The criteria for the novelty and inventive step of pharmaceutical selection inventions (T 1356/21)

The recent Board of Appeal decision in T 1356/21 covered a number of interesting legal points in the field of pharmaceutical patents. The case related to the novelty and inventive step of a second medical use claim. The only distinguishing feature of the claim in view of the prior art was the specified concentration of the active substance (insulin) in the pharmaceutical formulation. The Board of Appeal considered the appropriate application of EPO case law on the novelty of dosage regimes and selection inventions, and the reliance on an unexpected technical effect for inventive step. 

Legal background: Second medical use claims and dosage regimes

Methods of treatment are excluded from patentability in Europe (Article 53(c) EPC). However, it is possible to patent a "substance or composition for use" in a method of treatment. In this way, a previously known substance or composition may be patented for a medical use if the specific use is new (Articles 54(4) and (5) EPC). The "specific use" for which the second medical use format may be used includes new dosage regimes for known substances or compositions (G 2/08, IPKat). 

The appeal case T 1356/21 related to the novelty of Sanofi's patent (EP2571517). The granted patent claimed a pharmaceutical formulation comprising a defined concentration of insulin for use for the treatment of diabetes. The patent was opposed on the grounds that the claims lacked novelty and inventive step. 

Is the concentration of the substance a feature or use of the product?

The Opponent argued that the insulin concentration specified in the claims corresponded to a dosage regime. New dosage regimes are patentable in second medical use format (Articles 54(4) and (5) EPC) even where the only point of novelty in the claim is the dosage regime itself (G 2/08, IPKat). The Opponent argued that the second medical use format of the granted claims converted the insulin concentration feature into a dosage regime, i.e. a use, as opposed to a feature of the product itself. The Opponent further argued that the novelty of dosage regime claims should be considered differently. 

However, the Board of Appeal could see no justification for construing the specified "concentration" of insulin in the claim as a dosage regime. For the Board of Appeal, the concentration feature defined the composition itself, and not its use (r. 2.5). The question then became whether the defined concentration could be considered a novel selection.  

Purposive selection is no longer test for the novelty of selection inventions

Historically, subrange selection inventions were only considered novel if they represented a purposive selection supported by a technical effect. The Opponent submitted that the insulin concentration in the claim represented an arbitrary selection of a sub-range, and therefore could not confer novelty. The Opponent further argued that a higher novelty standard should be applied to dose selections, citing the Enlarged Board of Appeal in G 2/08, in which it was stated that a novel dosage regime should "reflect a different teaching". 

One-way street

However, as pointed out by the Board of Appeal, the "purposive selection" criteria for the novelty of sub-ranges has fallen out of favour in recent years. There is now a body of case law dismissing the purposive selection test. Purposive selection is now considered as an assessment more properly situated in inventive step than not novelty (IPKat). Following this case law, the Board of Appeal dismissed the novelty attack based on the lack of a purposive selection for the claimed sub-range (r. 2.4). The Board of Appeal also noted that the EBA in G 2/08 had provided that "the whole body of jurisprudence relating to the assessment of novelty and inventive step generally also" continues to apply to dosage regime inventions. The Board of Appeal concluded that the EBA in G 2/08 "did not seek to establish different novelty criteria for numerical ranges in the case of dosage regimen. Thus, the case law in the general situation of numerical ranges, as it has evolved over the years, must apply also in the case of dosage regimen." 

The Board of Appeal thus also rejected the Opponent novelty attack on the basis that purposive selection is not required for any type of selection invention, including those relating to a dosage regime (r. 2.6). Therefore, even if the insulin concentration specified in the claim were to be considered a dosage regime, this would not impinge the novelty of the claim. 

Unexpected technical effect

The distinguishing feature of the granted claim relied on for both novelty and inventive step was the selected insulin concentration. According to the patent specification, two technical effects were identified with respect to the selected concentration. First, the selected concentration reduced the volume of the formulation that needed to be injected into patients, and therefore reduced patient pain and discomfort. Second, the selected concentration had desirable pharmacokinetic properties leading to a longer duration of action. The Board of Appeal was satisfied that both effects were credibly (i.e. "plausibly" in old-money) achieved by the claimed invention in view of the disclosure of the application as filed (r. 3.4.1). 

The Opponent argued that the pharmacokinetic properties of the formulation was an inevitable and unsurprising result of the selected concentration and could not therefore be relied on for inventive step (T 506/92). However, the Board of Appeal was not convinced that this thereby rendered the selected concentration obvious. Particularly, the Board of Appeal did not consider that the fact that one technical effect of an invention was unsurprising, discounted a second unexpected technical effect from being relied on for inventive step: "In situations which do not qualify as a 'one-way street', the Board does not consider it appropriate that a crucial and unexpected technical advantage be disregarded in the assessment of inventive step as soon as any additional obvious effect is mentioned in the patent." (r. 3.4.3). 

Additionally, the Board of Appeal was not in any case convinced that either of the technical effects constituted a "one-way-street" (r. 3.4.4.). The claimed invention was therefore found inventive based on the unexpected technical effects of the selected concentration. The decision of the Board of Appeal in this case contrasts with recent UK court cases in which the bar for showing that a selection invention in the pharmaceutical field was not "obvious-to-try" is set relatively high (IPKat). 

Final thoughts

The Board of Appeal decision in T 1356/21 is another welcome reinforcement of the case law that "purposive selection" has no place in novelty analysis. The reasoning in T 1356/21 also highlights once again that the EPO generally views selection inventions in the pharmaceutical field in a more favourable light than the UK courts. 

Further reading

• Second medical use dosage regimen claim successfully traverses both insufficiency and "obvious-to-try" attacks (T 0799/16) (March 2021)
• Bayer v Teva: Drug patent found "the result of standard and routine considerations" ([2021] EWHC 2690 (Pat)) (Dec 2021)
• Updated EPO Guidelines 2019: A novel selected sub-range is no longer required to be a “purposive selection” (Oct 2019)
• Gold Standard test for novelty reigns supreme, even for subranges (T 1688/20) (Jan 2023)
• Make no bones about it: The "credibility test" has no place in the novelty assessment of second medical use claims (T 0558/20) (Aug 2023)

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