In Decision T 488/16, the Boards of Appeal of the European Patent Office (BoA) have revoked EP 1 169 038, which protected the blockbuster protein tyrosine kinase (PTK) inhibitor dasatinib (Sprycel®). The only request on file -- a single claim directed to dasatinib per se or a salt thereof -- was found to lack inventive step in view of the absence of evidence in the application as filed (and the common general knowledge) which rendered the activity of dasatinib in inhibiting PTK "plausible". A general statement in the application as filed that "Compounds described in the following Examples have been tested in one or more of these assays, and have shown activity" was not by itself considered enough to render it credible to the skilled person that the described compounds were PTK inhibitors. In the absence of a plausible disclosure of activity against PTK in the specification as filed, the objective technical problem was defined by the Board of Appeal as merely "the provision of a further chemical compound". The extensive clinical data which became available after the filing date of the patent evidencing biological activity was not taken into account when determining inventive step.
The Boards of Appeal of the European Patent Office have for many years imposed a requirement that claims for large molecules (e.g., proteins) must be supported by a plausible disclosure of biological activity in the application as filed (see, for example, T 1329/04). A similar requirement for a plausible disclosure of activity in the original specification has also been required to support medical use claims (see, for example, T 0609/02). However, this Decision indicates that the Boards are willing to apply the same strict standards when assessing claims for small molecule drugs per se.
This article was reprinted with permission from J A Kemp.
This decision is not out of the ordinary, and is classified as D (no distribution) in the EPO Appeal Board hierarchy of decisions, indicating that it is not considered to establish a new principle of law. Its main interest is that it provides a recent listing of the most important recent decisions in this area, and also that it contains a convenient summary of the relevant law as presently understood.
The patent originally covered a large Markush group of compounds and had some 580 examples. There was nothing to single out the dasatinib compound from any of the others.
The underlying objection is non-enablement (or lack of inventive step for all the covered embodiments). Credibility was initially raised as an issue as a proxy for evidence of non-enablement, as in the well-known decision T 939/92 Triazoles/AGREVO, the argument being that the size of the Markush group was so large that it was not plausible that all of its members would be active. In T 1329/04 there was similar reason for disbelieving that the claimed, protein was a member of the postulated superfamily as the following passages from the decision explain:
"Accordingly, as a significant structural feature fails to be identical in TGF-9 and the members of the TGF- Beta superfamily, and no functional characterisation of TGF-9 is forthcoming in the application, it is concluded that the application does not sufficiently identify this factor as a member of this family i.e. that there is not enough evidence in the application to make at least plausible that a solution was found to the problem which was purportedly solved.
The appellant filed post-published evidence (e.g. document (4) and Exhibit E) establishing that GDF-9 was indeed a growth differentiation factor. This cannot be regarded as supportive of an evidence which would have been given in the application as filed since there was not any. The said post-published documents are indeed the first disclosures going beyond speculation."
In the T 609/02 case, the catchwords form the decision say it all:
"If the description of a patent specification provides no more than a vague indication of a possible medical use for a chemical compound yet to be identified, later more detailed evidence cannot be used to remedy the fundamental insufficiency of disclosure of such subject-matter."
An important UK case which will be heard by the UK Supreme Court in 2018 is Warner-Lambert v Generics (pregabalin), where one of the important questions of law is hether the requirement of plausibility was applied over-expansively in the present proceedings and should deny validity to subject matter (pregabalin for treatment of central neuropathic pain and other forms of pain) for which extrapolation from the data in the patent application as filed was arguably an “educated guess” or bold extrapolation made contemporaneously by a skilled person within a reasonably sized field of possibilities (only two possibilities in relation to claim 3) and which had subsequently been confirmed as correct. The writer in amicus submissions to the court has argued that application of pregabalin to the treatment of central neuropathic pain plainly fell within accepted definitions of a testable scientific hypothesis postulated by a skilled researcher. Application of the relatively recent “credibility” test even in second medical use cases would have far-reaching consequences if applied to a degree that precludes protection for subject-matter based on scientific hypothesis and would have consequences in empirical research fields, and in particular for the life sciences which were arguably unintended by Parliament when the UK Patents Act was drafted and were also unintended by the framers of the Patents Cooperation Treaty and the European Patents Convention. My submission was that there must have been a reason apparent to the skilled reader at the time of filing for positively disbelieving as opposed to merely questioning the relevant prediction made by the inventor in its in its full breadth. It will be interesting to see the eventual UK Supreme Court decision in the case, and whether it throws any further light on current practice in this area.
Posted by: Paul Cole | August 07, 2017 at 08:37 AM