CAFC Addresses Written Description of Biological Inventions in Amgen v Sanofi

The Federal Circuit has again made it harder to establish written description of biotechnological inventions, particularly when attempting to claim an invention using functional language.

Biotechnological agents having similar functional characteristics often have very different chemical structures.  For this reason, biotechnological inventions are often claimed according functional characteristics.  One class of inventions that is frequently claimed in this manner is antibodies.  In the case of antibodies, the USPTO has long held that antibodies may be claimed based on the ability to bind to a recited antigen so long as the antigen is “well-characterized” by the specification, a test known as the “antibody exception.”  Although the CAFC has referred to this principle in previous cases, it has never explicitly endorsed or analyzed it.

In Amgen v. Sanofi, Docket No. 2017-1480 (Fed. Cir. Oct. 5, 2017) the CAFC considered a suit over monoclonal antibodies useful in the treatment of high cholesterol.  The patentee, Amgen, discovered that antibodies that block association between a protein PCSK-9 and an LDL receptor are useful for treating patients with high cholesterol.  Amgen obtained a patent claiming “[a]n isolated monoclonal antibody, wherein, when bound to PCSK9, the monoclonal antibody binds to [a specified epitope] . . . .”  The patent discloses that Amgen characterized 85 antibodies that blocked interaction between the PCSK9 and the LDLR.  The trial court instructed the jury that, with respect to these claims:

[written description] may also be satisfied by the disclosure of a newly characterized antigen by its structure, formula, chemical name, or physical properties if you find that the level of skill and knowledge in the art of antibodies at the time of filing was such that production of antibodies against such an antigen was conventional or routine.

The CAFC held that this instruction was improper.

The court’s principal criticism of the jury instruction was that it conflates an adequate written description with the ability to make and use the invention (i.e. the enablement requirement).  As explained by the Court:

We cannot say that this particular context, involving a “newly characterized antigen” and a functional genus claim to corresponding antibodies, is one in which the underlying science establishes that a finding of “make and use” (routine or conventional production) actually does equate to the required description of the claimed products.  For us to draw such a conclusion, and transform a factual issue into a legally required inference, we would have to declare a contested scientific proposition to be so settled as to be entitled to judicial notice.


Because the scientific premise behind the “newly characterized antigen” test stated in the instruction in this case was neither “generally known” nor “accurately and readily” ascertainable, we cannot take judicial notice of the premise and displace the required fact finding with what amounts to a rule of law.

Amgen, slip op. at 16-18.  The court further argued that “[the antibody exception] allows patentees to claim antibodies by describing something that is not the invention . . . [and] thus contradicts the statutory ‘quid pro quo’ of the patent system where ‘one describes an invention, and, if the law’s other requirements are met, one obtains a patent.’”

It is important to note that the Federal Circuit did not find that the claims lacked written description. It is therefore theoretically possible to still claim antibodies according to their functional characteristics. However, it is clear that at least this panel of the court believed that a well-characterized antigen is not sufficient to describe a genus of antibodies.  Unfortunately, the court did not state what facts would be sufficient to claim a genus of antibodies based on binding specificity.  Clearly, this case could have implications for a number of different biotechnological inventions, including therapeutic and diagnostic antibodies.  It therefore will become even more important in the future to include sufficient description of methods of making such inventions and methods of using such inventions, such that the antigen is a more tangible component of the invention.


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