SPC for HIV anti-retroviral drug Atripla invalidated

In Teva UK Limited v Merck Sharp & Dohme Corporation [2017] EWHC 539 (Pat), the UK Court held invalid MSD's SPC for a product described as "A combination of efavirenz, emtricitabine or a pharmaceutically acceptable salt or ester thereof, and tenofovir or a pharmaceutically acceptable prodrug, salt or ester thereof, particularly tenofovir disoproxil, especially tenofovir disoproxil fumarate" (the "Product"). BMS and Gilead market Atripla, which is an HIV anti-retroviral medication consisting of efavirenz, tenofovir in the form of the disoproxil fumarate, and emtricitabine.

Two attacks were mounted. First, the Claimants argued that the SPC did not comply with Article 3(a) of the SPC Regulation (which requires that "the product is protected by a basic patent in force"). MSD relied solely on claim 16 of its patent, which concerned "A combination of the compound of claim 12 [being efavirenz] or a pharmaceutically acceptable salt thereof with a nucleoside analog having biological activity against HIV reverse transcriptase". Mr Justice Arnold held that the scope of protection of claim 16 extended to a combination of efavirenz and tenofovir or to a combination of efavirenz and emtricitabine, but not to a combination of all three (the skilled person would understand "a" nucleoside analog in claim 16 to denote the singular, and thus limit claim 16 to double combinations only). It followed that the Product was not "protected" by the patent within the meaning of Article 3(a) since the minimum requirement for a product to be "protected" by a basic patent (i.e., that the product falls within the extent of protection of at least one claim) was not met.

Secondly, the Claimants argued that the SPC did not comply with Article 3(c) of the SPC Regulation (which requires that "the product has not already been the subject of a certificate") because MSD had previously obtained an earlier SPC for efavirenz based on the same patent that was being relied on as the basic patent for the SPC in issue. It was common ground between the parties that, given: (i) efavirenz was protected by the patent; and (ii) MSD had already obtained the earlier SPC in respect of efavirenz, that Article 3(c) precluded the grant of the later SPC in respect of the Product unless claim 16 of the patent independently valid over the claims which protected efavirenz and thus represented a distinct invention from the invention protected by those claims. (For the purposes of considering the case under Article 3(c), it was assumed, contrary to the conclusion reached with regard to the Article 3(a) attack, that claim 16 covered the combination of efavirenz with one or more nucleoside analogs, such as to cover the Product.)

Mr Justice Arnold held that the question to be considered was whether, given the invention of efavirenz, claim 16 represented a distinct invention such that it could in principle form the subject-matter of a separate patent. On the facts, the Judge did not consider claim 16 to be independently valid over the claims which protect efavirenz, and there was nothing in the patent to suggest that claim 16 represents a distinct invention. That should ordinarily be the end of the matter, given the need for a simple and transparent system for the grant of SPCs, but if it is appropriate to have regard to expert evidence, the Judge considered that the evidence established that, given efavirenz, it would have been obvious to combine it with a nucleoside reverse transcriptase inhibitor analog - it would have been an obvious thing to try and the skilled person would have had a fair expectation of success.

Finally, there was some discussion in the judgment on the relevant date for construing the claims of a patent. Mr Justice Arnold's view is that the claims should be construed as at the priority date (or the application date if priority is lost). He did not find it convincing that it should be construed as at the publication date (as suggested by the editors of Terrell on the Law of Patents, the leading book on patents in the UK).

This post was originally co-authored by Jin Ooi.