Abstract 7618: Genomic pathogenic alterations of the SWI/SNF complex genes compromise the outcomes to immunotherapy in Chinese KRAS-mutant non-small cell lung cancer by downregulated STING

Abstract Background: Immune checkpoint inhibitors (ICIs) have been standard of care in non-small cell lung cancer (NSCLC), but lack of response to ICIs remains a major hurdle in cancer immunotherapy. Switch/sucrose nonfermentable (SWI/SNF) chromatin-remodeling complex mutations have been reported in KRAS-mutant cancers with debated influence to clinical outcome of ICIs, which needs further investigation. Methods: According to the OncoKB, COSMIC, and PolyPhen-2 databases, genomic pathogenic alterations (GPAs) of SWI/SNF are defined. Lung tumors were classified according to the presence or absence of mutations in six SWI/SNF genes (ARID1A, ARID1B, ARID2, PBRM1, SMARCA4, and SMARCB1). Lung cancer cell lines with different genotypes of SWI/SNF were used for differentially expressed genes analysis by RNA sequencing. Protein expression of STING was detected by immunohistochemistry (IHC) in tumor specimens. Results: Out of 2660 NSCLC patients (NSCLCs), the GPAs of SWI/SNF were detected in 15. 0% (401/2660) patients. 23. 1% (69/299) EGFRwtALKwt and 27. 8% (25/90) STK11wtKEAP1wtKRASmut NSCLCs who received ICIs had SWI/SNF GPAs. Progression-free survival (mPFS) of SWI/SNF-wild type (wt) compared to SWI/SNF-mutant (mut) NSCLCs was not significantly different. However, GPAs of SWI/SNF in KRAS-mut ICI-treated NSCLCs associated with poorer clinical outcome. Patients with ARID1A, ARID1B, ARID2 or PBRM1 mutant tumors had a significantly shorter PFS (2. 7 vs 6. 5 months, HR=2. 44 95%CI: 1. 31-4. 54, P=0. 004) as compared to SWI/SNF-wt patients. In STK11wtKEAP1wtKRASmut NSCLCs, all SWI/SNF mutations (4. 9 vs 9. 1 months, HR=2. 03 95%CI: 1. 07-3. 86, P=0. 029) or ARID1A/ARID1B/ARID2/PBRM1 alterations (3. 2 vs 9. 1 months, HR=2. 68 95%CI: 1. 33-5. 41, P=0. 004) significantly shortened the mPFS. In cell lines, SWI/SNF-mut cells had downregulated STING expression compared to SWI/SNF-wt cells. Downregulated STING protein were observed in KRAS-mut NSCLCs without benefit from the treatment of ICIs. Conclusions: In KRAS-mut NSCLCs with or without STK11/KEAP1 mutations, the presence of GPAs of DNA binding genes ARID1A/ARID1B/ARID2 could compromise the clinical outcome of immunotherapy, which might be due to the downregulated STING. Citation Format: Lingling Gao, Jie Jiang, Zhi Xie, Linlin Zhu, Yu Chen, Zhiyi Lv, Yuqing Chen, Wenbin Zhou, Ji Chen, Yumin Zhong, Li Zhang, Penghui Zeng, Xiaodan Huang, Wenqing Yan, Danxia Lu, Shuilian Zhang, Weibang Guo, Xuchao Zhang. Genomic pathogenic alterations of the SWI/SNF complex genes compromise the outcomes to immunotherapy in Chinese KRAS-mutant non-small cell lung cancer by downregulated STING 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 (6Suppl): Abstract nr 7618.