Gilead's Tamiflu Patent Protection Possibly Now Subject to February 2015 Expiration

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By Tony Dutra  

April 22 --A patent underlying influenza-inhibiting drug Tamiflu that expires at the end of 2016 may well be invalid for obviousness in light of a similar patent, also owned by Gilead Sciences Inc., that expires in February 2015, the U.S. Court of Appeals for the Federal Circuit ruled April 22 in a 2-1 decision.

Vacating a district court decision, the majority held that the doctrine of obviousness-type double patenting can be applied based on when the earliest of related patents expires, regardless of the order in which they were issued. On remand, the lower court will have to determine if the patent expiring in 2016 is an obvious variant of the one expiring in 2015 and if so, the former will be rendered invalid.

The dissent argued that the doctrine “is largely no longer applicable” and, given the circumstances of this case, did not merit the expansion the majority enabled.

Patents Issue in Reverse Order of Application

Gilead Sciences Inc. is assignee of two patents (U.S. Patent Nos. 5,763,483 and 5,952,375) on carbocyclic compounds, including oseltamivir, and their methods of use. Gilead's discovery was licensed to Hoffmann-La Roche Inc., which markets oseltamivir phosphate under the trade name Tamiflu.

The two patent specifications disclose similar content but claim priority to different applications. Both expire 20 years from their application dates, but they were granted in reverse order from when the applications were filed. Thus, the '375 patent will expire on Feb. 27, 2015, 22 months before the later filed but earlier issuing '483 patent.

Gilead sued Natco Pharma Ltd. after the latter filed an Abbreviated New Drug Application to market generic oseltamivir phosphate. Natco, hoping to get into the market in February 2015 instead of December 2016, argued that the '483 patent was invalid for obviousness-type double patenting--that is, that it was obvious in light of Gilead's own '375 patent specification.

Judge Susan D. Wigenton of the U.S. District Court for the District of New Jersey determined that the later-issuing application could not be used for the double-patenting analysis. Natco appealed that judgment.

Earliest Expiration Date of Obvious Variants Applies

“This appeal presents a narrow question,” according to Judge Raymond T. Chen, writing for the majority. “Can a patent that issues after but expires before another patent qualify as a double patenting reference for that other patent?”

The court's opinion was driven by the policy concern that “obvious or patentably indistinct modifications” of an invention should be available for the public's free use upon expiration of any patent claiming that invention. Under the assumption--not yet addressed by the lower court--that the '483 patent claims are obvious variations of the disclosed invention in the '375 patent, the court said, the principle would be violated if the former can be enforced after the latter expires.

“Thus, come February 28, 2015, the public should have the right to use the invention claimed in the ['375] patent and all obvious variants of that invention.”

The majority highlighted actions taken by Gilead during prosecution of the two patents--they were handled by different examiners and Gilead did not disclose their relationship until after the '483 patent issued--as a precursor to describing the potential for “significant gamesmanship during prosecution” without a restriction on patent term.

The court thus set the rule that “the earliest expiration date of all the patents an inventor has on his invention and its obvious variants best fits and serves the purpose of the doctrine of double patenting.” Gilead could have filed a terminal disclaimer, under 35 U.S.C. §253, that would have given it rights to the claims of the '483 patent so long as it expired when the “earliest” '375 patent did. But it did not do so, leaving it subject to invalidity for obviousness-type double patenting.

Therefore, the court remanded for the lower court to determine if the '483 patent claimed obvious variants of the '375 patent specification.

Judge Sharon Prost joined the opinion.

Dissent: Doctrine Expansion Unwarranted

In dissent, Chief Judge Randall R. Rader generally minimized the policy concerns that dominated the majority's opinion.

The concern was important prior to the Uruguay Round Agreements Act and the General Agreement on Tariffs and Trade, when patent term extended 17 years from the date of issuance, he said. Obviousness-type double patenting allowed courts to prevent filing of continuations ad infinitum, he said.

But now, Rader said, when a patentee claims a later application priority date for a related patent, it is saying that it willingly gives up priority--exposing the second patent to invalidity on the basis of intervening prior art--in seeking the subsequent patent claims. And, he said, that is the only behavior attributable to Gilead here, rather than the assumption of gamesmanship.

“I do not perceive Gilead's conduct as so manifestly unreasonable to warrant a new judicially-created exception to invalidate patents,” Rader said.

Finally, he expressed a new concern given the change--effective March 16, 2013, per the America Invents Act--to a first-inventor-to-file system in the United States. Now, since “prospective patentees are under tremendous pressure to file their applications early,” he said, “I am concerned that today's opinion will have unforeseen consequences in this new race to the Patent Office.”

Leora Ben-Ami of Kirkland & Ellis LLP, New York, represented Gilead. Jeremy C. Lowe of Axinn Veltrop Harkrider LLP, Hartford, Conn., represented Natco.


To contact the reporter on this story: Tony Dutra in Washington at

To contact the editor responsible for this story: Naresh Sritharan at

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