Australia: Infringement of second medical use claims - Federal Court decision adds guidance

In pharmaceutical patent litigation, issues concerning infringement of method of treatment and Swiss-style claims covering new indications for known substances arise frequently. In this article, we discuss the recent Federal Court decision in Neurim Pharmaceuticals (1991) Ltd v Generic Partners Pty Ltd (No 5), which provides further guidance on these issues.

The decision highlights the importance of the precise wording of the approved indication compared to that of the patented indication. In this case, the TGA approved indication for the product was expressed in different terms from the claims of the patent, which created challenges for the patent owner.

Ultimately, Neurim was successful in establishing infringement of the method of treatment claims under s 117 of the Patents Act 1990 (Cth) (Patents Act), but not of the Swiss style claims. This adds further support to the view that adding method of treatment claims on entry to Australia (if not already present) may provide additional avenues of patent protection.

In this case, Neurim also succeeded in showing authorisation of infringement, itself an infringing act. The patent claims had, however, expired before judgment so the issue of an injunction did not directly arise. Nevertheless, Justice Nicholas expressed the view that it would not have been appropriate to grant a broad injunction restraining any and all supply of the generic product in this case, given the substantial scope for non-infringing use.

In light of those comments, patent owners should consider whether a more limited form of injunctive relief should be sought where substantial scope for non-infringing use of generic products exists.

Background to the Neurim V Generic Partners case

Australian Patent 2002326114 entitled "Method for treating primary insomnia" (Patent), relates to the use of melatonin to improve the quality and quantity of sleep in primary insomnia. The Patent included Swiss-style claims and method of treatment claims. All relevant claims related to the treatment of "a patient suffering from primary insomnia characterised by non-restorative sleep and improving the restorative quality of sleep in said patient".

Neurim brought patent infringement proceedings against Generic Partners and Apotex (Generics) in relation to their generic MELOTIN melatonin products, which have the same characteristics and indications as Neurim's CIRCADIN melatonin products.

The Generics cross-claimed for revocation of the Patent, alleging that the invention lacked novelty and did not involve an inventive step, and that the complete specification did not fully describe the invention and the claims were not fairly based or clear. The Court rejected these invalidity arguments.

We focus in this article on the infringement aspects of the case.

Infringement of method of treatment claims under s 117 of the Patents Act

Section 117 of the Patents Act provides a codified form of indirect infringement by supply. It is of particular significance in pharmaceutical patent disputes relating to method of treatment claims (since the generic supplier does not themselves practise the claimed method).

Neurim relied on s 117(2)(b) which provides for infringement where a supplier supplies a product which is not a staple commercial product having reason to believe it will be put to an infringing use, and s 117(2)(c) which provides for infringement where a supplier provides instructions or inducement to use a product in an infringing manner.

Was MELOTIN a staple commercial product (s 117(2)(b))?

The Generics argued that MELOTIN was a "staple commercial product" such that no infringement could arise under s 117(2)(b). This term is not defined in the Patents Act, but the High Court has characterised such a product as one that is supplied commercially for multiple uses.

To date, no pharmaceutical product has been found to be a staple commercial product under this test in Australia, and the Generics were also unsuccessful in their argument on that basis in Neurim. Notwithstanding that melatonin could be used for treating various sleep disorders, Justice Nicholas considered that this was a narrow field of use which did not qualify MELOTIN as a staple commercial product.²

Did the Generics have reason to believe Melotin would be prescribed or recommended by medical practitioners for the patented use (s 117(2)(b))?

The Generics' arguments on this point drew a distinction between treatment of insomnia characterised by "non-restorative sleep" as required by Neurim's patent claims and treatment for "poor quality of sleep" as referred to in the ARTG indication for CIRCADIN and MELOTIN. The matter was further complicated by the existence of several relevant diagnostic and disease classification manuals which referred to relevant disorders in different terms.

Ultimately, having regard to the expert evidence, Justice Nicholas was satisfied that a reasonable person engaged in the supply of the Generics' product for the treatment of primary insomnia characterised by poor quality sleep would have reason to believe that the medication would be prescribed by a not insignificant number of psychiatrists to treat primary insomnia where the patient complained of non-restorative (or unrefreshing) sleep,³ notwithstanding that it would also be used for other indications encompassed within the broader notion of "poor quality of sleep".

Neurim was successful on its infringement case on this basis.

Did the Generics provide instructions or inducement to use MELOTIN as a treatment for primary insomnia characterised by non-restorative sleep to improve the restorative quality of sleep (s 117(2)(c))?

Similar issues arose as to whether the Generics had provided instructions to use MELOTIN to improve non-restorative sleep, by way of their product information document (PI) which referred to "poor quality sleep". The PI supplied with Melotin made no reference to "non-restorative sleep" and Justice Nicholas was not persuaded that the PI provided any instruction to use Melotin as a treatment for that purpose.⁴

Accordingly, infringement under s 117(2)(c) was not established.

Infringement of Swiss-style claims

In accordance with the principles set out by the Full Federal Court in Mylan,⁵Justice Nicholas confirmed that "infringement of a Swiss type claim is concerned with what the allegedly infringing manufacturer has done, not what it intended to do". In this context the physical characteristics of a product, including its packaging, dosage and product information, are the most important considerations.⁶

Justice Nicholas found that, while Melotin was bioequivalent to Circadin, this did not determine the question of infringement.⁷ Contrary to Neurim's submissions, his Honour found that the meaning of "quality of sleep" in the approved indication was broader than the meaning of "non-restorative sleep" in the claims,⁸ and that Melotin would mostly be used for other therapeutic purposes such as in relation to its postulated hypnotic effect and regulation of circadian rhythms.⁹

His Honour was not persuaded that Melotin was a medicament manufactured for the therapeutic purpose specified in the Swiss-style claims.¹⁰ In contrast to the method of treatment claims, the fact that there was reason to believe that at least some psychiatrists would prescribe MELOTIN for non-restorative sleep was not sufficient to establish infringement of the Swiss-style claims, which turned on what the medication had been manufactured for, rather than what clinicians might use it for.

Authorisation of patent infringement

Neurim also alleged that the Generics had authorised, procured, induced or joined in a common design with physicians prescribing MELOTIN for the treatment of primary insomnia characterised by poor quality sleep, and had additionally infringed the method of treatment claims on this basis.¹¹

The Generics argued that there could be no authorisation of infringement if Neurim did not succeed in establishing infringement under s 117(2)(c).

Interestingly, Justice Nicholas took a broader view of the concept of authorisation, finding that the Generics had authorised use of their products by medical practitioners who they had reason to believe would use it for the patented indication, to the extent that this fell within the indications listed in the Generics' PI.

On the other hand, his Honour found that the Generics had not authorised off-label use of MELOTIN (e.g. in patients under 55 years).

Whether injunctive relief appropriate where there is substantial non-infringing use

As this case demonstrates, infringement of method of treatment claims may arise in Australia in circumstances where there is also likely to be substantial non-infringing use.

In several previous cases, the Courts have noted that a blanket injunction on supply of generic products may not be an appropriate remedy in circumstances where it would prevent non-infringing use of those products.

However, in each of these cases to date, the patents have been found invalid, such that no determination was necessary on the question of injunctive relief. A leading example of this approach is provided by the comments of the Full Federal Court in AstraZeneca FFC¹² at [444] that

"[i]t may be undesirable to impose a blanket restraint upon a supplier who has reason to believe that only some consumers, perhaps a very small minority, may put the product that is or may be supplied to them to an infringing use. This is because the effect of such an injunction may be to deny a supplier access to a market, and consumers' access to a product, in circumstances where the supplier could have no reason to believe that the majority of consumers would put the product to an infringing use."

Justice Nicholas made similar comments in Neurim¹³, expressing the view that it would not have been appropriate to grant broad injunctive relief in this case. However, given that the Patent had expired, again a determination on this issue was not required.

Footnotes

¹ Neurim Pharmaceuticals (1991) Ltd v Generic Partners Pty Ltd (No 5) [2024] FCA 360 (12 April 2024) (Neurim).

² Neurim at [246].

³ Neurim at [258].

⁴ Neurim at [281].

⁵ Mylan Health Pty Ltd v Sun Pharma ANZ Pty Ltd (2020) 279 FCR 354 (Mylan).

⁶ Neurim at [291].

⁷ Neurim at [292].

⁸ Neurim at [293].

⁹ Neurim at [296].

¹⁰ Neurim at [297].

¹¹ Neurim at [298].

¹² AstraZeneca AB v Apotex Pty Ltd (2014) 226 FCR 324 (AstraZeneca FFC).

¹³ Neurim at [247].

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.