Companion diagnostics ('in vitro diagnostics')

Guidance for notified bodies on the procedure for obtaining a scientific opinion from the European Medicines Agency (EMA) on the suitability of companion diagnostics for medicinal products.

A companion diagnostic is an in vitro diagnostic test that supports the safe and effective use of a specific medicinal product. It does so by identifying patients that are suitable or unsuitable for treatment. 

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

The Regulation applies from 26 May 2022.

For more information on medical devices, see:

• Medical devices

EMA role

Before it can issue a CE certificate, the notified body must seek a scientific opinion from EMA on the suitability of the companion diagnostic to the medicinal product concerned if:

• the medicinal product falls exclusively within the scope of the centralised procedure for the authorisation of medicines;
• the medicinal product is already authorised through the centralised procedure;
• a marketing authorisation application for the medicinal product has been submitted through the centralised procedure.

For other substances, the notified body can seek the opinion from a national competent authority or EMA.

EMA has established a Companion Diagnostic (CDx) Expert Group. The group supports the committees and the EMA regulatory network in the area of in vitro diagnostics (companion diagnostics) consultation procedures and related issues.

Guidance

A guidance document is available on the consultation procedure whereby notified bodies seek a scientific opinion from EMA. This is joined by a question-and-answer (Q&A) document on practical arrangements.

This guidance should help notified bodies, device manufacturers and medicinal product applicants understand the procedural aspects of the consultation process.

The FAQ document also available below provides an overview of EMA’s line of thinking on issues related to predictive biomarker-guided medicinal product development and assessment involving companion diagnostic (CDx).

Guidance on the procedural aspects for the consultation to the European Medicines Agency by a notified body on companion diagnostics - Revision 1

Reference Number: EMA/198592/2022 Rev.1 Legal effective date: 17/12/2024

Questions & answers - Practical arrangements on the companion diagnostics consultation procedure to the European Medicines Agency by notified bodies

Reference Number: EMA/619893/2022 Rev.2

Questions & answers - Practical arrangements on the companion diagnostics consultation procedure to the European Medicines Agency by notified bodies - tracked changes

Reference Number: EMA/619893/2022 Rev.2

Frequently asked questions on medicinal products development and assessment involving companion diagnostic (CDx)

Reference Number: EMA/CHMP/821321/2022

Application forms

Notified bodies should use the application forms below to request an initial or follow-up consultation.

Letter of intent for the submission of a consultation to the European Medicines Agency by a notified body on a companion diagnostic in accordance with Regulation (EU) 2017/746

Reference Number: EMA/781233/2021

Application form for initial consultation by a notified body on a companion diagnostic

Application form for follow-up consultation procedure by a notified body on a companion diagnostic

Consultation on companion diagnostic - Assessment report template

Submitted comments on 'Draft guidance on the procedural aspects for the consultation to the European Medicines Agency by a notified body on companion diagnostics'

For more information:

• Full list of procedural timetables

Superseded guidance

Superseded - Guidance on the procedural aspects for the consultation to the European Medicines Agency by a notified body on companion diagnostics

Adopted Reference Number: EMA/198592/2022 Legal effective date: 01/07/2022

Page update history

An update log is available to show the date and summary of changes to this webpage. It does not include updates to linked documents or minor edits like typos or broken link fixes.

The tracking of updates begins in March 2026.

See update history

2 March 2026

Page first published; Content has been moved from another webpage as part of a broader content reorganisation