In this retrospective study, we hypothesized that the potential relation between mutations in the Notch signaling pathway and tumor immune microenvironment by analyzing CD8+ T cells infiltration via PD‐L1, which lead to enhancement of antitumor immunity and confer clinical benefits to immune‐checkpoint inhibitor (ICI) in recurrent or metastatic oral squamous cell carcinoma (OSCC) patients. Here, CD274 is linked to oral cavity squamous cell carcinoma.