PROSPECT-C is a phase II study investigating the molecular markers of response or resistance to anti-epidermal growth factor receptor (EGFR) antibodies.

Cetuximab or panitumumab are two monoclonal antibodies that are routinely offered to patients with metastatic colorectal cancer when they have no mutation in RAS genes. In Royal Marsden Hospital patients, who are refractory to all standard therapies and have metastatic colorectal cancer are offered one of these agents in third line metastatic setting. Whilst the mechanisms of response/resistance to these therapies are well studies, they are still incompletely understood. The main hypothesis of this study is that finding mechanisms of response and/or resistance by using novel techniques such as next generation sequencing (NGS) and/or digital droplet polymerase chain reaction (ddPCR) to these therapies will allow better patient selection and application of precision medicine in such patients.

Inclusion Criteria:

1. patients with a histologically confirmed diagnosis of metastatic colorectal adenocarcinoma
2. wild-type RAS tumour status by molecular analysis at the Royal Marsden Hospital
3. patients with inoperable metastatic colorectal cancer who are scheduled to be treated with cetuximab (or panitumumab) either as monotherapy or in combination with chemotherapy with palliative intent
4. patients who have received prior treatment with oxaliplatin, irinotecan and fluoropyrimidine containing chemotherapy regimens OR intolerance/contraindication to either oxaliplatin or irinotecan based chemotherapy, and planned to receive retreatment with EGFR monoclonal antibody (mAB) monotherapy or with EGFR mAB combined with a chemotherapy (irinotecan or oxaliplatin-based) that a patient has already received for a minimum of 3 months during a previous line of therapy.
5. patients who have metastatic disease sites which are amenable to core biopsy (preferably liver, soft tissue or nodal disease, with at least one lesion 3cm or more in diameter. If largest lesion 2-3cm diameter, eligibility to be discussed with radiologist prior to study entry)
6. patients aged 18 years or older
7. able to provide fully informed consent, to comply with the trial and follow-up procedures
8. receiving treatment at the Royal Marsden Hospital

Exclusion Criteria:

1. patients who have previously received treatment with cetuximab or panitumumab
2. previous malignancy other than colorectal cancer in the past 5 years, other than pre-invasive malignancy of the cervix or basal cell carcinoma, EXCEPT when the patient has histological confirmation of metastatic colorectal cancer at the site that is planned to be biopsied at baseline and on progression of disease
3. patients who are being anti-coagulated with warfarin or heparin
4. Patients that are participating in another clinical trial involving an investigational medicinal product, unless it is more than 14 days after they have ceased the investigational medicinal product
5. Patients that are participating in another research study involving tumour tissue biopsies planned to take place during the time that the patient is participating in this study

patients with a histologically confirmed diagnosis of metastatic colorectal adenocarcinoma