Topoisomerase I copy number alterations as biomarker for irinotecan efficacy in metastatic colorectal cancer

No biomarker exists to guide the optimal choice of chemotherapy for patients with metastatic colorectal cancer. We examined the copy numbers (CN) of topoisomerase I (TOP1) as well as the ratios of TOP1/ CEN-20 and TOP1/CEN-2 as biomarkers for irinotecan efficacy in patients with metastatic colorectal cancer.