The Australian High Court recently handed down its long-awaited decision in Apotex Pty Ltd (“Apotex”) v Sanofi-Aventis Australia Pty Ltd (“Sanofi”). The Court upheld Sanofi’s Australian Patent for a method of preventing or treating psoriasis using Leflunomide and found that Apotex would not be liable for contributory infringement of the Patent.

The issues before the High Court

Apotex proposed to supply Leflunomide to treat psoriatic arthritis (“PsA”). The drug Leflunomide is the subject of an expired Patent, previously owned by Sanofi. Leflunomide was previously used to treat rheumatoid arthritis (“RA”) and Apotex specifically extended the use for psoriasis, a related disease, by including in their product information document a statement to the effect that the Leflunomide provided was “not indicated for the treatment of psoriasis that is not associated with manifestations of arthritic disease.”

Nevertheless, Sanofi sued Apotex for threatened contributory infringement of its Patent for the use of Leflunomide to treat PsA, because use of the compound to treat PsA would inevitably treat or prevent psoriasis. Apotex responded by seeking revocation of the Patent on various grounds, including that the claimed method of treatment of the human body was not a patentable invention according to Australian Law.

The Federal Court of Australia at first instance upheld Sanofi’s Patent and considered Apotex’s activities as threatening to constitute contributory infringement of the Patent. This finding was upheld on appeal to the Full Federal Court.  Apotex successfully requested Special Leave to Appeal to the High Court against the Full Federal Court’s decision to uphold Sanofi’s Patent.

The High Court was asked to consider whether: (a) methods of treatment are patentable subject matter and, if they are, (b) whether Apotex’s supply of the product would contribute to infringement of the Patent.

Method of treatment claims are patentable, but are now more difficult to enforce

It is unsurprising that the High Court answered the first question in the affirmative confirming that method of treatment claims are patentable in Australia. Methods of treatment have been viewed as patentable in Australia since the early 1970s based on the decision of the High Court in Bernhard Joos v Commissioner of Patents, in which it was held that medical and cosmetic procedures carried out on the human body which have a commercial application were proper subject matter for the grant of a Patent.

In a well-considered and eloquent summary of the historical patentability of claims directed to methods of treatment, the High Court has confirmed that methods of treatment are patentable subject matter in Australia, provided the invention claimed is novel, includes an inventive step, is useful, has not been used previously in Australia, and is a new manner of manufacture within Section 6 of the Statute of Monopolies.

However, what is noteworthy about this case is the finding of the Court on the second question relating to the infringement of the method of treatment claims.

The Court gave weight to the express statements of Apotex in its product information document for its proposed Leflunomide product that the product is not indicated for the treatment of psoriasis that is not associated with manifestations of arthritic disease.

The Court found that Apotex was not liable for contributory infringement of the patented method of treatment, because it was not shown, and could not be inferred, that Apotex had reason to believe that the off-patent pharmaceutical substance would be used according to Sanofi’s patented method and contrary to Apotex’s stated indication.

Take home message

It appears that in cases where a second medical use is the subject of a Patent, a third party may avoid being liable for contributory infringement of the patented second medical use by providing express instructions to the public to only use the pharmaceutical substance for the first medical use on which the Patent has now expired. The third party may avoid being liable for contributory infringement if the pharmaceutical substance is used by an end-user for the second medical use, contrary to the instructions provided.

While this Decision provides welcome certainty on the patentability of methods of treatment in Australia, it has complicated the enforceability of Patent Claims directed to methods of treatment in circumstances similar to those of the present case.