CDK4 and head and neck squamous cell carcinoma: No significant profiles were observed after palbociclib and trametinib combination treatment.372 Palbociclib and SAHA combination therapy also exhibited a synergistic effect in suppressing NPC growth.373 LY2835219, a selective CDK4/6 inhibitor, inhibited tumor cell proliferation and blocked the cell cycle by suppressing CDK4/6-dependent Ser780 phosphorylation, which showed a potent effect in treating HNSCC.