Abstract A134: Predicting activity of IMM-1-104 as single agent and in combination for patients with RAS or RAF mutant tumors

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Abstract Introduction: Many tumors are addicted to MAPK pathway activation, including the >20% of human tumors with mutations in RAS or RAF1. IMM-1-104 is an oral once-daily treatment currently in Phase 1 in patients with RAS-mutant solid tumors [NCT05585320]. To date, drugs disrupting the MAPK pathway have done so chronically, leading to dose-limiting toxicities (DLTs) and poor response durability. In contrast, IMM-1-104 was designed to provide deep cyclic inhibition (DCI) of the MAPK pathway via a unique pharmacokinetic (PK) profile with high peak plasma drug levels and a near zero drug trough between doses. This promotes pulsatile inhibition of MEK, depriving tumors of sustained signaling of a critical oncogenic pathway while limiting toxicity and durability issues associated with chronic MEK inhibition. In Phase 1a dose escalation, no DLTs were observed, the plasma drug half-life was ~2-hours, and pharmacodynamic (PD) data were consistent with DCI. Phase 1b dose expansion is underway. Translational efforts are focused on identifying MAPK pathway addiction and sensitivity to IMM-1-104. Tumor models displaying patient-aligned genomic profiles against large patient databases such as AACR Project GENIE1 were tested in humanized 3D tumor growth assays (3D-TGA). Computational modeling based on response and in-house genomic data was used to inform identification of patient populations for IMM-1-104 monotherapy and potential combination opportunities. Experimental Procedures: Using cancer-specific, patient-aligned cell lines, IMM-1-104 activity was characterized in the 3D-TGA. Whole exome sequencing was performed to confirm alteration status, and a further subset subjected to RNA sequencing. Pharmacogenomic data were used to generate a model predictive of response to IMM-1-104 and identify biomarker-aligned patient subpopulations. Selected model predictions were then tested in subcutaneous tumor xenograft models in female BALB/c nude mice. Summary of New Data: Assessment of IMM-1-104 across >190 patient-aligned models demonstrated diverse responses across a wide range of MAPK-driven tumor types, including those with RAS or RAF mutations. In addition to RAS, these data suggested additional potential for IMM-1-104 in BRAF-mutant disease. Therefore, IMM-1-104 was tested alone and with encorafenib in the HT-29 colorectal BRAFV600E mutant xenograft model. Monotherapy with either encorafenib or IMM-1-104 displayed superior tumor growth inhibition to binimetinib. IMM-1-104 in combination with encorafenib drove deeper regressions and superior durability of response in a head-to-head in vivo comparison versus binimetinib plus encorafenib. Conclusions: We used an integrated platform of translational experiments and informatics to identify patient-aligned model systems, prioritize factors relevant for response to IMM-1-104’s unique DCI profile, and elucidate combination opportunities to potentially inform clinical development strategies. Citation Format: Praveen Nair, Sarah Kolitz, Jason Funt, Jan de Jong, Peter King, Amy Yamamura, Mai Johnson, Jenny Zhang, Kevin D Fowler, Anna Travesa, Amy Axel, Chris Walker, Scott Barrett, Benjamin J Zeskind, Brett Hall. Predicting activity of IMM-1-104 as single agent and in combination for patients with RAS or RAF mutant 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 A134.