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Enablement Enigma: The Supreme Court Weighs In

Christopher Lacenere, Ph.D.

Christopher Lacenere, Ph.D. | Partner View more articles

Christopher is a member of our Patent Practice Group

In a unanimous decision, the Supreme Court has affirmed the lower court’s ruling that Amgen’s broad genus claims to cholesterol-lowering antibodies are invalid for lack of enablement.

Around the mid-2000’s, pharmaceutical companies began to look for antibodies to block a protein called PCSK9. PCSK9 binds to and degrades LDL receptors, which extract LDL cholesterol (so-called “bad cholesterol”) from the bloodstream. Thus, by blocking PCSK9, more LDL receptors are present to remove bad cholesterol.

In 2015, Sanofi gained FDA approval for its anti-PCSK9 antibody Praluent and, shortly thereafter, Amgen gained FDA approval for its own anti-PCSK9 antibody, Repatha. Each drug is a distinct antibody with its own unique amino acid sequence.

In 2011, Amgen obtained a patent for Repatha, and Sanofi received a patent for Praluent, each company claiming the relevant antibody by its amino acid sequence. However, the dispute in this case related to two patents that Amgen subsequently obtained in 2014, U.S. Patent No. 8,829,165 (the ’165 Patent) and U.S. Patent No. 8,859,741 (the ’741 Patent). The challenged claims of these patents broadly claimed a genus of antibodies that (1) bind to specific amino acid residues on PCSK9, and (2) block PCSK9 from binding to LDL receptors. Thus, the claims attempted to cover an entire genus of antibodies not by what “they are” (sequence or structure, for example), but by what “they do” (bind PCSK9 and block PCSK9 from binding LDL).

“Genus claims,” rather than covering a specific molecule or therapeutic compound, cover a group of molecules or therapeutic compounds. Genus claims are extremely important to patent holders as they provide protection against competitors that would make small, trivial changes to a claimed compound in order to avoid infringement.

Sanofi challenged the validity of Amgen’s genus claims, asserting that the ’165 Patent and the ’741 Patent did not enable such broad claims. 35 U.S.C. § 112(a) sets forth the requirement for enablement, namely that a patent “shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same.” Moreover, the Court of Appeals for the Federal Circuit has made clear that, to satisfy the enablement requirement, a person skilled in the art must be able practice the invention without undue experimentation.

The ’165 and ’741 Patents disclose the amino acid sequences of 26 antibodies that perform the two claimed functions of the genus claims. Beyond this, only two methods for making other antibodies that perform the claimed binding and blocking functions were disclosed.

The first method was called “the roadmap,” which generally directs scientists to (1) generate a range of antibodies in the lab; (2) test those antibodies to determine whether any bind to PCSK9; (3) test those antibodies that bind to PCSK9 to determine whether any bind to the sweet spot described in the claims; and (4) test those antibodies that bind to the sweet spot to determine whether any block PCSK9 from binding to LDL receptors.

The second method, “conservative substitution,” requires scientists to (1) start with an antibody known to perform the described functions; (2) replace select amino acids in the antibody with other amino acids known to have similar properties; and (3) test the resulting antibody to see if it also performs the described functions.

The Supreme Court, however, found that these two approaches amounted to little more than “research assignments,” given the unpredictability of the art. Although the Court did not close the door on such broad genus claims, e.g., if each species of the genus shares a “quality common,” such a quality common was not apparent here.

What are the practical implications of this opinion? First, it is essential to include as many working examples as possible in a patent application, especially in the chemical and biological arts. Broad generalizations, in the absence of theoretical rationale or experimental evidence, are unlikely to suffice in enabling claims to a broad genus of compounds, and narrower claims may need to be pursued. Second, claims should contain structural elements and should not rely on functional language, as did Amgen’s claims. Although structural claims may be narrower, they are also more likely to meet the enablement requirement.

As the Court emphasized, the more that a party claims, the more that it must enable.

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