Gemcitabine in the treatment of non-small-cell lung cancer

Gemcitabine is a nucleoside analogue with activity in non-small-cell lung cancer (NSCLC). Phase I trials have determined the best tolerated dose of gemcitabine in chemotherapy-naive patients to be 1250 mg/m2 given as a 30-minute infusion weekly x 3 every 4 weeks. The single-agent efficacy of gemcitabine has been assessed in 4 phase II trials (361 patients) at dose of 800-1250 mg/m2/weekly x 3 every 4 weeks. Single-agent response rates (externally verified by Oncology Review Board) were > 20%, with duration of response 7.6-12.7 months and median survival 8-9 months. Dose-limiting toxicity was neutropenia, but this was rare, even at the highest dose levels. In 3 Japanese studies, response rates of 16.3%, 26% and 20.9% were seen in untreated patients. Pooled data from all NSCLC studies shows that responses were seen in stages IIIA, IIIB and IV disease, and were similar in adeno and squamous cell types. Gemcitabine has also been studied in combination with other drugs active in NSCLC. In one study 50 patients were treated with gemcitabine and cisplatin given weekly x 3 every 4 weeks, cisplatin at a dosage of 25-30 mg/m2 and gemcitabine at doses escalating from 1000 mg/m2 in steps of 250 mg/m2 per cycle, 38 of 50 patients have been evaluated to date, with an overall response rate of 31.6%. Dose limiting toxicity was rare, but there was evidence of cumulative haematological toxicity with grade 4 granulocytopenia and thrombocytopenia becoming more frequent with repeated administration. Similar activity was seen when gemcitabine (1000 mg/m2) was combined with monthly cisplatin (60, 75, 100 mg/m2). Other studies have shown that gemcitabine can enhance radiosensitivity in NSCLC and other solid tumour types such as pancreas/breast and colorectal cancer cell lines.