Concentrations in cerebrospinal fluid exceeding the half maximal inhibitory concentration for EGFR mutant lung cancer cells in patients with BM and leptomeningeal metastases (LM) that developed despite standard daily erlotinib or other EGFR TKIs were achieved with weekly intermittent “pulsatile” administration of high-dose (1,500 mg) erlotinib (24). This evidence concerns the gene EGFR and lung cancer.