EGFR and non-small cell lung carcinoma: In EGFR-mutant advanced NSCLC with exon 19 deletion and exon 21 (L858R) mutation, patients who receive sequential therapy with erlotinib and cytotoxic drugs experience a longer median OS than those who receive cytotoxic drugs or erlotinib alone.[16] It may be important to administer both EGFR-TKIs and cytotoxic drugs throughout the course of treatment.