Abstract P240: Benchmarking the novel dual-MEK inhibitor, IMM-1-104, head-to-head and in combination with sotorasib (AMG-510) in the MIA PaCa-2 (KRAS-G12C) pancreatic cancer xenograft model
Authors: King Peter J. , Axel Amy E. , Fowler Kevin D. , Kolitz Sarah E. , Barrett Scott , Zeskind Benjamin J. , Hall Brett M. 
Published: December 2021

Abstract
Background: Approximately 9 out of 10 patients diagnosed with pancreatic cancer have tumors driven by a single activating mutation in KRAS. These tumors remain unaddressable by current therapies and collectively represent a high unmet clinical need. KRAS is the most commonly mutated form of RAS and represents approximately 85% of all RAS mutant human tumors with HRAS and NRAS accounting for the remaining 15%. Sotorasib (AMG-510), a covalent KRAS-G12C inhibitor, recently received accelerated regulatory approval for KRAS-G12C lung cancer in the United States. While the G12C mutation has been documented in up to 15% of all KRAS mutant tumors, it is rarely observed (&lt;1%) in human pancreatic cancer, which could severely limit this type of new inhibitor in certain histologies. IMM-1-104 is a novel dual-MEK inhibitor that resists CRAF-bypass (goal: improve activity against RAS mutant tumors), and is designed to have a short plasma drug half-life, which leads to deep, cyclic inhibition of the MAPK pathway (goal: improved tolerability). Materials & Methods: The novel, orally bioavailable dual-MEK inhibitor, IMM-1-104, was evaluated for antitumor activity, as a single agent (50, 100, 150 mg/kg BID p.o.) in a head-to-head format against sotorasib (10, 30, 100 mg/kg QD p.o.) or in combination (50, 100, 150 mg/kg BID p.o. IMM-1-104 with 30 mg/kg QD p.o. sotorasib) in the MIA PaCa-2 KRAS-G12C mutant pancreatic tumor xenograft model. Tumor-bearing animals were treated for 21 days of oral dosing, before drug treatments were terminated and animals monitored for additional 3 weeks. Results: IMM-1-104 and sotorasib were well-tolerated as single agents and in combination with each other across all dose levels tested. Both drugs demonstrated dose-dependent antitumor activity with tumor regressions noted at higher dose levels. IMM-1-104 in combination with sotorasib produced deep regressions that were sustained longer than either drug alone. Conclusions: The dual-MEK mechanism and short half-life of IMM-1-104 has demonstrated broad activity with low toxicity across multiple RAS and RAF mutant preclinical tumor models. Tumor regressions were observed in NRAS mutant melanoma (SK-MEL-2) and KRAS mutant colorectal (Colon-26) rodent tumor models, and tumor stasis was observed in KRAS mutant lung (A549) and BRAF mutant melanoma (A375) tumor xenograft models. Here, we report that IMM-1-104 treatment resulted in tumor regressions similar to that observed for sotorasib in the recently benchmarked KRAS-G12C mutant pancreatic cancer xenograft model (MIA PaCa-2). IMM-1-104 in combination with sotorasib promoted deep, durable tumor regressions, when compared to either drug alone. Therefore, future drug-drug combinations with upstream inhibitors such as sotorasib may afford greater durability in combination for patients with KRAS-G12C and other select tumor types. In totality, these data suggest the potential for broad, single agent activity of IMM-1-104 in tumors with inappropriately elevated MAPK signaling, including a large percentage of KRAS mutant pancreatic cancer.
Citation Format: Peter J. King, Amy E. Axel, Kevin D. Fowler, Sarah E. Kolitz, Scott Barrett, Benjamin J. Zeskind, Brett M. Hall. Benchmarking the novel dual-MEK inhibitor, IMM-1-104, head-to-head and in combination with sotorasib (AMG-510) in the MIA PaCa-2 (KRAS-G12C) pancreatic cancer xenograft model [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P240.