Is the genus claim dead, or has its demise been greatly exaggerated? We may soon have the Supreme Court’s answer. On April 18, following eight years of patent infringement litigation between Amgen and Sanofi, including two trials and two Federal Circuit appeals, the Supreme Court called for the views of the Solicitor General (“SG”) on Amgen’s petition for a writ of certiorari after the Federal Circuit invalidated its asserted patent claims for failing to satisfy the enablement requirement. See Amgen Inc. v. Sanofi, 987 F. 3d 1080 (Fed. Cir. 2021). The subject patents are directed to a genus of antibodies defined not by their structure (e.g., amino acid sequence) but by their function—specifically, the ability of the antibodies to bind certain parts of the PCSK9 antigen. Although these antibodies are not per se immunotherapeutic—PCSK9 is a target for treating high cholesterol and does not implicate immune system modulation—the Supreme Court’s resolution of the enablement questions presented will certainly have consequences for patenting protein immunotherapies, particularly antibodies, where claims are frequently drawn to genus-type claims with limitations to binding of immunoregulatory antigen targets.

The issue for the Supreme Court’s review if certiorari is granted is the standard for assessing enablement for broadly drafted claims to a functionally defined genus covering potentially many thousands (if not millions) of compositions when only a relatively few working embodiments are disclosed in the specification. Amgen’s petition argues that the Federal Circuit’s enablement legal framework for claims of this sort is wrong insofar as it “requires that the specification allow skilled artisans ‘to reach the full scope of claimed embodiments’—i.e., to cumulatively identify and make all or nearly all possible variations of the invention—without ‘substantial time and effort.’” Amgen Pet. at 2 (quoting Amgen, 987 F. 3d at 1088). In Amgen’s view, the error in applying this “special test” for genus claims is compounded by longstanding Federal Circuit case law holding that enablement is a question of law to be decided without deference, despite earlier Supreme Court precedent cited by Amgen that it is a question of fact to be determined by the jury. Id. at 1-2, 6. The effect of the Federal Circuit’s allegedly erroneous interpretation of § 112(a) is, according to Amgen, “devastating, particularly for critical biotech and pharmaceutical innovations” because “significant breakthroughs [in these industries] often involve identifying the mechanism for producing a desired effect and making a working embodiment… [where the] mechanism… may have the same effect when implemented in any number of structurally similar compounds.” Id. at 3, 29-30.

Sanofi countered in its opposition by characterizing Amgen’s “full scope” complaint as a “cumbersome formulation” that was “nothing more than a request for factbound error correction dressed up as a supposed legal dispute” that does not merit the Court’s review. Sanofi Opp. at 29. Moreover, Sanofi argued that the “full scope” requirement for enablement is grounded in the statute and is consistent with Supreme Court precedent for broadly claimed inventions. Id. at 30-31. As for the “question of law” versus “question of fact” conflict raised in the petition, Sanofi pointed to Supreme Court precedent that while there are frequently underlying factual inquiries, the “ultimate question of patent validity”—including enablement—“is one of law.” Id. at 14-16. Furthermore, Sanofi asserted that the law/fact distinction was not in urgent need of review, having been embedded in Federal Circuit precedent for nearly 40 years and challenged (unsuccessfully) only a handful of times. Finally, a “full scope” enablement requirement would not have profound effects on innovation; according to Sanofi, the Federal Circuit did not foreclose all genus claims—“[g]enus claims, to any type of invention, when properly supported, are alive and well.” Id. at 34 (quoting Court of Appeals Order Denying Rehearing En Banc). “Companies will simply ‘have to be more careful about crafting their patents.’” Id.

The call for the SG’s views is a reasonable indication that the Court believes the case could raise important issues concerning the Federal Circuit’s enablement jurisprudence that is potentially worthy of review on the merits. The Supreme Court generally relies on the opinion of the SG (as the so-called “Tenth Justice”) at the certiorari stage in determining whether to issue a writ, so what the SG does in the coming months—on average the SG files its brief four to five months after the Court’s invitation—will be closely watched. In addition to the involvement of the SG, other factors that can bear on the Court’s decision to grant certiorari are also worth considering: the number of amicus briefs filed, any dissents issued below, and whether the Federal Circuit heard the case en banc. The three amicus briefs filed were all in support of Amgen’s petition and included seven different companies in the pharmaceutical and life sciences space. One of the amicus briefs was filed by Mark Lemley of Stanford Law School on behalf of a group of intellectual property law professors. Professor Lemley is a thought leader in the field and the co-author of The Death of the Genus Claim, 35 Harv. J.L. & Tech. 1 (2021), a law review article heavily cited in Amgen’s petition. On the other hand, there were no dissents issued and the Federal Circuit declined to review the case en banc.

Interestingly, nearly identical issues of enablement of functionally defined genus claims were the subject of a cert petition filed by Idenix Pharmaceuticals after its loss on appeal in Idenix Pharmaceuticals LLC v. Gilead Sciences Inc., 941 F. 3d 1149 (Fed. Cir. 2019). That petition was also supported by three amicus briefs—including one from Amgen—and there was a dissent below from Judge Newman (but no en banc hearing). The petition was denied by the Court in January 2021. The composition of the Court has not changed in the intervening year, but something may have caught the Court’s eye in the Amgen petition which convinced them to consider the views of the SG on the subject. It is likely therefore that the SG’s opinion will carry great weight as a bellwether of how the Court will rule.