The limited efficacy of current chemotherapy approaches is epitomized in metastatic NSCLC, where time to progression ranges from 5.2 to 5.5 months, with different combinations of chemotherapy, such as docetaxel plus cisplatin[32] or new compounds like pemetrexed (an inhibitor of TS and DHFR) plus cisplatin[33]. The gene discussed is DHFR; the disease is non-small cell lung carcinoma.