PIK3CA Biomarker

The PIK3CA gene is responsible for making the p110 alpha protein, which is one part of an enzyme called phosphatidylinositol 3-kinase (PI3K). The p110 subunit is catalytic, which means that it performs the action of PI3K while the other subunit (produced by a different gene) regulates the activity of the enzyme. PI3K promotes and regulates many cellular processes including growth and division (proliferation), migration or movement of cells, apoptosis (programmed cell death) and survival. The mutation is a driver mutation that drives the growth of cells.

PIK3CA is in the PI3K/AKT/mTOR pathway, a pathway involved in several different processes in 
cell growth.

Routine testing for the PIK3CA biomarker is not currently recommended or standard of care. If you are diagnosed with stage IV, metastatic colorectal cancer (mCRC) and you have comprehensive biomarker panel testing done on your tumor through Next Generation Sequencing (NGS), PIK3CA will be part of the panel.

Knowing your biomarker status will help you and your doctor make a personalized treatment plan with therapies tailored specifically to your cancer.

• A mutation in the PIK3CA gene is a prognostic biomarker for aggressive tumor growth. Patients with this mutation have an increased risk for the tumor coming back or recurring.
• Research shows that taking a daily aspirin may be beneficial and reduce the risk of recurrence for patients with localized, early stage disease and a PIK3CA mutation.

Speak to your doctor before taking any medications including over-the-counter and herbal supplements.

• Research shows that patients with double mutations (PIK3CA and RAS) may have a slightly better prognosis than those patients with only the PIK3CA mutation or a PIK3CA mutation and BRAF wildtype.
• A mutation in PIK3CA is also a predictive biomarker for a poor response to anti-EGFR treatments, so patients with a PIK3CA mutation should not receive cetuximab or panitumumab.

Patients with PIK3CA-mutated colorectal cancer should receive standard chemotherapy such as: FOLFOX, CAPOX, or FOLFIRI with or without bevacizumab, an antibody that cuts off the blood supply to the tumor.

There is at least one drug being used successfully in PIK3CA-mutated breast cancer and it has opened up clinical trials for other PIK3CA-mutated solid tumors including colorectal cancer.

Every treatment has the potential to cause some side effects. Some people may be more sensitive than others to a drug. The response to a specific treatment also depends on your medications, vitamins, and herbal supplements.

Tell your doctor and pharmacist about all your medications, vitamins, and treatments. If you are experiencing severe side effects, call your doctor immediately.

For more on side effects of other chemotherapy regimens, click here.