Accord Healthcare Ltd & Ors v Regents of the University of California & Anor

Factual and Procedural Background

This appeal arises from an order made by Judge Mellor on 7 November 2024 dismissing the Claimants' claims for revocation of European Patent (UK) No. 1 893 196 ("the Patent") and SPC No. SPC/GB13/079 ("the SPC"). The Patent relates to enzalutamide as a treatment for prostate cancer, specifically hormone refractory prostate cancer ("HRPC"). The Patent and SPC are owned by the First Defendant and exclusively licensed to the Second Defendant, collectively referred to as "Astellas".

The Claimants challenged the validity of the Patent on grounds of obviousness over two items of prior art known as "the Poster" and "the Slides". The appeal focuses solely on the obviousness arguments over these two items, with a particular emphasis on the Poster. The Poster and the Slides both disclose a compound identified as RD162, while the claimed compound in the Patent is RD162' (enzalutamide), differing only in a substituent at a specific position on the molecule.

The skilled team relevant to the Patent includes a cancer biologist and a medicinal chemist, who together would seek to develop new antiandrogen therapies for prostate cancer. The trial involved expert evidence from specialists in these fields, with some criticism directed at the Claimants' medicinal chemist expert.

The Poster and Slides were publicly available before the Patent filing date and disclose research by the inventors, including data on compound activity, pharmacokinetics, and structure-activity relationships. The dispute concerns whether the claimed compound RD162' would have been obvious to the skilled team in light of the Poster and Slides.

Legal Issues Presented

1. Whether the claimed invention (RD162') was obvious in light of the prior art disclosed in the Poster.
2. Whether the claimed invention (RD162') was obvious in light of the prior art disclosed in the Slides.
3. The application of the Pozzoli structured approach to obviousness in the context of medicinal chemistry and drug development.
4. The extent to which hindsight affected the expert evidence and the court’s assessment of obviousness.

Arguments of the Parties

Claimants' Arguments

• The Claimants argued that it would not require any inventive step for the skilled medicinal chemist to modify RD162 by replacing the cyclobutyl substituent with a geminal dimethyl substituent, resulting in the claimed compound RD162'.
• They contended that the Poster and Slides disclosed that such substitutions would maintain or have similar therapeutic potential, supported by data showing similar or improved activity and pharmacokinetic properties.
• The Claimants maintained that the skilled team would expect variants of RD162 to have similar activity, and that substituting two methyl groups for the cyclobutyl group was an obvious modification due to their similar hydrocarbon nature and size.
• They challenged the judge’s requirement for a specific "context" or "scenario" to justify obviousness, arguing that the skilled team’s interest in alternative compounds with similar therapeutic potential was sufficient context.
• The Claimants alleged an internal inconsistency in the judge’s reasoning concerning hindsight in the evidence of their expert.

Defendants' Arguments (Astellas)

• Astellas argued that the Claimants’ expert evidence was tainted by hindsight, focusing improperly on a known target compound rather than the realistic research context of the skilled team.
• They contended that the skilled team would not have been motivated to investigate close analogues of RD162 due to patenting and competitive considerations, thus the modification to RD162' was not obvious.
• Astellas challenged the Claimants’ assertion that the step from cyclobutyl to dimethyl was trivial or immaterial, emphasizing the complexity of medicinal chemistry and the need to avoid substituting triviality for obviousness.
• They highlighted factual findings that certain compounds (e.g., RD37) had better activity than others (e.g., RD7), undermining the Claimants’ argument that the modification was an obvious step forward.

Table of Precedents Cited

Precedent	Rule or Principle Cited For	Application by the Court
Actavis Group PTC EHF v ICOS Corp [2019] UKSC 15	Structured approach to obviousness assessment (Pozzoli approach)	The court adopted the Pozzoli approach as the correct framework for assessing obviousness in this case.
Pozzoli SPA v BDMO SA [2007] EWCA Civ 588	Four-step test for obviousness	The court applied the Pozzoli test to identify the skilled person, common general knowledge, inventive concept, and differences with prior art.
Conor Medsystems Inc v Angiotech Pharmaceuticals Inc [2008] 4 All ER 621	Fact-specific approach to obviousness including motivation and effort	The court considered factors such as motivation to find a solution and the number of research avenues in assessing obviousness.
Brugger v Medic-Aid Ltd (No 2) [1996] RPC 635	Obviousness of multiple obvious routes	The court noted that the existence of multiple obvious routes does not negate obviousness of any one route.
Pharmacia Corp v Merck & Co Inc [2001] EWCA Civ 1610	Obviousness does not require motive; workshop modifications	The court held that a step may be obvious even without a reason to take it, including trivial modifications.
Lifestyle Equities CV v Amazon UK Services Ltd [2024] UKSC 8	Appellate review of obviousness findings	The court emphasized deference to the trial judge’s evaluative decision on obviousness absent error of law or principle.
Iconix Luxembourg Holdings SARL v Dream Pairs Europe Inc [2025] UKSC 25	Deference to trial judge’s findings on obviousness	The court reiterated that appellate courts should not overturn obviousness findings unless there is a legal error.
Research in Motion UK Ltd v Visto Corp [2008] EWHC 335 (Pat)	Obviousness of trivial changes producing same result	The court accepted that trivial changes to known products are often obvious.

Court's Reasoning and Analysis

The court applied the Pozzoli four-step approach to assess obviousness, identifying the skilled team as a cancer biologist and medicinal chemist working together on prostate cancer treatments. The inventive concept was construed as the compound RD162' with a geminal dimethyl substituent at a particular position.

Regarding the Poster, the court noted that although the Claimants’ expert provided technical reasoning supporting obviousness, he failed to articulate a clear context or scenario in which the skilled team would have been motivated to make the specific modification from cyclobutyl to dimethyl. The court found this absence of context significant and concluded that the expert’s evidence was tainted by hindsight, as it focused on a known target rather than the realistic research environment where the skilled team would seek novel compounds distinct from RD162 due to patent and competitive considerations.

The court acknowledged that trivial or immaterial changes can be obvious but emphasized that in medicinal chemistry such characterizations depend heavily on context. The judge considered that the skilled team would not have been motivated to investigate close analogues of RD162 and that the focus on such analogues was driven by hindsight knowledge of the Patent claim.

In relation to the Slides, the court observed that the Claimants’ expert’s reasoning was closely tied to the material in the Slides and was not challenged on technical grounds. However, the same absence of context persisted, and the court found insufficient primary evidence to establish obviousness over the Slides. The court also noted that some arguments for obviousness appeared to be cross-examination-driven rather than supported by evidence in chief.

The court rejected the Claimants’ contention that the judge erred in principle by requiring a scenario or context for obviousness. It affirmed that the judge was entitled to consider the absence of such context in assessing the expert evidence and that the findings were fact-dependent evaluative decisions to which appellate intervention was unwarranted.

Holding and Implications

The Court of Appeal DISMISSED THE APPEAL, upholding the trial judge’s decision to dismiss the Claimants’ claims for revocation of the Patent and SPC.

The direct effect of this decision is that the Patent and SPC remain valid and enforceable against the Claimants. The court’s ruling did not establish any new legal precedent but reaffirmed the importance of context and motivation in obviousness assessments, particularly in complex fields such as medicinal chemistry. It also highlighted the risk of hindsight in expert evidence and the deference appellate courts afford to trial judges’ evaluative judgments in specialist technical cases.