Abstract 421: Targeting WEE1 enhances the antitumor effect of <i>KRAS</i> mutated non-small cell lung cancer harboring <i>TP53</i> mutations

Abstract While KRAS-G12C inhibitors are clinically approved, the efficacy of sotorasib alone remains limited due to challenges such as co-mutations, intrinsic resistance, and acquired resistance. Overcoming these barriers requires innovative strategies to enhance apoptosis in KRAS-mutant non-small cell lung cancer (NSCLC). To identify genes whose loss induces apoptosis in KRAS-mutant NSCLC, we performed a CRISPR-knockout screen using a crRNA library targeting 746 protein kinase genes. This high-throughput approach identified WEE1 as a critical kinase whose inhibition significantly enhances apoptosis. Drug screening with a custom library of 432 kinase inhibitors also validated WEE1, CHK1, and CDK inhibitors as effective, with WEE1 emerging as the most potent target, particularly in TP53-mutant cells. WEE1’s primary role is to prevent cells with damaged DNA from entering mitosis by regulating the cell cycle through DNA damage checkpoints. Mechanistic analyses revealed that WEE1 inhibition accelerates the G2/M transition and markedly reduces the expression of CHK2 and Rad51, two critical regulators of the DNA damage response (DDR) pathway. This indicates that WEE1 operates upstream of the DDR pathway, playing a crucial role in DNA repair and cell cycle regulation in KRAS-mutant NSCLC cells. To further evaluate therapeutic potential, we investigated the combined effects of sotorasib and WEE1 inhibitors. Combined treatment significantly suppressed cell viability and enhanced c-caspase-3/7 activity in both sotorasib-sensitive and sotorasib-resistant cells. Multidimensional two-drug synergy assays revealed Bliss scores of 11.105 for H358 (sotorasib-sensitive) and 11.226 for H2122 (sotorasib-resistant) cells, indicating a potent synergistic effect across different resistance profiles. In patient-derived xenograft (PDX) models established from a patient with KRAS-G12C mutation and primary resistance to sotorasib, the combination of sotorasib and the WEE1 inhibitor, ZN-c3, resulted in near-complete tumor regression. This effect was consistently observed across four in vivo models, highlighting the translational potential of this combination therapy. Our findings highlight WEE1 inhibition as a promising therapeutic strategy for KRAS-mutant NSCLC with TP53 mutations. This approach provides a foundation for future clinical investigations to overcome initial resistance to KRAS-G12C inhibitors and improve outcomes for patients with KRAS-mutant NSCLC. Citation Format: Koji Fukuda, Shinji Takeuchi, Shigeki Sato, Sachiko Arai, Shigeki Nanjo, Hiroaki Taniguchi, Seiji Yano. Targeting WEE1 enhances the antitumor effect of KRAS mutated non-small cell lung cancer harboring TP53 mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 421.