Over the past twelve months, the Federal Circuit has issued a number of noteworthy decisions that will impact litigation strategy and business planning. Several of those cases pertain particularly to cases brought under the Hatch-Waxman Act. Here, Taft provides a brief overview of three key Hatch-Waxman decisions from 2024, and also looks ahead to a decision the Federal Circuit is likely to issue early in 2025.

Salix v. Norwich: Polymorph Patent Claims Are Susceptible to Obviousness Challenges

About the case

In April, the Federal Circuit breathed new life into the use of obviousness challenges to claims drawn to a drug compound’s solid state form.

At issue in Salix Pharmaceuticals Ltd. v. Norwich Pharmaceuticals Inc., 98 F.4th 1056 (Fed. Cir. 2024), was Norwich’s proposed generic version of rifaximin, which is the active ingredient in Salix’s commercial product Xifaxan®, used to treat hepatic encephalopathy (HE) and irritable bowel syndrome with diarrhea (IBS-D). Id. at 1059-60. Salix asserted patents directed to methods of treating HE, patents directed to methods of treating IBS-D, and patents directed to a solid form of rifaximin, namely form β.  Id. at 1060. Following the trial, the district court found the HE patents infringed and not invalid, and the IBS-D and polymorph patents infringed but invalid as obvious.

What did the court decide?

Relevant to this discussion, on appeal, Salix argued that the district court clearly erred in finding that a person of ordinary skill in the art would have had a reasonable expectation of success in obtaining the claimed rifaximin form β. Id. at 1064. Salix pointed to several prior Federal Circuit decisions finding polymorph claims non-obvious, including Grunenthal GmbH v. Alkem Laboratories Ltd., 919 F.3d 1333 (Fed. Cir. 1999), and Pharmacyclics LLC v. Alvogen, Inc., No. 2021-2270, 2022 WL 16943006 (Fed. Cir. Nov. 15, 2022). Those cases, as well as previous polymorph decisions, had seemed to render obviousness arguments difficult, to say the least, given the purported unpredictability of polymorph formation and preparation.

In Salix, the key prior art reference disclosed that “rifaximin exists in crystalline form,” and although that reference did not “discuss rifaximin’s crystal structure in detail,” it “does disclose several preparation protocols for rifaximin that include solvents used for crystallization.” Id. at 1064. Relying on expert testimony, the district court held that a person of ordinary skill in the art would have had reason to characterize the crystalline rifaximin obtained from the prior art protocols, that such characterization was routine, and that doing so would have led the person of ordinary skill to detect the claimed form. Id. at 1065. The court found no clear error by the district court. The court acknowledged and discussed Grunenthal and Pharmacyclics, both of which found no clear error in a district court finding of non-obviousness, but it distinguished those cases. Quoting Grunenthal, the court reiterated the fact-heavy analysis that undergirds polymorph obviousness considerations and returned to the teaching of the prior art: “In Grunenthal and Pharmacyclics, the issue was whether a skilled artisan would have had a reasonable expectation of success in producing a crystalline form of a compound[,] . . . Here, the prior art included a process to produce a crystalline form of rifaximin, and the dispute centered around characterizing the crystalline form resulting from that process.” Id. at 1065 (citations omitted; italics in original).

Implications for polymorph claim obviousness arguments

Salix breathes new life into polymorph claim obviousness arguments, as it reaffirms that, as a practical matter, polymorph claims are susceptible to obviousness challenges. Salix also highlights the need for a carefully crafted litigation strategy. Conventional wisdom had suggested that anticipation and obviousness challenges to polymorph patents are served by testing of material reproduced following prior art teachings. That reproduction and testing are not required by Salix, though advocates and experts will be wise to present the teachings of the prior art in a compelling fashion in order to analogize either to Salix on the one hand or Grunenthal and Pharmacyclics on the other.

Amarin v. Hikma: Public Statements Can Have a Major Impact on Carve-Out Analysis

About the case

In June, the Federal Circuit illuminated the state of the law with respect to so-called “skinny labels,” in which an ANDA applicant attempts to carve out label indications claimed by asserted method-of-treatment patents, leaving only one or more unclaimed indications.

Amarin Pharma, Inc. v. Hikma Pharmaceuticals USA Inc., 104 F.4th 1370 (Fed. Cir. 2024), involved Hikma’s generic version of icosapent ethyl, originally approved as Vascepa® for severe hypertriglyceridemia (the SH indication). The case has a lengthy history. Hikma had filed its ANDA in 2016; Amarin promptly filed suit, and its asserted patents were held invalid. See Amarin Pharma, Inc. v. Hikma Pharms. USA Inc., 449 F. Supp. 3d 967 (D. Nev. 2020), aff’d summarily, 819 F. App’x 932 (Fed. Cir. 2020). In 2019, the FDA approved Vascepa® as a treatment to reduce cardiovascular risk (the CV indication), which was allegedly covered by patents listed by Amarin in the Orange Book for Vascepa®. In turn Hikma filed a “section viii statement,” carving out the CV indication and leaving only the SH indication. Following approval in May 2020, Hikma launched its generic product in November 2020, and issued pre- and post-launch press releases. Following the launch, Amarin sued Hikma on the CV patents, and Hikma moved to dismiss under Rule 12(b)(6).

What did the court decide?

The case history highlights the difficult nature of the carve out evaluation. Magistrate Judge Hall recommended denying Hikma’s motion, but Judge Andrews declined to adopt her recommendation and instead granted the motion based on a narrow reading of GlaxoSmithKline LLC v. Teva Pharm. USA, Inc., 7 F.4th 1320 (Fed. Cir. 2021). On appeal, the Federal Circuit reversed the dismissal, pointing to certain of Hikma’s public statements announcing its launch. Amarin, 104 F.4th at 1378-81.

Considerations for carve-outs cases

Amarin is the newest in the continuing development of carve-out case law, and it presents several points for consideration. Amarin did not strictly foreclose the use of a motion to dismiss as a vehicle for disposition of a shaky complaint when a carve out is at play; yet, at minimum, litigants will need to bear in mind the effects not simply of label statements but also statements in press releases and other public announcements. Also, as a litigation strategy consideration, motions to dismiss can take considerable time to reach resolution, which is of particular concern in cases involving damages questions.

Allergan v. MSN: The Federal Circuit Addresses Obviousness-Type Double Patenting

About the case

In August, the Federal Circuit issued a decision addressing the application of obviousness-type double patenting in the wake of its 2023 decision In re Cellect, LLC, 81 F.4th 1216 (Fed. Cir. 2023).

In the relevant part, the issue in Allergan USA, Inc. v. MSN Laboratories Private Ltd., 11 F.4d 1358 (Fed. Cir. 2024), at issue was whether U.S. Patent No. 7,741,356 (the ’356 patent) is invalid based on obviousness-type double patenting in view of reference claims from U.S. Patent Nos. 8,344,011 (the ’011 patent) and 8,609,709 (the ’709 patent). Notably, both the ’011 patent and the ’709 patent claimed priority, indirectly, to the application that was issued as the ’356 patent, meaning that all three patents claimed the same priority date and had the same nominal expiration date; however, the ’356 patent had received a patent term adjustment pursuant to 35 U.S.C. § 154(b), rendering its effective expiration later than the other two. Id. at 1363. Defendant Sun took the position at trial that the ’356 patent is invalid for obviousness-type double patenting over reference claims of the ’011 and ’709 patents because the claims are not patentably distinct and because the ’356 patent expires after the ’011 and ’709 patents. Id. at 1365. The district court agreed and found the ’356 patent invalid; the district court reasoned that Allergan’s arguments were grounded in equitable considerations that Cellect had foreclosed in favor of a rigid application in view of the expiration of the ’356 patent and the ’011 and ’709 patents. Id. at 1366.

What did the court decide?

The Federal Circuit reversed the district court and stated that a first-filed, first-issued, later-expiring claim could not be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date. Id. at 1366. The court reasoned that the obviousness-type double patenting doctrine’s purpose is to prevent patentees from effectively extending the life of a first patent by obtaining a second patent claiming patentably indistinct subject matter. But here, the court said, the ’356 patent was not an extension of the later-filed, later-issued ’011 or ’709 patents, and to find it invalid would “abrogate the benefit Congress intended to bestow on patentees when codifying [patent term adjustment].” Id. at 1371. In reaching its decision, the court parsed the rules stemming from its prior case law, including Gilead Sciences, Inc. v. Natco Pharma Ltd., 753 F.3d 1208 (Fed. Cir. 2014), Abbvie Inv. v. Mathilda & Terence Kennedy Institute of Rheumatology Trust, 764 F.3d 1366 (Fed. Cir. 2014), and Novartis Pharmaceuticals Corp. v. Breckenridge Pharmaceuticals Inc., 909 F.3d 1355 (Fed. Cir. 2018) — each of which involved various iterations of filing dates and expiration dates of asserted patents in view of reference claims.

Looking Ahead: Will the Federal Circuit Clarify the Patent Listing Statute?

It is not too soon to consider how the Federal Circuit’s decisions in early 2025 will affect parties. At least one case is of particular interest.

On Nov. 8, 2024, the Federal Circuit heard oral argument in Teva Branded Pharmaceutical Products R&D, Inc. v. Amneal Pharmaceuticals of N.Y., LLC, No. 24-1936 (Fed. Cir.). At issue is whether patents Teva listed in the Orange Book for its metered dose inhaler product, ProAir® HFA (albuterol sulfate) Inhalation Aerosol, are properly listable under 21 U.S.C. § 355(b)(1)(A)(viii)(I), which requires a listing of patents that “claim[] the drug” that is the subject of the NDA. The parties have, in effect, set up the question to be whether, to be listable under the statute, the claims of the patent in question must recite by name the active ingredient of the drug product. The parties also dispute whether claim construction issues in this particular case preclude resolution.

Questions surrounding the scope of the listing statute and how it is to be applied have been on the minds of brands and ANDA filers. This case presents an opportunity for the Federal Circuit to provide useful guidance and clarity.

Taft Takeaways

Careful evaluation of Federal Circuit case law provides a foundation for litigation and broader business judgment. These three decisions from 2024 and one anticipated in 2025 will inform conscientious litigants, and careful case assessment at the outset, while critical, must remain nimble in order to craft robust positions to achieve the best result possible.