Abstract 5517: Overcoming sotorasib acquired resistance in KRASG12C mutant NSCLC by TUSC2 gene therapy

Abstract Acquired resistance (AR) to sotorasib, an FDA-approved KRAS inhibitor, poses a significant challenge in treating KRASG12C mutant NSCLC. Despite initial responses, patients invariably develop resistance, necessitating alternative therapeutic strategies. The mechanisms of AR include the emergence of additional mutations in KRAS gene, reactivation of KRAS pathway, or activation of alternative signaling pathways. TUSC2, a potent tumor suppressor gene with immunogenic properties, exhibits multifunctional activity by a) inhibiting signaling pathways, including MAPK and mTOR, b) arresting the growth and proliferation, c) inducing tumor cell death, and d) activating immune responses. This study shows that TUSC2 gene therapy effectively overcomes the AR in KRASG12C mutant NSCLC. AR patient-derived xenografts (PDX), cell line-derived xenografts (CDX), PDX-derived organoids (PDXO), and cell lines were generated. Both AR cell lines and PDXOs showed >100-fold resistance over sensitive counterparts. The resistant cell lines also showed resistance to adagrasib, another KRASG12C inhibitor. Whole Exome Sequencing (WES) was performed for AR PDXs, CDX, and cell lines and all retained the KRASG12C mutation with no additional KRAS mutations. Mass spectrometry (MS) on TC303AR and TC314AR PDXs showed significant sets of differentially regulated proteins in AR vs parental. A significant upregulation of MTORC1 signaling in AR PDXs was found. Proteins involved in the PI3K-AKT-mTOR pathway were significantly upregulated in AR PDX and cells. TUSC2 transfection reduced considerably colony formation and increased the annexin V-positive apoptotic cells in both H23AR and H358AR cells. Re-expression of TUSC2 into AR PDXOs significantly decreased the viability of organoids compared with the empty vector. The H23AR tumors, which exhibited no significant sensitivity to sotorasib, showed robust antitumor effects of quaratusugene ozeplasmid, a lipoplex gene therapy containing the TUSC2 gene in both H23AR and TC314AR PDXs. However, a synergistic antitumor effect was observed when TC314AR PDXs were treated with the combination of TUSC2 and sotorasib. To evaluate the antitumor immune responses, immune-competent humanized-NSG mice are generated by transplanting fresh human cord blood-derived CD34+ stem cells into sub-lethally irradiated NSG mice to reconstitute a human immune system. The robust antitumor effect of TUSC2 was observed in both PDX and xenograft humanized mice. When sotorasib was combined with TUSC2, synergistic antitumor activity was found. This antitumor effect was correlated with significant infiltration of human CD8 T, NK, DC, and M1 MQ, and downregulation of MDSCs and exhausted T cells. TUSC2 therapy, alone or in combination with sotorasib, induced apoptosis, inhibited colony formation, and showed significant antitumor efficacy in KRASG12C AR tumors Citation Format: Ismail M. Meraz, Mourad Majidi, Renduo Song, Shuhong Wu, Lihui Gao, Feng Meng, Chenghui Ren, Yi Xu, Qi Wang, Yuanxin Xi, Jing Wang, Sung Yun Jung, Elizabeth Shpall, Jack A. Roth. Overcoming sotorasib acquired resistance in KRAS mutant NSCLC by TUSC2 gene therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5517.