IP Law Daily Bayer’s patents on ‘erectile dysfunction’ compounds not invalid as obvious
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Tuesday, May 3, 2016

Bayer’s patents on ‘erectile dysfunction’ compounds not invalid as obvious

By Mark Engstrom, J.D.

Two patents involving the preparation and use of compounds that Bayer developed for the treatment of erectile dysfunction (ED) were not invalid as obvious, the federal district court in Wilmington, Delaware, has ruled (Bayer Pharma AG v. Watson Laboratories, Inc., May 2, 2016, Sleet, G.). Bayer’s motion for a judgment on the court’s partial findings was therefore granted.

Bayer Pharma AG, Bayer Intellectual Property GmbH, and Bayer HealthCare Pharmaceuticals Inc. (collectively, “Bayer”) sued Watson Laboratories Inc., Actavis Inc., and Actavis Pharma Inc. (collectively “Watson”) for the infringement of multiple claims of U.S. Patent Nos. 6,362,178 and 7,696,206. The claims at issue covered the compound vardenafil hydrochloride trihydrate, the active ingredient in the ED drug Levitra.

At the close of trial, the court ruled that seven claims of the ’178 patent and six claims of the ’206 patents were not obvious over prior art. Watson challenged the validity of both patents. According to Watson, both patents were obvious in light of the prior art.

Bayer argued that the claimed subject matter was not obvious to a person of skill in the relevant art because a skilled artisan would not have selected sildenafil as a lead compound. Bayer further argued that a skilled artisan would not have modified sildenafil in the way that the invention required.

Sildenafil as a lead compound. According to the court, a skilled artisan would have expected that the potency and selectivity of sildenafil were lacking compared to other compound leads. Although multiple review papers had discussed the properties of various PDE5 inhibitors, no review paper had described sildenafil as a lead compound. Moreover, other compounds were more potent than sildenafil, more selective than sildenafil, or both.

Watson noted the structural similarity of vardenafil to sildenafil, but the record evidence did not clearly and convincingly show that a skilled artisan would have expected the two molecules to bind to PDE5 similarly. Watson’s expert chemist testified that a skilled artisan would have wanted to copy sildenafil because the compound was “going to be a success.” The court dismissed that testimony as not credible, however, because it was significantly affected by hindsight bias.

Modification of sildenafil. Bayer argued that, even if a skilled artisan selected sildenafil as a lead compound, the development of vardenafil was not the result of an obvious path. More specifically, Bayer argued that seven independent choices would have been necessary to make vardenafil hydrochloride trihydrate, the active ingredient in Levitra.

The court agreed with Bayer. In the court’s view, each layer of decision-making would have required a lengthy process of research and development, and that process that would not have provided predictable results. Significantly, a skilled artisan would not have: (1) selected sildenafil as a lead compound and then modified its core structure; (2) found it obvious to change the pyrimidinone portion of sildenafil’s core; (3) used the core structure of vardenafil in a PDE5 inhibitor for the treatment of erectile dysfunction because the prior art taught away from it; (4) found it obvious to change the substituent from methyl-piperazine to ethyl-piperazine; (5) found it obvious to make the hydrochloride trihydrate form of vardenafil; (6) made the necessary modifications to obtain vardenafil hydrochloride trihydrate.

Ultimately, Watson failed to establish a prima facie case of invalidity due to obviousness for either the ’178 patent or the ’206 patent.

Secondary considerations. Even if the court found that Watson had established a prima facie case of invalidity, Bayer successfully argued that the secondary considerations of “unexpected properties” and “long-felt but unmet need” adequately rebutted the prima facie case. According to the court, the finding of non-obviousness was supported by secondary, objective indicia.

The case is No. 12-cv-517 (GMS).

Attorneys: Jack B. Blumenfeld (Morris, Nichols, Arsht & Tunnell, LLP) for Bayer Pharma AG, Bayer Intellectual Property GmbH, and Bayer Healthcare Pharmaceuticals Inc. David A. Bilson (Phillips, Goldman, Mclaughlin & Hall, P.A.) for Watson Laboratories Inc., Actavis Inc., and Actavis Pharma, Inc.

Companies: Bayer Pharma AG; Bayer Intellectual Property GmbH; Bayer Healthcare Pharmaceuticals, Inc.; Watson Laboratories, Inc.; Actavis, Inc.; Actavis Pharma, Inc.

MainStory: TopStory Patent DelawareNews

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