Drug development has, historically, been driven by the overriding assumption that all patients will respond to the same treatment in the same way, and clinical trials were typically built around this principle. However, this assumption was fundamentally flawed, and it is now known that many treatments are effective only for certain sub-sets of a disease or patient population.

This revelation has led to a greater understanding as to what makes an effective treatment, which in turn has led to a new era dubbed ‘precision medicine’ where treatments are tailored to a patient’s individual characteristics. As this approach continues to develop it is likely that we will reach a point where there is no such thing as a standard treatment, with each patient presenting with a particular disorder being treated in a wholly unique way that is likely never to be replicated.

Many drug developers are now returning to drug candidates that once showed initial promise but which went on to fail in clinical trials, in the hope that they may have greater success when then drug is targeted at a more specific group of patients.

Similarly, with the dawn of big data, analysis of information already contained in patient medical records may allow for the identification of patients for whom existing drug treatments are particularly effective, or for whom certain treatments should be avoided.

Nordic countries in particular are well placed to lead the way in the analysis of such data, as they typically have comprehensive medical records for millions of patients stretching back several decades. Indeed, the use of this big data approach in the field of precision medicine is a topic worthy of its own article.

More so than in any other field of endeavour, the ability to secure a period of market exclusivity for a new drug product or treatment is crucial to the ability of an innovator to reach the market. As innovation in the area of precision medicine develops, so too must the ways in which the resulting intellectual property can be protected. However, the protection available for new and innovative medical uses can vary between territories. By way of an example, we will focus on the practice of the European Patent Office (EPO).

Second medical use

Article 54(4) of the European Patent Convention provides that where a substance or composition is already known for use in treating a certain condition, its use for treating previously unknown conditions is patentable, provided such use satisfies the standard requirements for obtaining patent protection. Such inventions are commonly referred to as a second medical use.

Nevertheless, while it has been clear for some time that the use of substances or compositions in the treatment of a condition not previously known to be treatable this way is patentable, it was not clear that this type of protection would be available to new ways of treating the same indication, such as by focusing on a particular treatment protocol, method of administration or, of particular importance in relation to precision medicine, specific patient or disease sub-groups.

The question of whether the patentability of second medical use claims can rest only on new uses of a known substance or composition to treat a previously unknown condition or whether it can relate to any new and inventive use was addressed a few years ago by the EPO’s Enlarged Board of Appeal (in decision G2/08).

In this decision it was confirmed that where it is already known to use a particular medicament to treat a particular illness, use of the same medicament for treating the same illness by way of a different, new and inventive treatment is possible.

For example, Claim 1 of the application in question in this decision focused on the use of nicotinic acid in the treatment of hyperlipidaemia, wherein the treatment was by oral administration once per day prior to sleep. As the treatment of this indication using this particular drug was already known, it was the specific dosage regime that was the crux of the invention.

This decision not only confirmed that claims to new and inventive second medical uses are allowable when the only novel and inventive feature is a dosage regime, it more broadly confirmed that a new use need not be limited to the treatment of new diseases per se, but rather that the novelty of second medical use claims may be established in a number of ways, with the most common being novel dosage regimes and modes of administration, and the targeting of particular patient sub-groups.

Pigs II

Prior to the decision in G2/08, EPO case law had provided guidance on how a new treatment of a known disorder might be characterised. For example, decision T 19/86, commonly referred to as Pigs II, established that the treatment of a sub-group of pigs seropositive for Aujeszky’s disease was novel even though the vaccine used was already known for treating that disease, on the basis that it would have previously been expected to be targeted at only the seronegative population.

Similarly, in decision T 0893/90 it was found that the use of a known pharmaceutical composition in controlling bleeding in non-haemophilic patients was novel over the previous use of that composition in treating haemophilic patients.

Of particular note is the reasoning in decision T 233/96, which considered the use of a particular pharmacological stressor in the preparation of a diagnostic agent for detecting or assessing heart disease in a patient group defined as being those “unable to exercise adequately”. In rejecting this claim, the board found that novelty could be recognised only if the new group of subjects was distinguished from prior art by its physiological or pathological status.

While this line of reasoning is certainly of use when looking to define a patient group that is objectively identifiable, eg, through identification of a particular biomarker or physical characteristic, it does not account for situations in which the characteristic of the patient sub-group is more subjective than objective—for example, in the identification and classification of mental health disorders.

Diagnosis barrier

It is well known that developments in mental health treatment have typically lagged behind developments in traditional medicine. One of the main reasons for this is that diagnosing mental health disorders is extremely difficult and is often carried out by first ruling out possible physical problems, and only then psychologically evaluating the patient by way of a questionnaire.

As a consequence, protecting innovation in precision medicine in the field of mental health has proven more difficult, as a mental health patient or disease sub-group is typically not identifiable via a physiological marker based on the results of a physical scan, blood test, etc. However, recent case law has suggested that the EPO is willing to take a pragmatic approach towards acknowledging and rewarding innovation in this area.

In decision T 1491/14 the claims at issue were directed towards the use of a known drug in the treatment of depression and other disorders in patients who had previously received another medication for the treatment of those disorders and in whom the medication was ceased or reduced “due to sleep or sexually-related adverse events”.

It was known that adverse events of this type are common with other anti-depressants, and the invention was based on the discovery that the drug in question gave much lower levels of adverse events. Thus, the claims in question had been framed to capture the sub-group of patients that had previously had compliance issues due to the side-effects, who were the patients expected to benefit the most from the newly discovered properties.

Step in the right direction

Although it was argued by the opponent that the patient sub-group was not a distinguishing feature as it could not be identified based by reference to a physiological or pathological parameter, the board found the patient group could nevertheless be identified by a physician with the proper training in treating mental health disorders.

As there was no question that the underlying conditions of depression or anxiety could be diagnosed based on subjective assessment, there was no reason to doubt that the compliance issues could be identified using a similar diagnostic methodology.

This is clearly a step in the right direction for spurring innovation in the treatment of mental health disorders, and perhaps with more legal certainty more resources will be dedicated to improving the diagnosis and treatment of mental health disorders.

With the number of patients diagnosed with mental health disorders globally steadily increasing, such innovation cannot come soon enough.

Chris Cadman is a senior associate and patent attorney at Potter Clarkson. He can be contacted at: tony.proctor@potterclarkson.com

Tony Proctor is a partner and patent attorney at Potter Clarkson. He can be contacted at: tony.proctor@potterclarkson.com

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