Irinotecan/Cetuximab Followed by XELOX/Cetuximab vs the Reverse Sequence in Metastatic CRC

Because of the recent advances in the field of systemic chemotherapy for mCRC, like irinotecan, oxaliplatin, capecitabine, and targeted agents (Cetuximab, Bevacizumab) mCRC patients have an overall survival that in some cases reaches 25 months.Irinotecan is an inhibitor of the DNA enzyme topoisomerase I, with use in clinical practice for the last 10 years.In a phase II study with mCRC patients resistant to irinotecan based therapy the combination of irinotecan and Cetuximab (an IgG1 anti-EGFR antibody) yielded a response rate of 22.5%.Capecitabine was shown to have improved tolerability and response rate compared with bolus 5-FU, with comparable time to progression and survival.Oxaliplatin has been approved by the FDA for 2nd line treatment in the metastatic CRC setting as a number of trials have shown promising data for response rates, disease stabilization rates,median progression free survival (PFS) and overall survival (OS).KRAS is a predictive marker for clinical benefit from EGFR-based antibody treatment. KRAS is the first molecular marker for selection of a targeted therapy in combination with a standard chemotherapy regimen. Patients with KRAS wild-type tumors have a strong benefit from the administration of cetuximab with better PFS and objective responses.