Table 3 Detailed inclusion and exclusion criteria

• Histologically confirmed metastatic colorectal cancer

• KRAS-wildtype status of the tumor

• No history of therapy with an EGFR targeting agent

• No history of previous chemotherapy for advanced disease

• Measurable tumor lesion with a diameter no smaller than 1.0 cm detected by CT, MRIor ultrasound

• For contrast-enhanced ultrasound: metastases no smaller than 2.0 cm detected by ultrasound

• ECOG-performance status 0 or 1 or Karnofsky performance scale min. 70%

• Life expectancy > 12 weeks

• Age ≥ 18 years

• Adequate hematologic, renal and hepatic function

• Ability of the patient to understand the character and individual consequences of this clinical trial

• Written informed consent (must be available before enrolment in the trial)

• For women and men with childbearing potential adequate double barrier contraception, for women: negative pregnancy test

• Any contraindications for chemotherapy according to the Folfiri regimen

• Non-curatively treated malignancy within the last 5 years

• Uncontrolled or insulin-dependant diabetes mellitus

• Evidence of CNS metastases

• Uncontrolled infection

• Significant cardiac disease (unstable angina pectoris or cardiac symptoms according to NYHA classification III or IV)

• Active serious illness which renders the patient unsuitable for study entry or multiple blood sampling

• Pregnancy and lactation

• History of hypersensitivity to cetuximab or to any drug with similar chemical structure or to any excipient present in the pharmaceutical form of the investigational medicinal product

•Participation in other clinical trials or observation period of competing trials, respectively