Intratumoral administration of the alpha-Gal glycolipid AGI-134 to induce tumor regression in a mouse model of melanoma.

Abstract

68 Background: AGI-134 is a fully synthetic alpha-Gal glycolipid for intratumoral (i.t.) treatment of solid tumors to induce a patient-specific anti-tumor immune response. AGI-134 recruits pre-existing anti-Gal antibodies to the injected lesion, leading to complement activation and enhanced tumor antigen processing. Using the B16.F10 murine melanoma model, we have previously demonstrated that AGI-134 evokes a robust abscopal anti-tumor effect, with treatment of a primary lesion protecting mice from the growth of distant lesions. In the current study, we investigated the response of injected tumors to AGI-134 administration. Methods: Tumors were induced by s.c. injection of B16.F10 or ovalbumin expressing B16 (B16.OVA) cells into the flank of α1,3galactosyltransferase knock out mice. After reaching a treatable size, the tumors were injected twice, 24 hrs apart, with PBS or 1-1.25 mg AGI-134, and tumor growth monitored for up to 32 days. In addition, to measure the activation of complement after treatment with AGI-134, tumors were processed 2 hours after treatment and the i.t. concentration of complement fragment C5a determined by ELISA. Results: Almost 50% of AGI-134-treated B16.F10 tumors fully regressed vs. 24% in the PBS controls. Moreover, AGI-134 treatment had a significant survival benefit, with 23% of AGI-134-treated mice dying or requiring euthanisia due to tumor mass by Day 27 post treatment vs. 43% in the PBS groups (p < 0.05, Mantel-Cox test). In the B16.OVA model, 67% of the AGI-134 treated tumors fully regressed vs. 0% in PBS-treated mice in two independent assays. Comparison of C5a levels in B16.F10 tumors 2 hrs after AGI-134 or PBS treatment demonstrated that AGI-134 induced significant complement activation within injected tumors. Conclusions: Having previously shown that AGI-134 induces an abscopal effect that protects mice from the development of secondary tumors, we now show that AGI-134 also induces regression of injected tumors: AGI-134-treatment induces the activation of complement within the tumor and leads to complete regression of the tumor in significantly more AGI-134-treated mice than PBS-treated. Clinical trials with AGI-134 are planned for 2018.