T 1847/23 - technical effect not taken into account in view of G 2/21

T 1847/23 shows us that ‘stability’ of a pharmaceutical composition is not necessarily a ‘common’ technical problem in the pharmaceutical field. In addition, the decision demonstrates how application of G 2/21 could differ between different instances of the EPO; in the present case, the Opposition Division found in the favour of the patentee, while the Board took a stricter approach and did not allow the patentee to rely on the purported technical effect in question.

Background

Claim 1 of the Main Request defined a pharmaceutical composition comprising maropitant citrate, β-cyclodextrin and 7-18 mg/ml of a preservative of a specific chemical formula, the preservative being phenylmethanol (benzyl alcohol).

The patent was generally directed to compositions having an improved injection site tolerance when injected to animals such as cats or dogs, and which met the Pharmacopeia’s antimicrobial requirements.

The patentee wanted to rely on an effect of improved stability of the compositions.  They filed data allegedly showing improved stability following one or more freeze-thaw cycles relative to the embodiment of the closest prior art (a composition containing a higher concentration of benzyl alcohol).

The patent contained no mention of stability in the context of the claimed compositions.  The concept of stability was mentioned in the background section of the application, in the discussion of one of the prior art documents, which apparently showed that “meta-cresol was the only preservative tested that was also stable on storage…”.

During opposition

The OD considered the effect of “improved stability” to satisfy the principles of G 2/21 – in the OD’s view, “theproblem of stability” was a “common technical problem in the technical field of pharmaceutical compositions comprising active pharmaceutical compounds”.

According to the OD, the common general knowledge of the skilled person encompassed the general problem of stability; they also noted that “stability at low temperatures is important considering the fact that liquid formulations are possibly frozen during storage or transit”.  The OD also stressed that G 2/21 allowed the skilled person to rely on their common general knowledge.

The OD also took the mention of stability in the background section of the patent as something that “suggestively [hinted] at stability”.

Finally, one of the documents (D40) stated “Do not freeze” in the context of a commercial product comprising maropitant.  The OD took it merely as “a recommendation to the medical practitioner for commercial sales reasons”.

On appeal

For the Board, the purported effect did not meet the criteria of G 2/21.  In particular, the behaviour of compositions comprising maropitant under low or very low temperatures could not be considered as a “common technical problem” in the field of the patent.

Firstly, the application as filed did not contain any mention of stability, still less stability at low temperatures or following freeze/thaw cycles.  Nor could those aspects be derived from the application.  In addition, the patent did not discuss possible instability of compositions comprising higher concentrations of benzyl alcohol than that defined in claim 1; benzyl alcohol was merely disclosed in the patent as an antimicrobial preservative.

Perhaps more importantly, the Board noted that the preparation and/or storage of a drug composition at low or very low temperatures was “neither systematic nor widely practiced”, contrary to the view taken by the OD. There was nothing in the application or in the prior art that showed that compositions comprising maropitant had to be prepared and/or stored under these (low/very low temperature) conditions.

To support this reasoning, the Board referred to (i) one the documents (D10) which apparently showed that a formulation comprising maropitant was to be stored at a controlled temperature of from 20 to 25 °C ; and (ii) the “Do not freeze” statement in D40 (discussed above).

Overall, the Board said that “the preparation and/or the storage at extremely low temperatures, as well as the behaviour of the claimed compositions at these temperatures does not appear to constitute a property typically sought by a person skilled confronted with the problem of preparing this class of compositions”.

On this basis, the Board decided not to take into account the purported effect relied upon by the patentee.  Ultimately, the Main Request was found to be inventive, largely on the basis of how the closest prior art discussed the use of benzyl alcohol as a preservative.

Immediately, T 1989/19 (the ‘tiotropium bromide’ decision from Board 3.3.02) comes to mind, where the Board considered that the purported effect of improved storage stability (in terms of particle size distribution) satisfied the criteria of G 2/21. In that case, though, it seems that much more could be said (based on both the application and the evidence on file) about the importance of the effect to what was claimed in the patent.

If you’d like to catch up on how the Boards have been applying G 2/21 in practice, please feel free to check out my webinar on this topic:

https://www.md-ip.com/blog/webinar-reliance-on-technical-effect