In situ gel-forming dual drug delivery system for synergistic combination therapy of colorectal peritoneal carcinomatosis

Abstract

Colorectal peritoneal carcinomatosis (CRPC) is a common form of systemic metastasis of intra-abdominal cancers, occurring in as many as 50% of colon cancer patients, and is associated with a poor prognosis. For the treatment of CRPC, cytoreductive surgery alone is inadequate at the microscopic level, and systemic chemotherapy has a limited effect due to the peritoneal-plasma barrier. Intraperitoneal chemotherapy is logically proposed early after surgery to treat the residual small and microscopic tumors. Traditional chemotherapy is typically infused intravenously. However, intraperitoneal chemotherapy allows direct contact of anti-cancer agents with tumor cells, which could improve tumor regression efficacy and minimize systemic toxicity. Furthermore, injectable and thermosensitive polymer hydrogels have shown promising applications as controlled drug delivery systems for in situ chemotherapy. In this study, a biodegradable thermogelling block copolymer poly(L-lactide acid)–Pluronic L35–poly(L-lactide acid) (PLLA–L35–PLLA) was synthesized to fabricate a novel local drug delivery system (DOC-M/OXA-H) composed of docetaxel loaded micelles (DOC-M) and an oxaliplatin loaded hydrogel (OXA-H). DOC, a widely used anticancer drug with extremely high hydrophobicity, was loaded into the biodegradable copolymer micelles by the membrane dialysis method without using any surfactants or excipients. And DOC-M was encapsulated in OXA-H to achieve the aim of synergistic combination therapy with significantly high efficacy and good patient compliance. As a result, DOC-M/OXA-H was an injectable flowing sol at ambient temperature and became a solid-like gel at physiological temperature without any crosslinking agent. Meanwhile, DOC-M/OXA-H demonstrated a slow and sustained drug release profile and the combination therapy of DOC and OXA exhibited quite potent cytotoxicity in vitro. Furthermore, an in vivo antitumor test with CRPC-bearing mice suggested that DOC-M/OXA-H was more competent for suppressing tumor growth and prolonging survival time by inhibiting tumor cell proliferation and angiogenesis and increasing apoptosis of tumor cells. Overall, our data suggested that DOC-M/OXA-H may be potentially useful in the treatment of CRPC.