Michael D. Hammer, PhD, Patent Attorney


The underlying basis for the patent right is a simple quid pro quo: in exchange for a detailed description of a claimed invention, including how to make and use it, an inventor can receive a time-limited, exclusive right to practice that invention. Critics may argue that patents stifle innovation, but the goal is exactly the opposite – to incentivize disclosure and increase the dissemination of new ideas for societal benefit. In the United States, this goal is enshrined in the constitutional authorization that creates a patent system to “promote the progress of science and useful arts.” From an inventor’s perspective, a basic question naturally arises from this idealized exchange: “How much information do I need to give to live up to my side of the bargain?” Recently, the US Court of Appeals for the Federal Circuit issued a decision in the ongoing dispute between Amgen Inc. and Sanofi (Amgen v. Sanofi (Amgen), CAFC February 11, 2021), which helps to answer this question. 

Amgen involved antibodies for reducing blood levels of LDL cholesterol.  LDL cholesterol is removed from the blood by binding to the cellular LDL receptor (LDLR).  LDLRs are not constant in the body, and their presence is reduced following interaction with the protein PCSK9.  To prevent this interaction, Amgen developed antibodies that bind to PCSK9, and block its binding to LDLR. Amgen filed a patent application that described, in abundant detail, the development of these antibodies, and even provided protein crystal structures that precisely show the points of molecular interaction between the developed antibodies and PCSK9.  This patent application matured into several patents.  For example, US 8,168,762 claims antibodies that bind to PCSK9 which are defined by the amino acid sequences of the antibodies.  In contrast, in US 8,829,165 and US 8,859,741 the claimed antibodies are defined not by what they are (structure), but what they do (function).  In the current case, a lower court invalidated these functionally-defined antibody claims, holding that the description of the claimed invention was not sufficient to enable the full scope of the claims.  On appeal, the Federal Circuit agreed.

The Federal Circuit evaluated whether the challenged patents provided sufficient enabling disclosure under the typical standard: examining whether the patent provided enough description so that one of skill could produce antibodies within the full scope of the claims without undue experimentation.  The court emphasized that while a patentee does not need to show every possibility encompassed by a claim; if there is a range, then there must be reasonable enablement of the scope of that range. For the current case, this meant a requirement for the specification to describe enough antibodies that have the claimed functionality. The court noted that under this standard, a critical question becomes the number of possible antibodies that could fulfil the claimed function, not the structures that are shown to fulfil it.  If hundreds of thousands or even millions of species are possible, then the enablement bar will likely be nearly impossible to reach regardless of the degree of detail in the patent application. In affirming that the claims are invalid, the court stated a position that every patent attorney and inventor would do well to remember: “The functional limitations here are broad, the disclosed examples and guidance are narrow, and no reasonable jury could conclude under these facts that anything but ‘substantial time and effort’ would be required to reach the full scope of claimed embodiments.”

Amgen might be viewed as strictly a biotech case, but I think it is a more generally applicable expression of legal requirements and public policy than it may appear at first sight.  On the most practical level, Amgen is a reminder and a renewal of the basic principle that broad claims must be supported by equally broad disclosure. Moreover, a claim that seeks a monopoly to a functionally-defined structure must have enough supporting disclosure to enable all of the structures that can provide the defined function.  As a legal standard, this is not an absolute bar against functionally-defined claims, which remain available, given a sufficiently small range and a sufficiently robust disclosure.  

However, as an indication of policy, the court is clearly stating a preference: to fulfil her part of the bargain, an inventor must match the disclosure to the claimed property right. According to this view, the quid pro quo nearly becomes a one-to-one exchange.  While seemingly restrictive, this view is in reality quite advantageous to both sides.  For the public, it increases the incentive for an inventor to disclose – and could lead to greater disclosure in order to obtain a broader property right. For inventors, it will surely lead to patent claims being less open to challenge for lack of sufficient description, which is certainly something to be happy about.

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