Cetuximab - A review of its use in squamous cell carcinoma of the head and neck and metastatic colorectal cancer

Cetuximab (Erbitux (R)) is a human-mouse chimeric monoclonal antibody, which competitively binds to the accessible extracellular domain of the epidermal growth factor receptor (EGFR) to inhibit dimerisation and, subsequently, inhibit tumour growth and metastasis. In the EU and the US, cetuximab has been approved for use with concomitant radiotherapy in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) and in combination with irinotecan for the treatment of metastatic colorectal cancer (mCRC) in patients with EGFR-expressing tumours who are refractory to irinotecan-based therapy. In the US, cetuximab has also been approved as monotherapy in patients with recurrent or metastatic SCCHN for whom platinum-based therapy has failed and in patients with mCRC who are intolerant of irinotecan-based regimens. In treatment-naive patients with locoregionally advanced SCCHN, cetuximab plus radiotherapy was more effective than radiation therapy alone in prolonging locoregional disease control. In addition, more limited noncomparative data from a large trial indicated a 13% overall objective response rate (ORR) in platinum-refractory patients with SCCHN. In patients with EGFR-expressing mCRC, cetuximab plus irinotecan improved ORR more than cetuximab monotherapy in a trial in irinotecan-refractory patients; however, there was no difference in overall survival (OS) between cetuximab plus irinotecan and cetuximab monotherapy in oxaliplatin-refractory recipients in another trial. In an ongoing trial, progression-free survival (PFS) exceeded 50% after 12 weeks in irinotecan-refractory patients receiving three different dosages of cetuximab plus irinotecan. In another large trial, cetuximab monotherapy prolonged OS compared with best supportive care (BSC) in heavily pretreated patients. Overall, cetuximab treatment had an acceptable tolerability profile, with the majority of adverse events being mild or moderate in severity and clinically manageable. In particular, cetuximab therapy did not exacerbate toxicities commonly associated with chemo- or radiotherapeutic regimens. Albeit occurring with high incidence, adverse cutaneous reactions appear to be a marker for response.