IVD that is essential for the safe and effective use of a corresponding medicinal product to identify eligible patients or monitor treatment response.

Definition

Article 2(7) of the IVDR defines a companion diagnostic as a device essential for the safe and effective use of a corresponding medicinal product to (a) identify, before or during treatment, patients most likely to benefit, or (b) identify patients likely to be at increased risk of serious adverse reactions. Rule 3(c) of Annex VIII classifies companion diagnostics as Class C.

Why it matters

CDx conformity assessment requires a mandatory consultation between the notified body and the EMA (or a Member State competent authority) on the suitability of the device in relation to the medicinal product. This adds meaningful lead time versus a non-CDx Class C IVD and requires the manufacturer to align its evidence package with the drug label.

Common pitfalls

•Assuming a biomarker assay is a CDx only if the drug label names it. IVDR looks at the intended purpose claimed by the IVD manufacturer.
•Underestimating the EMA consultation timeline in project plans.
•Failing to coordinate label changes between pharma partner and IVD manufacturer, which can invalidate the CDx claim.

Sources

Regulation (EU) 2017/746, Article 2(7) and Article 48(5) · EUR-Lex
MDCG 2020-16 Rev.2 Guidance on Classification · MDCG
IMDRF Documents · IMDRF

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Regulatory pathway choice - 510(k) vs PMA, 510(k) vs De Novo, Abbreviated vs Special 510(k).
Quality systems - QSR vs ISO 13485, QMSR vs QSR.
Software classification - SaMD vs SiMD, Locked vs adaptive AI.
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