Two distinct phenotypes of immunologically hot gastric cancer subtypes.

An in-depth understanding of the tumor microenvironment (TME) is required for the development of improved combination immunotherapies for gastric cancer. Recently, we classified these cancers into four main types defined by their immunological attributes, namely Hot 1, Hot 2, Intermediate and Cold. Of these, the T cell-inflamed "Hot" tumors were further divided into Hot 1 and Hot 2 with different clinical outcomes. Thus, overall survival and progression-free survival of patients with Hot 1 tumors were shorter than with Hot 2. In the present study, we re-evaluated RNA-Seq data of 6 Hot 1 and 6 Hot 2 gastric cancers to elucidate the underlying reason for the poor prognosis and T cell dysfunction in the former. In addition, 56 Hot 1 and 27 Hot 2 tumors in The Cancer Genome Atlas (TCGA) were analyzed. We report that single sample Gene Set Enrichment Analysis (ssGSEA) and differential gene expression analysis identified differences between Hot 1 and Hot 2 tumors involved in metabolism and cell adhesion pathways. Therefore, it is suggested that strategies to modulate active metabolism in Hot 1 tumors should be integrated into the treatment of these gastric cancers.