Abstract IA011: Engineered IL-12 delivery to the tumor matrix to achieve enhanced efficacy and safety in multiple advanced tumors
Authors: Ishihara Jun 
Published: December 2023

Background. Our goal is to create an effective and novel immunotherapy against multiple solid tumors with minimal toxicity. IL-12 is an “ideal” immune-activator, capable of activating both innate and acquired immune response. We tested more than 20 reported pro-inflammatory cytokines, and found IL-12 shows the most potent anti-tumor activity. Peripheral toxicity limits the use of systemic IL-12 therapy in the clinic. We have hypothesized that the tumor-specific drug delivery system would improve IL-12 immunotherapies. We took original approaches of protein engineering.

Methods. We developed technologies to turn the tumor collagen into a drug reservoir after intravenous injections. The recombinant fusion of IL-12 to a collagen binding domain (CBD) derived from the VWF A3 domain allows for targeted IL-12 delivery into the tumor stroma. Here, we evaluated the pharmacology, safety, efficacy and the effects of CBD-IL-12 to the tumor microenvironment.

Results. Intravenously-injected CBD proteins preferentially localized to the tumor, but not in other organs in mice. Single intravenous injection of CBD-IL-12 (recombinant fusion protein) eradicated most EMT6 breast cold tumors. CBD-IL-12-treated mice that were tumor-free developed systemic immunological memory, as 12 mice out of 13 rejected rechallenge with the breast tumor cells in their contralateral mammary fat pad. Single intravenous injection of CBD-IL-12 induced 67% complete remission of established B16F10 tumors. CBD fusion to IL-12 reduced the systemic toxicity, such as 50% reduction of hepatotoxicity markers and cytokine storm. CBD-IL-12 treatment increased intratumoral cytokine and immune cell numbers. In short, this tumor collagen-targeting approach improves both safety and efficacy of IL-12. We showed that the CBD can target multiple solid tumor types, because the CBD exploits the abnormality of tumor vasculature-specific pathological structure (e.g. leakiness and exposure of collagen to the bloodstream). So far, we have shown that CBD-IL-12 has significant anti-tumor efficacy in breast, lung, ovarian, liver, colon, prostate, melanoma, head and neck, pancreatic cancers and melanoma, sarcoma, and glioblastoma in syngeneic mouse models. CBD-IL-12 is effective in cold, advanced, spontaneous tumors, low-mutation burden tumors, and prevents metastasis and recurrence. CBD-IL-12 stimulated antigen-presenting cells and T cells. Also, humanized mice treated with humanized CBD-IL-12 show great anti-tumor effects in patient-derived lung and ovarian tumors. Humanized CBD-IL-12 was tested in dogs, and showed great tolerability at the therapeutic dose. Human CBD-IL-12 molecule was successfully manufactured in a clinical-grade.

Conclusions. Intravenously injected CBD–IL-12 is effective to multiple difficult, immunologically cold tumors with low mutation burdens. Collagen is an attractive target because abnormally high expression of collagen is a shared nature of tumors, regardless of tumor types and patients. VWF A3 domain naturally exists in our body, minimizing the risk of immunogenicity.

Citation Format: Jun Ishihara. Engineered IL-12 delivery to the tumor matrix to achieve enhanced efficacy and safety in multiple advanced tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr IA011.