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Praxis: The Online Publication of The McCarthy Institute

By Timmy Basista

Timmy Basista is a 3L JD candidate at ASU Law with a strong interest in clerking aiming to carve a pathway up to clerking at the Federal Circuit. They are one of the Student Co-Executive Directors of the McCarthy Institute. They especially enjoy copyright and patent within the field of IP. Along with these IP interests, Timmy simply loves writing whether that is about constitutional law, copyright, ethics, or science.

Patent common law is largely a creature of the Federal Circuit Court of Appeals. The court has exclusive jurisdiction over patent appeals, and, because the Supreme Court has historically rarely weighed in on patent law, the Federal Circuit Court of Appeals usually has the final word on patent matters. However, the Supreme Court has begun reviewing patent matters more closely in recent years.[1] When the Court does make rulings on patent law, the Federal Circuit is swift to incorporate the Court’s new rulings to prove it is paying attention. As such, the Federal Circuit must be quick on its toes to ensure it is compliant with the binding authority of the Court—even when the Court’s ruling comes only months before the final disposition of a case.

In a recent Federal Circuit Court of Appeals case, Baxalta Inc. (“Baxalta”) received a patent for antibodies that treat hemophilia.[2] Hemophilia is an inability to form blood clots because of an absence of a particular enzyme, Factor VIII.[3] Activated Factor VIII complexes with activated Factor IX to activate Factor X which begins the blood clotting sequence.[4] Hemophilia is usually treated by injecting patients with the Factor VIII enzyme, yet many patients cannot accept such an injection due to antibodies in their bloodstream that attack Factor VIII.[5]

Baxalta resolved this issue by side-stepping Factor VIII and synthesizing antibodies to directly bind to activated Factor IX to increase its blood clotting (“coagulant”) ability.[6] Its patent specification described eleven specific antibodies that promote activated Factor IX coagulant activity out of thousands of antibodies it synthesized and screened.[7] It also claimed the entire genus of antibodies that increases activated Factor IX’s coagulant activity.[8] However, Baxalta only described the amino acid sequences of the eleven specific antibodies––it did not provide any details on the amino acid sequences of the claimed genus of Factor IX-binding, pro-coagulant antibodies.[9] Instead, it stated that a “skilled artisan may use well-known antibody engineering techniques to transform the resulting antibody into different structural formats.”[10]

Sometime after the Baxalta patent was filed, Genentech, Inc. (“Genentech”) created a product that performed the same function as the antibodies Baxalta described in its patent––an antibody that can functionally increase the coagulant ability of activated Factor IX without the presence of Factor VIII.[11] Baxalta sued, claiming Genentech’s product infringed their patent.[12]

Only four months prior to the resolution of this lengthy litigation, the Supreme Court released a relevant unanimous opinion in Amgen Inc. v. Sanofi.[13] Amgen Inc. described in its patent twenty-six specific antibodies that performed the claimed function.[14] However, it did not describe the amino acid sequences of any other antibodies in the genus despite claiming the entire genus of antibodies that could perform the claimed function.[15] The Court held that the specification did enable someone skilled in the art to recreate the described twenty-six antibodies under 35 U.S.C. § 112(a) (the “enablement” requirement), but the specification did not adequately enable the entire genus of antibodies Amgen claimed.[16] Thus, the claim in the patent that described the genus of antibodies was invalidated as overly broad.[17]

In Baxalta, the Federal Circuit applied the Supreme Court’s Amgen reasoning to a fortuitously nearly identical fact pattern. Like Amgen, in which twenty-six specific antibodies were fully enabled by the specification, the Federal Circuit held that Baxalta’s eleven specific antibodies were fully enabled by the specification. However, also like Amgen, in which the genus of unspecified antibodies was too broad to be enabled, the Federal Circuit held that Baxalta had not described enough specifics about the genus of Factor IX activating antibodies to enable a skilled artisan to create them without “unreasonable experimentation.”[18] The circuit court spelled out its underlying reasoning stating, “Amgen made clear that § 112(a) requires inventors to enable the ‘full scope’ of the claimed invention without unreasonable experimentation.”[19]

Importantly, the Federal Circuit also spoke to the cornerstone of the patent system, providing the public with the ability to practice the invention in exchange for a limited monopoly. It stated that Baxalta’s patent was “the definition of trial and error and 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.”[20]

Baxalta serves as a reminder that no inventor is owed a patent right for creativity and ingenuity. Instead, the holding in Baxalta reaffirms how central the public tradeoff in the patent system remains to the courts. Because Baxalta’s patent did not provide the public precise information on how to use the invention, the broad genus of its claimed antibodies was invalidated. Why? Without truly giving the public the benefit of the invention, Baxalta had not held up its end of the patent bargain. At that juncture, the government’s role in providing limited monopoly protection for Baxalta ceased, and Baxalta was returned to its pre-patent, pre-protective state for the unspecified genus of antibodies.

            Overall, the ruling in Baxalta makes it clear that the Federal Circuit will be applying the Supreme Court’s new “unreasonable experimentation” test with precision. In particular, medical researchers and drug manufacturers should proceed with caution before applying for patents—inventors must spend more time fully describing the entirety of the genus they claim or risk overly broad claims that may be denied or invalidated.


[1] See Daniel Kazhdan, Beyond Patents: The Supreme Court’s Evolving Relationship With the Federal Circuit, 94 J. Pat. & Trademark Off. Soc’y 275 (2013)

[2] Baxalta Inc. v. Genentech, Inc., 81 F.4th 1362, 1363 (Fed. Cir. 2023).

[3] Id.

[4] Id. Enzymes have two states: inactive and active. Once an enzyme is activated, it can perform its biological function.

[5] See id.

[6] Id.

[7] Id. at 1363–64.

[8] Id. at 1364.

[9] Id.

[10] Id.

[11] Id.

[12] Id.

[13] See generally Amgen Inc. v. Sanofi, 598 U.S. 594 (2023).

[14] Id. at 603.

[15] Id. at 615.

[16] Id.

[17] Id.

[18] Baxalta Inc. v. Genentech, Inc., 81 F.4th 1362, 1367 (Fed. Cir. 2023).

[19] Id.

[20] Id.