Abstract 365: Intratumoral delivery of aluminum hydroxide-tethered IL-12 induces potent anti-tumor immune response
Authors: Battula Sailaja , Papastoitsis Gregory , Kaufman Howard L. , Irvine Darrell J. , Wittrup K. Dane , Schmidt Michael M. 
Published: June 2022

Abstract
IL-12 is a potent cytokine that mediates anti-tumor immune response, but its clinical development has been hindered by systemic toxicity. Intratumoral (IT) delivery can improve the therapeutic window of cytokine drugs, but is in turn limited by rapid clearance of injected drug from the tumor which reduces efficacy, necessitates frequent administration, and increases systemic accumulation. Ankyra has developed a novel IT drug delivery platform for stable linking of engineered cytokines and other immune agonists to an aluminum hydroxide (Alhydrogel®) scaffold. Here, we describe the therapeutic and immune effects of Ankyra’s intratumoral IL-12 using relevant in vitro and in vivo murine models. Single-chain human IL-12 was genetically fused at its c-terminus to a proprietary, phosphorylated alum-binding peptide (IL-12-ABP) that forms a high affinity complex with Alhydrogel®. Human IL-12-ABP proteins were mixed with a 10-fold mass excess of Alhydrogel® to form the therapeutic complex, ANK-101. Since human IL-12 is not active in mice, a surrogate complex containing the mouse IL-12 sequence (mANK-101) was also generated. The functional potency of ANK-101 and mANK-101 was assessed in multiple cellular assays in comparison to their respective unmodified IL-12 controls. The therapeutic efficacy of mANK-101 was evaluated in syngeneic mouse tumor models including MC38, CT26, 4T1, and B16F10. The intratumoral retention of mANK-101 after a single IT dose was analyzed by IVIS imaging studies, and immune profiling of tumors was carried out by flow cytometry. Statistical analyses were done using Student’s t-test for comparison between groups and Kaplan-Meier method for survival. ANK-101 complexes retained IL-12 activity as demonstrated by concentration dependent increases in IFNγ production by anti-CD3 stimulated peripheral blood mononuclear cells. IVIS studies conducted in tumor bearing mice showed that the labeled mANK-101 complexes were retained in the tumor for &gt;21 days while free mIL-12-ABP protein was cleared in &lt;24 hours. One or two doses of IT administered mANK-101 induced tumor regressions in diverse syngeneic tumor models, including complete responses either alone or in combination with approved checkpoint blockers targeting PD-1 or CTLA-4 and other immunotherapies. Efficacious doses were well tolerated in mice with no significant weightloss compared to vehicle treated animals. Immune profiling of tumors 7 days post treatment showed an increased intratumoral CD8+/Treg ratio, and prolonged myeloid cell activation. In addition, IHC analysis of residual tumors post treatment showed increased infiltration of CD8+ T cells. In conclusion, Ankyra’s platform is a novel approach that expands the therapeutic window of IL-12, which will be tested in a phase I clinical trial and the platform has potential to extend the therapeutic effectiveness of other IT administered immunomodulatory drugs.
Citation Format: Sailaja Battula, Gregory Papastoitsis, Howard L. Kaufman, Darrell J. Irvine, K. Dane Wittrup, Michael M. Schmidt. Intratumoral delivery of aluminum hydroxide-tethered IL-12 induces potent anti-tumor immune response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 365.