To investigate whether tumor intrinsic cyclin D1‐CDK4/6 signaling was linked to response to immunotherapy, we utilized two HNSCC murine models that exhibit sensitivity (MOC1) or resistance (MOC2) to PD‐1 blockade in vivo (Figure 1d; Figure S1d, Supporting Information). This evidence concerns the gene CCND1 and head and neck squamous cell carcinoma.