Dual blockade of EGFR and CDK4/6 delays head and neck squamous cell carcinoma progression by inducing metabolic rewiring.

Abstract Despite preclinical success, monotherapies targeting EGFR or cyclin D1-CDK4/6 in Head and Neck squamous cell carcinoma (HNSCC) have shown a limited clinical outcome. Here, we aimed to determine the combined effect of palbociclib (CDK4/6) and afatinib (panEGFR) inhibitors as an effective strategy to target HNSCC. Using the TCGA-HNSCC co-expression analysis, we found that patients with high EGFR and cyclin D1 expression showed enrichment of gene clusters associated with cell-growth, glycolysis, and epithelial to mesenchymal transition processes. Phosphorylated S6 (p-S6), a downstream effector of EGFR and cyclin D1-CDK4/6 signalling, showed a progressive increase from normal oral tissues to leukoplakia and frank malignancy with poor outcome. While increased p-S6 level was drastically reduced during combination treatment in the HNSCC cell lines and mouse models. Combination treatment reduced the cell growth and induced senescence via increasing reactive oxygen species with concurrent ablation of glycolytic and tricarboxylic acid cycle intermediates. Additionally sub-cutaneous and genetically engineered mouse model (K14-CreERtam;LSL-KrasG12D;Trp53R172H) studies indicated reduction in the tumor growth and delayed tumor progression, respectively. This study collectively demonstrates that dual targeting may be a critical therapeutic strategy in blocking tumor progression via inducing metabolic alteration and warrants clinical evaluation.