Systemic delivery of stealth adenoviral vector to reinvigorate antitumor immunity by PD-L1 genome editing and TIGIT/CD155 blocking.

Treatment with combined immune checkpoint blockade (CICB) has been considered as an effective approach to increase the objective response rate for cancer immunotherapy, but at the cost of significantly increased immune-related adverse events (irAEs) and also sufferings from drug resistance due to the transitory working manner of antibody-based ICB inhibitors. We introduce an antibody-independent CICB strategy using an adenoviral vector (sgCas9-Adv@TCM) that delivers a PD-L1 targeted CRISPR/Cas9 system, with a cell membrane cloak presenting TIGIT proteins. The vector could effectively accumulate in tumors, allowing permanent PD-L1 genome editing and TIGIT/CD155 blocking through systemic administration while evading detection and degradation by the immune system. The sgCas9-Adv@TCM vector achieved complete tumor regression in 80% of mice in a subcutaneous hepatocellular carcinoma (HCC) model by globally reshaping the tumor immune microenvironment to elicit robust anti-tumor immunity. Furthermore, sgCas9-Adv@TCM was proven to be still competent and even superior to the standard FDA-approved CICB regimen of the combined anti-PD-L1 and anti-TIGIT in suppressing tumor progression, prolonging survival, and inducing immunological memory of mice in the orthotopic HCC model, but with a much lower risk of irAEs. In addition, the clinical translation potential of sgCas9-Adv@TCM was further validated in the patient-derived organoid (PDO) and patient-derived xenograft (PDX) models from patients diagnosed with HCC. Thus, this study presents a safe and highly efficient "stealth" adenoviral vector with improved CICB features for cancer treatment.