Single-agent paclitaxel by 3-hour infusion in the treatment of non-small cell lung cancer: links between p53 and K-ras gene status and chemosensitivity.

Currently available cytotoxic drugs are only moderately active in non-small cell lung cancer (NSCLC) and prolong survival only slightly. In two published trials, single-agent paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) was reported to have significant activity in NSCLC, with response rates of 21% and 24%. Treatment-limiting hypersensitivity reactions, however, were noted in a phase I trial of paclitaxel given as a 3-hour infusion at doses > or = 190 mg/m2. We report the results of a phase II trial of paclitaxel given by 3-hour intravenous infusion at 210 mg/m2 every 3 weeks in an outpatient setting. The study was conducted simultaneously at three centers and included chemotherapy-naive patients with unresectable locoregional or metastatic NSCLC. The study objectives were to evaluate response rate, the potential link between p53 and K-ras gene mutations and increased paclitaxel resistance, and toxicity. Sixty-two patients were eligible for this study. All patients were premedicated with dexamethasone 20 mg given orally or intravenously 12 and 6 hours before paclitaxel infusion and cimetidine 300 mg and diphenhydramine 50 mg, both given 60 minutes prior to initiation of paclitaxel infusion. Of the 62 patients who were initially enrolled, 50 (44 men and six women) were evaluable for toxicity at interim analysis; 47 of these patients were evaluable for response. Twenty-four had squamous cell carcinoma, 20 had adenocarcinoma, and six had undifferentiated large cell carcinoma. The median age was 61 years (age range, 36 to 75 years). The median Zubrod performance status was 1 (range, 0 to 2). Seventeen (36%) patients achieved either partial or complete response. Among 24 patients with squamous cell carcinoma, eight (33%; 95% confidence interval, 15% to 61%) had a partial response. Seven (41%; 95% confidence interval, 18% to 64%) of 17 patients with adenocarcinoma had a partial or complete response. Tissue blocks were obtained for analysis of K-ras and p53 gene mutations by means of polymerase chain reaction followed by single-strand conformation polymorphism assay. Our findings indicate that mutations are associated with a poor clinical course and may be prognostic of paclitaxel resistance. Paclitaxel was well tolerated. None of the patients experienced allergic reactions. Granulocytopenia was generally mild. Therapy was interrupted in only two patients because of the development of grade 3 neuropathy. In our experience, paclitaxel is one of the most active cytotoxic drugs targeting NSCLC.