# Competition watchdog probes Biogen over MS drug blood test

> The Authority for Consumers and Markets (ACM) is investigating whether drug maker Biogen abuses a dominant position by limiting who can get its Stratify blood test. That could affect price, supply and choice for MS patients and doctors.

Economy · published 2026-11-06 14:45 · https://nlnow.nl/a/competition-watchdog-probes-biogen-over-ms-drug-blood-test/

The ACM has opened an investigation into drug maker Biogen over possible abuse of a dominant position in multiple sclerosis (MS) medication and the blood tests that go with it. It is looking at how Biogen makes its anti-JCV blood test, Stratify, available in the Netherlands.

Stratify is only available to patients treated with Biogen's drug Tysabri, or considering that treatment. Patients on other MS medication cannot currently get it. The ACM says this may hinder new and existing suppliers of MS medicines based on natalizumab from competing effectively. That could affect price, supply and freedom of choice for healthcare providers and patients.

Tysabri contains the active substance natalizumab. Medicines with that substance carry a risk of a life-threatening brain disease. An anti-JCV blood test such as Stratify can be used to assess that risk.

Companies may hold a dominant position, the ACM says, but may not abuse it. Competition rules ban that. Abuse can include imposing unfair terms on customers, which can raise costs for companies and, in the end, mean higher prices and less innovation for consumers.

The Italian competition authority (AGCM) began a similar investigation into Biogen earlier this year. The ACM and the AGCM are cooperating where their investigations overlap.

The ACM will now examine whether Biogen broke competition rules. It says it may also conclude that the law was not broken. It asks anyone with relevant information on Tysabri or the Stratify test to report it to the ACM.

## Background

- **ACM (Autoriteit Consument & Markt)**: The Authority for Consumers and Markets is the Dutch regulator that supervises competition and consumer protection in the Netherlands. It checks whether companies abuse a dominant market position, form illegal cartels, or merge in ways that harm competition, and it also oversees sectors such as telecoms, energy and transport. Its investigations can lead to fines and binding orders for businesses operating in the Netherlands.

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