Aim: The open-label, nonrandomized, phase II APEC study enrolled 167 patients with RAS wild-type (wt) metastatic colorectal cancer (mCRC) to investigate the safety and efficacy of first-line, every-2-weeks cetuximab plus investigator's choice of FOLFIRI or FOLFOX in this patient population.
Methods: A subgroup analysis of the APEC study population by primary tumor location was performed.
Results: A total of 130 patients (81.8%) had left-sided and 29 (18.2%) had right-sided mCRC. Median progression-free survival (PFS), overall survival (OS) and overall response rate (ORR) were 14.0 months, 30.6 months and 68.5% for patients with left-sided tumors and 8.9 months, 24.6 months and 51.7% for patients with right-sided mCRC, concurring with pivotal phase III trial results. In patients with right-sided tumors, median PFS was 15.4 months vs 8.3 months with cetuximab plus FOLFIRI vs cetuximab plus FOLFOX, respectively; median OS was 32.1 months vs 21.8 months with cetuximab plus FOLFIRI vs cetuximab plus FOLFOX, respectively.
Conclusion: The APEC tumor-location subgroup analysis results were largely consistent with available literature regarding the equivalent efficacy of cetuximab plus FOLFIRI/FOLFOX in patients with left-sided RAS wt mCRC. A trend toward improved efficacy with cetuximab plus FOLFIRI compared with cetuximab plus FOLFOX was observed in patients with right-sided tumors; however, a direct comparison between groups cannot be made due to the nonrandomized study design. Nevertheless, the similar ORR observed with either chemotherapy backbone in patients with right-sided RAS wt mCRC suggests a potential role for both regimens in this patient population when cytoreduction is a treatment goal.
Keywords: cetuximab; metastatic colorectal cancer; tumor location.
© 2019 The Authors. Asia-Pacific Journal of Clinical Oncology Published by John Wiley & Sons Australia, Ltd.