Abstract 3916: TNG260, a small molecule CoREST inhibitor, sensitizes STK11-mutant NSCLC to anti-PD1 immunotherapy

Abstract Loss of function (LOF) of the serine-threonine kinase STK11/LKB1, which has been reported in ~15% of non-small cell lung cancer (NSCLC), drives resistance to immune checkpoint therapies such as PD1. In vivo CRISPR screens in tumor-bearing immune competent mice identified the Corepressor of Repressor Element 1 Silencing Transcription (CoREST) complex as a synthetic lethal immune evasion target for STK11- mutant tumors. Here, we demonstrate that TNG260, a small molecule drug specifically targeting the CoREST complex, can sensitize STK11 mutant lung cancers to anti-PD1 immunotherapy. Combination treatment with TNG260 and anti-PD1 arrested KRAS/STK11 mutant NSCLC tumor growth with no major toxicity observed, as confirmed in both allograft and genetically engineered mouse models (GEMMs) of STK11 mutant NSCLC. Further transcriptional analysis via bulk RNA-seq revealed that treatment of KRAS/STK11 mutant lung tumors with TNG260 promotes genes related to inflammatory responses and suppresses genes related to cell cycle and mitotic checkpoint(s). This phenotype was not observed in STK11 wildtype KRAS/P53 mutant lung tumors. Furthermore, combinational treatment of TNG260 with PD1 antibody showed increased macrophages, neutrophils and dendritic cells signatures in vivo. Our data suggests that epigenetic reprogramming via TNG260 sensitizes STK11 mutant NSCLC tumors to anti- PD1 treatment via targeting of the CoREST complex. This work identifies new vulnerabilities in STK11 LOF cancers that can be exploited therapeutically. TNG260 is currently being investigated in combination with pembrolizumab for the treatment of STK11-mutant cancer (NCT05887492), including NSCLC. Citation Format: Ayushi Patel, Soumyadip Sahu, Ke Geng, Salman Punekar, Janaye Stephens, Jiehui Deng, Ting Chen, Leanne Ahronian, Minjie Zhang, Jannik Andersen, Brian Haines, Kwok-Kin Wong. TNG260, a small molecule CoREST inhibitor, sensitizes STK11-mutant NSCLC to anti-PD1 immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3916.