Topoisomerase I Inhibitors in Small-Cell Lung Cancer
June 01, 2004
Among patients with lung cancer, approximately 15% have smallcelllung cancer (SCLC). The clinical characteristics of SCLC tend tobe more aggressive, but also more sensitive to chemotherapy and radiationtherapy than those of non-SCLC. Irinotecan (Camptosar) is aderivative of camptothecin, an inhibitor of the nuclear enzymetopoisomerase I. Irinotecan has been shown to exhibit excellent antitumoractivity against SCLC in monotherapy regimens and in combinationwith cisplatin. A phase III trial comparing irinotecan and cisplatin(IP) with etoposide and cisplatin (EP) in patients with previously untreatedextensive-stage SCLC (ED-SCLC) was conducted. Patients inthe IP arm responded significantly better than patients in the EP arm.In the IP arm, the response rate was 84%, and median overall survivalwas 12.8 months. A phase II trial of irinotecan, cisplatin, and etoposide(IPE) administered weekly (arm A) or every 4 weeks (arm B) for EDSCLC(JCOG 9902-DI) was also performed. In arm B, the responserate was 77% and the median overall survival was 12.9 months. A randomizedtrial comparing IP with IPE administered every 3 weeks inpatients with previously untreated ED-SCLC is presently being performedin Japan.