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EBA addresses plausibility


Case G 2/21 concerned a patent application for an insecticide composition used for controlling an insect pest. The applicant argued that the two claimed compounds had a synergistic effect which resulted in improved insecticide activity. However, this effect was only supported by test data published after the filing date of the patent application.


The Board clarified two principles for assessing whether post-published evidence may be relied upon in assessing inventive step:


  1. Evidence submitted by a patent applicant to prove a technical effect relied upon for inventive step may not be disregarded solely on the ground that such evidence was filed after the filing date of the application.
  2. A patent applicant 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.


The EBA’s decision confirmed that, while post-published data may be considered during prosecution, the technical effect of the invention must be encompassed by the technical teaching disclosed in the application as originally filed.

Impact on medical use claims


The G 2/21 decision prompted much discussion about how the principles would be applied in cases in different sectors. There was further guidance in decision T 0258/21, decided in July 2023, which concerned a patent for a second medical use. The patent, filed by Italian pharmaceutical company Chiesi, claimed the use of clevidipine for reducing ischemic stroke damage. In arguing for the inventive step of the claims, Chiesi submitted that clevidipine had improved activity and reduced side-effects compared to other antihypertensive agents, in particular nicardipine in patients with specifically ischemic strokes. However, the application included no data evidencing this technical effect.


Referring to the second principle stated in G 2/21, the Board concluded that in this case the effect “was neither contemplated nor even suggested in the original application”, adding, “Indeed the original application did not mention any comparison to other anti-hypertensive agents”. In this case, even though the disclosure “encompassed the treatment of both haemorrhagic and ischemic stroke”, the Board ruled that lack of comparative data meant that the “technical effect relied upon by the applicant cannot be taken into account for the assessment of inventive step in accordance with G 2/21.”


In this case, therefore, the applicant was unsuccessful in pivoting their claims to a certain medical use (reduced side effects when treating ischemic stroke damage), because the application as filed did not foresee that use, and there was no data supporting it.


No to armchair inventing


The decision in T 0258/21 shows the specific problems that can arise in life sciences cases where the technical effect shown by post-filed data was not embodied in the original disclosure. There is a higher bar for data required to support an alleged technical effect in cases related to medical uses, compared to other technical areas.


In cases where an invention may have multiple potential uses, therefore, the applicant’s ability to change the focus of the application during prosecution may be limited. This also applies to those wishing to pursue broad claims. Put simply, applicants need to consider: have we got enough data to demonstrate plausibility for all potential uses when we file?


This point was reinforced in decision T 0116/18, which was the Technical Board of Appeal’s final decision in the case that led to the EBA decision G 2/21. The Board summarised G 2/21 as follows: “The Enlarged Board thus did not give patent applicants and proprietors ‘carte blanche’ to be able to rely on a purported technical effect at any stage of the proceedings. … patent applicants and proprietors should not be able to invoke any technical effect at will. Instead, the focus on the application as filed and the filing date … is intended to prevent the filing of applications directed purely to speculative (armchair) inventions made only after the filing date.”


The contrast with other technical fields is well illustrated by another recent Technical Board of Appeal decision, T 1989/19, which concerned an application for “Micronised crystalline tiotropium bromide”. In its decision in June 2023, the Board upheld the rejection of the opposition to the patent, finding in favour of the patentee.


In this case the Board further discussed G 2/21, stating: “In order for a technical effect to be recognized in the context of the assessment of inventive step, it is not a prerequisite that this claimed effect must be expressly mentioned or proven in the application as originally filed. Rather, a technical effect proven by subsequently published evidence within the meaning of point 2 of decision G 2/21 can be recognized if it is included in the technical teaching of the originally filed application and can be derived from the same originally disclosed invention.”


These cases illustrate that the EPO continues to apply a high standard for plausibility of medical use claims, in contrast to other fields, such as the chemical claims discussed in T 1989/19.


File early or delay?


These decisions provide guidance on how much data may be required to render the technical effect of an invention plausible. This in turn should frame applicants’ decisions about when to file a patent application.


Of course, filing at an early stage of research can mean getting ahead of competitors and, particularly for small and medium-sized companies, can help when it comes to raising finance. But these cases show that there is a risk associated with filing too soon, especially in the life sciences sector. Filing a patent application before you have enough data may limit your ability to pivot the claims or navigate inventive step challenges during prosecution, particularly if there are concerns about the plausibility of the invention.


The assessment about when to file a patent application, particularly in the life science area, should therefore consider what data is available, what data is likely to be available later on during prosecution and what the potential applications or uses of the technology will be.


An experienced patent attorney can provide advice on how to envisage the invention in the patent application, giving a patent application the best chance of being eligible for grant while retaining flexibility to adapt the application during prosecution. If you would like to discuss this further, please do contact us.

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