FibroGen v. Akebia: Arnold LJ addresses insufficiency, equivalence, second medical use claims, and much more

Courts, lawyers and legal scholars in many places across the globe have adjusted to the new normal that COVID-19 has imposed. It's far from ideal but with a range of special measures, from extended deadlines [here] to virtual hearings [here], we make do as well as we can. At the end of the day, we are fortunate to be able to continue our work despite the unfolding of a global crisis of near-Lovecraftian proportions and that, for many of us, it's business as usual—even in unusual circumstances. 

And so, this week Arnold LJ handed down his judgment in FibroGen v. Akebia [here] that displays his characteristic sharpness of reasoning and, to this young Kat at least, astonishing productivity. At 137 pages, it tackles a range of thorny patent law issues. Not all of them can be discussed here in detail. This post thus provides an "index" of the most interesting parts of the decision.

Background to case and overview of most pertinent points

Fibrogen holds a number of patents on enzyme inhibitors for treating various types of anaemia and related conditions. Akebia and Otsuka sought to revoke these patents to clear the way for an intended launch. Consequently, Astellas – Fibrogen's exclusive licensee – brought a counterclaim for infringement of the patents. The six patents that were subject of the proceedings were grouped into two patent families, each deriving from a common international application: Families A and B.

The outcome was that, for five out of six patents, all claims in the proceedings were invalid for insufficiency, and in addition the Family B claims were invalid because they were obvious over the priority document for Family A. Two claims – one from each family – survived the invalidity challenges, but they were not infringed by Akebia and Otsuka. Had the claims been valid, Akebia and Otsuka would have infringed the claims in issue from the Family A patents (except for the valid claim), but not the claims in issue from the Family B patents.

Here is a list of the paragraphs tackling the most relevant issues:
  • 36: Discussing the proper way to instruct expert witnesses to avoid hindsight.
  • 199-201: Discussing when individual papers can be considered common general knowledge: yes if a paper "has been cited 610 times" by the priority date, no if it is "simply too old and obscure".
  • 204 ff: Discussing incorporation by reference in an application of patent and non-patent literature, and finding in 221 that "the skilled team would not necessarily follow up any of the cited publications" in the absence of "direction as to which would be worth following up".
  • 283 ff: Discussing how the skilled person would read a passage in the description stating that "an aryl radical may be substituted by 1 to 5 substituents" and, in particular, whether they would understand that some limitation to potential substitutes was intended.
  • 303: Discussing the interpretation of the expression "structural mimetic of 2-oxoglutarate" and finding that the skilled person would be uncertain what it meant, because neither the specification nor the cited publications specified its meaning.
  • 344: Discussing inventive step and finding that the claimed compound would not be found through routine research, even though it would have been obvious to search for it.
  • 347 ff: Discussing three types of insufficiency – "classical", "Biogen" and "Uncertainty" – and summarizing the case law on the latter two categories.
  • 376 ff: Discussing Biogen-insufficiency and finding that claims are insufficient where a patent implicitly promises that substantially all compounds which satisfy the structural definitions in the claims will have the claimed therapeutic efficacy, whereas this is only demonstrated for five compounds.
  • 453: Discussing the interface between claim amendments and equivalence and finding, that where a claim is limited to a single compound to save its validity, it would be contradictory that its scope of protection reaches well beyond that compound by way of equivalence, in particular to compounds covered by the original claim.
  • 456: Discussing the principle of "disclosed but not claimed is disclaimed".
  • 590 ff: Discussing infringement of a second medical use claim in a case where the infringing product is not yet marketed and the Summary of Main Product Characteristics (SMPC) is not finalized yet.
The IPKat takes advantage of the lockdown to catch up on its reading backlog (Image by fellow Kay Riana Harvey)
Two comments on claim construction from a Dutch perspective

It is impossible to do justice to all of these issues in a single short blog post, so I chose two that, from a Dutch perspective, are of particular interest [Cue to readers who are looking for a way to rid themselves of some mental Coronaspeck: this is a great opportunity for comments or even guest contributions on any of the outstanding issues!].

Claim scope: validity versus infringement. Paragraph 418 raises the interesting question whether, if infringement by equivalents is found, the same scope of claim should be adopted when considering any issue of validity. At first glance, it seems that the answer should be yes, following the reasoning of the well-known Gillette defence [after a 1913 House of Lords decision, excerpt here], known in Germany as the Formstein defence [after a 1986 Federal Supreme Court decision, here]. These doctrines state that a patent cannot be infringed by the prior art or obvious variations thereof: hence, the infringer either works outside of the scope of the patent, or the patent is invalid. 

But validity of a patent must be established at the priority date, whereas infringement – including by way of equivalence – is established at the date of infringement. This was confirmed by the Dutch Supreme Court in a 2014 decision [here], in which it held that there are two relevant points in time for claim construction: the priority date for validity and the date of infringement for scope of protection. Thus, equivalents of the claimed invention that became obvious over the prior art only after the priority date might infringe a patent, without being prejudicial to its validity. That would suggest that, in fact, the scope of claim including equivalents is not always decisive for validity, but only where the relation of those equivalents to the prior art has not changed since the priority date.

Disclosed but not claimed is disclaimed? The principle that, where the specification discloses several ways in which a particular technical effect can be achieved only one of which is claimed, the other ways to achieve the technical effect cannot amount to infringement ("disclosed but not claimed is disclaimed") seems settled in German case-law and is followed by Arnold LJ in this decision. Indeed, describing an embodiment but failing to claim it will normally be a strong indication that the patentee chose not to seek protection for that embodiment.

But this rule should not be applied mechanically and exceptions can arise. In this respect, two of this Kat's former colleagues have advanced the following hypothetical [Den Hartog & Blomme, BIE 2016/15 – in Dutch]: suppose a claim protects a nucleotide sequence with 600 base pairs, and the specification states that deviations in some of the pairs have no influence on the effects of the claimed amino acid. In such a case, it seems unreasonable to deny the patentee protection against sequences which deviate minimally from the claimed sequence.

Denying protection against effective equivalents on the basis of these types of statements would have the undesirable result of incentivizing overly careful and sparse drafting of patent applications, potentially hampering their disclosure function. Although the question has not been put to the Dutch Supreme Court in literal terms, two recent decisions – Resolution/AstraZeneca (2018) and Bayer/Sandoz (2016) – suggest that under Dutch patent law, "disclosed but not claimed is disclaimed" is not an absolute maxim.

FibroGen v. Akebia: Arnold LJ addresses insufficiency, equivalence, second medical use claims, and much more FibroGen v. Akebia: Arnold LJ addresses insufficiency, equivalence, second medical use claims, and much more Reviewed by Léon Dijkman on Saturday, April 25, 2020 Rating: 5


  1. Thank you, Arnold Lj, Dijkman Leon and the IPKat blog for writing the decision, for alerting me to it and for providing such a stimulating opening commentary. I'm looking forward to reading the 137 pages in full (even though I'm not a pharma nerd).

    The best decisions bring clarity to the case law. Also with Art 83 EPC? I note we are now up to three categories of insufficiency. I recall a decision at the EPO which was suggesting that while the English courts need two categories, at the EPO the Boards need only one.

    So in terms of Darwinian evolution, what line of insufficiency reasoning is the fittest, the one that should survive? One, two or three categories? How many is optimal?

  2. Having now read the Decision, I think its most interesting section starts around para 454, on the issue of infringement by equivalent/file history/recapture (of scope not pursued during prosecution). Arnold defers to Activis v. Lilly but then summarily eviscerates it, by throwing back at Lord Neuberger the very words that Neuberger chose when deciding the Activis case in the Supreme Court.

    By that, I mean that (see para 459) that Arnold sees the present case as being one of those "where it would be contrary to the public interest for the contents of the prosecution file to be ignored". In Activis, the reason the claim was restricted to the disodium salt was grotesquely and painfully evident from the file history and (in my opinion) very much "contrary to the public interest" to "ignore" that history when construing the claim to cover salts other than the disodium.

    Is this the way that Binding Precedent works? The lower courts are bound, but creative interpretation of the Precedent allows a judge, bent on doing justice, to "do a job" on the Precedent that is Binding?

    All in all, for an impartial observer, with no dog in the fight, a thoroughly satisfying read, and a masterly demonstration of the value added by litigating in the Patents Court of England. Appeal? What's the point? How are you ever going to get an appeal up and running, given the self-evidently unassailable reasoning of this 640 paragraph judgement of the facts and the law.

    Compare with the average judgement of an Opposition Division at the EPO. Is there ever any point in NOT appealing it?

  3. Thanks a lot MaxDrei for your generous comments, and interesting point about Actavis and the prosecution history. Note another jab at the decision by Arnold LJ in para 417, where he that it is pointless for him to consider criticisms of Actavis, "given that the decision is binding on [him]." And yet he takes the time to write this down...

  4. Good catch, Leon. I did see that para but took it more as a gesture of courtesy to the Defendants.

    In the meantime, I have come round to a more charitable view of the three kinds of insufficiency. It is clear to me that, at least in an EPC jurisdiction which declines to use the EPO's Problem-Solution Approach to obviousness, all three are needed. Only with PSA is Biogen-type insufficiency not needed. But, hey, when the claim deserves despatch to the Papierkorb, where's the harm in knocking it on the head twice, first under Art 83 and then again, just to make sure (like in that old joke about Jeremy Beadle) under Art 56 EPC.

  5. It occurs to me that some readers might not appreciate what I am getting at, with my "file history" point. In Activis, the contribution to the art was at a level of generality mid-way between the ludicrously wide original claim 1 and the unnecessarily narrow di-sodium of the granted claim. The absent level of generality was a level which any competent chemical drafter would have immediately seen as that crying out to be claimed. Yet it was not claimed in the PCT, and could not be claimed later, during prosecution, because under the EPC (and in all those countries which find the EPC case law useful) it was an undisclosed intermediate generalisation.

    Now, Lord Neuberger, who shall suffer the consequences in Europe of such incompetent, lamentable, only in America-type drafting, when it is found in a patent application under the PCT, for use everywhere in the world except the USA? The patent owner? Or perhaps the competitor accused of infringing the poor little di-sodium claim?

    I suspect that Arnold LJ is, like a great many others, of a mind different from Lord Neuberger.

  6. Hi MaxDrei.

    Arnold is a great judge, but I don't think he realises the disadvantages of file wrapper estoppel. The UK does not like having to think about intention or 'equitable' issues in claim interpretation. Bringing in a component to interpretation which is dependent on the behaviour of the relevant party is not the UK approach. It would not be trivial to change that, and it would open up a lot of can of worms as we developed the case law

    I think Neuberger's decision has a lot of merit to it which the UK attorney profession have not appreciated. We needed to define a doctrine of equivalents as it is in the EPC. To do this based on the breadth of the technical effect is the only fair way to do it. We now all need to readjust to the new normal, which is painful

    I think the UK courts are going a bit too far with all the rapidly multiplying tests for insufficiency. They have their merits, but their boundaries should remain very clear and defined, and not gradually increase case by case. It is better to use an old test creatively rather than creating new ones, and I think it is not a good idea for Biogen insufficiency to become fashionable again.

  7. Thanks for that, Dannish. You prompt me to flag up repercussions for patent drafting, of decisions like Activis and this one from Arnold LJ. The writer of the blog post mentions one consequence. You speak of another one, namely "the breadth of the technical effect" by which I suppose you mean only those technical effects made plausible by the original drafting.

    In that context, I would vigorously assert that one of the biggest benefits of EPO-PSA, as it toggles between technical effects disclosed and technical features claimed, is the huge pressure on drafters to disclose exhaustively all plausible effects, and how they are achieved, by which feature combinations, at which level of generality, already in the priority filing.

    Where would we be, these days, without that pressure on drafters, imposed by EPO-PSA, These past 40 years? I'll tell you. Engineers and scientists would find patent publications not worth reading (like they still do in the USA) because of their obscene lawyerly prose, their proud and deliberate verbosity and their endless deliberate ambiguities and obfuscations.

  8. MaxDrei, I would argue that the strict view on added matter at the EPO might be more important than the PSA in improving drafting quality. I must admit I prefer the US system where as soon as one shows one is clear of the prior art, one can then relax and draft the claims however one wants, without worrying too much about basis.

    However I also agree that PSA as developed by the EPO remains an incredibly useful tool to assess inventive step, plausibility and sufficiency

  9. Ha! I detect that there is a need to define "quality" in the context of "drafting quality".

    I agree with you that unflinching vigilance to exclude "added matter" is what raises the quality of FTO opinions rendered under the EPC.Indirectly then, it raises drafting quality.

    But if the very purpose, the over-riding objective, of any patent system is to "promote the progress" of technology, then those who husband the system must do their best to render A publications interesting for the person skilled in the art to read, promptly upon publication, for their informational content and inspirational value. The EPO, in making the PSA its established case law, has done its bit. Now it's the turn of the courts.

    In England, they are doing fine. In the USA, by contrast, they have, for years, and wittingly or otherwise, been rowing in the wrong direction. Sad.

  10. MaxDrei, I work in the field of biotech, and we often have to redefine the problem in view of documents identified in the search. Can I just voice the counter-view that if one drafts according to a specific assumed problem then redefining the problem becomes more difficult in examination. Examiners will essentially then object that we said the data showed X, when it now needs to show Y. Examiners are not kind at the EPO to a specification which presents the contribution (solved a particular problem) a certain way. So one must be very tentative in how one uses PSA during drafting, because so often we need to rely on a different contribution to what we originally thought. Being less than totally clear in drafting can therefore be an advantage. I have found that some specifications drafted by EP attorneys were simply to firm and concrete in defining the problem, and when that was knocked out by the prior art it is very difficult to salvage anything.

  11. Thank you Léon Dijkman for this very useful analysis. I hope you won't mind a couple of questions.

    You wrote: "Two claims – one from each family – survived the invalidity challenges,"
    Did any of the claims in issue from Family B survive? I think claim 36A of patent EP'333 is found to be bad for obviousness although not insufficiency.

    Also, why is the exclusive licensee, Astellas, suing the patent owner Fibrogen? And what for? Sorry if the answer to that should be obvious to me.

    Thanks again

  12. A very thorough judgement indeed and truly engaging comments. I havent read it in full, but many thnx to the autor for providing some guidance for being able to quickly get to the interesting bits. I am wondering, is this the 1st time a ref in UK was made to the BGH "dedication to public" principle? If yes, is anyone expecing some more implications from this reference? Just curious, cheers :)

  13. This would have been a fantastic desicion for sufficiency and inventive step if it had stood the test of time. MaxDrei said "a thoroughly satisfying read, and a masterly demonstration of the value added by litigating in the Patents Court of England. Appeal? What's the point? How are you ever going to get an appeal up and running, given the self-evidently unassailable reasoning of this 640 paragraph judgement of the facts and the law.". Sadly, much of the certainty provided by this case seems to have been undone by the Court of Appeal. The whole point of setting out a structure property relationship for chemical compounds is that it is the newly identified structural features of the compounds that provide their resultant function. No pharmaceutical chemist can ever seek to separate the functional activity from a compounds structure. If you provide the compound structure in a claim (or a class of structurally similar compounds), then, the large marjority of those compounds had better work with that function, or else the whole concept cannot be said to be a general principle. My feeling is that the court of appeal was therefore wrong to reconsider this decision and to go on to separate the concept of the function aspect from the compound structure.


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