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    Trial Design

    Companion Diagnostic

    A companion diagnostic is an in vitro device or imaging tool that provides information essential for the safe and effective use of a corresponding therapeutic product, typically by identifying patients eligible for treatment.

    Companion diagnostics (CDx) are co-developed and co-approved with their associated therapy. Classic examples include HER2 testing for trastuzumab, BRAF testing for vemurafenib, and PD-L1 testing for pembrolizumab.

    FDA regulates CDx under the In Vitro Diagnostic regulations and typically requires a PMA submission. Co-development is governed by the 2014 In Vitro Companion Diagnostic Devices guidance.

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