E5501: phase II study of topotecan sequenced with etoposide/cisplatin, and irinotecan/cisplatin sequenced with etoposide for extensive-stage small-cell lung cancer
Sequence-dependent improved efficacy of topoisomerase I followed by topoisomerase 2 inhibitors was assessed in a randomized phase II study in extensive-stage small-cell lung cancer (SCLC). Patients with previously untreated extensive-stage SCLC with measurable disease, ECOG performance status of 0–3 and stable brain metastases were eligible. Arm A consisted of topotecan (0.75 mg/m2) on days 1, 2 and 3, etoposide (70 mg/m2) and cisplatin (20 mg/m2) (PET) on days 8, 9 and 10 in a 3-week cycle. Arm B consisted of irinotecan (50 mg/m2) and cisplatin (20 mg/m2) on days 1 and 8 followed by etoposide (85 mg/m2 PO bid) on days 3 and 10 (PIE) in a 3-week cycle. We enrolled 140 patients and randomized 66 eligible patients to each arm. Only 54.5 % of all patients completed the planned maximum 6 cycles. There were grade ≥3 treatment-related adverse events in approximately 70 % of the patients on both arms including 6 treatment-related grade 5 events. The overall response rates (CR + PR) were 69.7 % (90 % CI 59.1–78.9, 95 % CI 57.1–80.4 %) for arm A and 57.6 % (90 % CI 46.7–67.9, 95 % CI 44.8–69.7 %) for arm B. The median progression-free survival and overall survival were 6.4 months (95 % CI 5.4–7.5 months) and 11.9 months (95 % CI 9.6–13.7 months) for arm A and 6.0 months (95 % CI 5.4–7.0 months) and 11.0 months (95 % CI 8.6–13.1 months) for arm B. Sequential administration of topoisomerase inhibitors did not improve on the historical efficacy of standard platinum-doublet chemotherapy for extensive-stage SCLC.