T 2128/13 - Result to be achieved and clarity

Key points:

• In this case, claim 1 is directed to a method that involves forming a coating comprising a taxane compound. In the single example, the specific compound paclitaxel was used. The Board finds the claim to be insufficiently discloses, because the claim has as feature that a certain result is achieved (decreased solubility) and the application does not provide sufficient guidance for obtaining this result with other compounds than the paclitaxel used in the example.
• The patent proprietor submitted that even if claim 1 lacked essential features, "that was an issue under Article 84 EPC already present in the claims as granted and hence excluded from these appeal proceedings." 
• The Board: "Notwithstanding whether claim 1 lacks essential features, the claimed invention is considered lacking sufficient disclosure for the reasons already explained."

T 2128/13 - link

Summary of Facts and Submissions

I. The appellant (opponent) lodged an appeal against the interlocutory decision of the opposition division to maintain European patent No. 2 043 704 in the form of the then pending auxiliary request 3.

V. With the response to the grounds of appeal, the respondent (patent proprietor) filed a main request, identical to auxiliary request 3 pending before the opposition division, and auxiliary requests 1 to 9.

Claim 1 of the main request reads as follows:

"A method of manufacturing a coated endolumenal medical device having at least one coated surface, the method comprising the steps of:

a) applying a taxane therapeutic agent to at least one surface of an endolumenal medical device to form a coating of the taxane therapeutic agent on at least one surface of the endolumenal medical device; and

b) conditioning the taxane therapeutic agent coating by maintaining the coating of the taxane therapeutic agent at a temperature of between 30 and 60ºC and a relative humidity of 75 - 100% for a time period of between 12 - 24 hours to decrease the solubility of the coating of the taxane therapeutic agent in a 0.5% w/w aqueous solution of Heptakis-(2,6-di-O-methyl)-ß-cyclodextrin (HCD) elution medium at 25ºC for 24 hours."

Claim 1 of auxiliary requests 1 and 2 contains, in addition to the features of claim 1 of the main request, the following:

"wherein the taxane therapeutic agent is paclitaxel."

Reasons for the Decision

1. The appeal is admissible.

Main request, sufficiency of disclosure

2. Claim 1 of the main request is directed to a method of manufacturing a coated endolumenal medical device comprising two steps. Step (a) requires applying a taxane to a surface of the device to form a coating. Step (b) requires conditioning this coating at defined temperature and humidity for a defined period of time to decrease the solubility rate of the coating, said solubility rate being determined under defined conditions.

A number of compounds embraced by the term "taxane" in the sense of the claimed invention can be found on paragraphs [86] to [95] of the description.

The claimed method, in particular the conditioning step (b) is defined by a functional feature indicating the result to be achieved, namely to decrease the solubility rate of the taxane coating under defined conditions.

3. According to the case law of the Boards of Appeal, the requirements of sufficiency of disclosure are only met if the claimed invention can be performed by a person skilled in the art in the whole area claimed without undue burden, using common general knowledge and having regard to the information in the patent in suit (T 409/91, OJ 1994, 653, Reasons 3.5; T 435/91, OJ 1995, 188, Reasons 2.2.1). The disclosure of one way of performing the invention is only sufficient if it allows the invention to be performed in the whole range claimed. A claim containing functional features defined by means of a result to be achieved comprises an indefinite and innumerable host of possible alternatives and is sufficiently disclosed as long as all these alternatives are available to the skilled person.

In the present case, it needs to be examined whether or not the host of variants encompassed by the functional definition "to decrease the solubility of the coating..." required by step (b) of claim 1 are made available to the skilled reader, and in particular whether the skilled person is in the position to identify within the required ranges the specific temperatures, humidity levels and time periods of the conditioning step that decreased the solubility rate of every taxane therapeutic coating.

4. It has not been contested that the patent provides one way to carry out the invention, namely by coating a medical device with amorphous paclitaxel and subjecting the coated device to a specific conditioning step.

The patent further proposes a mechanism according to which the conditioning step achieves the conversion of non-hydrated into hydrated forms.

5. The first issue to be examined is whether the conditioning step required by claim 1 inevitably reduces the solubility rate of every coating containing a taxane, in other words, whether the required functional definition is nothing more than the direct and inevitable consequence of the further features of claim 1.

The patent discloses in paragraph [0006] that taxane solvated forms typically dissolve more slowly than the corresponding non-solvate. Thus, the patent does not base its teaching on the assumption than every solvated taxane inevitably dissolves more slowly than its non-solvated solid forms. For this reason alone, it is concluded that a decrease of the solubility rate is not the inevitable consequence of the conditioning step required by claim 1.

6. The next issue to be examined is whether the patent, nevertheless, contains sufficient information allowing the skilled person, without an undue burden, to turn a failure into success or whether, on the contrary, the claims extend to subject-matter which, after reading the patent specification, would still not be at the disposal of the skilled reader.

The claimed invention relies on the conversion of non-hydrated forms of taxane into hydrated forms. However, the patent does not disclose which hydrated forms further to paclitaxel dihydrate dissolve more slowly that their corresponding unsolvated forms.

The term "taxane" refers to a large number of compounds (see paragraphs [0086] to [0095] of the description) and the skilled person is aware that, among these compounds, the existence of (multiple) solid forms of each of them cannot be predicted, let alone their relative solubility rate. Therefore, the skilled person can only establish by trial and error whether or not the required conditioning step, applied to a coating containing a specific (solid) form of a specific taxane would or would not reduce the solubility rate of said coating. Thus, the functional definition of the conditioning step required by claim 1 is no more than an invitation to perform a research program in order to find forms of taxanes suitable for the claimed method, which represents an undue burden for the skilled reader.

For this reason, it is concluded that the patent in suit does not provide sufficient guidance on how to carry out a method of manufacture of medical devices coated with any taxane in which the conditioning step required by claim 1 inevitably leads to a decrease of the solubility rate of the coating. As the patent in suit does not provide sufficient information in order to put the claimed invention into practice for every taxane required by claim 1, it does not disclose the claimed invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art.

7. The respondent argued that there was a general principle disclosed in the patent, namely that an unsolvated form may be transformed into a solvated form due to the required conditioning step, and a generalisation of this principle should be allowable. Taxanes shared a core structure and were not, hence, an infinite number of compounds, and their solid forms were known. For these reasons, the skilled person could find out every embodiment within claim 1 with only a reasonable amount of trial and error and thus without an undue burden.

However, the compounds defined as "taxanes" in paragraphs [0086] to [0095] are, despite sharing a core structure, a broad class of compounds, and the patent does not provide any information on any solid form further to those of paclitaxel, let alone on their solubility rates. Thus, finding taxane forms suitable for the claimed method of manufacture cannot be carried out, as alleged by the respondent, merely by a reasonable amount of trial and error.

This argument of the respondent therefore fails to convince the board.

8. The respondent [proprietor] argued that claim 1 could be lacking essential features, but that was an issue under Article 84 EPC already present in the claims as granted and hence excluded from these appeal proceedings.

Notwithstanding whether claim 1 lacks essential features, the claimed invention is considered lacking sufficient disclosure for the reasons already explained.

This argument of the respondent is also unsuccessful.

9. The respondent further argued that the appellant had not discharged its burden of proof since it had not provided any evidence which could show that the claimed invention could not be carried out, and a lack of disclosure could only be established upon serious doubts, substantiated by verifiable facts.

However, the patent itself does not rely upon the assumption that every hydrated solid taxane must be less soluble than a corresponding non-hydrated form (see paragraph [0006]). The appellant, who in this case was the opponent, does not have to provide evidence on a point which is already acknowledged in the patent in suit.

This argument is therefore rejected.

10. It is thus concluded that the invention as claimed in the main request is not sufficiently disclosed for it to be carried out by a person skilled in the art, with the consequence that the main request is not allowable.