Based on the denial of rehearing and the Amgen v. Sanofi decision itself, inventors should:

1. Claim as many separate species as possible.
2. Attempt to fashion genus claims that have a limited number of members supported by several actual examples.
3. Include “prophetic” examples, including predicted modifications and perhaps variants generated using computational research and/or computer aided experiments.

Over the past decade, the U.S. Court of Appeals for the Federal Circuit (“Federal Circuit”) has issued several decisions on enablement that limit the ability of patent applicants to claim broad genera for biotech inventions such as antibodies. The Federal Circuit’s Amgen Inc. v. Sanofi decision severely limits functional limitations for antibody and other biotech claims, admittedly posing “high hurdles” and “rais[ing] the bar” for enablement of such claims. 987 F.3d 1080, 1087 (Fed. Cir. 2021). On June 21, 2021, the Federal Circuit denied rehearing en banc of this decision. See Amgen Inc. v. Sanofi, Case 20-1074 (Fed. Cir. June 21, 2021).

Although Amgen could request review by the Supreme Court, the Federal Circuit’s denial of rehearing en banc leaves the Amgen v. Sanofi decision in place for now and perhaps permanently. The decision invalidated Amgen patents describing antibodies that bind to the PCSK9 protein and lower low density lipoprotein (“LDL”) levels by blocking PCSK9 from binding to LDL receptors. The limitations of the claims are largely functional, including the identification of binding locations and the ability to block the PCSK9/LDL receptor interaction. Amgen v. Sanofi held that the enablement requirement was not satisfied by demonstrating that the method disclosed in the patent predictably worked to make antibodies that fell within the scope of the claims. See 987 F.3d at 1088. The ability to screen variants through routine methods to determine whether they met the functional limitations likewise did not enable the disclosed invention. Id. at 1087.

The Federal Circuit held that the binding and blocking limitations in the claims, standing alone, required undue experimentation because the field was unpredictable and testing was required to determine whether substitutions altered those functions. Id. at 1087. Further, the record lacked evidence that the described methods predictably generated the “full scope of the functional limitations,” and the record evidence only demonstrated that the described methods would predictably generate “a small subset of examples.” Id. at 1087-1088. The Federal Circuit determined that undisclosed, claimed embodiments would need to be discovered either by trial and error or by making structural changes to the disclosed embodiments and screening those embodiments for the claimed function. Id. at 1088. “[N]o 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.” Id. While the Federal Circuit stated that the enablement requirement does not preclude functional claims, id. at 1085, the Amgen v. Sanofi decision seems raise substantial barriers to such claims for antibodies and other biotech and pharmaceutical inventions.

The denial of en banc consideration did provide some guidance, although it is not clear how claims for biotech inventions can be written to comply with this guidance. Judge Lourie, joined by Judges Prost and Hughes, wrote separately to state that the Federal Circuit has not created a new test for enablement and noted that:

1. Actual and Prophetic Examples: Prior to the widespread claiming of biological materials as a genus, chemical genus claims were enabled by actual or constructive (prophetic) examples, the former indicated by the use of the past tense to describe the procedures and the latter described in the present tense, with starting materials and process details resulting in named compounds within the scope of the claims. Whether actual or constructive, the examples enabled the full scope of the claims. These “well-supported” generic claims do not lack enablement or written description.
2. Constructive Description: As with genus claims to chemical compounds, if genus claims to biological materials encompass more subject matter than just a few species, they need to be enabled accordingly. “Biological compositions not actually prepared need to be described constructively, if required to enable the full scope of the claims, with procedures and names of resultant compositions, as with chemical compositions.”
3. Disclosure of Sufficient Species: “Invention of a genus means to conceive and reduce to practice a reasonable number and distribution of species constituting the genus.”
4. Functional Claims: Defining a composition of matter by function raises “special problems” because it is not known whether a species is within the scope of a generic claim until it is made and tested for the claimed function. “In such cases, it is circular; enablement comes only with success, which depends upon enablement.”

Amgen Inc. v. Sanofi, Case 20-1074, at *2-3 (Fed. Cir. June 21, 2021).

The non-precedential opinion rejected the argument that the decision in Amgen v. Sanofi threatens innovation and will “devastate” the incentives to invest in drug discovery. The enablement requirement, according to the order, prevents patent applicants from “trying to control” what they have not invented. Id. at * 4. The opinion noted that Amgen had obtained separate patent protection on the PCSK9 antibody, and the failure to obtain broad (and in the Federal Circuit’s opinion, unsupported) genus claims “has not deprived it of patent protection on the fruits of its investment.” Id. Moreover, the invention of additional species not described or enabled by a first inventor, and therefore not encompassed by a properly-enabled generic claim, promotes the progress of the useful arts. And the inventor of such a new species may in any event “encounter the expensive hurdle of having to meet its own regulatory requirements, if it does not qualify for ANDA or biosimilar status.” Id. at *4-5.

The separate opinion also rejected Amgen’s request to overrule prior Federal Circuit case law holding that enablement is a question of law based on underlying factual findings.

Based on the denial of rehearing and the Amgen v. Sanofi decision itself, inventors should:

4. Claim as many separate species as possible.
5. Attempt to fashion genus claims that have a limited number of members supported by several actual examples.
6. Include “prophetic” examples, including predicted modifications and perhaps variants generated using computational research and/or computer aided experiments.