Consistent response to treatment with cetuximab monotherapy in patients with metastatic colorectal cancer

Abstract

3536 Background: Erbitux (Cetuximab), an IgG1 monoclonal antibody, is active in patients with metastatic colorectal cancer (CRC). A phase II study explored the activity of cetuximab in patients with heavily pretreated CRC. Methods: Patients with metastatic CRC were eligible if they had failed at least two prior chemotherapy regimens, containing irinotecan, oxaliplatin, and a fluoropyrimidine. There was no limit in the number of lines of prior treatment. Patients received cetuximab at an initial dose of 400 mg/m2, followed by weekly doses of 250 mg/m2, until disease progression or unacceptable toxicity. Response was assessed by an independent review committee, using a modified version of WHO criteria. Results: 346 patients treated had a median age of 59 years; 54% were male, and an ECOG performance status of 0 (42%) or 1 (58%). Patients received a median of 4 regimens of prior CRC therapy (range 2–9). Median cetuximab therapy was 9 doses (range 1–56+). Patients achieved a 12% PR rate (95% CI 8%–15%) and a median survival time of 6.6 months (95% CI 5.6–7.6 months). 259 patients received oxaliplatin after irinotecan. The other 87 patients received irinotecan after or with oxaliplatin. The response rate was 12% in both groups. 282 patients (81%) progressed on, or within 30 days of the last dose of the latest prior regimen with a response rate of 11%. 64 patients (19%) either progressed after 30 days of the last dose or were intolerant of the latest prior regimen, with a response rate of 14%. Conclusion: Cetuximab is active in patients with heavily pre-treated metastatic colorectal cancer with a consistent response rate regardless of the number of the lines of prior therapy, or sequence of prior agents. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration ImClone Systems Bristol-Myers Squibb, Chiron, Response Genetics, Genentech Bristol-Myers Squibb, Roche, Pfizer, Lilly Oncology, Sanofi Bristol-Myers Squibb, National Cancer Institute, National Institutes of Health