Oncolytic adenovirus armed with cGAS activates STING pathway and enhances antitumor immunity in lung cancer with superior combined efficacy of PD-L1 therapy.

INTRODUCTION: The extensive expression of STING in patients with non-small cell lung cancer (NSCLC) is closely associated with overall survival and other factors. Activation of the STING pathway can suppress NSCLC. However, the clinical translation of STING agonists remains hindered by challenges such as off-target effects, metabolic instability, and suboptimal pharmacokinetics. METHODS: In this study, we engineered two oncolytic adenoviruses (OAds), OAd-HcGAS and OAd-McGAS, expressing human or murine cGAS, respectively, using an Ad5/3 chimeric adenovirus platform under regulation by the hTERT promoter to evaluate whether OVs carrying the cGAS gene are capable of specifically activating the STING pathway within tumors and enhancing the anti-tumor efficacy of OVs both in vitro and in vivo. RESULTS: In vitro, OAd-HcGAS exhibited robust replication and potent cytolytic activity in tumor cells. It activated the STING-TBK1-IRF3 signaling axis, triggering a strong type I interferon (IFN-I) and pro-inflammatory cytokine response without compromising viral replication. In a murine Lewis lung carcinoma allograft model, intratumoral (i.t.) administration of OAd-McGAS led to substantial cGAS expression and consequential activation of the STING pathway. Moreover, the combination with anti-PD-L1 therapy resulted in tumor regression in over half of the cases. Notably, this armed oncolytic virus strategy enhanced the activation and infiltration of multiple immune cell populations. DISCUSSION: Collectively, these findings establish cGAS-expressing oncolytic adenoviruses as a novel and effective therapeutic strategy for lung cancer treatment.