Anonymized Summary of Judgment

Factual and Procedural Background

This judgment concerns the Plaintiff's challenge to the validity of Irish patent EP (IE) 1 845 961 ("the Patent"), a patent directed to a once-daily dosing regimen for the oral anticoagulant rivaroxaban (the active compound in issue). The Defendant owns the Patent and markets the drug commercially under a tradename. The Patent relates to a dosing regimen (once-daily administration) rather than the compound itself.

The Plaintiff (a manufacturer of generic medicines) brought the proceedings seeking revocation of the Patent on the statutory grounds available under the Patents Act 1992 (as amended). Although the Defendant counterclaimed for infringement, the Plaintiff had not yet sought to market a generic product so the only issue tried was validity. The only ground pursued at the hearing was that the claimed invention lacked an inventive step (i.e. was obvious).

Procedural timeline (as given in the judgment): the proceedings commenced by plenary summons on 9 May 2024 and were entered in the Commercial list on 13 May 2024. The trial occupied 14 hearing days between 29 April 2025 and 23 May 2025, with a further short hearing on 18 June 2025 to address a discrete procedural issue. Judgment was delivered by Judge Mulcahy on 25 June 2025. Both parties called two expert witnesses each (one clinician and one pharmacologist); no factual witnesses were called. The Patent was due to expire on 19 January 2026.

Legal Issues Presented

1. Whether the Patent (EP (IE) 1 845 961), directed to once-daily dosing of rivaroxaban, lacked an inventive step (was obvious) having regard to the state of the art as at the priority date (31 January 2005).
2. Whether, in particular, once-daily dosing would have been "obvious to try" with a reasonable or fair expectation of success to the notional skilled team (a clinician and a pharmacologist) based on the prior art relied on by the parties (notably three conference abstracts and corresponding posters and a contemporaneous article).
3. What weight should be afforded to: (a) the assay data reported in the prior art (including experimental thrombin-generation assays) given they were not correlated with clinical endpoints; (b) secondary evidence (internal development documents disclosed by the Defendant); and (c) foreign decisions on the validity of equivalent patents (the role of judicial comity).
4. How the statutory and conventional tests for inventive step (including the Pozzoli four-step approach and the "obvious to try" considerations articulated in later authorities) should be applied to a dosing patent for an anticoagulant, given the particular safety considerations in anticoagulant development.

Arguments of the Parties

Plaintiff's Arguments

• The prior art — in particular the conference poster and abstract evidence (referred to in these proceedings as Poster A / Abstract A and Poster B/C / Abstracts B/C) and the relevant published article — would have led the skilled team to consider once-daily dosing for rivaroxaban as an obvious option to test in Phase II clinical trials.
• The Harder-type poster (Poster A) explicitly suggested that some assay parameters "suggest suitability for a once-daily dosing regimen"; read together with the Kubitza-type posters (Posters B and C), this taught the inventive concept and therefore made the claimed once-daily regimen obvious.
• Assays that had not been correlated with clinical endpoints could nevertheless be informative and provide a reasonable basis for dose-selection and for moving from Phase I to Phase II; regulatory and guidance documents supported the use of unvalidated biomarkers to inform dose ranges.
• Secondary evidence disclosed in discovery (internal development documents of the Defendant) was consistent with the proposition that Defendant itself relied on thrombin-generation results when adding a once-daily arm to Phase II studies; this supported the Plaintiff's experts' account of what a skilled team would do.
• Decisions in other jurisdictions, especially the UK decisions declaring the equivalent patent invalid, were persuasive and consistent with the Plaintiff's case; judicial comity favoured giving weight to those decisions.

Defendant's Arguments

• The asserted inventive step was not obvious from the prior art. The prior art did not provide a sufficient basis for a skilled team to have a reasonable expectation that once-daily dosing would be both safe and effective for an anticoagulant.
• The Harder poster relied upon by the Plaintiff used experimental assays that had not been correlated with clinical effect; therefore the poster could not be relied on to justify an expectation of success for once-daily dosing.
• There was a "data deficit": the skilled team would not have had the information necessary — or confidence in it — to devise a Phase II dosing regimen; in the Defendant's expert evidence it was said that no dosing regimen could be recommended solely on the basis of the publicly available prior art.
• The Plaintiff impermissibly sought to supplement or infer underlying data not disclosed in the prior art and to rely on confidential internal documents or material post-dating the priority date; such material could not be used to establish lack of inventive step under section 13.
• The weight of foreign decisions differed; in a number of jurisdictions the Patent was upheld on the basis that the poster data was insufficient to support once-daily dosing, and those decisions should be respected under principles of comity.

Table of Precedents Cited

Court's Reasoning and Analysis

Legal framework and approach

The court began by identifying the statutory framework under the Patents Act 1992 and the relevant EPC provisions governing inventive step. It adopted the accepted four-step Pozzoli approach to obviousness (identify the skilled person and common general knowledge (CGK); identify inventive concept; identify differences between the prior art and the inventive concept; decide whether those differences would have been obvious), and it also engaged with the factors set out in Actavis and Medimmune when considering whether a route was "obvious to try" with a reasonable expectation of success. The court emphasised repeatedly the need to avoid hindsight.

Characterisation of the notional skilled team and CGK

The court accepted that the skilled team for the issues in the case could be confined to a skilled clinician and a skilled pharmacologist. It adopted and summarised the agreed CGK in the field of anticoagulant drug development at the priority date (31 January 2005): the nature of thrombosis, the major clinical indications (hip and knee surgery, atrial fibrillation), the commonly used comparators (warfarin, heparins, and LMWHs such as enoxaparin), distinctions between pharmacokinetics (PK) and pharmacodynamics (PD), the role of half-life in dose selection, the concept of therapeutic window, and that Phase I studies yield PD/PK and safety data while Phase II studies are the first efficacy trials in patients.

Prior art and technical facts accepted as relevant

• The court summarised the prior art relied on by the parties: three conference abstracts (the "Blood" abstracts) and the associated posters and one contemporaneous article. For convenience the court referred to (i) the Kubitza single ascending dose (SAD) study (Poster B/Abstract B), (ii) the Kubitza multiple ascending dose (MAD) study (Poster C/Abstract C), and (iii) the thrombin-generation study presented in the Harder poster (Poster A / Abstract A). The Perzborn article was also on the record but was of lesser prominence in the debate.
• The Kubitza SAD and MAD materials reported PK/PD profiles and half-life estimates in the range of roughly 3–6 hours and showed correlation between PK and PD in those Phase I trials. They reported that BAY 59 (the compound) was safe and well tolerated across a range of doses.
• The Harder poster described thrombin-generation assays (ETP, PITT, PICT) in healthy volunteers and reported sustained effects in some assay parameters up to 12 hours and, by certain readings of the graphs and as recorded in one abstract, there were assay signals at 24 hours for the 30 mg dose; the poster's conclusions included the suggestion that some parameters "suggest suitability for a once-daily dosing regimen".

Assessment of the assays and their evidential value

A central point of contest was the proper weight to be given to the experimental thrombin-generation assays reported in Poster A, which had not been correlated with clinical endpoints. The Defendant's experts gave evidence that the lack of correlation rendered those assays unreliable for predicting clinical efficacy or safety. The court carefully examined this position and the contemporaneous regulatory guidance and literature.

The court concluded that:

• Regulatory guidance (FDA/EMA guidance cited by the experts) accepted that biomarkers and experimental assays that had not been validated as surrogates could nevertheless inform dose-range selection and the design of clinical trials. Thus, the absence of formal correlation did not mean the assays were without value.
• The alleged inconsistency in defendants' witnesses — relying on the Kubitza data in some respects while minimising the Harder data because it was "experimental" or uncorrelated — was not justified. Both the Kubitza and Harder materials used assays that were not correlated with clinical outcomes for direct factor Xa inhibitors at the priority date.
• The skilled team would treat Poster A's results as informative biological evidence (a PD signal) that could be used, together with the Kubitza PK/PD data and common general knowledge, to formulate a reasoned basis for Phase II dosing arms.

Evaluation of expert evidence and credibility

The court made a careful "in the round" assessment of the four experts (two for each side). The court emphasised established criteria for assessing expert evidence (sound reasoning, internal consistency, handling of cross-examination and willingness to reassess). It recorded that:

• The Plaintiff's experts (the clinician and the pharmacologist) presented evidence that, on the prior art and CGK, the skilled team would have been inclined to test once-daily dosing and would have had a reasonable expectation of success.
• The Defendant's experts emphasised the data deficit, assay variability, lack of correlation with clinical effect and safety concerns for anticoagulants; one of the Defendant's pharmacology witnesses (Expert Pharmacologist B) made a material and unexplained change in his oral evidence compared to his written report about whether he would recommend dosing arms based on the prior art, which undermined the persuasive force of his evidence.
• The court found aspects of the Defendant witnesses' positions over-stated (in particular their emphasis that uncorrelated assays should be disregarded entirely), and considered that Plaintiff's experts gave the more convincing account of how a skilled team would have approached the prior art at the priority date.

Application of the legal tests to the facts

Applying the Pozzoli steps and Actavis/Medimmune considerations the court found:

1. The inventive concept was readily identifiable: once-daily dosing of the claimed immediate-release formulation for at least five consecutive days.
2. Poster A (the thrombin-generation poster) explicitly suggested once-daily suitability in its conclusions and showed dose-dependent PD effects that were, on a plain reading of the graphs, directionally consistent up to 12 and in some readings up to 24 hours for the 30 mg dose. Poster A was authored by largely the same team involved in the Kubitza work and included recognized experts in the field; the skilled team would "seize upon" such a document directed at the problem at issue.
3. Given CGK (including the accepted starting point of half-life-based dosing but also recognition that dissociation between PK and PD can occur, and the example of LMWHs where dose-frequency does not follow half-life), and the combination of the Kubitza and Harder materials, the court concluded the skilled team would have regarded once-daily dosing as an option worth testing and would have had a reasonable expectation of success (safety and efficacy) sufficient to justify moving into Phase II with a once-daily arm.
4. The court rejected the Defendant's submission that the skilled team would not have been able to design any dosing regimen on the basis of the public prior art; that position was inconsistent with the prior art and with the expert evidence in other jurisdictions and undermined by material features of the Defendant's own discovery documents.

Secondary evidence and documentary record

The court analysed a limited set of discovery documents disclosed by the Defendant (internal minutes, slide decks, amendments to protocols and similar materials). Applying Molnlycke, the court treated those documents as secondary evidence to test the plausibility of the expert evidence. The court concluded that, on their face, the documents tended to corroborate the view that the Defendant's own development team placed significance on the thrombin-generation findings when deciding to include once-daily dosing arms in Phase II trials — a point which lent weight to the Plaintiff's experts' evidence and undermined the Defendant's contention that the public prior art could not have supported once-daily dosing.

Foreign judgments and comity

The court reviewed a range of foreign decisions (some upholding the Patent, others declaring it invalid). It accepted that comity requires regard to those decisions but emphasised that it must decide the case on the evidence before it. The court noted that where those foreign decisions differed, the divergence largely reflected differing factual assessments of the weight to be given to Poster A and to the assay data; the UK decisions (High Court and Court of Appeal) that declared the patent invalid were particularly relevant because the same expert witnesses had given evidence in the UK and been tested by cross-examination there. The court concluded that the foreign authorities did not displace its conclusion based on its own assessment of the evidence.

Holding and Implications

Holding:

The court concluded that the Patent did not involve an inventive step and declared that the Patent is invalid on the ground of obviousness.

Implications:

• Direct effect on the parties: the court proposed to make a declaration that the Patent is invalid; the parties were to be heard on the precise form of the order and on consequential issues. The Patent's invalidity disposes of the Plaintiff's declared challenge to its validity in these proceedings.
• Broader legal implications: the court addressed the proper treatment of experimental assays and secondary documentary evidence in obviousness inquiries and applied established principles (Pozzoli, Actavis/Medimmune, Molnlycke) to the particular factual matrix of a dosing patent for an anticoagulant. The judgment explained that uncorrelated PD assays can have legitimate value in informing dose selection and that documentary evidence can be used as secondary material to test expert evidence.
• Judicial comity: the court considered but did not follow slavishly foreign decisions; it treated decisions from other jurisdictions as persuasive where their factual and evidential matrices were comparable but emphasised its duty to decide the case on the evidence before it.

Next Steps Recorded by the Court

The court stated that it would hear the parties on the precise form of the declaratory relief and any ancillary orders to be made.

Note on anonymization: all personally identifying names mentioned in the source judgment (parties, witnesses, or other individuals) have been replaced with neutral functional descriptors in this summary (for example, "Plaintiff", "Defendant", "Expert Clinician", "Expert Pharmacologist", "Poster A/B/C"). Case citations and statutory references are reproduced as they appeared in the judgment extract provided to the court.