New drugs in the treatment of non-small cell lung cancer

Non-small cell lung cancer accounts for 75% of all lung tumours, and only about 10% of patients will remain alive 5 years after diagnosis. Few cytotoxic drugs currently registered produce more than a 15% response rate as a single agent or 30%-35% in combination, with only modest survival benefits. New cytotoxic drugs entering phase II and III studies, however, appear to have more than 20% activity against this disease. They include the taxanes (taxol and taxotere), camptothecin analogues (CPT-11 and topotecan), antimetabolites (edatrexate and gemcitabine) and the vinca alkaloid, navelbine. Taxol produces response rates of about 25% in previously untreated patients and is currently undergoing trials at higher doses in combination with cisplatin and granulocyte colony-stimulating factor. Taxotere produces response rates of 33% in previously untreated patients and 21% in patients previously refractory to platinum-containing regimens. The camptothecin analogues, which are inhibitors of topoisomerase I, may produce response rates of up to 41% in previously untreated patients, but these results have varied considerably between different trials (response rates as low as 13.5% have been reported for topotecan). A phase II study with edatrexate produced a response rate of 32% but subsequent trials using combination chemotherapy including this agent have been disappointing. The activity of gemcitabine as a single agent is 20%-25%. Three ongoing phase II studies combining cisplatin and gemcitabine have shown response rates of up to 50%. Gemcitabine has minimal subjective toxicity. Navelbine produces response rates of 22%-33% as a single agent and up to 65% in combination. These new cytotoxic agents with significant activity in non-small cell lung cancer provide exciting potential for developing novel combination regimens in the advanced setting and as neoadjuvant and adjuvant therapy.