Anti-programmed cell death-1 (PD-1) immunotherapy and platinum-based chemotherapy are key components of first-line treatment for advanced Gastric or Gastroesophageal Junction (G/GEJ) cancer. However, the role of immune cells infiltrating the tumor microenvironment (TME) in predicting both therapy responses is still unclear. ORIENT-16 is a randomized, double-blind, placebo-controlled, phase 3 clinical trial, and enrolled 650 patients with unresectable locally advanced or metastatic G/GEJ cancer between January 3, 2019, and August 5, 2020. For patients enrolled from the First Affiliated Hospital of Zhejiang University School of Medicine, we analyzed progression-free survival(PFS) and overall survival (OS) based on PD-L1 expression and landmark analysis, and developed a multiplexed immunofluorescence (mIF) assay for CD4, CD8, PD-L1, CD68 and FoxP3 coupled with digital image analysis and machine learning to assess prognostic survival associations of immune cells. A total of 54 eligible patients were enrolled in this study, 35 received sintilimab plus platinum-based chemotherapy and 19 received placebo plus platinum-based chemotherapy. For patients with PD-L1 combined positive score (CPS) < 10, survival disparities between anti-PD-1 immunotherapy and chemotherapy emerged 300 days post-treatment. High PD-L1 expression correlated with longer survival in anti-PD-1 therapy but less benefit in platinum-based chemotherapy. The mIF analysis also demonstrated significantly higher stromal PD-L1 density in immunotherapy responders, but tended to be lower in chemotherapy responders. Besides, high tumor stromal CD8 expression could be used as a positive biomarker in anti-PD-1 immunotherapy, and high tumor stromal CD4 expression was found associated with worse prognosis in platinum-based chemotherapy. Increased PD-L1 expression was associated with an increased effect on anti-PD-1 immunotherapy and reduced benefit from chemotherapy. The signature of TME immune cells has the potential to predict the response of anti-PD-1 immunotherapy and chemotherapy in G/GEJ cancer. ClinicalTrials.gov Identifier: NCT03745170.
Wu et al. (Mon,) studied this question.