Preliminary injunction against Lupin over metaformin vacated

In the case Sciele Pharma (now Shionogi Pharma ) v. Lupin , the Court of Appeals for the Federal Circuit [CAFC] vacated a preliminary injunction against generic drug manufacturer Lupin:

Because the district court incorrectly concluded that Lupin failed to raise a substantial question of validity regarding the asserted claims of the ’866 patent, it abused its discretion by issuing a preliminary injunction enjoining Lupin from selling its generic product [related to metaformin]. Accordingly, we vacate the preliminary injunction and remand to the district court for further proceedings.

Lupin had made an obviousness argument against the claims in question, but relied on prior art that had been previously considered by the USPTO. The CAFC found that such references could lead to a finding of obviousness. The CAFC wrote:

While the ultimate burden of proof does not change, new evidence not considered by the PTO “may ‘carry more weight’ . . . than evidence previously considered by the PTO,” and may “‘go further toward sustaining the attacker’s unchanging burden.’” Id. at 2251 (quoting Am. Hoist & Derrick Co. v. Sowa & Sons, Inc., 725 F.2d 1350 (Fed. Cir. 1984)). “[I]f the PTO did not have all material facts before it, its considered judgment may lose significant force” and the burden to persuade the finder of fact by clear and con- vincing evidence may, therefore, “be easier to sustain.” Id. Instead, the fact that references were previously before the PTO goes to the weight the court or jury might assign to the proffered evidence. Id.

For example, it could be reasonable to give more weight to new arguments or references that were not explicitly considered by the PTO when determining whether a defen- dant met its burden of providing clear and convincing evidence of invalidity. Id. Conversely, it may be harder to meet the clear and convincing burden when the invalidity contention is based upon the same argument on the same reference that the PTO already considered. Importantly, whether a reference was before the PTO goes to the weight of the evidence, and the parties are of course free to, and generally do, make these arguments to the fact finder. But the presumption of validity and accompanying burden of proof, clear and convincing evidence, are not altered.

**One separate sub-theme in the case was the interplay of enablement and obviousness. Frequently, applicants who have not provided explicit data on enablement will argue that the "missing details" could be filled in with general knowledge available to the skilled artisan. Of course, if one makes such an argument to rebut an enablement rejection, one exposes oneself to an obviousness rejection. That happened in this case. The CAFC wrote:

The applicant’s arguments during prosecution further buttress our belief that Lupin has raised a substantial question of validity with respect to the ’866 patent. During prosecution the applicant indicated “that one skilled in the art would be able to manipulate the processes and formulations of the [prior art] by other methods to obtain the claimed pharmacokinetic parameters of the present inven-
tion by routine experimentation.” J.A. 2621. While Shionogi argued, and the district court seemed to accept, that this statement applies only to enablement, we are hard pressed to understand this distinction. Coupled with the motivation to lower the Tmax, as disclosed in Timmins, the applicant’s characterization of the predictability and skill in the art during prosecution provides further evidence that it would have been a routine and obvious design choice to make an extended release dosage form with a lower Tmax. After all, “[i]f a person of ordinary skill can implement a predictable variation, § 103 likely bars its patentability.” KSR, 550 U.S. at 417.

**As a footnote, in "In re '639 Litigation," patent claims to the drug nabumetone were invalidated based on art that was before the USPTO.