The marriage between molecular biology and in silico technologies has driven medical innovation at an unprecedented rate in recent years.

Notably, artificial intelligence is assisting the discovery and development of treatments for complex diseases. AI-based research requires the interrogation of vast datasets to identify biological features (or 'biomarkers') that suggest certain drugs can be used for particular indications and/or subsets of patients within a particular disease group, and working out what those drugs are. This form of medicine is often referred to as personalised or targeted medicine, because it can reach smaller groups of people with rarer conditions than has previously been the case.

For research and development companies working in this area, however, a dilemma arises: as drugs target smaller populations of people, how can sufficient returns be obtained to make the investment worthwhile? 

Can the patent system adapt?

The usual answer to this commercial question is marketing exclusivity and, in particular, patents. The area of targeted medicine will, however, bring forward problems that are already stretching the patent system.

For instance, there is the unresolved question about where the novelty in patent claims to targeted uses can be found. Novelty of the claimed subject matter – that it is new – over the prior art is an essential requirement for obtaining a patent. But sub-populations, as the name suggests, may be within a wider population for which treatment by the drug has already been tried.

Although such patent claims are granted centrally by the European Patent Office, there has been no decision of the English courts directly addressing the issue of novelty in these kinds of personalised medicine claims.

It is also unclear how such claims can be enforced against infringers.

Finding novelty in personalised medicine claims

The closest authority on the novelty issue in the UK is Actavis v Janssen, which suggests that novelty cannot lie in a new explanation of the mechanism of an old use.

In this case, Actavis sought revocation of Janssen’s European patent concerning the stereochemistry of an important blood pressure lowering drug, nebivolol. The relevant part of claim 1 of the patent is in Swiss form: "use for the manufacture of a medicament for potentiating the effects of blood pressure reducing agents having adrenergic and/or vasodilating activity … of a compound of the formula (I)."

The question was whether this claim, in particular the feature of potentiating activity, was novel over the use in the prior art of a compound falling within the claim, for the same treatment, but without the disclosure of that potentiating activity. The judge concluded that it was not and that it is not the case that every discovery about the mode of action of a drug can be translated into a novel purpose and claimed as such.

As a result, the case appears to infer, the difference between successfully patenting the use of a known drug for a new sub-population with a newly disclosed biomarker, on the one hand, and an unsuccessful patent claim to a new explanation for the mechanism of an old use, on the other, may not always be clear.

The crucial difference between the two kinds of claim appears to be that the latter provides a new technical contribution by disclosing a physiological or pathological characteristic that may be targeted to produce improved treatment. The former merely provides information on the causal relationship that makes it work.

As a result, the precise drafting of targeted medicine claims may be particularly critical, but clear guidance from the court is needed on this issue.

Questions about infringement

Assume there is a valid patent claim for a drug to treat a sub-population of a disease group, and the patent for treating the whole disease population has expired. How does the owner or licensee of the patent claim demonstrate that it has been infringed if a generic is sold for the whole population which is no longer patent protected?

Or, if you are a generic, selling the drug for the whole population, how do you defend against an infringement attack on the basis of the personalised claim?

The ‟outward presentation‟ test in the recent Supreme Court decision in Warner-Lambert v Generics suggests it is a matter of outward appearance of the medicinal product. So, different dosage sizes and regimes for the sub-population might indicate it is for one purpose only. But, otherwise, how do you sell a drug for a population of people who don’t have the patented biomarker?

Without a solution, the overall effect would be that the patentee or licensee re-monopolises the indication as a whole.

One solution may be a regulatory change in prescribing practice, to require doctors to test for the biomarker and prescribe the patented brand accordingly. But this seems unrealistic.

Alternatively, the courts may have to revisit whether an approach to infringement based on the subjective or objective intention of the generic manufacturer when they market their product is suitable in these cases.

Difficult questions face the courts

With advances in technology driving towards the discovery of more personalised medicines, cases in which the novelty and infringement of patent claims to these treatments will inevitably be seen in the courts in future. The courts can be expected to examine the wording of such claims very carefully case-by-case, but clear guidance on the patentability – particularly novelty – of such claims is needed.

How the courts will approach the complex question of infringement is more difficult to predict.

Find out more

To discuss the issues raised in this article in greater detail, please contact a member of our Life Sciences and Healthcare team.

Paul England is co-author, together with Simon Cohen, of A User's Guide to Intellectual Property in the Life Sciences (published by Bloomsbury Professional in December 2020).