Objective: Gastric cancer (GC) ranks fifth in incidence and fourth for mortality worldwide. The response to immune checkpoint blockade (ICB) therapy in GC is heterogeneous due to tumour-intrinsic and acquired immunotherapy resistance. We developed an immunophenotype-based subtyping of human GC based on immune cells infiltration to develop a novel treatment option.
Design: A algorithm was developed to reclassify GC into immune inflamed, excluded and desert subtypes. Bioinformatics, human and mouse GC cell lines, syngeneic murine gastric tumour model, and CTLA4 blockade were used to investigate the immunotherapeutic effects by restricting receptor tyrosine kinase (RTK) signalling in immune desert (ICB-resistant) type GC.
Results: Our algorithm restratified subtypes of human GC in public databases and showed that immune desert-type and excluded-type tumours are ICB-resistant compared with immune-inflamed GC. Moreover, epithelial-mesenchymal transition (EMT) signalling was highly enriched in immune desert-type GC, and syngeneic murine tumours exhibiting mesenchymal-like, compared with epithelial-like, properties are T cell-excluded and resistant to CTLA4 blockade. Our analysis further identified a panel of RTKs as potential druggable targets in the immune desert-type GC. Dovitinib, an inhibitor of multiple RTKs, strikingly repressed EMT programming in mesenchymal-like immune desert syngeneic GC models. Dovitinib activated the tumour-intrinsic SNAI1/2-IFN-γ signalling axis and impeded the EMT programme, converting immune desert-type tumours to immune inflamed-type tumours, sensitising these mesenchymal-like 'cold' tumours to CTLA4 blockade.
Conclusion: Our findings identified potential druggable targets relevant to patient groups, especially for refractory immune desert-type/ 'cold' GC. Dovitinib, an RTK inhibitor, sensitised desert-type immune-cold GC to CTLA4 blockade by restricting EMT and recruiting T cells.
Keywords: carcinogenesis; cell biology; gastric cancer.
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