Abstract 278: <i>In vivo</i> adenine base editing of <i>STK11</i> Q37* reprograms tumor for radiosensitizing effect.

Abstract In this study, we aim to investigate the therapeutic potential of in vivo genetic therapy using AAV-mediated adenine base editor (ABE) delivery for non-small cell lung cancer (NSCLC) carrying the STK11 nonsense mutation STK11Q37* (c.109C&amp;gt;T), and further explore the molecular mechanisms underlying its impact on radiosensitivity. Radiotherapy is a standard treatment for locally advanced or inoperable NSCLC patients, radiation resistance driven by tumor-promoting somatic mutations severely limits clinical efficacy, underscoring the urgent need for targeted strategies such as precise gene correction to overcome this barrier. Through CRISPR-based in vivo mutation library screening combined with whole-exome sequencing, we identified STK11Q37* as a critical driver of radiation resistance. To restore STK11 function, we engineered a panel of ABEs with distinct PAM/TAM compatibilities and further developed a high-fidelity variant, A8E-N108Q-R26G, which enables precise correction of the pathogenic adenine without bystander editing. Using HEK293T reporter cells stably harboring the STK11Q37* locus, we found that spCas9-A8EQR (N108Q-R26G) achieved the highest overall correction efficiency, repairing up to 60% of mutant alleles with superior fidelity. The optimized editor was subsequently packaged into a dual-AAV system and delivered in vivo to humanized mice bearing subcutaneous patient-derived organoid xenografts. AAV-mediated base editing combined with radiotherapy produced synergistic antitumor effects and significantly suppressed tumor progression. Mechanistic studies revealed that precise correction of STK11Q37* restores endogenous LKB1 protein expression and kinase activity, reactivating downstream signaling required for maintaining redox homeostasis. Restored LKB1 directly stabilizes the transcriptional regulator BACH1 by limiting its ubiquitination and proteasomal degradation, thereby preserving BACH1-mediated repression of antioxidant gene programs. Concurrently, LKB1 re-expression dampens NRF2 nuclear accumulation and transcriptional activity, leading to reduced expression of NRF2-driven detoxification and antioxidant pathways. This coordinated regulation markedly elevates intracellular ROS levels following irradiation and reinstates radiation-induced cytotoxic stress, collectively enhancing tumor radiosensitivity. In summary, our study identifies STK11Q37* as a therapeutically actionable driver of radiation resistance and demonstrates that precise ABE-mediated correction provides a promising gene-editing-based strategy to improve treatment outcomes in NSCLC. Citation Format: Jiazhuo Yan, Yihan Xu, Qingxiao Fang, Jinpu Yu, Zhiyong Yuan. In vivo adenine base editing of STK11 Q37* reprograms tumor for radiosensitizing effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 278.