Nice models required

The title of this post was not – only – selected in order to artificially boost the stats of this blog, although I guess this could be a possible side effect. No, there is an actual relationship with today’s discussion, which is again the appraisal of sufficiency of disclosure for some pharmaceutical patents.

Very often, these patents are filed too early in a drug development process to comprise any clinical data. At best, they only contain preliminary results from in vitro or animal sudies. Whether this is deemed to be sufficient for the skilled person to implement the claimed invention will depend on the models that are used – that is, the disease models, I am afraid.

I will now leave the floor to Lionel Vial who will explain how this all works.

Renaud’s previous post related to the French way of dealing with the sufficiency of disclosure requirement regarding therapeutic purpose-limited product claims (compound X for use the treatment of Y) when there is a doubt that the therapeutic technical effect has been attained. But how does the EPO deal with it nowadays?

Decision T 2059/13 of December 7, 2015 was rendered on the appeal lodged by patentee Otsuka Pharmaceutical against the decision of the opposition division to revoke European patent No. 1712225.

The patent was revoked under the ground of Article 100(b) EPC (i.e. insufficiency of disclosure) by applying the landmark decision T 609/02 of October 27, 2004, which was discussed in Renaud’s previous post. As a reminder, the catchword of this decision is that

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 (emphasis added).

Claim 1 of the main request in the appeal proceedings at hand read:

A compound which is a pharmaceutically acceptable acid-addition salt or solvate of a carbostyril compound of the formula (1):


wherein the dotted line represents a single or a double bond, for use in the treatment of disorders of the central nervous system associated with 5-HT1A receptor subtype, selected from

(i) bipolar I disorder with most recent hypomanic, manic, mixed, depressed or unspecific episode, and

(ii) bipolar II disorder with recurrent major depressive episodes with hypomanic episodes, and cyclothymic disorder.

The other claims also related to the compounds of formula (1) for a further medical use and it was not contested by the parties that in such cases, for the requirement of sufficiency of disclosure to be fulfilled, the suitability of these compounds for the claimed therapeutic application must be disclosed (point 4.1 of the Reasons).

The patentee argued that the facts and circumstances of the present case differed from those underlying T 609/02 in which the chemical structure of the compounds was not identified (point 4.2.2 of the Reasons). Indeed, the above claims are restricted to a group of only two, well identified, compounds.

The Board only partly concurred with the patentee and explained that the usefulness of case law is not confined to similar or identical facts, but lies in the principles or guidance which can be extracted from earlier cases (point 4.2.3 of the Reasons).

In accordance with these considerations the Board then offered the following statement:

Therefore, for a patent claiming a compound for use in therapy, grounds under Article 100(b) EPC will prejudice the maintenance if the application does not disclose the suitability of the product for the claimed therapeutic application to the skilled person using its common general knowledge. Only once this evidence is available from the patent application, may postpublished evidence be taken into account when assessing sufficiency of disclosure (point 4.2.4 of the Reasons, emphasis added).

Going back to the particulars of the case at hand, the patent in suit properly disclosed and proved that the claimed compounds bind to a receptor called 5-HT1A, or in other terms were 5-HT1A agonists – this was not challenged by the respondents. But the real issue was the link between this biochemical property and the treatment of bipolar disorders.

In this respect, the Board found that the patent as disclosed at its filing date did not render the suitability of either of the compounds of formula (1) for the treatment of any type of bipolar disorder plausible; nor did it provide the information that there is a clear relationship between 5-HT1A receptor agonism and the suitability for the treatment of bipolar disorder (point 4.4.5 of the Reasons).

The Board went on to consider that there was no evidence on file showing that the person skilled in the art was in the possession of common general knowledge at the filing date of the patent in suit (only represented by basic handbooks and textbooks on the subject in question, see points 4.5.1 and 2 of the Reasons) which, together with the disclosure of the application as filed, led to the direct and unambiguous conclusion that 5-HT1A agonists in general, or either of the compounds of formula (1) in particular, were useful in the treatment of any type of bipolar disorder (point 4.5.3 of the Reasons).

Eventually, the Board concluded that the application as filed in combination with common knowledge at the filing date did not disclose the suitability of either of the compounds of formula (1) in the treatment of any type of bipolar disorder. Consequently, the minimum requirements set out in T 609/02 for taking into account post-published evidence were not met (point 4.5.3 of the Reasons).

Modelling of bipolar disorders at a very early stage.
Modelling of bipolar disorders at a very early stage.

The present decision follows the jurisprudence set by T 609/02 (point 9 of the Reasons) and confirmed inter alia by T 433/05 of June 14, 2007 (point 28 of the Reasons), T 801/06 of March 4, 2009 (point 25 of the Reasons), T 1437/07 of October 26, 2009 (point 37 of the Reasons), T 866/08 of September 16, 2010 (point 2 of the Reasons) (kindly brought to our attention by our reader Raoul), T 1685/10 of June 6, 2011 (point 3.1 of the Reasons), and T 801/10 of July 8, 2014 (point 4.1 of the Reasons).

However, it adds a twist to the existing case law by requiring that the skilled person can only rely on common general knowledge, represented by basic handbooks and textbooks, and excluding patent literature and scientific articles, to determine if the experimental data presented in a patent is representative of a metabolic mechanism specifically involved in the disease purported to be treated according to the claimed invention.

This was not expressly mentioned in T 609/02, which although it stated that:

As a consequence, under Article 83 EPC, unless this is already known to the skilled person at the priority date, the application must disclose the suitability of the product to be manufactured for the claimed therapeutic application (point 9 of the Reasons for the Decision, emphasis added),

also considered that:

It is required that the patent provides some information in the form of, for example, experimental tests, to the avail that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease, this mechanism being either known from the prior art [i.e. not only from the common general knowledge of the skilled person] or demonstrated in the patent per se. Showing a pharmaceutical effect in vitro may be sufficient if for the skilled person this observed effect directly and unambiguously reflects such a therapeutic application […] (point 9 of the Reasons for the Decision, emphasis added).

In fact, it is not clear if the skilled person mentioned in T 609/02 should be akin to the one of Article 100(a) EPC, who has access to all the prior art, or to the one of Article 100(b) or of Article 100(c) EPC, who has only access to the contents of the patent and common technical knowledge.

The present decision appears to have decided for the latter solution, while previous decisions did not seem to set restrictions on the type of prior art that should be relied on for assessing the suitability of a product for a claimed therapeutic application (see for example T 433/05, point 29 of the Reasons and T 801/06, point 29 of the Reasons – even though in the latter case the prior art documents used were cited in the opposed patent, but this was not mentioned by the Board).

We cannot foresee if this decision will set a new trend in applying the teachings of T 609/02, but it is surely advisable for applicants to strengthen the description of the in vitro or in vivo disease models relied on in applications containing therapeutic purpose-limited claims, in particular by fully citing the scientific literature on which such models are based.

We would also like to add that even though this decision seems to add a further burden on applicants in regard of the sufficiency of disclosure requirement, it may conversely be a benefit to them when considering the novelty requirement. Indeed, as is clearly expressed in the above-mentioned decision T 1437/07:

A disclosure in a prior art document is novelty-destroying only if the teaching it contains is reproducible. This need for an enabling disclosure is in conformity with the principle expressed in Article 83 EPC. Thus, the requirements of sufficiency of disclosure are identical for a prior art document and a patent (point 25 of the Reasons, emphasis added).

Thanks Lionel! I guess the bottom line is that EPO case law is still in an adjustment phase as to the appropriate sufficiency threshold for second medical use patents. Although this topic is of crucial importance for all practitioners in the pharma industry, I think it is rather unlikely to find its way up to the Enlarged Board of Appeal, which – for better or worse – less often deals with substantive issues of patentability than with procedural questions.

CASE REFERENCE: Board of Appeal 3.3.01, T 2059/13, Otsuka Pharmaceutical Co. Ltd. v. Stada Arzneimittel AG et al., December 7, 2015

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