Definition of biomarkers and efficacy end-points


1. Introduction

1.3. Companion Diagnostics

A validated (proven) test for each biomarker is needed.The test will accurately measure whether a biomarker is present and at what level. It may be a laboratory test or a test kit. The test may help to:

  • Select patients who are likely to respond to a medicine.
  • Exclude patients who are likely to have an adverse reaction.
  • Determine the best dose for a patient.

‘Companion diagnostics’ are tests that are validated and approved for marketing in combination with a new medicine. They can be:

  • Developed once a medicine is on the market.
  • Developed alongside a medicine that is still under development.

Many companies that develop therapies for cancer have also begun to consider how a diagnostic test can benefit the treatment. The trend is to develop medicines and companion diagnostics together, rather than have both developments happen in isolation. Some examples: Sight: Companion diagnostics (CDx): definition, importance and role ( or Foundation Medicine: Companion Diagnostics Explained: Their Critical Role in Cancer Care and Our Latest Approvals | Foundation Medicine

More information:

1) EMA: The In-Vitro Diagnostic Devices Regulation (Regulation (EU) 2017/746) introduces a new classification system for companion diagnostics and the obligation to undergo a conformity assessment by a notified body.

2) Biomarker and Companion Diagnostics—A Review of Medicinal Products Approved by the European Medicines Agency

3) Questions & Answers-practical arrangements on the companion diagnostics consultation procedure to the European Medicines Agency by notified bodies