KEAP1 mutation in lung adenocarcinoma promotes immune evasion and immunotherapy resistance

Summary: Lung cancer treatment has benefited greatly through advancements in immunotherapies. However, immunotherapy often fails in patients with specific mutations like KEAP1, which are frequently found in lung adenocarcinoma. We established an antigenic lung cancer model and used it to explore how Keap1 mutations remodel the tumor immune microenvironment. Using single-cell technology and depletion studies, we demonstrate that Keap1-mutant tumors diminish dendritic cell and T cell responses driving immunotherapy resistance. This observation was corroborated in patient samples. CRISPR-Cas9-mediated gene targeting revealed that hyperactivation of the NRF2 antioxidant pathway is responsible for diminished immune responses in Keap1-mutant tumors. Importantly, we demonstrate that combining glutaminase inhibition with immune checkpoint blockade can reverse immunosuppression, making Keap1-mutant tumors susceptible to immunotherapy. Our study provides new insight into the role of KEAP1 mutations in immune evasion, paving the way for novel immune-based therapeutic strategies for KEAP1-mutant cancers

Rlf–Mycl Gene Fusion Drives Tumorigenesis and Metastasis in a Mouse Model of Small Cell Lung Cancer

Abstract Small cell lung cancer (SCLC) has limited therapeutic options and an exceptionally poor prognosis. Understanding the oncogenic drivers of SCLC may help define novel therapeutic targets. Recurrent genomic rearrangements have been identified in SCLC, most notably an in-frame gene fusion between RLF and MYCL found in up to 7% of the predominant ASCL1-expressing subtype. To explore the role of this fusion in oncogenesis and tumor progression, we used CRISPR/Cas9 somatic editing to generate a Rlf–Mycl-driven mouse model of SCLC. RLF–MYCL fusion accelerated transformation and proliferation of murine SCLC and increased metastatic dissemination and the diversity of metastatic sites. Tumors from the RLF–MYCL genetically engineered mouse model displayed gene expression similarities with human RLF–MYCL SCLC. Together, our studies support RLF–MYCL as the first demonstrated fusion oncogenic driver in SCLC and provide a new preclinical mouse model for the study of this subtype of SCLC. Significance: The biological and therapeutic implications of gene fusions in SCLC, an aggressive metastatic lung cancer, are unknown. Our study investigates the functional significance of the in-frame RLF–MYCL gene fusion by developing a Rlf–Mycl-driven genetically engineered mouse model and defining the impact on tumor growth and metastasis. This article is highlighted in the In This Issue feature, p. 2945 </jats:sec

Keap1 loss promotes Kras-driven lung cancer and results in a dependence on glutaminolysis

Treating KRAS-mutant lung adenocarcinoma (LUAD) remains a major challenge in cancer treatment given the difficulties associated with directly inhibiting the KRAS oncoprotein1. One approach to addressing this challenge is to define frequently co-occurring mutations with KRAS, which themselves may lead to therapeutic vulnerabilities in tumors. Approximately 20% of KRAS-mutant LUAD tumors carry loss-of-function (LOF) mutations in Kelch-like ECH-associated protein 1 (KEAP1)2-4, a negative regulator of nuclear factor erythroid 2-like 2 (NFE2L2; hereafter NRF2), which is the master transcriptional regulator of the endogenous antioxidant response5-10. The high frequency of mutations in KEAP1 suggests an important role for the oxidative stress response in lung tumorigenesis. Using a CRISPR/Cas9-based approach in a mouse model of Kras-driven LUAD we examined the effects of Keap1 loss in lung cancer progression. We show that loss of Keap1 hyper-activates Nrf2 and promotes Kras-driven LUAD. Combining CRISPR/Cas9-based genetic screening and metabolomic analyses, we show that Keap1/Nrf2-mutant cancers are dependent on increased glutaminolysis, and this property can be therapeutically exploited through the pharmacological inhibition of glutaminase. Finally, we provide a rationale for sub-stratification of human lung cancer patients with KRAS-KEAP1 or -NRF2-mutant tumors as likely to respond to glutaminase inhibition