Biomarcer-2: This study aims to determine whether people with a high level of AREG/EREG cancer cell markers for advanced stage colorectal (bowel) cancer have a better treatment response to a combined chemo- and biological regimePhase II single arm study to explore the efficacy of cetuximab (in combination with irinotecan based treatment) in advanced stage RAS/BRAF wild-type right-sided colorectal cancer with high AREG/EREG expression

Exclusion

1. Previous exposure to an EGFR inhibitor
2. Grade 2 or greater diarrhoea at time of enrolment
3. Any contraindication to combination treatment with cetuximab + irinotecan based treatment
4. History of another primary cancer within the last 3 years that was either not treated with curative intent or has persisted or relapsed.
5. Patients with multiple primary colorectal cancers
6. Inadequate paraffin tumour sample available for AREG/EREG expression confirmation.
7. Tumours with low AREG/EREG expression levels ( less than 50% tumour cell positivity for either ligand) as determined by central laboratory testing of archival tumour tissue.
8. Inadequate organ function:
a. Moderate/severe renal impairment (GFR less than 45 ml/min), as calculated by the Cockcroft-Gault equation
b. Absolute neutrophil count less than 1.0x109/L
c. Platelet count less than 75x109/L
d. Haemoglobin less than 80 g/L (transfusion permitted)
e. Aspartate aminotransferase or Alanine aminotransferase greater than 2.5x upper limit of normal, or greater than 5x upper limit of normal if liver metastases are present
9. Medical or psychiatric condition or occupational responsibilities that may preclude compliance with the protocol
10. Participants of child bearing potential unwilling to comply with effective contraceptive use for the duration of the study, including period of screening and 90 days following administration of last dose anti-cancer therapy.
11. Use of any concurrent chemotherapy (excluding irinotecan +/- a fluoropyrimidine), investigational product, biologic or hormonal therapy for cancer treatment. Concurrent use of hormonal therapy for non-cancer related conditions (e.g. Hormone replacement) is acceptable. Palliative radiotherapy for symptom control is allowed for sites of metastatic disease, which are non-target lesions and not included in RECIST response assessment.