Another Painful Loss for Warner-Lambert in Singapore

Background

Warner-Lambert LLC ("Warner-Lambert") owns a patent for the use of pregabalin for the treatment of pain (the "Patent") and sells pregabalin under the name of "Lyrica" in Singapore.

In 2015, Novartis (Singapore) Pte Ltd ("Novartis") applied for several product licences to market its pregabalin products (i.e. generics) with the Singapore Health Sciences Authority.

Pursuant to Section 12A of the Singapore Medicines Act, Novartis notified Warner-Lambert of these applications and declared that the Patent would not be infringed by the acts for which the product licences were sought.

Warner-Lambert commenced an action seeking a declaration that the Patent would be infringed by Novartis. This declaration was necessary to stop Novartis from obtaining approval for its pregabalin product licences. In the defence and counterclaim, Novartis sought to revoke the Patent on the ground that it was invalid because it contained method of treatment claims, which are expressly prohibited under Section 16(2) of the Singapore Patents Act (the "SPA").

In an attempt to cure the invalidity, Warner-Lambert applied for post-grant amendments before the High Court to amend the method claims to the Swiss-style format. The High Court refused the amendment application on the ground that:

• The amendments extended the scope of protection of the Patent; and
• There was undue delay in bringing the amendments.

Warner-Lambert appealed against the High Court decision.

The amendments sought extend the scope of protection of the Patent

The Court of Appeal ("COA") held that amendments to "obviously invalid patents" should be rejected, without any need to consider whether the amendments sought would extend the scope of protection. This is because the amendments cannot rectify a patent which was invalid at the time of grant and had no protection in the first place. As Warner-Lambert’s Patent was an “obviously invalid patent”, given that all of the claims of the Patent are impermissible method of treatment claims, the COA refused the post-grant amendment application.

Nevertheless, for completeness, the COA affirmed the High Court's finding that the post-grant amendments sought would extend the protection conferred by the patent as granted. The rationale was that while the granted claims protect the method of treatment, the proposed amendments protect the manufacture of the medicament, which is beyond the scope of the granted claims.

There was undue delay in bringing the amendments

Regarding whether there was undue delay in bringing the amendments, at the appeal Warner-Lambert argued that the High Court had set too low a threshold for the "extent and quality of knowledge required to start the clock running". It contended that the threshold point should be after the patentee receives legal advice that the patent is problematic.

Rejecting Warner-Lambert’s arguments, the COA affirmed the High Court's conclusion that constructive knowledge of a patent's potential invalidity is enough to cross the threshold. Based on the facts, Warner-Lambert had constructive knowledge, as early as 1998, that the Patent was problematic.

The COA also rejected Warner-Lambert's argument that a "lenient approach" for the post-grant amendments should be adopted given that the Patent was granted under a self-assessment system. The COA found that the fact the Patent was granted under a self-assessment system did not give the patentee "the liberty of taking a lackadaisical approach in ensuring that the patent claims in the register comply with the requirements of patentability".

The COA opines on the necessity of Swiss-style claims

Although the issues at hand did not require the COA to deal with the validity and necessity of Swiss-style claims, the COA nevertheless made some important observations.

The COA acknowledged that Swiss-style claims are currently allowed by the Intellectual Property Office of Singapore to protect second and subsequent medical uses of a known substance and it does not disagree with the validity of such claims at this time. However, it opined that purpose-limited product claims may be sufficient to protect second and subsequent medical uses of a known substance.

Thus far, purpose-limited product claims have generally not been used to protect second and subsequent medical uses of a known substance due to the perceived lack of novelty under Section 14(7) of the SPA. The COA observed that if a wider and more purposive interpretation were adopted for Section 14(7), it would in fact confer novelty to second or subsequent medical uses of a known substance.

On this premise, the COA observed that inventors of second or subsequent medical uses of a known substance would then be able to rely on purpose-limited product claims and would negate the need for Swiss-style claims.

The COA further observed that both Europe and the United Kingdom have introduced legislations to allow patent protection for second or subsequent medical uses of a known substance through purpose-limited product claims.

Much can be learned from Warner-Lambert's painful loss regarding post-grant amendments:

• Amendments of "obviously invalid patents" will be rejected. It is not possible to amend a patent that is invalid for example, due to lack of patentable subject-matter and had no protection in the first place.
• Amendments from method of treatment claims to Swiss-style claims will be rejected on the ground that the protection conferred by the patent as granted would be extended by such amendments.
• The court may exercise its discretion to refuse the application to amend on the ground of undue delay. Constructive knowledge that the patent is problematic is sufficient to put the patentee on notice of the need to amend and no actual knowledge is required.

It remains to be seen whether the COA’s observation on Swiss-style claims may trigger legislative changes, like those in Europe and the United Kingdom, to allow patent protection for second and subsequent medical uses of a known substance through purpose-limited product claims. Until then, Swiss-style claims will continue to be allowed in Singapore for the protection of second and subsequent medical uses of a known substance.