Regeneron v. Mylan, “It Ain’t Necessarily So.”

Posted on April 27, 2025 by Warren Woessner

Regeneron v. Mylan, appeal nos. 2024-2058, 2024-2147 (Fed. Cir., March 5, 2025) is the most recent appeal in a long line of Hatch-Waxman suits filed by Regeneron to block generic versions of its VEGF antagonist (or “trap”) EYLEA®, that is a used to treat angiogenesis in the eye. Regeneron’s asserted patent, U.S. Patent No. 11,084,865 is part of a large family of continuations, one of which also includes U.S. Patent No. 9,340,594. The ‘594 patent expired in 2021 and was argued to be a reference patent that rendered the later-issued ‘865 patent invalid for obviousness-type double-patenting (“ODP”).

The central argument raised by defendant-appellant Celltrion was that the claims of the ‘865 patent that recited the stability of the claimed formulation were anticipated or obvious in view of claims of the ‘594 patent. Apart from the recitation of structural features of the VEGF trap and the other ingredients in the formulation, the relevant stability elements in the ‘594 patent are that the formulated VEGF trap is stable for at least 4 or 5 months. The recitation of the stability element in claim 1 of the ‘865 patent is that “at least 98% of the VEGF antagonist is present in native conformation following storage at 5 degrees C. for two months as measured by size exclusion chromatography”.

The district court, in denying Celltrion’s arguments that it was entitled to a preliminary injunction, found that the 98% native conformation claim limitation is neither inherent nor obvious in the subject matter claimed in claim 5 (4 months). On appeal, Celltrion argued that the district court erred in declining to construe “stable” to require the more detailed recitation of stability in claim of the ‘865 patent. The district court rejected this interpretation and found that the “specification of the ‘594 patent has numerous descriptions of stability beyond simple 98% native conformation as measured by SEC.” The district court noted that the specification describes multiple aspects of stability and multiple ways to determine stability, not just SEC.  The Fed. Cir. agreed and ruled that there was no express anticipation of the asserted ‘865 patent.

Celltrion’s argument that the 98% native VEGF claim limitation is inherent in claim 5 of the ‘594 patent was unavailing. The district court found that claim 5 does not “necessarily” meet the 98% native conformation limitation:

“That the practice of ‘594 claim 5 sometimes results in 98% native conformation is insufficient; inherency requires that the 98% native conformation limitation be present necessarily, not just possibly or probably.” The Fed. Cir. agreed. This is a heavy burden, both on litigators tasked with proving anticipation when claim elements are missing, as well as on applicants who need to distinguish prior art than may or may not anticipate. Of course, in this case, the courts agreed with Sportin’ Life in a line from Show Boat that attorney argument based on inherency “ain’t necessarily so.” This standard for successfully arguing inherency has been around for a long time. Inherency must be certain. See, e.g., Ex parte McQueen, 123 USPQ 27 (Bd. App. 1958).

Celltrion also made a hard-to-follow argument that the common knowledge of a POSA  and the intrinsic evidence make clear that the “at least 98% limitation “defines a rate of aggregation over a particular time, under particular conditions.” The Fed. Cir. dismissed this argument as contradicting the plain claim language: “Nothing in the claims or the specification suggests that a “rare [of aggregation] must be calculated. Rather the claims states that after two months, the formulation is measured by SEC, and the result is either above 98%–within the scope of the claim—or below 98%–outside the scope of the claim.”

Celltrion’s obviousness argument was dismissed in one paragraph. The Fed. Cir. agreed with the district court: “[B]eginning with claim 5 of the ‘594 patent, [the POSA] would not have been motivated to achieve the 98% native conformation limitation and would not have had a reasonable expectation of achieving that level of conformation after two-months storage…[I]t suffices for us to  conclude that one claim difference—the stability limitation—renders claim 5 of the ‘594 patent patentably distinct  from the asserted claims of the ‘865 patent.” The panel did not discuss OTD in view of this difference. The opinion closes with some dicta about the presence or absence of glycosylated VEGF peptides that is, thankfully, beyond the scope of this post.

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Obviousness-type double patenting in the Age of the Twenty-Year Term and Patent Term Adjustment

Posted on March 31, 2025 by Warren Woessner

Obviousness-type double patenting (ODP) attempts to prevent the term of a “reference patent” claiming an obvious variant of a parent patent to exceed the term of the parent. This fulfills the mandate of the patent statute of “one patent per invention.”

When issuance dates were compared pre URAA (1994), the need to file for terminal disclaimer (TD) in the later-issued patent was simple to resolve. But then came patent term adjustment (PTA) – time tacked onto an expiration date for PTO delay—and URAA (1994)’s twenty years from filing or priority date term –arrived to complicate determination of if and when ODP is an issue.” A common priority date does not always guarantee a common expiration date.” (The quotes are all from Allegan).

The problem is that commonly owned patents that would otherwise expire on the same day due to a shared priority date may have different expiration dates due to award of PTA in one but not the other; or there may be a scattering of expiration dates due to differing PTA’s. “The patent subject to the TD cannot expire on any date later then the parent over which that TD was filed, even if it received [PTA]”. The TD specified expiration date rules.

In re Cellect, 81 F.4th 1216 (Fed. Cir. 2023), the Fed. Cir. established a “rule that, when it comes to evaluating ODP for a patent that has received PTA, the relevant expiration date is the expiration date including PTA. “(Owner had a number of interlocked patents with same priority date and a scattering of varying expiration dates due to different grants of PTA.)

In Allergan v MSN Labs. [and Sun], 111 F. 4th 1368 (Fed. Cir. 2024) the panel spent about 20 pages trying (and succeeding) to arrive at a just conclusion for what initially appeared to be a simple set of facts. In a para IV situation, Allegan sued MSN (“Sun “) for infringement of three patents related to an anti-pain drug. The three comprised the original ‘356 patent, claiming the drug per se, and two continuations—the ‘011 patent and the ‘709 patent. Apart from the key fact that the ‘356 patent had received 467 days of PTA, all three of the patents would have expired on the same date. So did the ‘356 patent improperly grab a much longer expiration date than the other two?

The district court said “yes” to Sun’s argument of improper extension of the term of the ‘356 patent, but Fed. Cir. reversed. The panel found that a finding of improper extension based solely on expiration dates was itself improper. The Court framed the question as “Can a first-filed, first issued, later-expiring claim be invalidated by a later-filed, later issued, earlier-expiring reference claim having a common priority date? We hold that it cannot.”

To rule otherwise would permit a first-issued patent to be treated like a later issued patent that can be invalidated by ODP. “The claims of the ‘356 patent do not “extend or prolong the monopoly [on the drug] beyond the period allowed by law, and therefore are not subject to ODP over the ‘011 and ‘709 patents…  Put otherwise, the fact that the ‘356 patent expires later is of no consequence here because it is not a second later expiring patent for the same invention.” Because the ‘356 patent was the first patent in its family to be filed and to issue it does not extend any period of exclusivity on the claimed subject matter.”

The opinion further distinguishes precedent such as Gilead and Abbvie and uses the facts of Breckenridge to illustrate the injustice of a contrary holding. “A holding [that a first-filed, first-issued] parent patent having received PTA can be invalidated by a later-filed, later issued child parent with less if any PTA] would require patent owners …to file a TD disclaiming any term of the parent [patent] that extends beyond that of the child, which, given that the [parent and child] patents share a priority date, would amount to the disclaimer of only PTA. The parent patent, then would not receive the benefit of its congressionally guaranteed patent term. See 35 USC s.154(b) and would instead be limited to the presumably shorter term of its own child. Such a result would be untenable.”

 

 

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Allergan v. Sun – A Glidant Slips Past the Written Description Requirement

Posted on August 31, 2024 by Warren Woessner

The most interesting part of this decision by the Fed. Cir. (No. 24- 1061, Aug. 13, 2024) is that the court was faced with an argument by Sun that Allergan’s claims in U.S. Pat. No.11,311,516 et al. are invalid as failing to meet the WDR of § 112. Sun argued that the claims of certain of Allergan’s patent thicket were invalid because the specifications did not support a pharmaceutical composition containing the drug eluxadoline with a number of inert ingredients that did not include a “glidant.” In other words, Sun argued that there was no support for the absence of a glidant in any of the patent claims, a component Sun was apparently using in its compositions. Continue reading →

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The Chisum Patent Academy Makes an Appearance in Cincinnati

Posted on August 5, 2024 by Warren Woessner

When I was in law school, we had but one treatise to use, the weighty “Choate on Patents” (1973). A number of “horn books” have appeared since, including the authoritative “Chisum on Patents” and his wife’s weighty treatise “Mueller on Patent Law.” With the beehive of information sources buzzing around every patent attorney’s head, any one of us would be wise to keep abreast of developments in IP law, even if they do not appear immediately to impact one’s practice.

Continue reading →

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