G 2/21 does not permit armchair inventing (T 0258/21)

Interpretations of G 2/21 by the EPO Boards of Appeal have so far been reasonably patentee-friendly. Boards of Appeal have interpreted G 2/21 as permitting patentees to rely on technical effects for which the application as filed is completely silent (IPKat, IPKat). The recent decision in T 0258/21, by contrast, is the first interpretation of G 2/21 leading to a finding of a lack of inventive step in view of an inadequate disclosure of the purported technical effect. However, T 0258/21 related to subject matter for which the EPO has always required additional evidence. Particularly, the claim in question was directed to a second medical use of a known therapeutic in a subpopulation of patients. The Board of Appeal considered there to be a complete lack of any convincing supporting data for the claimed use, either post-published or in the application as filed. The decision in T 0258/21 is therefore not surprising, and confirms that whilst G 2/21 is broadly favourable to patentees, it does not permit armchair inventing. 

T 0258/21: Case background

T 0258/21 related to the EP patent application EP 12716828.4. The application claimed clevidipine for the treatment of ischemic stroke. Clevidipine is a anti-hypertensive drug marketed by Chiesi as Cleviprex. The closest prior art was identified as a journal article mentioning the use of clevidipine for the treatment of haemorrhagic stroke. The difference between the claimed invention and the closest prior art was identified as being that the invention related to ischemic stroke instead of haemorrhagic stroke. Importantly, ischemic and haemorrhagic strokes have very different causes. Ischemic strokes are caused by blood clots blocking the supply of blood to the brain. Haemorrhagic strokes are caused by a ruptured blood vessel in the brain. 

Rather surprisingly for a medical use application, the application itself did not contain any data relating to the therapeutic effect. The original application was no more than 20 pages in length and didn't include any data, examples or figures. In view of this rather sparse disclosure, the Board of Appeal concluded that "[n]o technical effect directly linked to the identified distinguishing feature, namely the reduction of ischemic stroke damage, has thus been demonstrated in the application documents". 

Reliance on a post-hoc identified technical effect of medical use in the absence of any data 

Armchair inventing

On appeal, the applicant argued that the selection of clevidipine for the treatment of ischemic stroke was inventive in view of the unexpected technical effect of clevidipine for the treatment of ischemic stroke. Particularly, the applicant argued that clevidipine was surprisingly safe and efficacious in the treatment of ischemic stroke compared to other anti-hypertensive agents. The applicant submitted post-filed data purporting to support this technical effect. 

However, the Board of Appeal was not convinced that either the application as filed or the post-filed data adequately supported the technical effect proposed by the applicant. First, with regards to whether it was even possible for the applicant to rely on the post-hoc technical effect, the Board of Appeal noted the order from G 2/21 that "a patent applicant or proprietor may rely upon a technical effect for inventive step if the skilled person, having the common general knowledge in mind, and based on the application as originally filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention". 

For the Board of Appeal in the case in question, the technical effect on which the applicant was seeking to rely "was neither contemplated nor even suggested in the original application. Indeed the original application did not mention any comparison to other anti-hypertensive agents and it encompassed the treatment of both haemorrhagic and ischemic stroke [...]. It follows that this technical effect relied upon by the applicant cannot be taken into account for the assessment of inventive step in accordance with G 2/21." The Board of Appeal also noted that even if the purported technical effect could have been derivable from the original application, the additional submissions from the applicant purporting to support the technical effect did not "provide any detailed results nor any details on the protocols used [...] The meaningfulness of the appellant's exploitation of the data provided in these abstracts is therefore prima facie questionable."

The Board of Appeal was thus not convinced that the technical effect on which the applicant wished to rely on for inventive step was convincingly encompassed and embodied by the application as filed. The Board of Appeal went on to conclude that, in the absence of a surprising technical effect derivable from the application as filed (or even the post-filed data), it would be obvious in view of the prior art for a skilled person to select clevidipine for the treatment of ischemic stroke. 

The applicant also found themselves in an inventive step / sufficiency squeeze in their attempt to argue that the prior art did not plausibly demonstrate the use of clevidipine to treat ischemic stroke: 

"the Board underlines that, should the appellant's unpredictability approach have been followed (i.e. the effect of clevidipine in the treatment of ischemic stroke damage in patients with ischemic stroke not be considered plausible on the basis of [the prior art]), an issue of lack of sufficiency of disclosure would have arisen since the original application does not provide any experimental data substantiating the claimed medical use."

The Board of Appeal thus upheld the decision of the Examining Division to refuse the application. 

Final thoughts

The implementation of G 2/21 in this case could be said to contrast with previous decisions, in which G 2/21 has not been interpreted as preventing applicants from relying on a technical effect on which the application as filed is completely silent (IPKat). However, none of the previous decisions interpreting G 2/21 have contemplated the evidence requirement for a technical effect for a biotech invention for which no supporting data or statements could be identified from any of the application as filed, common general knowledge (absent an obviousness squeeze) or post-published submissions.  

It is not a surprise that a second medical use claim may be refused by the EPO in view of the complete absence of any data, either in the original application or submitted post-filing, supporting the medical use. As has been discussed extensively in the context of the plausibility debate (IPKat), second medical use inventions represent a class of invention where there is additional burden on the patentee to provide supporting evidence. In most cases, there will be substantial doubt over whether any particular substance or composition will be safe and efficacious at treating a particular disease, hence the need for long and protracted clinical trials and regulatory processes. It is therefore not surprising that patent offices require some evidence to support a medical use claim. G 2/21 has not changed this requirement. 

Further reading

• Plausibility demystified - a review of EPO case law before G 2/21 (Feb 2023)
• G 2/21: Is the technical effect embodied by the invention as originally disclosed? (March 2023)
• UK divergence from the EPO on plausibility (Sandoz v BMS), Part 1: Is the "plausibility" test the same for both sufficiency and inventive step? (July 2023)
• UK divergence from the EPO on plausibility (Sandoz v BMS), Part 2: Interpretation of G 2/21 (July 2023)
• Chocolate teapots and nuclear bombs: Whole range sufficiency of mechanical inventions (T 0149/21) (July 2023)
• The relevance of G 2/21 to machine learning inventions (T 2803/18) (Aug 2023)
• Interpretation of G 2/21: Inventive step may be supported solely by post-published data (T 0116/18) (Sep 2023)
• Reliance on a silent technical effect: Application of G 2/21 to semiconductors (T 2465/19) (Oct 2023)

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