOX-pH-GA formed a stable gel . imaging studies demonstrated that DOX-pH-GA was released in a sustained manner. The anti-tumor activity of the DOX releasing injectable hydrogel was examined using a HepG2 liver cancer xenograft model. The antitumor effect demonstrated that the DOX releasing hydrogel depot remarkably suppresses the tumor growth. These results demonstrate that the pH-responsive DOX releasing thermo-responsive hydrogel depot has great potential for application in localized anticancer therapy.