Repurposing known drugs for novel therapeutic applications offers huge potential for advancing medicine and encourages the use of known medication – with known pharmacokinetics, side effects etc. – for the treatment of new diseases. However, the legal landscape surrounding patentability can be intricate. Here we explore some of the recent case law surrounding ‘second medical use’ claims, exclusions to patentability, selection inventions and dosage regimes.
Key points:
For those working and filing second medical use claims in the pharmaceutical field, there are some key takeaway messages:
- Consider the claimed use holistically, i.e., in addition to the substance or composition itself, can method of treatment steps, which are excluded from patentability per se, or dosage regimes, etc, be used to confer novelty and inventive step?
- Consider selection inventions to subranges, etc. The removal of the requirement for a selected subrange to be purposive to confer novelty means that the bar has arguably been lowered for establishing novelty for a selection invention.
- Leverage unexpected – or bonus – technical effects to strengthen inventive step arguments.
T 0558/20: second medical use and exclusions to patentability
Under European practice, a previously known drug found to be effective for the treatment of a new condition may be patentable in the form of a second medical use claim. Such claims must be in the form of “drug X for use in the treatment of condition Y”. Although it is well established that such claims are patentable per se, the assessment of the novelty of second (or further) medical use claims has been the subject of various decisions from the European Patent Office (EPO).
In T 0558/20 the Board of Appeal considered how the assessment of second medical use claims should be approached. The case related to EP 2,588,154 B1 and focused on the patentability of a second medical use claim related to a known composition for use in the treatment of a degenerative bone condition, whereby the treatment included specific surgical method steps. Methods for treatment by surgery or therapy are excluded from patentability in Europe (Article 53(c) EPC). However, this exclusion does not apply to substances or compositions ‘for use’ in such methods. A previously known substance or composition can still be patented for a medical use, if the specific use is new (Articles 54(4) and (5) EPC).
It was not disputed that the claimed compositions and their general use in the treatment of degenerative bone disease was known. Therefore, the Board had to consider whether the claim was novel in view of the fact that the only distinguishing features over the prior art were the surgical method steps (which per se were excluded from patentability under Article 53(c) EPC). On this point, the Board noted two different approaches.
The approach followed by the Patentee (as appellant) was to first assess whether the method steps referred to in the claim should be excluded under Article 53(c) EPC. If yes, then the use and the method steps should be considered as limiting features of the claim, and it must be determined whether the specifically claimed use of the composition in such a method is novel. The Opposition Division essentially used the reverse approach, first assessing whether the specific use of the composition is known, then, if not, considering whether the method steps are excluded from patentability. If the specific use of the composition is known, then the claim is not novel and it is not necessary to assess whether the method steps are excluded from patentability. Interestingly, the Board noted that the two approaches should result in the same outcome. However, it felt that the second approach was more prone to error.
During first instance proceedings, the Opposition Division agreed with the Opponent’s argument that the surgical method steps did not specifically relate to the claimed compositions and, as such, could not contribute to the novelty of the claimed therapy. The Opposition Division further noted that the claim could not be considered novel because:
i) the use of the compositions for the treatment of degenerative bone disease was already known in the art; and
ii) the Patentee had not made it “credible that a new technical teaching was provided” by said use. Although the Board of Appeal took a different approach (see below), it is interesting that the Opposition Division appeared to use credibility – or plausibility – test in its assessment of the novelty of second medical use claims. (see our review of G2/21 here).
As mentioned, the Board concluded differently, finding that the novelty of a second medical should be assessed using a holistic approach whereby the entirety of the claimed use, encompassing both the composition and the specific method steps involved, is considered. This appears to recognize that therapeutic value often springs from the synergistic interaction between the substance and the chosen method of administration (i.e., surgical steps, dosage regime, etc.). The Board found an auxiliary request to be novel on the basis that the specific surgical method steps were not disclosed in the prior art with respect to the claimed compositions.
T 1356/21: selection inventions, dosage regimes and unexpected technical effects
The patentability of second medical use claims was also considered in T 1356/21. This case related to EP 2,571,517 (Sanofi) and included a main claim to a pharmaceutical formulation comprising a specified concentration of insulin glargine for use in the treatment of Type I and Type II Diabetes Mellitus. The only distinguishing feature over the prior was the concentration of insulin in the formulation.
In Europe, new dosage regimes are patentable in second medical use claims, even in cases where the dosage regime itself is the only novel feature (G 2/08). In this case, the Opponent argued that the concentration of insulin in the claim amounted to a dosage regime. However, the Board disagreed, finding that the concentration as claimed was not related to the use of the formulation, i.e., in a dosage regime, but was a defining feature of the formulation itself. As such, the point to be considered was whether the specified concentration of insulin was a novel selection.
The Opponent argued that the claimed concentration represented an arbitrary, rather than purposive, selection over the art, and therefore could not confer novelty. This argument is in line with the outdated (pre-2019) requirement that a subrange can only be novel if it is a specific – i.e., purposive – selection that confers a technical effect (T 198/84 and T 279/89). However, more recent case law has moved away from the ‘purposive selection’ test for the novelty of subranges (as discussed in our article here), considering it instead to be an assessment under inventive step. Its removal simplifies the novelty analysis for inventions involving subranges.
In applying the updated case law, the Board of Appeal found that the claimed subrange could not be considered to lack novelty because a purposive selection was not a requirement. It also noted that the same test was relevant to the assessment of the novelty of dosage regimes. On this point, the Board referred to G 2/08 and noted that “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 question therefore came down to whether the specified subrange was inventive.
The patent identified two technical effects associated with the use of the claimed subrange of insulin:
i) reduced discomfort to the patient as a reduced volume of the formulation could be injected; and
ii) a flatter pharmacokinetic/pharmacodynamic (PK/PD) profile leading to a longer duration of action.
The Opponent argued that it was the reduction in injection volume that resulted in decreased discomfort, and that the PK/PD profile was an inevitable bonus effect that could not be relied on for inventive step (T 506/92).
However, the Board did not agree, and concluded that the fact that two technical effects arising from the same distinguishing feature does not mean that one must necessarily be disregarded as unsurprising, stating:
“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.”
It instead considered that both effects must be taken into account, leading to the claim being found inventive.
Conclusion
It remains the case that the European Patent Office (EPO) now favours the “Gold Standard” test for assessing novelty, including the novelty of a second medical use claim. Under this approach a finding of lack of novelty requires a feature to be directly and unambiguously derivable in the prior art, by a skilled person using their common general knowledge.
The evolving legal framework surrounding second medical use claims, as exemplified in T 0558/20 and T 1356/21, offers exciting possibilities for advancing medicine and improving patient outcomes. By understanding the nuances of this landscape and strategically navigating its complexities, innovators can unlock the potential of repurposed drugs and contribute to the development of groundbreaking therapeutic solutions.
