EPO Board of Appeal provides guidance on the sufficiency requirements for second medical use claims

The EPO’s Technical Board of Appeal 3.3.01 in recent decision T421/14 (and related decision T799/16) has provided guidance on when the requirements of sufficiency are met for claims directed to a second (or further) medical use of a known product – in particular where the therapeutic effect is only achieved in a subpopulation of responders and not the patient population as a whole. The decision confirmed that the existence of a group of non-responders does not result in a lack of sufficiency for claims directed to a general population and that the group of non-responders does not need to be excluded.

Established EPO case law for second medical use claims states that the attainment of the claimed therapeutic effect is a functional technical feature of such claims. To meet the requirements of sufficiency, the therapeutic efficacy of the composition and dosage regimen for the claimed indication must be credible. EPO case law has also established that the presence of a non-working embodiment is acceptable, as long as the specification contains information on the criteria needed to identify the working embodiments. Against this background, decision T421/14 considers the issue of sufficiency in a situation where the claim is directed to a general population of patients but encompasses a large group of non-responders.

The claims in question related to a dosage regime comprising aminopyridine for increasing walking speed in multiple sclerosis (MS) patients. MS, like many other diseases, shows a wide variability in pathology which results in only a proportion of patients responding to treatments. The application as filed acknowledged that it was known that only a proportion of patients, estimated to be about one third, responded to treatment with aminopyridine.

The opponent argued that the data within the patent did not demonstrate a therapeutic effect across the full scope of the claims due to the large proportion of the patient population treated being ‘non-responders’. Since the claims did not specify a step of initially identifying a patient as either a responder or non-responder, the opponent argued that the claim scope was incommensurately broad because it encompassed the treatment of patients not responding to the claimed treatment.

The Board of Appeal did not agree with the opponent’s position and stated that “the existence of non-responders is not a reason to deny sufficiency of disclosure” and that non-responders do not have to be excluded or disclaimed. The Board of Appeal also acknowledged that the existence of non-responders is “a common phenomenon which is observed with drugs in many treatment areas” and that it is common practice to treat patients with a drug and change their medication if they do not respond to treatment.

The Board of Appeal held that the criterion of sufficiency of disclosure is met if it can be shown that a relevant proportion of patients benefits from a treatment and that it has acceptable safety, since in these circumstances the skilled person in the art has the necessary technical information to perform the treatment. As the Board notes, the existence of non-responders is a common phenomenon, and innovators will therefore be reassured that in general this does not preclude a second medical use patent from being obtained. Questions remain regarding the requirement that a ‘relevant proportion’ of patients must benefit from the treatment, but it is interesting to note that the Board found that this requirement was met even when only a minority of patients were responders.

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