A phase II study of amrubicin and topotecan combination therapy in patients with relapsed or extensive-disease small-cell lung cancer: Okayama Lung Cancer Study Group Trial 0401

Backgrounds: Chemotherapy is a mainstay in the treatment of extensive-disease small-cell lung cancer (ED-SCLC), although the survival benefit remains modest. We conducted a phase II trial of amrubicin (a topoisomerase II inhibitor) and topotecan (a topoisomerase I inhibitor) in chemotherapy-naïve and relapsed SCLC patients. Methods: Amrubicin (35mg/m ²) and topotecan (0.75mg/m ²) were administered on days 3-5 and 1-5, respectively. The objective response rate (ORR) was set as the primary endpoint, which was assessed separately in chemotherapy-naïve and relapsed cases. Results: Fifty-nine patients were enrolled (chemotherapy-naïve 31, relapsed 28). The ORRs were 74% and 43% in the chemotherapy-naïve and relapsed cases, respectively. Survival data were also promising, with a median progression-free survival time and median survival time of 5.3 and 14.9 months and 4.7 and 10.2 months in the chemotherapy-naïve and relapsed cases, respectively. Even refractory-relapsed cases responded to the treatment favorably (27% ORR). The primary toxicity was myelosuppression with grades 3 or 4 neutropenia in 97% of the patients, which led to grades 3 or 4 febrile neutropenia in 41% of the patients and two toxic deaths. Conclusion: This phase II study showed the favorable efficacy and moderate safety profiles of a topotecan and amrubicin two-drug combination especially in relapsed patients with ED-SCLC.