Draft Trans-Pacific Partnership Treaty – Patentability of Second Medical Use Claims

The leaked TPP treaty has a number of provisions concerning medically related claims, in particular second medical use claims, a prohibition on any requirement of enhanced efficacy for pharmaceuticals, and claims related to methods of medical treatment. I will deal with these in separate posts, beginning with second medical use claims, which are addressed in Art E.1(1)(a):

Article QQ.E.1: {Patents / Patentable Subject matter}

1. The Parties confirm that:

(a) patents shall be available for any new uses or methods of using a known product,

The US and Australia support this, Japan is considering, and all others, including Canada, oppose this provision. This most prominent impact of this provision would be to ensure that second medical use claims are patentable, though it would apply more broadly, to any second use of a known product.

It is not clear to me why Canada opposes this provision, as it would do no more than affirm existing law. That patents are available for new inventive uses of a known product is the central holding of Shell Oil [1982] 2 SCR 536. In Wellcome / AZT [2001] 1 FC 495 (FCA), Rothstein J, [72-75] applied Shell Oil to hold a second medical use claim (to the use of AZT for the treatment of HIV/AIDS) to be valid, and this was affirmed by 2002 SCC 77 [49-50].

With that said, there is a real controversy over second medical use claims in particular. The advantage of Swiss form claims, to the use of a known compound for the manufacture of a pharmaceutical composition for the new therapeutic application, is that it can encompass a new use for a known product, but only the manufacturer could be liable for infringement, and not a physician prescribing or administering the drug. Thus prohibiting patenting of a second medical use, while allowing Swiss form claims, allows physicians to treat their patients according to their best medical judgment, without fear of an infringement actions. An alternative approach to achieve the same end is to allow second medical use claims but provide a defence for physicians; this is the approach used is the US under 35 USC § 287(c)(1).

It is conceivable that this concern is driving the Canadian opposition to E.1(a), but this seems unlikely. Since E.1(a) reflects existing Canadian law, even if E.1(a) is not adopted, Canada would still have to amend the Patent Act if it wants to protect physicians by abolishing second medical use claims. If we are going to amend the Act for this purpose, surely the simpler approach would be to amend it to provide for a US-style defence, which addresses the root problem directly. Further, it is not clear that TPP members would be required to allow Swiss form claims in the absence of E.1(a), since it could be said that functionally, Swiss form claims do provide patents for new uses of a known product, even though there is an important substantive difference between Swiss form claims and second medical use claims as such. And in any event, this argument respecting second medical use claims does not apply to second use claims more generally; for example, the invention at issue in Shell Oil was for a use as a plant growth regulator. This obviously does not raise concerns about physician’s freedom to treat their patients. It may be that Canada’s opposition to this provision is driven by its broader negotiating strategy, rather than opposition to this provision in particular.