HAVCR2 and head and neck squamous cell carcinoma: Furthermore, the expression of SLC13A4 in HNSCC is negatively correlated with a variety of T cell exhaustion markers, including LAG3 ( p < 0.001), TIM-3( p < 0.001) and CTLA-4 ( p < 0.001), indicating its potential mechanism in regulating tumor immunity (Supplementary Table S1).