PIK3CA and head and neck squamous cell carcinoma: A case in point is that in sophisticated in silico analyses of HNSCC [108], where an immune-related gene prognostic index (IRGPI) was constructed to better molecularly subtype patients with HNSCC to benefit from therapy with immune checkpoint inhibitors (ICIs), the PIK3CA mutation rate was found to be high, along with high infiltration of B cells and M0 and M2 macrophages in the subgroup with a low IRGPI, which benefited less from ICI therapy than did the subgroup with a high IRGPI.