Investigating the efficacy of Cetuximab Monotherapy versus Continuation after induction treatment with chemotherapy + Cetuximab in inoperable or irresectable and non-progressive metastatic colorectal cancer after first line induction treatment for 24 weeks with mFOLFOX6/FOLFIRI and Cetuximab treatment. Reinduction treatment will be done in case of progression.

Investigating the efficacy of Cetuximab Monotherapy versus Continuation after induction treatment with chemotherapy + Cetuximab in inoperable or irresectable and non-progressive metastatic colorectal cancer after first line induction treatment for 24 weeks with mFOLFOX6/FOLFIRI and Cetuximab treatment. Reinduction treatment will be done in case of progression. This treatment is continued until progression or severe toxicity.

Inclusion Criteria:

• Histological proof of colorectal cancer (in case of a single metastasis, histological or cytological proof of this lesion should be obtained);
• Distant metastases (patients with only local recurrence are not eligible);
• Unidimensionally measurable disease (> 1 cm on spiral CT scan or > 2 cm on chest X-ray; liver ultrasound is not allowed). Serum CEA may not be used as a parameter for disease evaluation;
• In case of previous radiotherapy, at least one measurable lesion should be located outside the irradiated field;
• Ongoing or planned first line treatment with 6 cycles of mFOLFOX6/FOLFIRI plus Cetuximab.

At randomisation:

• WHO performance status 0-1 (Karnofsky PS > 70%);

• Laboratory values obtained ≤ 2 weeks prior to randomisation:

  • adequate bone marrow function (Hb > 6.0 mmol/L, absolute neutrophil count > 1.5 x 109/L, platelets > 100 x 109/L),
  • renal function (serum creatinine ≤ 1.5x ULN and creatinine clearance, Cockroft formula, > 30 ml/min),
  • liver function (serum bilirubin ≤ 2 x ULN, serum transaminases ≤ 3 x ULN without presence of liver metastases or ≤ 5x ULN with presence of liver metastases);

• Negative pregnancy test in women with childbearing potential;

• Expected adequacy of follow-up;

• Institutional Review Board approval;

• Written informed consent Exclusion criteria;

• History or clinical signs/symptoms of CNS metastases;

• History of a second malignancy ≤ 5 years with the exception of adequately treated carcinoma of cervix or basal/squamous cell carcinoma of skin.

Exclusion Criteria:

• Prior adjuvant treatment for stage II/III colorectal cancer ending within 6 months before the start of induction treatment;
• Any prior adjuvant treatment after resection of distant metastases;
• Previous systemic treatment for advanced disease.