Abstract A084: Establishment of KRAS G12C Mutant Brain Metastasis Models for Pre-clinical Evaluation of KRAS G12C Targeted Anti-Cancer Therapy

Abstract This study aimed to develop KRAS biochemical assay platform and evaluate the in vivo efficacy of the KRAS G12C inhibitor, AMG 510 (sotorasib) against non-small cell lung cancer (NSCLC) brain metastases, assess its ability to penetrate the blood-brain barrier, and establish validated orthotopic models to support future development and screening of KRAS-targeted therapies. Kirsten rat sarcoma (KRAS) has been long recognized as the most mutated protooncogene, present in ∼25% of tumors and KRAS mutations are frequent drivers in lung, colorectal and pancreatic cancer. Clinical research has shown that ∼14% of non-small cell lung cancers (NSCLCs) carry the KRAS G12C mutation. Patients with NSCLC and the KRAS G12C mutation have an increased risk of developing brain metastases (30%); with limited treatment options, the clinical outcome for these patients is poor. AMG 510 is a small-molecule inhibitor of KRAS G12C that specifically binds to inactive GDP-bound KRAS G12C, preventing its protooncogenic signaling. Sotorasib has been approved by the FDA for the treatment of NSCLC and recent clinical studies have demonstrated some activity of sotorasib against KRAS G12C NSCLC brain metastases. We have developed a comprehensive KRAS biochemical assay platform that includes GTP association assay, KRAS GTP/GAP/SOS1 activity assay, and KRAS-RAF / KRAS PI3K binding assays, facilitating fast and reproducible screening of new KRAS-targeted inhibitors. To evaluate the in vivo activity of AMG 510 for NSCLC brain metastasis treatment and gain insights for developing new KRAS-targeted inhibitors, we have also established technically challenging orthotopic models. The cell line used for inoculation was the NCI-H358-luc cell line; a non-small cell lung cancer cell line which harbors the KRAS G12C mutation. Models established include intracranial, intracarotid and intracardiac metastatic models, and each model was validated with AMG 510 as a single agent and/or combined with radiation, a common approach in brain tumor therapy. This approach aimed to investigate both the efficacy and the ability of AMG 510 to cross the blood-brain barrier (BBB) and target the KRAS G12C mutant tumor. Tumor growth and metastasis was measured using bioluminescence imaging (BLI) and all animal studies adhered to AAALAC guidelines and animal welfare regulations. Preliminary results suggest that AMG 510 can penetrate the blood-brain barrier and demonstrate therapeutic activity against KRAS G12C metastatic brain tumors as demonstrated using the intracarotid and intracardiac models that leave the blood-brain barrier intact. Furthermore, using the intracranial model, we demonstrated that the combination of AMG 510 with radiation increased efficacy compared to radiation alone. The in vivo models represent powerful tools for clinically relevant assessment of the efficacy of KRAS G12C inhibitors. The in vivo and in vitro models can also be expanded for research on other KRAS mutations associated with brain metastases or new inhibitor development. Citation Format: Takashi Willebrand, Amanda Miles, Yinfei Yin, Guilan Wang, Min Liu, Zichun Wang, Yuzhou Xu, Qikuan Chen, Yinfei Yin. Establishment of KRAS G12C Mutant Brain Metastasis Models for Pre-clinical Evaluation of KRAS G12C Targeted Anti-Cancer Therapy [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr A084.