New investigative regimens and cytotoxic agents in thoracic cancers: gemcitabine and pemetrexed.

Several new antimetabolites, administered alone or in combination, are changing the therapeutic landscape for thoracic cancer. Two-drug combinations involving these newer drugs are becoming the standard of care for non-small-cell lung cancer (NSCLC), largely due to improvements in survival rates, time to disease progression, and response rates as well as an improved safety profile. Gemcitabine (Gemzar) has elicited considerable interest in this disease, as a combination partner in chemotherapeutic regimens. Another promising agent is pemetrexed (Alimta), a folate-based inhibitor of thymidylate synthase. In preclinical development, pemetrexed both alone and in combination with other cytotoxic agents has exhibited activity across a broad range of tumor models, including NSCLC and mesothelioma. In clinical trials of patients with NSCLC, pemetrexed has been an effective, well-tolerated agent that can be used as monotherapy or in combination with other agents at full dose. In clinical trials of patients with mesothelioma, the combination of pemetrexed and cisplatin demonstrated a significant improvement in survival, response, and patient quality-of-life parameters. The principle toxicities of pemetrexed can be minimized by folate and vitamin B12 supplements.