Psoriasis treatment patent valid and infringed

An Australian appeal court has upheld the validity of Sanofi’s leflunomide psoriasis treatment patent and dismissed an appeal by Apotex on infringement under Australia’s ‘contributory infringement’ provisions*.

Summary of decision

Sanofi’s Australian patent 670,941 has a single claim directed to a method of treating psoriasis by administering leflunomide. Apotex had registered its generic version of leflunomide for treatment of psoriatic arthritis and rheumatoid arthritis. Sanofi then sued for patent infringement and Apotex cross claimed, alleging that the patent was either invalid or not infringed.

At first instance, the primary judge found the patent to be valid and infringed. The judge stated in her reasons for judgement that ‘if leflunomide is administered to a patient with psoriatic arthritis, that administration would be expected to prevent or treat the patient’s psoriasis, to some extent at least’. The patent was found to be infringed because of the effect of the drug, even though it was not prescribed for the treatment of psoriasis (so called ‘off-label’ use).

Apotex appealed to the Full Federal Court, arguing that the patent was directed to a method of preventing or treating only the specified skin disorder, psoriasis. It also argued that the patent was invalid for want of novelty.

The Court unanimously dismissed Apotex’s appeal. The Court rejected Sanofi’s argument that the patent claim covered any administration of leflunomide that happened to result in the treatment of psoriasis. However, Apotex’s statement in its Product Information documentation (PI) that its leflunomide product ‘is not indicated for the treatment of psoriasis that is not associated with manifestations of arthritic disease’, was found to be an instruction to use the product for the treatment of psoriasis in conjunction with the treatment or prevention of psoriatic arthritis. Therefore, the sale of the leflunomide product was found to be a contributory infringement provisions under s 117(2)(c) of the Patents Act 1990.

On the question of novelty, the only prior art relied upon was an earlier patent directed to a method of treating arthritic and inflammatory conditions and multiple sclerosis using leflunomide. The court rejected an ‘inevitable result’ argument and found that this patent did not disclose the use of leflunomide to treat skin diseases such as psoriasis.

There was also an issue of whether Apotex had infringed Sanofi’s copyright in its PI. Evidence was submitted of a long-standing and widespread practice among pharmaceutical companies in Australia of generic companies copying an originator company’s PI without provoking an objection from the originator. However, the primary judge found that this was not sufficient to establish that there was an implied licence, and this was upheld on appeal.


The decision is somewhat disturbing. The Federal Court has endorsed the proposition that a ‘second use’ of a drug is patentable, even when the earlier treatment is identical to the later treatment, and where the diseases (and thus the patients treated) overlap. However, the Court has rejected the argument that the patent is invalid due to that overlap, despite the fact that the same patient already receives the benefit of the second use.

The decision also raises serious questions on the scope of copyright protection in a pharmaceutical context. However, the Federal Government has taken steps to exclude the copying of PIs from copyright protection.

It is not known whether an appeal to the High Court is in prospect, but if not, some legislative action may be necessary to address this anomaly.

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

Contact: If you have any enquiries about the leflunomide case in Australia, please contact Debra Tulloch or Paul Jones.