So-called second medical use claims are a type of patent claim
in the field of medicine. These claims are typically used to
protect the use of a known substance or compound for a new and
specific medical purpose.
For example, if Drug X is known for treating hypertension, a second
medical use claim might cover the use of Drug X for treating
migraine. The novelty lies in the discovery of a new therapeutic
application for the existing compound. As well as treating a new
disease or condition, a new therapeutic application may involve
treating a specific target population, or achieving a therapeutic
effect in a novel way.
These claims are valuable to the pharmaceutical industry as they
allow companies to extend the patent protection of their drugs by
identifying new therapeutic uses for existing compounds. They can
thus incentivise further research and development in the medical
field.
Last year, the Enlarged Board of Appeal (EBA) of the European
Patent Office (EPO) issued decision G2/21, concerning the permitted use of
post-filed evidence to support the patentability of a claimed
invention. Others, including some of my colleagues (see here, and here), have commented on this decision and I
do not wish to go over old ground here. However, it is important to
point out that the binding part of the decision only refers to the
submission of post-filed evidence in the support of proving a
technical effect relied upon for acknowledgement of
inventive step. Does this leave open the question
of post-filed evidence in support of sufficiency?
Interestingly, the EBA in a preliminary communication (dated 13
October 2022) indicated that "the referral arose in the
context of inventive step" and so did not consider
"it appropriate to extend the clear scope of the referral
beyond what the referring board identified as decisive for its
decision". Thus, the EBA chose not to consider the effect
of post-filed evidence in support of sufficiency (Article 83 EPC).
Nevertheless, in its decision, the EBA expressed an intermediate
conclusion concerning sufficiency of disclosure, as "the
Enlarged Board accepts the appropriateness of a comparative
analysis and comparative considerations", between
inventive step and sufficiency requirements.
Whilst it is common for the EBA only to rule on the specific point
of law that has been referred to it, it would seem that the EBA
wanted to lay out its views in relation to sufficiency and the use
of post-filed evidence, perhaps to mitigate against possible
further referrals being made in the future.
With respect to second medial use claims, the EBA wrote at point 74
of the decision:
"Indeed, a technical effect, which in the case of for
example a second medical use claim is usually a therapeutic effect,
is a feature of the claim, so that the issue of whether it has been
shown that this effect is achieved is a question of sufficiency of
disclosure under Article 83 EPC.
Hence, because the subject-matter of second medical use claims
is commonly limited to a known therapeutic agent for use in a new
therapeutic application, it is necessary that the patent at the
date of its filing renders it credible that the known therapeutic
agent, i.e. the product, is suitable for the claimed therapeutic
application".
The EBA reviewed and considered some of the relevant case law in
respect of therapeutic applications and sufficiency of disclosure
and concluded at point 77:
"The reasoned findings of the boards of appeal in the
decisions referred to above make clear that the scope of reliance
on post published evidence is much narrower under sufficiency of
disclosure (Article 83 EPC) compared to the situation under
inventive step (Article 56 EPC). In order to meet the requirement
that the disclosure of the invention be sufficiently clear and
complete for it to be carried out by the person skilled in the art,
the proof of a claimed therapeutic effect has to be provided in the
application as filed, in particular if, in the absence of
experimental data in the application as filed, it would not be
credible to the skilled person that the therapeutic effect is
achieved. A lack in this respect cannot be remedied by
post-published evidence".
Thus, the EBA gave a clear indication, even though the binding part
of the decision was formally restricted to the consideration of
inventive step, that it did not consider it appropriate to diverge
from the existing case law in respect of the use of post-filed
evidence in the support of sufficiency arguments. It is well
established in the case law from the Boards of Appeal of the EPO,
that a patent application directed to a second medical use, must
provide evidence to support the claimed therapeutic application.
Seminal decision T609/02 summarises the position nicely:
"It is required that the patent provides some information
in the form of, for example, experimental tests, to the avail that
the claimed compound has a direct effect on a metabolic mechanism
specifically involved in the disease, this mechanism being either
known from the prior art or demonstrated in the patent per se.
[...] Once this evidence is available from the patent application,
then post-published (so-called) expert evidence (if any) may be
taken into account, but only to back-up the findings in the patent
application in relation to the use of the ingredient as a
pharmaceutical, and not to establish sufficiency of disclosure on
their own.".
However, it is not always necessary that the evidence be in the
form of experimental tests, as confirmed in T950/13 (when referring
to T788/06):
"the disclosure of experimental results in the application
is not always required to establish sufficiency, in particular if
the application discloses a plausible technical concept and there
are no substantiated doubts that the claimed concept can be put
into practice".
Nevertheless, it seems clear that, unless a second medical use
patent application as filed includes evidence to support the
claimed second medical use, the patent application may be deemed
insufficient and be refused. Moreover, absence of this cannot be
remedied by use of post-filed evidence.
However, care must be exercised when drafting second medical use
patent applications, to ensure the evidence presented in the
specification will meet sufficiency requirements. This is
elaborated in T1045/13, where the Board found that:
"The application as filed does not provide any indication
of the principle underlying the relationship between the activity
of the pharmaceutically active agent, i.e. the NGF, and the
therapeutic effect, i.e. the alleviation of the symptoms of the
psychological conditions claimed. The description does not provide
any information on the mechanism of action of NGF. No background
references are cited that link NGF to the therapeutic effects to be
obtained, and no in vitro assays are provided to illustrate any
such effect. In the complete absence of such information, the
experimental evidence on file is of decisive
importance"
and:
"To sum up, the appellant has chosen to rely solely on
experimental evidence in support of the therapeutic treatment as
claimed in claim 1. The experimental evidence on file fails however
to provide evidence for the effects claimed. The examples do not
cover the whole scope of the claim and do not provide evidence of
therapeutic efficacy that meets scientific standards (statistically
significant number of patients, control group). Effective treatment
of the medical conditions under consideration has thus not been
shown".
The Board further confirmed that failure to meet sufficiency
requirement comes with a heavy price, as this cannot be rectified
by post-filed evidence, where it said:
It is established case law that once evidence is available from
the patent application as filed, then post-published evidence may
be taken into account, but only to back up the findings in the
patent application. Post-published evidence cannot establish
sufficiency of disclosure on its own.
In summary, it seems clear from the EPO case law that, in order for
second medical use claims to be considered allowable, it is
necessary for the application to include appropriate evidence in
the specification as filed. Moreover, failure to include
appropriate evidence to establish sufficiency, at the time of
filing, cannot be rectified by the use of post-filed evidence.
Although the binding portion of G2/21 is directed to matters
concerning inventive step, it nevertheless appears that the
decision provides additional weight to support the established case
law in respect of patent applications and claims directed to second
medical uses meeting the requirements of sufficiency.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.