In the not-so-distant past, obtaining patent protection for a new therapeutic drug (or the new use of a known drug) was simpler than it is today. The therapeutic landscape was comparatively unexplored, and our knowledge of disease pathology uninformed by the battery of molecular techniques available today. This lack of detailed information meant the factors to consider when assessing a new therapeutic application were relatively few and, consequently, the required analysis was relatively straightforward.

Fast-forwarding to today, the number and sophistication of the analytical techniques available mean that it is not uncommon for researchers to make discoveries beyond simply the disease(s) which a compound has the potential to treat. For example, the research may characterize the sub-set of patients in which a drug works best (or not at all).

Examples of this type of ‘personalised medicine’ abound in the scientific literature, and patients can be defined by, for example, genotype, SNPs, or protein markers. This allows targeted treatment of the best-responding patients while avoiding non-responders or those likely to suffer adverse effects.

In some cases, defining the patient group means the difference between clinical trial success and failure, enabling rational design of smaller trials with high success rates in defined patient sub-groups. The progression toward a personalised approach to therapeutics poses a challenge for the patent system: can it protect this type of contribution - which has such clear benefits for both patient and practitioner? And, if such protection is available, how should the patent office decide which ‘personalised medicine’ inventions meet the requirements for patentability?

In Europe, at least, the law has developed in a way that is generally favourable to patent applicants in the field of personalised medicine. The European Patent Office (EPO) has long recognized that a newly discovered medical use of a known agent is patentable over the earlier use of the same agent. Through successive decisions of the Boards of Appeal, this principle developed to the point where identifying a new class of patient treatable using a known drug or a new clinical situation constituted patentable subject matter.

Significantly, the Board in T1020/03 (a case handled by Mewburn Ellis partner, Adrian Brasnett) explicitly acknowledged that the investment in clinical trials to find new applications of therapies needed the reward of patent protection to justify it on economic grounds.

Following-on from the T1020/03 decision, the revised version of the EPC which came into force on 13 December 2007 brought with it, for the first time, explicit legal basis in the EPC for medical use inventions by way of a new “composition for use in a method for treatment” claim format. This new claim format defines a method of treating patients rather than obliquely referring to manufacturing drugs like the earlier “Swiss claim” format, and can be easily adapted to “test and treat” claims, in which analytical results are used to identify patients as being eligible for treatment.

The combined results of these changes means that, by defining markers or other clinical criteria by which patients can be selected for treatment, applicants can define a subset of patients who would not have been treated without the insight obtained through the analytical step. This definition can provide the basis for acknowledgement of novelty and inventive step.

The situation gets more complex in cases where the identified target patient group overlaps with the group of patients that the drug was already known or intended to treat. For example, a drug may already have received regulatory approval for treating a certain disease and may have been administered to a diverse population of patients with the disease. Naturally, inventors wish to obtain patents reflecting this advance, including claims directed to the drug for use in treating the disease in the well-responding patient subgroup.

However, the EPO has struggled with the question of whether treatment of the same disease in a newly-defined patient subgroup represents a genuinely new medical use of the drug, or whether such claims are merely the old medical use described in a different way (and therefore not novel).

To the advantage of applicants, the EPO has decided that it is possible to obtain personalised medicine patents under these circumstances. For example, if the former use was described only in theory, with no patients actually treated (or there was a poor or unknown response to the limited clinical use), then use of the drug for treating patients who have a biomarker indicative of good drug response may be considered novel when the biomarker is specified in the claim.

The EPO have also indicated that reciting an active step of determining a patient’s biomarker status (e.g. genotype) will be considered to render a claim novel, since the step of testing the patient to determine the presence of the biomarker is new, even if the drug was previously used successfully for treating the same disease in the same type of patients.

Whilst specifying a particular genotype is a common way of defining a patient group, the new EP medical use claim format lends itself just as easily to defining sub-groups by responders, assays or patterns of administration. This approach was backed by the EPO’s Enlarged Board of Appeal in G2/08, where the Board explicitly confirmed the potential patentability of medical use claims where the pattern of administration was the only novel feature.

Altogether this means that, by performing follow-up patient studies, companies have the possibility of identifying patient sub-groups and obtaining personalised medicine patents. Such patents would effectively lengthen protection they have for treatment of key patient groups and so provide additional revenue to the companies. Moreover, both patients and healthcare providers would reap the benefits of better targeted treatment (viz reduced unnecessary / ineffective treatments).

Thus, applicants seeking European protection for inventions in the personalised medicine field are well placed to obtain useful protection, as is reflected by the increasing numbers of applications that define patient subgroups.

Thankfully then, it seems the European patent system is managing to keep pace with the fast-moving therapeutic field - to the advantage of innovator companies, healthcare providers and patients alike.

This article is also being published in LSIPR