Inclusion Criteria:

- Age>18 years

- Histological diagnosis of colorectal cancer

- Metastatic disease not amenable to resection

- Measurable disease as assessed by CT scan using RECIST criteria

- Received and failed fluoropyrimidine therapy, where failure is defined as
radiological progression after therapy for metastatic disease, prior adjuvant
therapy, or toxicity limiting further therapy

- Received and failed oxaliplatin therapy, where failure is defined as radiological
progression after therapy for metastatic disease, prior adjuvant therapy ,or
toxicity (including neuro-toxicity) limiting further therapy

- Received and failed irinotecan therapy, where failure is defined as radiological
progression after therapy for metastatic disease or toxicity limiting further
therapy

- ECOG PS 0-1

- Adequate bone marrow function with platelets > 100 X 109/l; neutrophils > 1.5 X 109/l

- Adequate renal function, with calculated creatinine clearance >40 ml/min (Cockcroft
and Gault).

- Adequate hepatic function with serum total bilirubin < 1.25 X upper limit of normal
range and ALT or AST<2.5xULN (<5xULN if liver metastases present)

- Life expectancy of at least 12 weeks

- No other concurrent uncontrolled medical conditions

- No other malignant disease apart from non-melanotic skin cancer or carcinoma in situ
of the uterine cervix or any other cancer treated with curative intent >2 years
previously without evidence of relapse

- Women and partners of women of childbearing potential must agree to use adequate
contraception

- Written informed consent including consent for biomarker studies

Exclusion Criteria:

- Medical or psychiatric conditions that compromise the patient's ability to give
informed consent or to complete the protocol

- Prior treatment with drugs targeting EGFR such as cetuximab, panitumumab or erlotinib

- Participation in any investigational drug study within the previous 4 weeks

- Patients with uncontrolled clinically significant cardiac disease, arrhythmias or
angina pectoris

- Untreated CNS metastases

- Pregnancy or lactation

- k-ras mutant tumours now excluded