Biomarker - Panitumumab Response With KRAS Wild Type MCC

Colon cancer affects 20,000 Canadians a year. Despite efforts to improve screening, 8,500 patients will die of the disease (1). The agents used in both the adjuvant and metastatic setting have dramatically changed over the past ten years. Even with the optimal treatment and careful follow-up many patients will develop metastasis. For most this is an incurable condition and the median survival for these patients is only 2 years (2). Therapy with 5-Fluorouracil (FU)/Leucovorin, oxaliplatin and irinotecan with or without bevacizumab are conventionally used as first and second line therapy for metastatic colorectal cancer. Third line therapy options are limited to anti-epidermal growth factor receptor (EGFR) therapy Cetuximab or Panitumumab either as monotherapy or in combination with Irinotecan. Recent data (see Table 1) has demonstrated that KRAS mutation status is a predictor of benefit to anti-EGFR therapy, with wild-type tumours demonstrating a response rate of 10-17% to monotherapy while a 0% response rate is observed among KRAS mutant tumours. The purpose of this exploratory study is to examine the correlation of biomarkers (PTEN, BRAF, amphiregulin, c-MET, EGFR) with response rate among patients with KRAS wild type tumours treated with panitumumab. If a high response subgroup can be identified, this may support the use of Panitumumab with combination therapy in the first line setting. Secondary objectives are to determine the prognostic and predictive value of CTCs for patients treated with single agent panitumumab and to describe overall survival (OS) and progression free survival (PFS) in registered patients.