Court of Appeal clarifies what constitutes infringement of a second medical use claim

Second medical use patents protect new medical uses for existing medicines – an example might be the use of a known medicine (e.g. aspirin) for a new therapeutic use (e.g. heart failure). But what if a company manufactures aspirin ostensibly for headaches but it is in fact used for heart failure? To what extent should the manufacturer be held responsible for the use to which the medicine is put?  IP Associate Henry Milas considers the Court of Appeal’s ruling on this issue.

In its recent judgment, the Court of Appeal has upheld that two claims in a second medical use patent for pain relief, upon which Warner-Lambert had alleged infringement by Mylan and Actavis, are invalid on insufficiency grounds.  The Court held that the claims were too broad: the assertion that the invention would work across the breadth of the claims was implausible.  In reaching this decision, the Court considered that appropriate weight had been granted to the patent’s supporting data, and the common general knowledge of the skilled person. Despite this outcome, the Court made clear that the threshold in the test for plausibility remained low.

Application to amend patent claims was made too late
In some situations a patentee may be able to save an over-broad claim by amending it during the course of patent infringement or revocation proceedings. However, in this case the Court held that a late application to amend one of the invalid claims amounted to an abuse of process.  On this issue, the Court agreed with the lower court’s refusal to allow such amendments, given that the opportunity to bring such a request had been available to the patentee in earlier proceedings between the parties.  To allow the amendment would be to give the patentee an alternative route to an infringement finding, to which, through delay, Mylan and Actavis had been denied a fair opportunity to collate evidence and prepare a defence to.

The Court gave important guidance on infringement of second medical use claims
Although both of the claims alleged to have been infringed were found to be invalid, the Court of Appeal did consider and provide some commentary as to the correct interpretation of direct and indirect infringement of second medical use claims (in the ‘Swiss’ form), albeit in obiter.  In doing so, it considered the differing approaches adopted in various other EU countries in which similar proceedings had been brought by the patentee, recognising the absence of a universal approach.

Second medical use claims protect new therapeutic uses for existing medicines. Difficult issues of infringement arise where the ‘old’ use is not (or is no longer) subject to patent protection. In such a situation the patentee’s competitors are free to manufacture and sell the drug for the old use but not for the new, patented use. The courts are faced with the question how, in practice, can one distinguish between manufacture and sale for the old use (which does not infringe) and the new use (which does).

In respect of direct infringement, the Court confirmed that the test is one of intention and that an objective approach to the question of intention was required, extending to what the manufacturer knew or could reasonably foresee as the consequences of its actions.  Whilst it was acknowledged that a manufacturer might negate this intention through evidencing that all reasonable steps had been taken to prevent such consequences, the Court did not provide guidance as to what such steps may be.  Further, the Court acknowledged that post-manufacture labelling by the pharmacists could amount to a relevant preparatory act (i.e. for delivery), therefore giving rise to the possibility of further liability for indirect infringement if done with the necessary intention.

The case is Warner Lambert Company LLC v Generics (UK) Limited and Ors [2016]EWCA Civ 1006 13 October 2016

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