Incorporation of pemetrexed (Alimta) into the treatment of non-small cell lung cancer (thoracic tumors).

Lung cancer is the leading cause of cancer death in the United States and throughout the world. The overall 5-year survival rate for lung cancer is dismal: 14% in the United States and even lower in other parts of the world. Recent developments in the armamentarium of chemotherapeutic agents for lung cancer have shown that two-drug combinations improve survival, relieve symptoms, and improve quality of life; however, complete response rates are still approximately 1% in stage IV disease and less than 20% of advanced stage patients survive 2 years. Therefore, improved therapeutic agents that increase efficacy are sorely needed. Most lung cancers overexpress thymidylate synthase and a variety of genes involved in cell cycle regulation. Previous studies have shown that some inhibitors of DNA synthesis (eg, gemcitabine) can improve the survival of advanced lung cancer patients, especially when combined with other agents such as cisplatin. The multitargeted antifolate, pemetrexed (Alimta; Eli Lilly and Co, Indianapolis, IN) was developed because it inhibits multiple enzymes involved in DNA synthesis including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyl transferase. The early studies of pemetrexed showed that the important dose-limiting toxicities were myelosuppression, mucositis, and diarrhea, all of which are common with any antimetabolite. Subsequent studies described in this article will show that these toxicities can be significantly reduced by the use of vitamin supplementation with folate and B12, and that pemetrexed has considerable activity in non-small cell lung cancer and mesothelioma.