Can extra tests on cancer samples identify more patients with bowel/colon cancer who should be treated with drugs called anti-EGFR agents?

See also: https://www.cancerresearchuk.org/about-cancer/find-a-clinical-trial/a-trial-to-find-out-if-more-people-with-bowel-cancer-could-have-cetuximab-and-panitumumab-ariel
Background and study aims
Not all bowel (colon) cancers are the same. It is known that tumours which start in the right side of the bowel (right-sided), behave differently than those on the left side. Patients with advanced cancer (cancer that has spread to other areas) whose tumours are right-sided do not tend to live as long as those with left-sided. Right-sided tumours may not respond as well to drugs used to treat cancer. It is therefore important for researchers to find ways to improve the treatments and cancer outcomes for patients with right-sided tumours.
Anti-EGFR agents (cetuximab and panitumumab) are drugs that switch off the growth signals from the Epidermal Growth Factor Receptor (EGFR), which is a protein on the cancer cell which makes cancer grow and spread. We know that if a protein (RAS) is altered and becomes abnormal on the tumour then a patient will not respond to treatment with anti-EGFR drugs. Doctors now test the tumours of all patients and only treat those patients without these abnormal RAS proteins (RAS-wt) with anti-EGFR drugs.
These drugs are available to patients in the UK with RAS-wt advanced bowel cancer alongside chemotherapy. However in some patients with RAS-wt cancers the drugs do not work, despite the proteins being normal. This means that patients experience unpleasant side effects without any benefits. Cancer researchers have tried to understand why some patients benefit from anti-EGFR drugs, and some do not.
Research has shown that some patients with tumours that start in the right-side of the bowel do not respond to this treatment and in many countries anti-EGFR drugs are not recommended for patients with a right-sided tumour. UK data shows that some patients with right-sided bowel cancers respond well to anti-EGFR drugs, but some patients do worse and their cancer grows more quickly and the side effects are more severe, than when treated with chemotherapy alone. This creates a problem for oncologists and patients. An extra test to help identify patients with right-sided bowel cancer that are most likely to benefit from anti-EGFR drugs would help resolve this.
Further research has found different tumour proteins (EREG and AREG) that identify those patients most likely to respond to anti-EGFR drugs, including patients with right-sided bowel cancers. Further research on the importance of this protein is needed before it can be used in clinics.
Who can participate?
Study participants will have been diagnosed with advanced bowel cancer which started on the right side of the abdomen (tummy). Participants will have a gene (RAS) which is normal i.e. RAS wild type (RAS-wt). Each participant is carefully assessed using tests to check that they are suitable for inclusion in the study. These include: blood tests, an assessment of medical history, clinical examination, pregnancy test (where appropriate) and a CT scan.
What does the study involve?
Patients who are suitable will be randomised to receive treatment with chemotherapy alone or chemotherapy with anti-EGFR drugs. The chemotherapy given will be the standard treatment for this type of cancer. A computer will chose at random which participants receive an anti-EGFR agent, with the chemotherapy. Participants allocated to this treatment, will discuss with their doctor which of the anti-EGFR agents, cetuximab and panitumumab, might be most suitable. The treatment is given every two weeks for as long as the drugs continue to control the cancer, and as long the treatment is tolerable.