Amgen Inc. v. Sanofi (2023): Patent Law Parameters

Background/Facts of the Case

Amgen Inc. v Sanofi examines the Patent Act, clarifying how the enablement clause applies to broad scientific patents. In this ruling, the Supreme Court asked whether Amgen Inc.’s antibody patents provided sufficient detail so that a “skilled artisan” could “make and use” the antibodies.

In 2011, Amgen Inc. and rival pharmaceutical company Sanofi each obtained patents for immune system proteins known as antibodies. Each company’s antibodies reduce the concentration of a chemical compound known as LDL (low-density lipoprotein) in our bloodstream. If left unchecked, LDL accumulates and causes heart disease. Our cells normally remove that LDL for us in order to balance our cholesterol levels. However, a protein known as PCSK9 can prevent our cells from extracting LDL, increasing the risk for stroke. To restore proper cholesterol levels, both Amgen and Sanofi designed their antibodies to attack PCSK9.

When it filed its 2011 patent, Amgen claimed the rights to 26 antibodies.  However, the company filed another patent in 2014 insisting that it owned all antibodies that block PCSK9. To substantiate this declaration, Amgen referenced two methods which would allow scientists to derive all PCSK9 antibodies from the original 26. The roadmap method instructed scientists to simply create new antibodies and test if they inhibit PCSK9. The second method, conservative substitution, directed researchers to add molecules to known antibodies and test the new combination. With these methods, Amgen attempted to establish a monopoly on PCSK9-inhibiting antibodies. Under its 2014 patent, Amgen sued its rival Sanofi for patent infringement for antibodies developed back in 2011.

Sanofi contested the lawsuit under 35 U.S. Code § 112, the enablement clause, which requires patent-holders to use “clear, concise, and exact terms as to enable any person skilled in the art…to make and use the invention.” As Amgen’s methods were so general that they could incorporate virtually any antibody into their patent, Sanofi asserted that its rival failed to meet the enablement clause’s conditions. 

The district court agreed with Sanofi, and Amgen appealed to the Court of Appeals for the Federal Circuit. The Federal Circuit Court, unlike typical circuit courts, can rule on major patent law violations. The court’s specialization in patent law creates consistent national precedent on these claims. Using this knowledge and experience, the Federal Circuit Court also sided with Sanofi, so Amgen appealed to the Supreme Court.


The Supreme Court sided with Sanofi, affirming that under the enablement clause “the specification must enable the full scope of the invention as defined by its claims.” In other words, if Amgen avows that it has authority over all antibodies for PCSK9, it must include explicit instructions on how to make each antibody. Amgen’s methods merely recounted the scientific method in order to substantiate the company’s claim, providing insufficient description of all the antibodies. 

To inform its decision, the Supreme Court cited historical patent law cases, including O’Reilly v. Morse and The Incandescent Lamp Patent. In both examples, the plaintiff made a broad claim that encompassed all similar inventions. The Court denied those lawsuits’ validity because “the broader the monopoly it demands, the more it must enable.” If a patent asserts ownership over an entire class of inventions, it must describe every unit in that class. 

However, the Supreme Court recognizes that a scientist need not specify each individual detail in order to obtain a patent. Rather, one way to account for an entire class of antibodies is to identify a distinguishing characteristic common to the antibodies. In particular, the inventor should enumerate “some general quality running through the class that gives it a peculiar fitness for the particular purpose.” To satisfy this condition, that identifying characteristic must be part of an antibody’s composition, not its function; otherwise, the company would not be able to prove that it invented the class. Amgen failed to name such a feature and was only able to cite its antibodies’ common function: disabling the PCSK9 protein and lowering cholesterol. As a result, the Supreme Court denied Amgen’s claim over antibodies beyond the original 26.

The Supreme Court’s ruling upheld prior patent law interpretations, maintaining a traditional view on what researchers must disclose in order to corroborate their claims. The enablement clause requires inventors to provide sufficient detail about their design so that a capable researcher could replicate their process.


While the Amgen case did not catalyze a revolution in patent law, it will likely cause more scrupulous writing when future inventors file for patents on their research. In order to successfully defend their jurisdiction, patent owners must refrain from making broad claims that could jeopardize their ability to satisfy the enablement clause. If researchers believe they have grounds to claim a comprehensive patent, they must now enumerate the experimental process thoroughly to defend their invention.

Experts predict that patent-holders will defend their claims through new avenues in Amgen’s aftermath, especially with respect to whether their inventions “bear more than a passing resemblance” to the precedents cited by the Supreme Court. Future lawsuits might center on whether a class of inventions has a clear distinguishing feature and to what extent the inventor should detail the research process.

Kara Bivens is from Waxhaw, NC, studying Political Science, Statistical Science, and Spanish. 

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