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Singapore High Court delivers its own brand of pain by refusing post grant amendments

8 minute read

A recent judgement by the High Court in respect of Warner-Lambert’s application to amend method of medical treatment claims to a Swiss-style use claim format has highlighted the variation in scope between these two claim formats. 

The patent was granted in Singapore in May 2000 with the main claim reading: 

  1. A method for treating pain comprising administering a therapeutically effective amount of a compound of formula I … to a mammal in need thereof.

Amendment was requested under Section 83 to transform this claim and the other method of treatment claims, into the following Swiss-style claim format:

  1. Use of a compound of Formula I … in the preparation of a medicament for treating pain in a mammal.

The amendment was requested under section 84(3) of the Patents Act which allows amendment of a patent before the Court in particular circumstances.  An amendment is not allowable if the result of the amendment is that the specification (a) discloses additional matter or (b) extends the protection conferred by the patent. The Court also considered whether it should exercise its discretion to allow the proposed amendments, assuming that both conditions stipulated under section 84(3) were met.

In Singapore, claims to methods for medically treating humans are specifically excluded from patentability under section 16(2) of the Patents Act. However, section 16(3) clarifies that any product that was invented for use in a method of treatment is not subject to the exclusion. Accordingly, second medical use claims, such as the Swiss-style use claims proposed to replace the granted method of treatment claims, are generally considered allowable. While the Court did not make a determination of the ultimate legitimacy of Swiss-style claims in light of Section 16(3), it did consider the allowability of an amendment to replace a method of treatment claim with a Swiss-style claim.  In considering this question the Court made reference to UK/EPO case law. 

The Patent Office construes Swiss-style second medical use claims based on the UK/EPO doctrine of Jacob J in Bristol-Myers Squibb v Baker Norton Pharmaceuticals Inc [1999] RPC at 50- 51: 

Nor do I accept that on his construction the claim amounts to merely to a method of treatment. It is to the manufacture of the medicines to be used in that treatment. I am reinforced in that view by the consideration that the Article 54(4)
provision about methods of treatment is an exception to patentability and as an exception should be construed narrowly…A like approach is indicated in Plant Genetic Systems/Plant Cells (EPO[1995] 545, T0356/93 OJ). There is also the limited purpose of the exception to be considered. It is not so broad as to stop doctors using whatever they feel they need to treat patients. If that were the purpose then one would not allow patents for medicines or medical implements at all. The purpose of the limitation is much narrower, merely to keep patent law from interfering directly with what the doctor actually does to the patient. Patent monopolies are permitted to control what he administers to, or the implements he uses on, the patient. The thinking behind the exception is not particularly rational: if one accepts that a patent monopoly is a fair price to pay for the extra research incentive, then there is no reason to suppose that that would not apply also to methods of treatment. It is noteworthy that in the US any such exception has gone, and yet no-one, so far as I know, suggests that its removal has caused any trouble.

Whether the proposed amendments disclose additional matter

In considering whether the proposed amendments result in the disclosure of additional subject matter the Court emphasised that an objection based on “additional matter” was not the same as an objection based on “extension of protection”. The rationale explained by the Court was that patentees should not be allowed to improve their position by adding subject matter not disclosed in the application as filed, as this would provide an unwarranted advantage which could damage the legal security of third parties relying upon the content of the original application. Therefore, the test is whether the skilled addressee would learn from the amended specification anything about the invention which he or she could not learn from the unamended specification (citing with approval, the decision of Aldous J in Bonzel and another v Intervention Ltd and another (No 3) [1991] RPC 553 at 574). 

The Court concluded that an amendment to convert a method of treatment claim to a Swiss-style use claim did not create or disclose any “added matter”. The rationale was that the skilled person would understand that it is necessary for the Swiss-style claim format to include a manufacturing step to ensure that this claim does not encompass the activities of a doctor and fall foul of the method of treatment exclusion. The skilled person, looking at the original claims, would also realise that the medicament comprising the therapeutically effective amount of the disclosed compound would have to exist and this could be gleaned from the original disclosure. 

Whether the proposed amendments extend the protection conferred by the patent

The Court confirmed that the test as to whether the proposed amendments extend the scope of protection is whether the amendment results in something that falls outside the scope of the granted claims falling within the scope of the claims as proposed to be amended. As such, the Court considered that the manufacture/preparation of a medicament, an activity caught by the Swiss-style claims, is not an activity which falls within the ambit of a method of treatment claim, and that the proposed amendments would therefore have the effect of extending the protection conferred by the patent and should not be allowed. 

The rationale of the Court was that while both sets of claims are broadly connected by the same final objective, which is the treatment of pain, the method of treatment claims and the Swiss-style use claim format target different activities. Specifically, the latter covers the making of a compound for the purpose of administration to treat pain whereas the former covers only the act of administration of the compound to treat pain. The Court considered that the inclusion of the manufacturing process step to produce the medicament for the defined use amounts to an extension of the scope of protection, which is outside the ambit of method of treatment claims. 

In concluding, the Court also clarified that in determining whether the scope of the patent has been extended or not, one is not entitled to take into account secondary or indirect infringement. The Singapore patent legislation does not provide for indirect infringement, which is instead to left to the common law joint tortfeasor of proof of a common design to procure or actually participate in an infringing act.

Whether the Court should exercise its discretion to allow the proposed amendments.

The Court also considered that even if the Patents Act allowed for proposed amendments to be made, in light of the “undue and unreasonable delay” on behalf of the Plaintiff, the Court would have not allowed the amendments to be made at this time. The Court considered that as the Plaintiff was a well established pharmaceutical company it should have taken steps earlier to seek appropriate legal advice in relation to its patent, and in particular, whether the patent complied with local patentability requirements. The Court noted that the Plaintiff had ample opportunity to amend its patent both pre- and post-grant and had not provided an adequate explanation for not doing so.

Take home points:

  1. Always ensure that any method of treatment claims included in a Singapore patent application are replaced with Singapore allowable second medical use claims. The following claim formats are allowable under patent office practice:
    – The use of compound X in the manufacture of a medicament for the treatment of medical condition Y.
    – The use of compound X for the manufacture of a medicament for the therapeutic and/or prophylactic treatment of medical condition Y.
    – The use of compound X in the manufacture of an anti-Y agent in a package together with instructions for its use in the treatment of medical condition Y.
    – The use of compound X in the preparation of an anti-Y agent in ready-to-use drug form for treating or preventing medical condition Y.
  2. Be aware that voluntary amendments are not always possible under Singapore patent law. For instance, voluntary amendments are not possible after requesting examination, unless the amendment is contained in a response.
  3. Be mindful of the adverse effect of “undue and unreasonable delay” if trying to make amendments before a Court.