The Role of Companion Diagnostics (CDx) in Personalized Healthc…

As science and technology are rapidly advancing, we are moving towards personalized healthcare — developing treatments tailored to individuals based on their genomes. This is especially helpful for patients who have acquired a disease through mutations in their genes such as cancer.

At the moment we use a “one size fits all” approach when it comes to treatments, however certain medicines and drugs may work differently on individuals — some people may not respond at all, whilst others may experience undesired side effects and it may be difficult to predict. The key to personalized healthcare is to understand how an individual’s genes work with each other and interact with the environment. This knowledge can then help predict how they will respond to medication, and thus reducing the rate of risk, and increasing the chances of recovery, especially when time is of utmost importance.

In oncology (the study of cancers) we can do this by using companion diagnostic (CDx) tests. These are medical devices that help to identify specific gene changes in a tumor or biomarkers targeted by a specific drug that can be used to determine a reaction. The results of tests can help doctors and healthcare providers to make a better-informed decision on if a patient should receive the drug or not in terms of safety and effectiveness. Companion diagnostics are designed to be used hand in hand with drugs and are developed before a new drug enters clinical trials, thus it increases the likelihood that patients in clinical trials will benefit from the treatment that they are receiving. CDx is transforming the speed of healthcare collaborations and in turn providing faster access to treatment for patients with life-threatening illnesses.

The first companion diagnostic test was approved by the FDA in 1998. It was called the HercepTest and developed by Dako Denmark (now known as Agilent Technologies). It was an Immunohistochemistry (IHC) assay, that could detect human epidermal growth factor receptor 2 (HER2) protein overexpression in breast tumors. Using this test, it was possible to identify patients suffering from breast cancer who could benefit from the targeted therapy Herceptin (trastuzumab). It was a game-changer for the industry, and since then over 38 other CDx tests have been approved by the FDA.