Phase II study of dose-intense chemotherapy with sequential topoisomerase-targeting regimens with irinotecan/oxaliplatin followed by etoposide/carboplatin in chemotherapy naive patients with extensive small cell lung cancer.

INTRODUCTION

Topoisomerase inhibitors are active agents in small cell lung cancer (SCLC), and preclinical models indicate that sequential administration of a topoisomerase I inhibitor followed by a topoisomerase II inhibitor can result in enhanced cytotoxicity.

PATIENTS AND METHODS

In this phase II study, patients with extensive SCLC were treated with two sequential topoisomerase-based regimens: irinotecan (150 mg/m(2))/oxaliplatin (85 mg/m(2)) [regimen A] on day 1 followed by etoposide (100 mg/m(2)×3)/carboplatin (AUC 6) [regimen B] on day 15. Regimen A was repeated 3 weeks later. The primary objective was objective response rate. Secondary endpoints included progression-free survival (PFS), overall survival (OS), toxicity, and exploratory correlative analysis of the tumor expression of the excision repair cross complementing (ERCC1) and topoisomerase II-α. Patients received a maximum of 5 cycles of sequential therapy of regimen A→B.

RESULTS

The overall response rate was 96%, the 6-month PFS was 76.9%, the median PFS was 8.95 months, and OS was 12.9 months in 26 evaluable patients. Grade 4 neutropenia (23%) and thrombocytopenia (58%) were observed with regimen B; and grade 2/3 nausea-vomiting (54%) and diarrhea (46%) with regimen A. Seven patients required dose reductions in regimen A and 19 patients in regimen B. The dose intensity, delivered during the first three cycles was 89%. No significant correlations were observed between the tumor expression of the ERCC1 and topoisomerase II-α and clinical outcomes (PFS or OS).

CONCLUSIONS

Although cross-study comparisons are difficult to make, our data suggests that sequential topoisomerase-targeting regimens may enhance the efficacy of chemotherapy in newly diagnosed SCLC patients (Clinical Trial Registration Number, 9 NCT00240097; Clinical Trials.gov number, NCT00240097).