Second Medical Uses Cannot Reset the SPC First-Authorisation Requirement for the Same Active Ingredient

1. Introduction

The High Court dismissed Merck Serono S.A.’s appeal against the Controller of Intellectual Property’s refusal to grant a supplementary protection certificate (“SPC”) for Mavenclad, a treatment for relapsing-remitting multiple sclerosis. Although Mavenclad’s patented dosage regimen represented substantial pharmaceutical innovation, its active ingredient, cladribine, had already received marketing authorisation in another medicinal product, Litak.

The central issue was whether a patent protecting a new therapeutic use of an existing active ingredient could support an SPC where the authorisation for that new use was the first falling within the patent’s protection, but not the first authorisation for the active ingredient itself.

Applying the Court of Justice of the European Union’s (“CJEU”) decision in Santen SAS v. Directeur général de l'Institut national de la propriété industrielle, Case C-673/18, the High Court held that it could not. For Article 3(d) of Regulation (EC) No. 469/2009, the relevant “product” is the active ingredient or combination of active ingredients, not its patented therapeutic application.

The judgment principally confirms and applies an existing EU rule rather than establishing a new EU eligibility test. Its particular significance lies in rejecting an attempt to distinguish the same active ingredient by reference to its different pharmacological, immunological and metabolic actions in different treatments.

2. Background and Procedural History

The patented innovation

Merck owned Irish patent EP (IE) 1 827 461 B1, entitled “Cladribine Regimen for Treating Multiple Sclerosis”. The patent application was filed on 20 December 2005, the patent was granted on 29 February 2012, and it expired on 19 December 2025.

The invention concerned pulsed oral administration of cladribine: treatment over a short period, followed by a treatment-free interval and subsequent administration. The claims protected cladribine formulations for use according to the specified regimen and the use of cladribine to prepare the relevant formulation. The innovation therefore lay in its therapeutic application and dosage regimen, rather than in the discovery of cladribine itself.

The competing marketing authorisations

Mavenclad received marketing authorisation on 22 August 2017, approximately twelve years after the patent application. However, cladribine had already been authorised on 14 April 2004 as the active ingredient in Litak, a treatment for hairy cell leukaemia supplied by an unrelated company.

The basic patent did not cover Litak. Nevertheless, both medicinal products contained the same active ingredient. Whether the earlier authorisation fell within Merck’s patent protection became a central point of disagreement.

The SPC application and refusal

Merck applied for an SPC on 9 February 2018. If granted, it would have expired on 19 December 2030. The application initially relied on the approach taken in Neurim Pharmaceuticals (1991) Ltd v. Comptroller-General of Patents, Case C-130/11, which appeared to permit SPC protection for certain new therapeutic applications notwithstanding an earlier authorisation for the same ingredient.

The Controller stayed examination pending the CJEU’s decision in Santen SAS v. Directeur général de l'Institut national de la propriété industrielle. Following that decision, further submissions, scientific evidence and a hearing, the Controller refused the application on 8 September 2025. The Mavenclad authorisation was not the first authorisation to place cladribine on the market as a medicinal product.

Merck appealed under section 96 of the Patents Act 1992, as applied to SPC decisions through the relevant EU and domestic provisions. It sought an order replacing the refusal with a grant and, if necessary, a preliminary reference to the CJEU under Article 267 TFEU.

3. Summary of the Judgment

The High Court refused the appeal. Its principal conclusions were:

1. The earlier cladribine authorisation was decisive. Mavenclad’s new therapeutic use did not make cladribine a distinct “product” for SPC purposes.
2. Patent coverage and first authorisation are separate requirements. Satisfaction of Article 3(a) did not resolve the independent requirement in Article 3(d).
3. Different biological effects did not establish a different active ingredient. The accepted scientific evidence did not alter the undisputed identification of cladribine as the active ingredient in both medicines.
4. Research incentives could not displace the statutory test. Arguments for greater protection of second medical uses concerned legislative policy rather than an unresolved interpretative question.
5. No preliminary reference was necessary. The CJEU’s existing interpretation was sufficiently clear to determine the appeal.

The court provisionally considered that the Controller should recover its costs under section 169 of the Legal Services Regulation Act 2015, with adjudication if agreement could not be reached. Final submissions, including any required on costs, were listed for 8 October 2026.

4. The Statutory Framework

The purpose and limits of SPC protection

SPCs address the erosion of effective patent protection caused by the time required to obtain regulatory approval for medicinal products. Because the patent term runs from the application date, clinical trials and authorisation procedures can consume a substantial part of the period before commercial exploitation becomes possible.

However, Regulation (EC) No. 469/2009 does not promise compensation for every patented pharmaceutical innovation. Recitals 3–5 emphasise research incentives and investment protection, while recital 10 requires consideration of all relevant interests, including public health, and limits the certificate’s duration to five years.

Three distinct statutory concepts

Medicinal product

The broader medicine or substance presented or administered for treatment, prevention, diagnosis or modification of physiological functions.

Product

Under Article 1(b), “the active ingredient or combination of active ingredients of a medicinal product”. This narrower definition governed the dispute.

Basic patent

A patent protecting a product, a process for obtaining it, or an application of it, designated by its holder for the SPC application.

The cumulative Article 3 conditions

These conditions are assessed at the date of the SPC application. Accordingly, the patent’s expiry before the High Court judgment did not undermine the accepted finding that Article 3(a) had been satisfied when Merck applied.

5. Precedents Cited and Their Influence

A. The nature of the statutory appeal

Carrickdale Hotel v. Controller of Patents [2004] 3 I.R. 410, Diesel SPA v. Controller of Patents [2023] 1 I.R. 1, and Fitzgibbon v. Law Society of Ireland [2015] 1 I.R. 516 supported the agreed standard of review.

The High Court conducted a full rehearing on the materials before the Controller, rather than merely asking whether an identifiable error justified intervention. It could reach its own conclusions without deference to the Controller’s decision. The refusal therefore survived independent judicial examination, not simply a limited review of administrative legality.

B. The development of second medical use patents

Warner-Lambert Co LLC v. Generics (UK) Ltd (t/a Mylan) [2019] 3 All ER 95 supplied the historical explanation of second medical use protection. Known substances traditionally faced obstacles both because they lacked novelty and because methods of medical treatment were excluded from patentability.

“Swiss form” claims addressed those difficulties through purpose-limited process protection. Subsequent changes to the European Patent Convention allowed purpose-limited product claims. This history explained how Merck could possess a valid patent for an innovative use of a known substance. It did not establish that such a patent necessarily satisfied the separate SPC conditions.

C. The earlier strict approach to “product”

Pharmacia Italia SPA, Case C-31/03

This decision concerned an earlier veterinary authorisation for an ingredient later used in a human medicine. The CJEU held that intended use was not the decisive factor and that the Regulation did not draw the proposed distinction between human and veterinary applications.

Its importance was foundational: the relevant continuity was the active ingredient, not the disease treated or the category of patient. The High Court treated it as part of the coherent pre-Neurim jurisprudence subsequently reaffirmed in Santen.

Massachusetts Institute of Technology, Case C-431/04

The medicinal product combined carmustine with a biodegradable delivery material. Although that material enabled therapeutically useful delivery, it did not have a therapeutic effect of its own and was not an active ingredient.

The CJEU consequently interpreted “product” strictly. A pharmaceutical form or delivery mechanism did not become part of the statutory product merely because it made treatment effective. This supported the distinction between a valuable pharmaceutical innovation and a new product within Article 1(b).

Yissum Research and Development Company of the Hebrew University of Jerusalem v. Comptroller General of Patents, Case C-202/05

This case directly addressed a second medical application of calcitriol. Earlier authorisations existed for other uses, while the later patent concerned treatment of skin disorders.

The CJEU held that a therapeutic use protected by a basic patent did not form part of the definition of “product”. This was especially relevant to Merck’s argument: the statutory identity of an ingredient does not change simply because the patent protects a different therapeutic application.

D. Patent protection does not replace the remaining SPC requirements

Medeva BV v. Comptroller of Patents, Case C-322/10

Medeva concerned vaccines and combinations of active ingredients. It explained the Regulation’s uniform EU framework, the relationship between an SPC and the basic patent, and the possibility of obtaining protection for a patented combination even where the authorised medicine contained additional ingredients.

The qualification was important: the other Article 3 requirements still had to be satisfied. The decision therefore supported neither an automatic entitlement based on patent coverage nor an interpretation allowing the patent to redefine the first-authorisation requirement.

Actavis UK Ltd v. Sanofi, Case C-443/12

This decision concerned successive SPCs for an active ingredient and a combination containing that ingredient. The CJEU held that satisfaction of Article 3(a) did not necessarily overcome the separate restriction in Article 3(c).

Although the present appeal concerned Article 3(d), the case illustrated the cumulative structure of Article 3. A favourable conclusion on patent protection cannot substitute for compliance with another statutory condition.

E. The opening created by Neurim

Neurim Pharmaceuticals (1991) Ltd v. Comptroller-General of Patents, Case C-130/11, concerned a patented human use of melatonin following an earlier veterinary authorisation for the same ingredient.

The CJEU allowed an approach under which the earlier authorisation did not necessarily preclude an SPC for the new application, provided that application fell within the basic patent’s protection. The relevant first authorisation could be identified by reference to the therapeutic use protected by that patent.

This represented a marked departure from the earlier authorities and supplied the basis for Merck’s original application. The High Court understood the later Santen judgment as overturning, or at least significantly restricting, that approach and restoring clarity to the scheme.

F. Authorities concerning Article 3(a)

Teva UK Ltd v. Gilead Sciences Inc., Case C-121/17, concerned whether a combination of active ingredients was protected by the basic patent. The CJEU explained that patent coverage was determined through the applicable patent rules and the claims, read in their proper technical context. A combination not expressly named could qualify where the claims related necessarily and specifically to it and the stated identification requirements were met.

Merck relied on that authority, together with Merck Sharp & Dohme v. Clonmel Healthcare, Case C-149/22, to emphasise the role of patent law in identifying the protected subject matter. The judgment records the latter authority as part of that submission but does not separately analyse its reasoning in detail.

The High Court accepted the relevance of patent rules to Article 3(a). It rejected the further proposition that those rules could determine the meaning of “product” or “first authorisation” under Article 3(d).

G. New formulations and the limits of Neurim

Abraxis Bioscience LLC v. Comptroller General of Patents, Case C-443/17, concerned a new formulation of paclitaxel using an albumin carrier. The formulation improved therapeutic efficacy, but paclitaxel had already been authorised.

The CJEU held that a carrier without therapeutic effects of its own did not create a distinct product. Nor did the first authorisation for the patented formulation become the first authorisation for the active ingredient. The judgment distinguished Neurim rather than extending it to new formulations.

Abraxis also stressed legal certainty and rejected the premise that the Regulation protects every research development resulting in a patent and a new medicinal product. Those themes materially informed the High Court’s interpretation of the subsequent Santen ruling.

H. The controlling authority: Santen

Santen SAS v. Directeur général de l'Institut national de la propriété industrielle, Case C-673/18, concerned a ciclosporin medicine following an earlier authorisation for that ingredient in a different treatment.

The CJEU addressed the premise underlying Neurim, rather than merely resolving narrow factual distinctions. It established two propositions central to this appeal:

• A new therapeutic application does not give the same active ingredient the status of a distinct product under Article 1(b).
• An authorisation for that application is not the first authorisation under Article 3(d) where the ingredient has already been authorised for another therapeutic application.

Crucially, the CJEU rejected the need to identify the first authorisation by reference to the limits of the basic patent’s protection. The High Court regarded this as a deliberate clarification intended to restore simplicity and predictability.

I. The parallel English decision

Merck Serono SA v. Comptroller-General of Patents [2025] EWCA Civ. 45 concerned the corresponding Mavenclad SPC application. The High Court did not need that decision to resolve the Irish appeal, but found its analysis persuasive and consistent with its own conclusions.

The English Court of Appeal considered questions arising from the United Kingdom’s withdrawal from the EU, including departure from retained EU decisions. Those questions did not arise in Ireland. Nevertheless, its conclusion that Santen restored coherence and reduced the uncertainty generated by Neurim reinforced the High Court’s reading.

6. Analysis of the Court’s Legal Reasoning

A. “Product” is not synonymous with the patented invention

Merck’s arguments depended substantially on aligning the authorised product with the invention protected by its patent. The patented regimen was new, Litak did not fall within its claims, and the Mavenclad authorisation was the first enabling exploitation of that invention.

The court nevertheless distinguished the innovation protected by patent law from the “product” defined by the SPC Regulation. For Article 3(d), the relevant inquiry concerned cladribine. It did not concern cladribine described by reference to Merck’s particular indication, administration route or treatment schedule.

This distinction explains why an accepted and valuable second medical use patent can coexist with refusal of an SPC. Patentability and SPC eligibility answer different legal questions.

B. Article 3(a) and Article 3(d) require separate analyses

At paragraphs 134–135, the court rejected the suggestion that the patent-law analysis under Article 3(a) controlled the subsequent first-authorisation analysis. Patent rules determine the extent of protection. They do not permit an earlier authorisation to be disregarded because it concerns a use outside that protection.

Merck therefore succeeded on patent coverage but failed on first authorisation. Neither the absence of a previous SPC nor ownership of the earlier authorisation by an unrelated company supplied an exception.

C. Different mechanisms of action did not create a different ingredient

The alternative scientific argument was particularly significant. Merck relied on evidence that Mavenclad’s treatment involved different pharmacological, immunological and metabolic actions from Litak’s treatment of hairy cell leukaemia. The Controller had accepted that the evidence was genuine and persuasive and reflected extensive research.

The High Court did not reject those scientific findings. It held that they did not answer the statutory question. There was no dispute that the active ingredient in both medicines was cladribine.

At paragraph 141, the court found no basis in the Regulation or authorities for proceeding beyond that identification to compare the ingredient’s effects in different treatments. Such an inquiry would undermine the simplicity and predictability emphasised in Santen.

The conclusion is therefore legally focused: different effects of the same ingredient were insufficient in this case. It is not a finding that mechanisms of action are scientifically unimportant, nor a determination of an unraised dispute about whether two genuinely different substances constitute different active ingredients.

D. Research incentives were not an overriding interpretative command

Merck’s policy argument had substantial factual force: the earlier Litak authorisation did not compensate Merck for the lengthy process of securing approval for its distinct innovation. Nevertheless, the court held that the Regulation balances research protection against other interests, including public health.

On the binding interpretation in Santen, that balance does not guarantee an SPC for every costly and patentable therapeutic development. An argument that second medical uses deserve broader protection is therefore directed to the EU legislature, not a basis for a national court to depart from the governing interpretation.

E. No unresolved question justified a preliminary reference

The court considered that Merck was seeking to reopen a relationship between Articles 3(a) and 3(d) already resolved by the CJEU. At paragraph 145, it found no lack of clarity requiring a reference.

The refusal was based on the sufficiency of existing authority to decide this dispute. The judgment does not establish that every future SPC question involving a second medical use is necessarily free from interpretative difficulty.

F. The limited significance of the timing argument

The judgment records that Merck had argued before the Controller that Santen should apply prospectively rather than retrospectively. The High Court applied Santen to this application, which had been lodged before that decision, but did not provide a separate substantive analysis of temporal limitation. Its reasoning should not be expanded into a general ruling on every question concerning the temporal effects of CJEU judgments.

7. Impact and Limits of the Decision

Greater certainty in Irish SPC examination

The judgment gives the Controller and applicants a clear approach where the same active ingredient has already been authorised. A later patented indication or dosage regimen does not restart the first-authorisation inquiry. Evidence of different biological effects cannot, without more, overcome the undisputed identity of the ingredient.

Consequences for second medical use research

Developers cannot assume that a second medical use patent will attract SPC protection merely because obtaining authorisation for the new use consumes much of the patent term. Earlier authorisations held by unrelated businesses may still prevent compliance with Article 3(d).

This creates a potential gap between the commercial value of a therapeutic innovation and the additional protection available under the SPC regime. The court acknowledged the policy concern but treated its resolution as legislative.

No blanket exclusion of second medical use patents

The decision does not hold that every patent protecting an application of a substance is incapable of supporting an SPC. The court expressly distinguished an application involving a product not previously authorised as a medicinal product from a new application of one that had already been authorised. All Article 3 conditions remain material.

Boundaries of future litigation

Challenges remain possible where the identity of the active ingredient or another statutory condition is genuinely disputed. What this judgment substantially forecloses is recharacterising an undisputedly identical ingredient as a different product solely because a new regimen produces different therapeutic or biological effects.

The outcome also promotes consistency with the corresponding English litigation, while preserving the distinction between Ireland’s obligation to apply EU law and the separate post-withdrawal questions considered by the English courts.

8. Complex Concepts Simplified

Supplementary protection certificate

A statutory form of additional protection taking effect after patent expiry, within the relevant patent and regulatory limits. It is not automatically available whenever regulatory approval has taken a long time.

Second medical use patent

A patent protecting a new medical application of a known substance, potentially including a qualifying dosage regimen. It does not necessarily confer protection over the substance for every use.

First marketing authorisation

For the issue decided here, the first authorisation for a medicinal product incorporating the active ingredient—not simply the first approval for the patent holder’s particular treatment.

Cumulative requirements

Conditions that must all be met. Passing the patent-coverage test does not excuse failure of the first-authorisation test.

Full rehearing

An appeal in which the court independently determines the issues on the relevant materials, rather than reviewing the original decision only for a limited category of errors.

Preliminary reference

A request by a national court for the CJEU to clarify EU law. Here, the High Court considered the existing clarification sufficient.

9. Conclusion

The judgment confirms that a new patented therapeutic use cannot reset the SPC first-authorisation requirement for the same active ingredient. Patent coverage, substantial research investment and distinct biological effects did not overcome the earlier authorisation for cladribine.

Its broader significance is the separation of patentable innovation from SPC eligibility. Applying Santen, the High Court prioritised the Regulation’s defined product, cumulative conditions and predictable administration, leaving broader protection for second medical uses to legislative reform.