Federal Circuit Evaluates Enablement for Antibody Claims for the First Time Since Amgen v. Sanofi in Baxalta Inc. et al. v. Genentech, Inc.

Co-Authored by: Rosalynd Upton, Ph.D.

On May 18, 2023, the Supreme Court in Amgen Inc. v. Sanofi unanimously affirmed the Federal Circuit’s holding that U.S. Patent Nos. 8,829,165 and 8,859,741 did not enable certain functional genus claims describing a class of antibodies with unknown amino acid sequences. Amgen Inc. v. Sanofi, 598 U.S. 594 (2023). The Court held that under 35 U.S.C. § 112(a), “Amgen has failed to enable all that it has claimed, even allowing for a reasonable degree of experimentation.” 598 U.S. 594, at 613. After analyzing the specification and testimony presented, the Court disagreed with Amgen’s argument that disputed claims are enabled because “scientists can make and use every undisclosed but functional antibody if they simply follow the company’s ‘roadmap’ or its proposal for ‘conservative substitution.’” Id. at *613-614. In short, the ruling affirmed the Federal Circuit’s reading of the Patent Act’s “enablement” requirement, a requirement that states that a patent must enable someone who is reasonably skilled in the art to use or make the patented invention without undue experimentation.

Now, four months later, the Federal Circuit’s recent decision in Baxalta Inc. et al. v. Genentech, Inc., 2023 WL 6135930 (Fed. Cir. Sept. 20, 2023), is the first to apply Amgen’s holding in the context of a patent covering antibodies.

Key takeaways from Baxalta v. Genentech:

• Claims describing a genus of antibodies that bind a certain target to produce a functional result may be invalid for lack of enablement if the specification merely directs a skilled artisan to use a trial-and-error approach to identify the full scope of the claimed genus.
• Genus antibody claims may survive an enablement challenge if the specification describes a common characteristic found within the genus that is responsible for the claimed functional activity.
• More Federal Circuit case law is needed to fully flesh out the new enablement standard under Amgen.
• The Federal Circuit’s Baxalta decision does not contradict its holding in In re Wands, 858 F.2d 731 (Fed. Cir. 1988).

Baxalta, Inc., and Baxalta GmbH (collectively, Baxalta) asserted infringement of U.S. Patent No. 7,033,590 (“the ’590 patent”) against Genentech, Inc. (Genentech) over Genentech’s Hemlibra® (emicizumab) product. Baxalta Inc. v. Genentech, Inc., No. 17-CV-00509 (D. Del.). The ’590 patent describes antibodies indicated for the treatment of Hemophilia A, a blood clotting disorder. See ’590 patent at 2:29–38. Representative claim 1 of the ’590 patent describes antibodies that bind to proteins involved in the blood clotting process (Factors IX and IXa) to yield a functional result (an increase of pro-coagulant activity of Factor IXa):

1. An isolated antibody or antibody fragment thereof that binds Factor IX or Factor IXa and increases the procoagulant activity of Factor IXa.

Id. at claim 1.

The ’590 patent’s specification describes how the inventors generated the claimed antibodies using a well-known hybridoma technique. See id. at 9:62–10:37. The specification goes on to explain how the inventors screened the antibodies they generated to identify those that bind to Factors IX/IXa and increase pro-coagulant activity. See id. at 10:39–12:56. The ’590 patent also lists 11 antibodies that satisfied the inventors’ screening criteria. See id. at 12:36–49.

Genentech moved for summary judgment of invalidity for claims 1-4, 19, and 20 of the ’590 patent (all of which depend on independent claim 1) for lack of, inter alia, enablement. See Baxalta Inc. v. Genentech, Inc., 579 F. Supp. 3d 595, 599 (D. Del. 2022), aff’d, 2023 WL 6135930 (Fed. Cir. Sept. 20, 2023). The District Court granted Genentech’s motion, and Baxalta appealed. Id.

With Chief Judge Moore writing for a unanimous panel consisting of Judges Chen and Clevenger, the Federal Circuit affirmed. The panel found that “[t]he facts of this case are materially indistinguishable from those in Amgen.” Baxalta, 2023 WL 6135930 at *4. Like the claims in Amgen, which covered all antibodies that bind a specific protein to produce a functional result, the Federal Circuit found that the ’590 patent’s claims describe all antibodies that bind to Factor IX/IXa and functionally increase the pro-coagulant activity of Factor IXa. Id. And like the specification in Amgen, the ’590 patent’s specification only listed 11 of the claimed antibodies and relied on a “roadmap” to describe how to obtain the rest. Id. The panel noted that, “[j]ust like the roadmap rejected by the Supreme Court in Amgen, the ’590 patent’s roadmap simply directs skilled artisans to engage in the same iterative, trial-and-error process the inventors followed to discover the eleven antibodies they elected to disclose.” Id. (citing Amgen, 598 U.S. at 613–614). Such a “roadmap,” reasoned the panel, “leaves the public no better equipped to make and use the claimed antibodies than the inventors were when they set out to discover the antibodies over which they now have an exclusive right.” Id. Without more, the panel held that the ’590 patent’s “roadmap” did not enable a skilled artisan to practice the full scope of the claims. Id.

The panel also remarked in dicta on the ’590 patent’s silence on “a quality common to every functional embodiment[] . . . that would allow a skilled artisan to predict which antibodies will perform the claimed functions.” Id. (citation omitted) (internal quotation marks omitted). By noting this absence of evidence in the ’590 patent, the panel hinted that patent specifications containing such evidence might survive an enablement challenge under Amgen. Patents disclosing common features (e.g., structure) that are responsible for delineating which antibodies will bind specific targets and produce certain functional outcomes, for example, might survive muster. Id. And patents explaining why certain antibodies generated and screened in a particular manner perform or do not perform the claimed functions might also survive. Id. Though this dicta is a preliminary guiding principle for practitioners, future Federal Circuit cases will have to further flesh out what satisfies enablement after Amgen.

Finally, the panel held that its affirmance of the District Court did not contradict its holding in In re Wands, 858 F.2d 731 (Fed. Cir. 1988). Id. at *5.