EGFR and head and neck squamous cell carcinoma: Erbitux® approved for K-ras wild-type, EGFR-expressing metastatic colorectal cancer and recurrent/metastatic HNSCCa; NSCLC; HNSCC; colorectal cancerVectibixTM approved for colorectal cancera; HNSCC; colorectal cancerIressa® approved for NSCLCa; HNC; skin, breast, colorectal cancer; GBM; NSCLCTarceva® approved for NSCLC and pancreatic cancera; HNC; prostate, breast, esophageal, colorectal cancer; NSCLC; pancreatic cancer