Apotex Pty Ltd v Sanofi-Aventis Australia Pty Ltd v (No. 2) [2012] FCAFC 102

The Full Federal Court has recently handed down its decision on Apotex's appeal against the earlier finding that its proposed sale of Apo-Leflunomide would infringe Sanofi's claim to a method of treating psoriasis.  Although the Court held that a claim to a method of treatment should be construed with the "objective purpose" in mind, it nevertheless found that the use of Apotex's Apo-Leflunomide to treat psoriatic arthritis would invoke the operation of contributory infringement provision section 117.

Sanofi's allegation of patent infringement

As previously reported (Sanofi-Aventis v Apotex, September 2011) Sanofi had asserted that Apotex had infringed its claim to a method for treating psoriasis by registering a generic version of its drug, leflunomide, on the Australian Register of Therapeutic Goods (ARTG) for the treatment of psoriatic arthritis (PsA) and rheumatoid arthritis (RA).  In its defence, Apotex argued that the supply of leflunomide for the treatment of PsA would not infringe the claim because, if properly construed, the claimed method is for the treatment of a skin disease only (psoriasis) and not for the treatment of joint conditions such as PsA or RA.  Apotex also cross-claimed for revocation, asserting that the patent was invalid for want of novelty.

The findings at first instance

Apotex argued before the primary judge that the claim should be construed based on the "objective purpose" of the administration of leflunomide; that is, for the treatment of psoriasis.  Justice Jagot  dismissed Apotex's constructionand found in favour of Sanofi, distinguishing between the purpose of administration of leflunomide and the result to be achieved.

Separately to the question of construction, the primary judge also concluded that the supply of Apo-Leflunomide would bring section 117 of the Patents Act 1990 into operation and render Apotex liable for infringement as the supplier.

On the question of validity, Apotex argued that the claim lacked novelty in light of the disclosure of the specification of Australian Patent No 529,341 (the '341 patent), which taught that leflunomide was effective in the treatment of RA and multiple sclerosis. However, absent any explicit reference to PsA or psoriasis, her Honour found that the '341 specification did not direct, recommend or suggest the administration of leflunomide for the treatment of PsA or psoriasis and, therefore did not anticipate the claim.

Full Court confirms that the method of treatment claim is novel and infringed by Apotex's proposed activities 

On appeal, Apotex argued that her Honour erred in (i) her construction of a claim to a method of medical treatment; (ii) her finding that contributory infringement under section 117 of the Patents Act applied to the circumstances of the present case; and (iii) her finding that the invention as claimed was novel in light of the publication of the '341 patent .

On the question of claim construction, the Full Court unanimously agreed with Apotex's submission and held that the primary judge erred in her approach to the construction of the claim being based on the "result or effect" achieved rather than the objective purpose  Their Honours' view was that the construction preferred by the primary judge would result in an exclusive right to exploit the invention in a manner that extended beyond the claimed advance in the art.

It was their Honours' opinion that the wording of the claim made it clear that the invention (i.e., the claimed advance in the art) concerned a method directed to preventing or treating psoriasis.  Their Honours stated that the correct inquiry was to the "object or end in view" of the method of treatment involving the administration of leflunomide by the medical practitioner, noting that what distinguished the claimed invention from what had gone before is the recognition that leflunomide can be used in a new method of treatment involving a new and different therapeutic use, regardless of the result to be achieved.

Notwithstanding that the Full Court found that the primary judge had erred on the question of construction, this was not sufficient to save Apotex on the question of contributory infringement under section 117 which could be decided independently on fact.

The Court considered the forms of use which could invoke the operation of section 117 and relied on Apotex's own Product Information Document (PID) as well as expert evidence to determine whether any such use would apply.  The evidence established that psoriasis is a diagnostic criterion of psoriatic arthritis, and that patients with psoriatic arthritis will have or eventually develop psoriasis.  Thus it was accepted that rheumatologists would routinely prescribe leflunomide to treat PsA as well as psoriasis in patients presenting with concurrent conditions.  Furthermore, although the PDI expressly disclaimed the treatment of psoriasis in the absence of manifestations not associated with arthritic disease, the Full Court agreed with the primary Judge and construed the double negative as a positive instruction for the treatment of psoriasis associated with arthritic disease,  On the basis of these findings the Full Court concluded that either of sections 117(2)(b) or (c) would be sufficient to engage the application of section 117(1) and render Apotex liable for infringement.

On the question of validity, the Full Court agreed with the primary judge and saw no error in her Honour's finding that the person skilled in the art would have understood the '341 patent as being concerned only with the most common form of inflammatory arthritis, RA, and multiple sclerosis, which are expressly mentioned.  Their Honours agreed that the '341 patent did not provide clear and unmistakable directions to administer leflunomide for the purpose of treating or preventing psoriasis (or PsA).  Hence, the disclosure made by the '341 specification did not anticipate the claim.

Finally, the Full Court also considered, but ultimately rejected, Apotex's submission that claims to methods of medical treatment should not be patentable.  In doing so, their Honours said that they would not depart from the position represented by the previous dicta of the Court that had supported the patentability of methods of medical treatment, noting that although it had ample opportunity to do so in recent years, the Australian Parliament has not been persuaded to legislate any change to the Patents Act to give specific effect to policy considerations that argue against the patentability of methods of medical treatment.

The value of second medical use claims

Although sometimes dismissed as the poor cousin of a "composition of matter"-type claim, the decision highlights the valuable role a second medical use-type claim can play in a patent portfolio.  Notwithstanding that the claim would not be directly infringed by a medical practitioner prescribing the drug for a previously identified indication, such a claim may still afford useful protection by excluding competitors under contributory infringement provisions.