LAUSR

Background: Interleukin-13 (IL-13) exhibits high affinity for the IL-13 decoy receptor (IL13Rα2) but retains binding to IL13α1, a component of the functional Type II IL4R complex (IL4Rα/IL13Rα1) that elicits a Th2 immune response. IL13Rα2 expression is limited in normal tissues but is highly overexpressed by various tumors including pancreatic, colorectal, glioblastomas, and prostate cancer. MDNA132 is an engineered IL-13 superkine with high specificity for IL13Rα2 and no binding to IL13Rα1 enabling targeted delivery of therapeutic immune modulators to the tumor microenvironment (TME). Herein, we characterize a long-acting version of MDNA132 and Bi-functional SuperKine ImmunoTherapies (BiSKITs) comprising fusion of MDNA132 with an IL-2 super-agonist or anti-PD1 antibody. Materials and Methods: MDNA132 fused to Fc scaffold (to improve half-life), MDNA109FEAA (‘beta’ only IL-2 super-agonist) or anti-PD1 were characterized by SPR and in vitro functional assays. IL2R activity was evaluated based on pSTAT5 signaling and anti-PD1 mediated blockade by a cell-based reporter assay. Flow cytometry studies were conducted to evaluate receptor internalization by cells expressing IL13Rα2. Localization of Fc-MDNA132 in IL13Rα2-expressing tumor bearing animals was determined by in vivo imaging system (IVIS). Results: Fc-MDNA132 does not bind to IL13Rα1 while exhibiting high affinity for both human and murine IL13Rα2. MDNA132 BiSKITs incorporating either IL-2 agonist (MDNA109FEAA-Fc-MDNA132) or anti-PD1 antibody (anti-PD1-MDNA132) maintained selective affinity towards their respective receptors (IL13Rα2, IL2Rβ and PD1). In reporter cell assays, MDNA109FEAA-Fc-MDNA132 showed increased potency of pSTAT5 stimulation relative to IL-2 (25-fold) and anti-PD1-MDNA132 reversed PD1/PDL1 blockade similar to parental anti-PD1 antibody. Receptor internalization studies showed that MDNA132/IL13Rα2 ligand-receptor complex is retained on cell surface indicating the potential to achieve durable exposure of the immune-modulatory payloads in the TME. IVIS analysis of athymic mice implanted contralaterally with IL13Rα2 positive (A375 or U87) and IL-13Rα2 negative (A549) tumors showed durable (>6 days) and selective localization of Fc-MDNA132 to IL13α2 expressing tumors following intravenous administration. In vivo studies are currently underway to establish the efficacy of MDNA132 BiSKITs. Conclusions: MDNA132 is an engineered IL13Rα2 selective superkine that accumulates in TME of IL13Rα2 expressing tumors in mice. MDNA109FEAA-Fc-MDNA132 and anti-PD1-MDNA132 retain their respective receptor binding profile, IL2R agonism and PD1/PDL1 blockade illustrating the versatility of MDNA132 BiSKIT platform for targeted delivery of a broad range of therapeutic and/or immune-modulatory agents to tumors overexpressing the IL13α2 decoy receptor. Citation Format: Aanchal Sharma, Hardeep Kataria, Fahar Merchant. Characterization of MDNA132, an IL-13 decoy receptor selective superkine for targeted delivery of immunotherapies to the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 708.