Canada: Allegations Against Canadian Tenofovir Patent Found Unjustified (Again)

Gilead's Canadian Patent 2,261,619 (the "619 Patent")—the compound patent for tenofovir disoproxil fumarate ("TDF")—is no stranger to Canadian courts. Adding to its litigious history, the Federal Court recently dismissed each of Apotex's claims in an application under Canada's NOC Regulations to find—for a second time—allegations relating to the 619 Patent's validity unjustified.

Background

The multitude of Canadian proceedings pertaining to the 619 Patent stems in part from the fact that TDF is the active ingredient in a number of anti-HIV medications: Gilead markets two different drugs containing TDF (TRUVADA® and VIREAD®), while Bristol Myers Squibb (BMS) markets ATRIPLA® which also contains TDF.

In late 2011, Teva served Gilead with a separate Notice of Allegation (NOA) with respect to each of TRUVADA® and VIREAD®, and another NOA on BMS in respect to ATRIPLA®. In response, Gilead and BMS commenced three separation applications (Court Files T-8-12, T-280-12 and T-1708-12) under Canada's NOC Regulations seeking orders prohibiting the Minister from issuing NOCs to Teva until the expiry of two patents, including the 619 Patent. Ultimately, the Court dismissed Teva's allegations of invalidity concerning the 619 Patent and granted an order prohibiting the Minister from issuing NOCs to Teva until expiry of the 619 Patent on July 25, 2017.¹

While the prohibition proceedings were still pending, in August 2012, Teva commenced an impeachment action against Gilead, seeking, inter alia, a declaration that the 619 Patent was invalid, void and of no force and effect (Court File T-1529-12). Notwithstanding its unsuccessful result in the prohibition proceeding, Teva continues to prosecute its impeachment action, which is set to be heard in November 2016.

The Apotex Case

Despite allegations of invalidity already having been dismissed by the Court relating to the 619 Patent, an ongoing impeachment action with another generic manufacturer, and the 619 Patent's expiry in July 2017, Apotex too sent NOAs to Gilead in respect of both TRUVADA® and VIREAD®.

While TDF is the sole active ingredient in VIREAD®, TRUVADA® is a combination drug comprised of VIREAD® (TDF) and another drug: emtricitabine or FTC. In response, Gilead commenced two applications pursuant to Canada's PM(NOC) Regulations relating to VIREAD® (Court File No. T-1694-14) and TRUVADA® (Court File T-1693-14). In the TRUVADA® case, the Court had determined earlier that the 619 Patent was ineligible for listing on the Patent Register and therefore ineligible for inclusion in that proceeding² (see our earlier report on the decision here).

In the VIREAD® case reported here, at issue was a single claim (claim 32) that disclosed the compound tenofovir disoproxil ("TD") and its salts, tautomers and solvates. While Apotex admitted infringement it alleged a number of grounds of invalidity including anticipation, obviousness, invalid selection and inutility. Ultimately the Court dismissed each of Apotex's allegations and granted an order prohibiting Apotex from receiving a NOC for VIREAD® until expiry of the 619 Patent.

Anticipation

As Teva had argued earlier (unsuccessfully), Apotex alleged that the 619 Patent was anticipated in light of European Patent Application 214. Central to Apotex' argument was whether a particular carbonate on TDF was disclosed as a possible substitution in the genus described in EP214. The Court concluded EP214 did not satisfy the disclosure requirement as the particular carbonate was not explicitly referred to and thus, the application did not provide so clear a direction that a skilled person reading and following it would in every case and without possibility of error be led to the claimed invention.

Selection Patent

Apotex argued that the 619 Patent was an invalid selection from the genus disclosed in EP214. As it had determined in respect of Apotex's anticipation allegation, the Court concluded on the evidence that EP214 did not include within its genus a class encompassing TD. Nevertheless, the Court was satisfied that even if EP214 included TD, the 619 Patent still presented a particular and special advantage over other members of the claimed genus not disclosed in EP214.

Obviousness

In addressing Apotex's allegation of obviousness, ultimately the Court was unsatisfied that the skilled person would have been directly led to the solution given the experiments demonstrating chemical instability of carbonate moieties for parent drugs similar to tenofovir and given the unpredictable results when combining moieties—it was simply not obvious that a carbonate subgroup ought to work.

Of particular note was the Court's comments with respect of one of Apotex's witness who filed an affidavit "in which he admitted contained two significant false statements", which related to the reference in the prior art to the application of the prodrug strategy to tenofovir. In this respect, the Court found that because the statements were simply "too important to the dispute [...] to have been accidental", that they were "obviously" inserted by the drafter of the affidavit. The Court made reference to the fact that it was "significant that these material untrue statements" remained in the affidavit "after whatever number of reviews and preparation took place leading up to a significant legal challenge as mounted here".

Utility

In considering Apotex' utility allegation, the Court made note of the difference between goals and outcomes that a patent promises: goals may relate to potential uses for the patent, while promises are explicit and define guaranteed or anticipated results from the patent (depending on whether the promise is demonstrated or soundly predicted). Gilead had argued the only promise of the 619 Patent was the offer of efficient oral delivery of tenofovir, while Apotex maintained that the Patent also promised an effective treatment for, among other things, HIV. The Court found that while the goal of the 619 Patent was to improve treatment for HIV, ultimately the promised utility was simply effective oral bioavailability of the parent drug through its prodrug.

In determining the utility of the Patent, Gilead relied solely on demonstrated utility (making no submission on sound prediction) based on laboratory notes as well as two examples stated in the Patent. On this evidence, and after noting that the Court is not bound only by the contents of the 619 Patent when determining demonstrated utility, the Court was satisfied that Apotex's inutility allegation was unjustified.

Footnotes

1. Gilead Sciences, Inc. et al. v. Teva Canada Limited et al., 2013 FC 1270; Bristol-Myers Squibb et al. v. Teva Canada Limited et al., 2013 FC 1271; Gilead Sciences, Inc. et al. v. Teva Canada Limited et al., 2013 FC 1272,

2. Gilead Sciences, Inc. et al. v. Apotex, Inc. et al., 2016 FC 231; aff'd 2016 FCA 140.

To view the original article please click here.

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.