Chemotherapy-naive patients with ED-SCLC were randomly assigned to receive IP , composed of irinotecan 60 mg/m ( 2 ) on days 1 , 8 , and 15 and cisplatin 60 mg/m ( 2 ) on day 1 every 4 weeks , or AP , composed of amrubicin 40 mg/m ( 2 ) on days 1 , 2 , and 3 and cisplatin 60 mg/m ( 2 ) on day 1 every 3 weeks .