Intraperitoneal administration of carcinoembryonic antigen-directed CAR-T cells is a robust delivery route for effective treatment of peritoneal carcinomatosis from colorectal cancer

Abstract Background: Peritoneal carcinomatosis from colorectal cancer is a highly challenging disease to treat, and as such constitutes a pressing issue in medicine. Adoptive transfer of chimeric antigen receptor-T (CAR-T) cells has shown impressive efficacy in hematologic malignancies, though the approach has been less effective in solid tumors when delivered via intravenous (i.v.) routes. We explored whether intraperitoneal administration of CAR-T cells could provide an effective and robust route for treatment of peritoneal carcinomatosis from colorectal cancer. Methods: To generate carcinoembryonic antigen (CEA)-specific CAR-T cells, we constructed a lentiviral transfer plasmid encoding a second-generation CAR composed of the single-chain variable fragment (scFv) from BW431/26, the CD8 alpha hinge region, 4-1BB co-stimulatory domain, and the CD3zeta T cell activation domain. We established various animal models of peritoneal carcinomatosis with intraperitoneal (i.p.) and extraperitoneal metastasis. Tumor-bearing animals were treated by i.p. or i.v. administration of CEA CAR-T cells. Treatment efficacy was evaluated and kinetic expansion and tissue distribution of CAR-T cells were studied. Results: CEA-directed CAR-T cells showed high tumor cell cytotoxicity in vitro. Intraperitoneally administered CAR-T cells exhibited superior antitumor activity compared to systemic i.v. cell infusion in an animal model of peritoneal carcinomatosis. In addition, i.p. administration conferred a durable effect and protection against tumor recurrence and exerted strong antitumor activity in an animal model of peritoneal carcinomatosis with metastasis in intraperitoneal or extraperitoneal organs. Our data further indicate that when compared to systemic delivery, i.p. transfer of CAR-T cells could provide increased antitumor activity in extraperitoneal tumors without PC. This phenomenon was further confirmed in an animal model of pancreatic carcinoma after intraperitoneal administration of our newly constructed prostate stem cell antigen (PSCA)-directed CAR-T cells. On a mechanistic level, our data evidenced rapid and high CAR-T cell expansion and high persistence in peripheral blood following i.p. cell administration. Conclusions: Intraperitoneal administration of CAR-T cells could be an effective and robust route for therapy of peritoneal carcinomatosis with metastasis in intra- and extraperitoneal organs. These findings hold great promise for CAR-T cell therapy in patients with peritoneal carcinomatosis.