Pemetrexed (Alimta) in small cell lung cancer

Small cell lung cancer (SCLC) comprises approximately 13% of all lung cancers. In limited stage (LS)-SCLC, combined-modality therapy represents the standard of care. Therapy should be approached curatively in fit patients with a good performance status because 5-year survival rates approach 26% in aggressively treated patients. In contrast, cure is not possible in extensive stage (ES)-SCLC with median 2-year survival rates with current therapy remaining at less than 10%. Pemetrexed (Alimta; Eli Lilly and Co, Indianapolis, IN) is a novel, multi-targeted antifolate that inhibits several folate-dependent enzymes involved in purine and pyrimidine synthesis, and is active as a single-agent or in combination with a platinum in both non-small cell lung cancer and malignant pleural mesothelioma. Pemetrexed/platinum combinations appear active in ES-SCLC based on objective response rates observed in a randomized phase II trial. However, no survival data is yet available from this trial. The toxicity profile of both cisplatin and carboplatin in combination with pemetrexed was extremely favorable, as was the ability to deliver full doses of each of the component drugs. Given the limited options available for patients in the relapsed setting, the activity of single-agent pemetrexed is interesting. Also, preliminary data indicates that full doses of carboplatin/pemetrexed can be administered with thoracic radiation therapy, supporting a future clinical trial initiative in LS-SCLC.