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New uses for old drugs – where’s the patent protection?

28th Apr 2017

Scientists announced earlier this month that they have found two drugs which act to block a pathway that leads to brain cell death in mice and thus prevent neurodegeneration. One of these, trazodone hydrochloride, is already a licensed antidepressant for use in humans, so is ready for clinical trials.  The other, dibenzoylmethane (DBM), is already being trialled as an anti-cancer drug.

Professor Giovanna Mallucci led the team from the Medical Research Council’s (MRC) Toxicology Unit in Leicester and the University of Cambridge. As reported by the MRC, Professor Mallucci said:

“We know that trazodone is safe to use in humans, so a clinical trial is now possible to test whether the protective effects of the drug we see on brain cells in mice with neurodegeneration also applies to people in the early stages of Alzheimer’s disease and other dementias. We could know in 2-3 years whether this approach can slow down disease progression, which would be a very exciting first step in treating these disorders.

“Interestingly, trazodone has been used to treat the symptoms of patients in later stages of dementia, so we know it is safe for this group. We now need to find out whether giving the drug to patients at an early stage could help arrest or slow down the disease through its effects on this pathway.”

So faced with a known drug and a faster time to market, can the developments be patented?

The very first time a substance is found to have a medical effect, patent protection should be available for a pharmaceutical composition including the substance. Those patents can then be enforced against marketing of the drug for any therapeutic indication.

However, that does not close the door on patent protection if the drug is found to be useful in a new medical indication; the development may be patentable under what is known as further medical use protection. Some patent offices allow patent claims directed to a method of treatment of the disease newly of interest. Others, including the European Patent Office, have developed language directed to a composition including the drug for use in the treatment of the disease newly of interest.

Patent claim drafting is more challenging if in fact the earlier use has already hinted at efficacy in the treatment now of interest. It is mentioned that trazodone has been used already in later stages of dementia, so after that disclosure it would not be possible to claim an application to treat dementia defined broadly.

All is not lost, however.  It may be possible to claim a specific dose or dose regime, if it can be shown to be unexpectedly effective. For example, if in the later stages of dementia a specific dose or dose regime is required, it may be possible for a patent to cover an entirely different dose or regime (e.g. a lower dose, or intermittent dosing) if it can be shown that it would not have been expected to be effective in early-stage patients. Protection may also be available if it can be shown that the drug is working by a different mechanism in early-stage patients, as opposed to the known later-stage studies.

Further, the European Patent Office, at least, is increasingly willing to allow and maintain patents which claim the treatment of a specific novel patient sub-group. In this example this could be patients with early-stage dementia. For such patents to be granted it may be necessary to establish that treatment of the new patient group was unexpectedly effective given what had gone before, and/or that the new sub-group was not arbitrarily selected (there is a functional relationship between the patient treated and the pharmacological effect).

It may also be possible to protect new mode of administration of the drug in the medical indication, if for example administration sublingually as a liquid rather than a traditional tablet for swallowing, led to some kind of unexpected effect, or would not have been expected to work in this medical indication.

Bearing in mind the rewards available, it is always worth considering whether it is possible to obtain effective patent protection for an invention which is a new use of a known drug.

This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.

Phil Bates
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Helen Wakerley
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Would you like to know more? You can talk to Phil Bates who will be able to help. Call +44 (0)20 7242 0901


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