Few will have missed recent reports giving interim data on the efficacy of recently developed vaccines aiming to prevent SARS-CoV-2, the virus behind the Covid-19 pandemic.

At time of writing, the University of Oxford, in collaboration with AstraZeneca plc, have announced data from Phase III trials showing that their candidate vaccine can indeed effectively prevent the disease, including an observed reduction in asymptomatic infections.

There are many reasons to be excited about these findings. The speed of development and testing is unprecedented. A large number of doses are already manufactured, with many more on their way. Then there is the fact that the temperature stability and low cost of this particular vaccine (in comparison to others under development) could mean that it can be rolled out to the developing world more effectively, and so possibly mark the beginning of the end for the devastating pandemic worldwide.

Of course, just as importantly, it provides an opportunity to consider the patentability of medical inventions relating to different dosage regimes at the European Patent Office (EPO).

Patents for methods of treatment and prevention of disease

Like many patent systems, the European Patent Convention (EPC) does not allow patents which claim “methods for treatment of the human or animal body by surgery or therapy” (Article 53(c) EPC). Such methods include prophylactic treatment, such as immunisation against disease. The usual explanation for these restrictions is that a medical professional should be able to prescribe or carry out whichever treatment or intervention he or she considers best, without needing to worry about infringing a patent.  

However, mindful of the considerable scope for patent protection to spur innovation in the pharmaceutical field, the EPO’s prohibition on methods of treatment does not extend to claims “to products, in particular substances or compositions, for use in any of these methods”. Also, substances or compositions can be patented “for any specific use” in a method of treatment even if the substance itself is already known, as long as the use is not known (Article 54(4) and (5) EPC).

Thus, if a drug X is already known to be able to treat disease Z, but is then found to treat disease Y, the standard approach in Europe is to write a composition claim which is limited by the new use, that is: “Substance X for use in a method of treatment of disease Y”, which will be allowable unless that use is known or obvious over the prior art.

Is a different dosage enough?

This approach is straightforward enough when new treatments for entirely different diseases are considered, but it is less clear whether the same principles should apply if new methods of treating the same disease are developed. For example, should a patent be granted to a composition for use in a method of treatment if the only new feature of the method is the dosage regime used?

After all, as shown by the present story of the Oxford vaccine, dosage can be surprisingly important.

The initial data indicate that the vaccine is around 70% effective, that is, participants receiving the vaccine are 70% less likely to catch Covid-19 than participants receiving a dummy vaccine, but notes that this is a combination of results in two groups of participants. One group (of almost 9,000 participants) received two full doses of the vaccine, administered at least one month apart, with a 62% efficacy found. Another group received a half-dose to begin with, followed by a full second dose at least one month later, but in this group a higher efficacy of 90% was achieved.

Immunology is almost legendarily complicated, and not a little counter-intuitive, but even by those standards this difference in results is not easy to explain. There have been reports that the groups being given different doses was the result of an error in the first place, and there could well be changes to the story when more details are known. However, if the current data hold up, this case demonstrates that a counter-intuitive but highly advantageous effect can result from changes in dosage.

The approach taken by the European Patent Office to this question has changed over time. In an earlier case T 0317/95, the Board of Appeal regarded that the claims, which were new only in that they described a new dosage regime, related to the administration of medicine as a treatment, and so should be unpatentable.

However, current practice (following case G2/08) now gives a broad interpretation to the wording in Article 54(5) EPC stating that medical compositions “for any specific use” in a therapeutic method are not excluded from patentability. The novelty and inventiveness is held not to be found in the composition itself, but in its intended therapeutic use, and so there is no reason to treat a new dosage regime for a known compound differently from any other new use. The upshot is that a patent indeed can be granted on the basis of a new dosage regime, even for the same composition used to treat the same disease.

For those who perceive an inconsistency between this approach and the prohibition on patents for methods of treatment, it is important to note that the method itself is still not protected, but rather only the composition indicated to be used in the new way. This indicates restrictions on how such a composition can be formulated, marketed, and described on its packaging and usage literature.

Implications and implementations

Since a newly filed patent to a new use can in theory extend the length of time that a patent owner can exercise control over a product, some consider that this approach allows for ‘evergreening’, that is, unjustified extension of patent lifetimes for drugs to prevent generic products entering the market after original patents expire.

However, the EPO has stressed that the standard requirements for a patent to be novel and inventive still apply to such claims. Therefore, claims of this sort should not be granted unless the dosage regime is not only new, but also not obvious from previously available information.

In more recent cases, the EPO has considered the question of what changes of dosage might be obvious, asking what a person of skill in the art might consider changing as a matter of course, and what conclusions about likely dosage regimes can be drawn from existing data.          

For example, in T 2506/12 the EPO Board of Appeal considered it would be typical, and therefore obvious, for a person skilled in the art to identify suitable dosages in a routine dose-finding trial, even if such trials were laborious and time consuming.

In the UK, the Court of Appeal (Actavis v ICOS) has taken a similar approach. The prior art disclosed the erectile dysfunction drug Tadalafil and a tablet containing a 50 mg dose. The patent in question claimed a composition of 1 to 5 mg, for a maximum total dose of 5 mg a day. The Court of Appeal found the claims to be obvious, and considered that even if efficacy at the low dose of 5 mg would be surprising, the information was found by standard and routine enquiries into dose response which are required by clinical trials and would not have required any inventive input.

Therefore, while current practice in Europe allows claims relating to a new dosage regime, it does seem that something special is required for protection to be granted, with a particularly surprising result and/or a dosage which would not be tried by a team carrying out standard investigations. Therefore, when preparing applications relating to compositions for use in methods of treatment, where dosage is an important factor, it is advisable to discuss the reasons for using particular dosage regimes, and how the approach of the inventors is different from usual clinical trial procedures.

Incidentally, this article does not mean to imply the patent strategy of the developers of this or any other vaccine, or indeed to comment on patents to vaccines in general or SARS-CoV-2 in particular. The University of Oxford and AstraZeneca have made a joint commitment to provide the vaccine on a not-for-profit basis for the duration of the pandemic across the world, and in perpetuity to low- and middle-income countries. Though this author has seen some impressively poor takes on the subject, questions of the role of patents during a pandemic are not considered here.

Paul Waldron 8 December 2020

[Photo by CDC on Unsplash]