Abstract
Vascular endothelial growth factor inhibitors, including tyrosine kinase inhibitors (TKIs), possess immunomodulatory properties and have shown promising outcomes when combined with anti-PD-1 antibodies. The OASIS phase II trial (NCT04503967) is designed to determine the clinical activity and safety of nivolumab (anti-PD-1) and anlotinib hydrochloride (a multi-targets TKI) as second-line or above therapy in patients with advanced gastric adenocarcinoma (GAC) and esophageal squamous cell carcinoma (ESCC). From December 2020 to September 2022, 45 patients with GAC and 3 with ESCC were enrolled in this study. The pre-specified endpoints were reached, with the primary endpoint of overall response rate achieving 29.2%. For secondary objectives, disease control rate was 64.6%; median progression-free survival was 4.0 months; and median overall survival was 11.1 months with a manageable toxicity profile. The exploratory analyses unveiled that the balance of gut bacteria and the presence of a pre-existing immune signature characterized by a high percentage of CD68+PD-L1+ PD-1+ macrophages and low pretreatment variant allele frequencies (VAF), as well as low expression of certain cytokines were significantly associated with improved clinical outcomes in patients with GAC.