Review of the pemetrexed and gemcitabine combination in patients with advanced-stage non-small cell lung cancer.

Pemetrexed is a new multitargeted antifolate that can be easily administered as a 10-min infusion every 3 weeks. The use of folic acid, vitamin B(12), and corticoid prophylaxis has significantly reduced pemetrexed-induced toxicity. Single-agent pemetrexed has shown antitumor activity in a wide range of solid tumors, including non-small cell lung cancer (NSCLC). Association with vinorelbine, cisplatin, carboplatin, and oxaliplatin have been tried, but the pemetrexed and gemcitabine combination, an easy to administer cisplatin-free doublet, has been documented in many phase 2 trials in the first-line treatment of advanced NSCLC. In vitro cytotoxic assays and phase I studies have defined several schedules of administration for pemetrexed and gemcitabine. The recommended dose is pemetrexed 500 mg/m(2) on day 1 or 8, and gemcitabine 1250 mg/m(2) on day 1 and 8, but it is unknown if pemetrexed should precede or follow gemcitabine and at what time interval. Published studies have failed to show significant differences in overall survival times despites response rates oscillating between 15% and 41%. The main toxicities are neutropenia, fatigue, skin rashes and elevated transaminases and seem to occur with similar rates in the many phase 2 trials. Hopes for the future are in tailored chemotherapy, since molecular markers of sensitivity are available for gemcitabine and pemetrexed, allowing to determinate in the future which patients will be most likely to benefit from the gemcitabine-pemetrexed doublet.