Protecting a New Medical Use of a Known Substance
The ability to protect known compounds and compositions where a new medical indication has been discovered can be extremely valuable. However, it is not possible to obtain protection for a new medical use of a known substance in some jurisdictions. Furthermore, even in jurisdictions where it is possible to obtain protection, the form the claims should take to comply with local practice can vary significantly. Knowing where protection can be pursued, and the form the claims should take, better enables us to work with clients to devise a targeted filing strategy. This article provides a summary of how patent protection can be pursued for a new medical use of a known substance in five key jurisdictions.
The European Patent Convention (EPC) states that a European patent shall not be granted in respect of methods for treatment of the human or animal body by therapy. This excludes from patentability methods of treatment and prophylaxis, but this exclusion does not apply to products, in particular substances and compositions, for use in such methods.
If a known compound has not previously been used in a method of treatment by therapy, it is possible to protect the product using a so-called first medical use type claim, which may be written like so:
- “Compound/composition X for use as a medicament.”
Even if the product had previously been used as a medicament, further medical indications could still be protected by a so-called second medical use claim, which would take the form:
- “Compound/composition X for use in treating disease Y.”
It should be noted that second medical use claims are not limited to treatments of new diseases. In fact, an Enlarged Board of Appeal Decision (G 5/83) reached the conclusion that the use of a known compound or composition to treat a known disease can be patentable if the medical use is linked to a novel and inventive dosage regime.
Furthermore, established case law of the Boards of Appeal (for instance, see T 233/96) states that it is also possible to obtain protection for the use of a known compound or composition to treat a known disease where the compound or composition is administered to a novel patient group. The patient group must be distinguishable from former patients due to their physiological or pathological status.
Unites States of America
It is possible to obtain protection for methods of treatment in the United States. Accordingly, it is possible to obtain protection for new indications of known compounds and compositions by using a method of treatment claim. Such claims would generally take the form:
- “A method of treating disease X in a subject, the method comprising administering to a subject in need thereof a therapeutically effective amount of compound/composition Y.”
Such claims can also define dosage regimes and specific patient groups.
In China it is possible to obtain protection for the medical use of a known compound using so called Swiss-style claims. These are written like so:
- “Use of compound/composition X for the manufacture of a medicament.”
- “Use of compound/composition X for the manufacture of a medicament for treatment of disease Y.”
It will be noted that these claims correspond closely to first and second medical use claims. If a PCT application is drafted with first and second medical use type claims or method of treatment claims, these can be converted to Swiss-style claims upon entry to the Chinese national phase.
However, a decision by the Supreme People’s Court found that use features which do not have any effect on the manufacture of a medicament cannot be considered to form a contribution over the prior art. Accordingly, claims where the distinguishing feature is a specific dosage regime or the treatment of a specific patient group may be invalid in China.
The Japanese Patent Office allows a number of different formats for claiming a new medical use of a known substance. These are:
- “A pharmaceutical composition for the treatment of disease X, comprising compound Y.”
- “An anti-disease X agent comprising compound Y.”
- “Use of compound Y to treat disease X.”
- “Use of compound Y in the manufacture of a medicament for the treatment of disease X.”
Similar to the situation in China, the claims of a PCT application can be adapted to comply with Japanese practice on national phase entry or during subsequent prosecution of the application.
In addition, new dosage regimes and the treatment of new patient groups may also be patentable if it can be argued that there is an unexpected technical effect associated with the novel feature.
It is not possible to obtain protection for a new use of a known substance or a method of treatment in India. Accordingly, second medical use claims are not allowable.
However, chemical and pharmaceutical substances became patentable in India in 2005. Accordingly, it is now possible to obtain protection for new compounds and compositions. Additionally, it is also possible to obtain protection for new forms of a pharmaceutical product. For instance, if an unexpected improvement is observed for a polymorph or salt of a known compound then this may be protected in India. Additionally, a synergistic composition possessing unexpected chemical properties may also be protected.
Different jurisdictions have significantly different approaches when determining whether or not a new medical use of a known compound may be patentable. However, careful drafting of the patent specification and claims can ensure that there is basis to protect your inventions in key markets. Please contact one of our attorneys for further advice.