Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

FDA Provides Guidance on Companion Diagnostics

Print this article
Share this page:
August 15, 2014

This month, the U.S. Food and Drug Administration (FDA) released its new final document that will guide the development and subsequent approval of companion diagnostics. These are laboratory tests that are developed specifically to "provide information that is essential for the safe and effective use of a corresponding therapeutic product," explains the FDA. In many cases, results from these tests are needed for health practitioners to be able to make clinical decisions regarding treatment of their patients.

As an example, many new therapies developed in recent years target cancers that have certain genetic mutations, and these drugs generally have fewer side effects than traditional chemotherapy. Because only patients who have cancer with the specific mutations will benefit from the targeted therapy, laboratory tests must be developed to detect the mutations (see Genetic Tests for Targeted Cancer Therapy). Usually, the cancer drug and genetic test are developed concurrently, thus the tests are referred to as "companion diagnostics." One such example is the genetic test for HER2/neu that can help determine whether the drug trastuzumab (Herceptin®) will be effective in treating a person's breast cancer.

The FDA is the agency responsible for regulating laboratory tests that are marketed in the U.S. to ensure that they perform as intended and cause no harm. Companion diagnostics, like other commercial laboratory tests, must be shown to be reliable in detecting or measuring the substance of interest before they are approved for use. (For more details on this, see the article Commercial Laboratory Tests and FDA Approval.)

With the recent emergence of many new therapies and accompanying tests, the FDA saw the need for defining what is and is not a companion diagnostic and therefore prepared this new guidance. The document is also intended to explain why FDA oversight is needed in the development and approval of this relatively new category of tests. It includes specifics such as that labeling for both the drug (or other therapeutic product) and the test should contain language stating that the test is essential if the therapy is to be prescribed for a patient. In the guidance, the FDA also recommends that, in most cases, the therapy and the test be cleared for use simultaneously.

"The companion diagnostics guidance is intended to help companies identify the need for these tests during the earliest stages of drug development and to plan for the development of a drug and a companion test at the same time. The ultimate goal of the final guidance is to stimulate early collaborations that will result in faster access to promising new treatments for patients living with serious and life-threatening diseases," says the FDA.

Article Sources

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used. To access online sources, copy and paste the URL into your browser.

(July 31, 2014) FDA Press Release. FDA takes steps to help ensure the reliability of certain diagnostic tests. Available online at through Accessed August 6, 2014.

(August 6, 2014) In Vitro Companion Diagnostic Devices, Guidance for Industry and Food and Drug Administration Staff. Available online at through Accessed August 6, 2014.