Based on these preclinical data, we treated two patients with HER2-positive SCLC by combination of trastuzumab (6 mg/kg, day 1) and irinotecan (80 mg/m(2), days 1 and 8) every 21 days as the third-line chemotherapy following two prior regimens, first-line carboplatin plus etoposide and second-line amrubicin...One patient achieved partial response after the first cycle and received 6 cycles in total without disease progression for 4.5 months...The other also received 4 cycles and kept stable disease for 3.5 months.