The Italian Competition Authority is investigating allegations that Biogen abused its dominant position by bundling its multiple sclerosis (MS) treatment and related diagnostic test in a manner that harmed competition from Sandoz’s biosimilar MS treatment.

On 27 May 2026, the Italian competition authority (AGCM) announced inspections and a formal investigation of Biogen following a complaint from a biosimilar competitor.

The AGCM is investigating allegations that Biogen abused its dominant position by bundling its multiple sclerosis (MS) treatment and related diagnostic test in a manner that harmed competition from Sandoz’s biosimilar MS treatment.

This case will be very important for pharmaceutical companies offering medicines together with diagnostics, as it addresses whether the diagnostics must be made available for use with competing treatments (including biosimilars and generics), or may be limited solely for use with the company’s own medicines.

Factual Background

Biogen’s MS treatment and diagnostic.  Biogen’s MS treatment Tysabri (natalizumab – NZB) has been marketed in Italy since February 2007.  As patients treated with NZB must be regularly tested for the risk of developing progressive multifocal leukoencephalopathy (PML), Biogen developed the Stratify diagnostic (offered through the Unilabs laboratory network) and provides it free of charge to patients receiving Biogen’s Tysabri.

Sandoz’s entry with a biosimilar MS treatment and a diagnostic.  In 2024, after expiry of Biogen’s patent for Tysabri, Sandoz launched a competing biosimilar Tyruko at a list price approximately 20% lower than Tysabri.  Sandoz also supplies a diagnostic ImmunoWell to patients free of charge to test for risk of PML.

Limited uptake of Sandoz’s MS treatment.  Since entry, Sandoz has successfully won procurement tenders in Italy covering approximately 75% of national NZB demand by volume. However, Sandoz’s actual sales of Tyruko have been significantly lower, apparently because HCPs prefer Biogen’s Stratify diagnostic (developed based on more than 15 years of data) over Sandoz’s ImmunoWell (for which more limited data is available).

The Alleged Anticompetitive Bundling

According to the AGCM’s decision opening the investigation, Biogen has conditioned the supply and use of the Stratify diagnostic solely for patients treated with Biogen’s Tysabri and has refused to supply Stratify to Sandoz.  Healthcare facilities seeking to obtain the Stratify test for use with patients treated with Sandoz’s Tyruko receive the following automated refusal:

“We regret to inform you that the request for the Stratify JCV test for this patient cannot be processed. The JCV testing service is fully funded by Biogen for patients who are being evaluated for or have been prescribed TYSABRI. Biogen does not have clinical data on the risk of PML associated with products other than TYSABRI and therefore cannot provide guidance on mitigating the risk of PML with products other than TYSABRI.”

The AGCM suspects that such bundling allows Biogen to leverage its market power from its Stratify diagnostic to protect its sales of Tysabri and hinder competition from Sandoz’s Tyruko.  The AGCM decision also states that Biogen has filed applications for divisional patents aimed at tying Stratify with Tysabri (several of which were subsequently annulled) and that Biogen appears to have issued misleading communications indicating that Stratify had been developed exclusively in the context of the supply of Tysabri, thus excluding its use for patients treated with other medicines.

Key Issues in this Case

Are diagnostics separate products from the MS treatments? For a finding of anticompetitive bundling, the AGCM must establish that Biogen has bundled two distinct products for which there is separate customer demand. Biogen is likely to argue that, in this case, the relevant diagnostics do not constitute separate products, particularly as both Biogen and Sandoz provide the diagnostics free of charge.  Further, while the AGCM cites Biogen’s patent as evidence that the relevant diagnostics could potentially be supplied separately for other purposes, the data in the AGCM’s market definition section acknowledges that, in practice, such diagnostics are solely supplied for MS patients treated with Tysabri or Tyruko.

Obligation to provide access to a competitor?  Especially as Sandoz has access to its own diagnostic, Biogen will question why it would be obliged to share access to its Stratify diagnostic for use with Sandoz’s Tyruko.  The figures provided by the AGCM indicate that Sandoz has not been excluded from the market, and that Tyruko and ImmunoWell are used by approximately 30% of patients.  In this context, Biogen may argue that Sandoz should similarly be required to invest in the further collection of data to demonstrate the quality of its ImmunoWell diagnostic, rather than asking the competition authority to intervene and force Biogen to share its proprietary diagnostic.

Objective clinical justification?  As Biogen’s PML risk probability table was built exclusively on Tysabri/Stratify patient data, Biogen will also likely argue that it has an objective justification to prevent the use of Stratify to predict risks arising for patients receiving different treatments.

Key Takeaways

Pharmaceutical companies supplying treatments alongside diagnostics should proactively review the competition law implications of any strategy that conditions access to a proprietary diagnostic on use of the company’s own treatment. The Biogen investigation illustrates that competitors may raise complaints and competition authorities may conduct inspections and investigations, particularly if there is potential impact on the public health system.

That said, this case does not mean that innovative pharmaceutical companies must always make diagnostics available for use with competing treatments. As noted above, there are several issues that the AGCM would have to address in order to establish an infringement.

Companies evaluating whether to supply diagnostics to competitors must also consider the competition law risks of the alternatives. Had Biogen supplied the Stratify diagnostic for use with Tyruko, it would have presumably set a high price for Stratify (rather than providing it for free), and might instead have faced competition law claims by Sandoz of excessive pricing.

Ultimately, whether innovative pharmaceutical companies are required to make diagnostics available for use with competing treatments is a question that will depend on the specific facts and market conditions.  Companies should ensure that any commercial strategy involving diagnostics is subject to competition law review before implementation and that internal strategy documents support the legitimacy of the strategy in the event of later challenge.