Bernardo, S. | bioRxiv Science

bioRxiv2025

Genetic mechanisms of resistance to targeted KRAS inhibition

KRAS mutations are among the most prevalent oncogenic drivers in non-small cell lung cancer (NSCLC), yet the mechanisms of therapeutic resistance to KRAS inhibitors in these cancers remains poorly understood. Here, we deploy high-throughput CRISPR base editing screens to systematically map resistance mutations to three mechanistically distinct KRAS-targeted therapies, including KRAS-G12C(OFF) inhibitor (adagrasib), RAS(ON) G12C-selective tri-complex inhibitor (RMC-4998), and RAS(ON) multi-selective tri-complex inhibitor (RMC-7977). Using both a saturation Kras tiling approach and cancer-associated mutation library, we identify common and compound-selective second-site resistance mutations in Kras, as well as gain-of-function and loss-of-function variants across cancer-associated genes that rewire signaling networks in a context-dependent manner. Notably, we identify a recurrent missense mutation in capicua (Cic), that promotes resistance to RMC-7977 in vitro and in vivo. Moreover, we show that targeting NF{kappa}B signaling in CIC-mutant cells can resensitize them to RAS pathway inhibition and overcome resistance.

cancer biology↗

bioRxiv2024

MDM2 stabilization of Notch intracellular domain upon DNA damage plays a major role in non-small cell lung carcinoma response to platinum chemotherapy

Despite major advances in lung cancer clinical management, majority of patients suffering non-small cell lung carcinoma (NSCLC) are treated in first line with platinum in combination with immune checkpoint inhibitors. Although platinum compounds normally display an initial therapeutic effect, relapse constitutes a major challenge in the clinical management of NSCLC patients. Therefore, it is fundamental to understand the relapse underlying mechanisms to find new therapeutic opportunities to improve patients survival. Here, we found that different DNA damage inducers increase the protein levels of Notch Intracellular Domain (NICD), i.e., the active form of NOTCH1. Mechanistically, we unveiled that upon platinum treatment, there was a concomitant increase of MDM2 together with NICD, and we also observed an MDM2-mediated ubiquitination and stabilization of NICD. Of note, using patient-derived xenografts displaying intrinsic carboplatin resistance, we demonstrated that the combination of carboplatin with MDM2 and NICD inhibitors increased survival and reduced tumor growth compared with carboplatin in monotherapy. Moreover, in patients with NSCLC who received platinum chemotherapy, MDM2 expression level in the tumor was correlated with poor progression-free survival, further validating MDM2 key role in the response to platinum compounds. Our findings open a therapeutic opportunity for NSCLC patients, the main lung cancer subtype of the leading cause of death by cancer worldwide.

cancer biology↗