Pfizer Inc. v. Teva Pharm. U.S.A., Inc.

Case Name: Pfizer Inc. v. Teva Pharm. U.S.A., Inc., Case No. 2009-cv-307, 2012 U.S. Dist. LEXIS 100567 (D. Del. July 19, 2012) (Sleet, C.J.)

Drug Product and Patent(s)-in-Suit:Lyrica® (3-isobutylGABA); U.S. Patent Nos. 6,197,819 (“the ’819 patent”); 5,563,175 (“the ’175 patent”); and Reissued Patent No. RE 41,920 (“the ’920 patent”)

Nature of the Case and Issue(s) Presented: Defendants raised numerous invalidity defenses against the asserted patents, including obviousness, anticipation, lack of enablement, and lack of written description. In particular, defendants asserted that it was obvious to use 3-isobutylGABA to improve seizure treatment and to treat neuropathic pain. Plaintiffs argued that there was no reasonable expectation of success in using 3-isobutylGABA for these treatments and that secondary considerations of commercial success and long-felt need demonstrate that the inventions were not obvious.

The defendants argued that the ’819 patent was anticipated, and presented re-creations of an example in the prior art to demonstrate that the claims of the ’819 patent were invalid. The plaintiffs responded by challenging defendants’ expert’s re-creation as improper and unreliable. 

The defendants argued that the ’819 patent was not enabled because it did not teach how to isolate one stereoisomer of 3-isobutylGABA, and that a later-filed patent on the method to isolate this stereoisomer shows that it was not known in the art to isolate the isomer. The plaintiffs asserted that the claims of the ’819 patent were not directed at isolating the isomer, but that one of skill in the art could, nonetheless, create and isolate the isomer. 

Finally, one of the defendants asserted that the ’819 patent was invalid for lack of written description because the specification does not demonstrate that the inventors were in possession of the S enantiomer of 3-isobutylGABA. Plaintiffs responded by arguing that in the original patent application, the inventors claimed this enantiomer in its racemic and non-racemic mixtures.

With regard to infringement, the plaintiffs contend that defendants literally infringe the asserted claims of the ’819, ’175, and ’920 patents. The parties filed a stipulation wherein defendants stipulated that, should the court find the asserted claims of the patents-in-suit valid, the defendants’ proposed products would infringe all asserted claims of the patents-in-suit except claims 1 and 4 of the ’819 Patent. Because the court would ultimately find the patents-in-suit valid, it examined literal infringement and infringement under the doctrine of equivalents only with regard to claims 1 and 4 of the '819 Patent. The central issue for infringement was the presence of the R enantiomer as the claims expressly required the product to be “free of R enantiomer.” The defendants asserted that the plaintiffs had not shown by a preponderance of the evidence that their products would be free of R enantiomer. The court held that the asserted claims were valid and infringed under the doctrine of equivalents.

Why Pfizer Prevailed: First, the court found that one of skill in the art would not have had a reasonable expectation of success that 3-isobutylGABA could be used to treat seizures or neuropathic pain. The court based its findings on plaintiff’s expert witness testimony and evidence of secondary considerations, including commercial success of Lyrica and the long-felt need for better drugs to treat those conditions.

Next, concerning defendants’ anticipation argument, the court found that the defendants’ expert had failed to reliably re-create an example from the prior art. Moreover, the court found that the test itself was unreliable because the expert failed to include proper controls to confirm that his results were related to 3-isobutylGABA.  Thus, the court held that defendants had not met their clear and convincing burden of showing anticipation.

The court then held that the ’819 patent was enabled because the claims did not require a person of ordinary skill in the art to isolate the different enantiomers of 3-isobutylGABA. In addition, one of skill at the relevant time would have been able to isolate the enantiomers such that the specification did not need to teach those methods as it was not the novel aspect of the patented invention. Likewise, the court held that the ’819 patent conformed with the written description requirement because the original claims were directed at 3-isobutylGABA in its racemic and non-racemic mixtures. These mixtures would have included the S enantiomer of 3-isobutylGABA. This disclosure was sufficient to show one of skill that the inventors were in possession of the claimed invention.

Turning to infringement, the court disagreed with plaintiffs that because the ANDAs do not contain a specific minimum of the R enantiomer, infringement is established. The court held that the plaintiffs bore the burden to prove that the hypothetical products more than likely infringe, and the lack of minimum in the ANDAs does not prove infringement by this standard. Further, because some of the tests in the ANDAs showed any R enantiomers in the proposed generic products, the court held that defendants did not literally infringe. However, the court noted that the R enantiomer was present as an impurity, and it had no impact on the pharmaceutical activity of the product. The issue was whether the narrowing amendments during prosecution were sufficient for prosecution history estoppel to arise. The court held that nowhere in the prosecution did the plaintiffs expressly disavow a claim scope that would include the presence of the R enantiomer. The examiner did not require plaintiffs to forgo this claim scope during prosecution, and with a clear and unmistakable statement of disavowal, prosecution history estoppel would not apply. Thus, all of the defendants infringed the disputed claims under the doctrine of equivalents.