Collin M. Blakely

Epidermal growth factor receptor (EGFR)–mutant lung adenocarcinomas (LUAD) harbor a complex landscape of genetic co-alterations and potential oncogenic interactions. Among them are recurrent amplifications of the cell cycle regulatory genes CDK4 and CDK6, which have been clinically implicated in resistance to EGFR tyrosine kinase inhibitors (TKIs). However, the mechanisms by which CDK4/6 upregulation promotes therapy resistance remain poorly defined. Here, we demonstrate that CDK4 or CDK6 overexpression limits EGFR inhibitor-induced proliferative arrest, promoting continued cell cycle progression. This is accompanied by elevated replication stress, increased TPX2 expression, DNA damage leading to ATM activation, and ultimately genomic instability. Integrative transcriptomic and copy number analyses of EGFR-mutant LUAD tumors from both patients and preclinical models revealed that CDK4 or CDK6 amplification is associated with the upregulation of genes linked to tumor progression, including AGR2, ASNS, and STEAP1. CDK4 amplification was also highly correlated with gene expression changes associated with epithelial-to-mesenchymal transition (EMT) in a single-cell RNA sequencing dataset from patient biopsies. In preclinical models, co-treatment with CDK4/6 and EGFR inhibitors restored proliferative arrest, induced tumor cell apoptosis, and reduced replication stress, DNA damage, and genomic instability. Our findings uncover a mechanistic basis for EGFR inhibitor resistance of CDK4 and CDK6 amplified EGFR-mutant LUAD. They also provide a rationale for the biomarker-driven clinical development of combination EGFR and CDK4/6-targeted therapies for the treatment of a subset of EGFR-mutant LUAD patients.

Introduction: MET tyrosine kinase (TKI) therapy has improved outcomes in patients with non-small cell lung cancer (NSCLC) harboring MET alterations. However, primary and acquired resistance ultimately limits durability of response. This study evaluated the safety and efficacy of the MET inhibitor capmatinib with the MEK inhibitor trametinib in patients with metastatic MET-driven NSCLC who had progressed on prior treatment with at least one MET inhibitor. Methods: A multicenter phase I study evaluated capmatinib in combination with trametinib in patients with advanced stage NSCLC harboring activating MET alterations and prior exposure to at least one MET TKI. A 3+3 dose-escalation design was employed to assess safety and tolerability of the combination. Results: Three patients (n = 3) were enrolled in the study and completed a median of 3 cycles of therapy. Dose-limiting toxicities, including rash, edema, and nausea, necessitated dose reductions in the first two patients and initiation of the third patient at a lower dose level. Ultimately, all patients discontinued therapy due to treatment-related adverse events. The study was terminated early due to poor accrual and TRAEs. No radiographic objective responses were observed. Conclusions: In this phase I trial, capmatinib plus trametinib was associated with significant treatment-related adverse events and treatment was discontinued in all participants. Based on these findings, further investigation of this combination of MET and MEK inhibitors is not recommended.

Progression-free survival (left) and overall survival (right) according to co-mutation status for (A) CHEK2 and (B) ATRX in the overall mutation-evaluable population.

Integrated model for patient stratification and clinical outcome prediction with KRAS G12Ci monotherapy in KRASG12C-mutant NSCLC.

A) Venn diagram depicting co-mutation overlap between KEAP1, SMARCA4, and CDKN2A – KSC genes; survival outcomes according to co-mutation overlap in any of the KSC genes - PFS (B) and OS (C). Only patients whose tumor was profiled with a NGS panel providing coverage for all 3 genes were included in this analysis.

Survival outcomes according to KEAP1 (A), SMARCA4 (B), and CDKN2A (C) co-mutation status in Cohorts A and B.

Baseline Patient Characteristics – Cohort B

Clinical outcomes in Cohorts A (left) and B (right). A) progression-free survival; B) overall survival.

Survival outcomes according to KEAP1 and STK11 co-mutation status: A) Cohort A; B) Cohort B; C) further subclassifying KEAP1MUT tumors according to STK11 mutation status; D) PFS and OS according to STK11 co-mutation status in KSCWT tumors in the overall study cohort.

Baseline Patient Characteristics – Cohort A