Phase II study of carboplatin in small cell lung cancer.

Carboplatin (CBDCA; cis-diammine-1, 1-cyclobutane dicarboxylate platinum II), a new platinum analogue, was administered to 18 patients with small cell lung cancer (SCLC) at a dose of 300-450 mg/m2 intravenously every four weeks, in a phase II study. All patients could be evaluated to assess response and 17 for toxicity. The overall response rate was 28% (5/18), including one complete response. Of eight patients previously untreated, four (50%) showed a response, including one complete response. The response rate in patients with no previous cisplatin-treatment was 50% (5/10). Response durations in five responders were 2, 3, greater than 4, greater than 10 and 11 months. Toxicity was primarily hematologic, with thrombocytopenia being dose-limiting. Thrombocytopenia (less than 75,000/mm3) was observed in 12 patients (71%), six requiring platelet transfusion. Leukopenia (less than 3,000/mm3) was observed in 11 patients (65%). There were no episodes of serious infection or bleeding, however. Myelosuppression was more severe in heavily pretreated patients than in patients previously untreated. Dose reductions were required following multiple treatments for cumulative myelotoxicity. Mild to moderate nausea and vomiting occurred in seven patients (44%). Nephrotoxicity and ototoxicity were not observed. Carboplatin was demonstrated to be an active agent against SCLC. Further investigation into dose and schedule of CBDCA in combination chemotherapy is warranted.