companion diagnostic
Also written as: CDx — Companion Diagnostic
An FDA-approved test required to identify patients eligible for specific targeted cancer therapies.
Full Definition
A companion diagnostic is a medical device, often an in vitro diagnostic test, that provides information essential for the safe and effective use of a corresponding therapeutic product. In oncology, companion diagnostics identify patients who are most likely to benefit from a particular targeted therapy or who may be at increased risk for adverse reactions. These tests are developed concurrently with therapeutic agents and undergo rigorous FDA review to ensure analytical and clinical validity for specific drug-diagnostic combinations.
Usage
Usage note: Distinct from complementary diagnostics, which are not required for drug approval.
In Context
- "The companion diagnostic test confirmed HER2 overexpression, making the patient eligible for trastuzumab therapy." — Clinical documentation
- "FDA approval of the new targeted therapy included a specific companion diagnostic requirement for patient selection." — Regulatory documentation