U.S. Supreme Court take on Enablement
The U.S. Supreme Court’s opinion in Amgen v. Sanofi (No. 21–757, Decided May 18, 2023) was indeed a big deal. From a small molecule chemistry perspective however, I do not believe that the Amgen decision will alter chemical patent prosecution practice regarding enablement law. True, applications may need even more examples to enable small molecule genus claims. But providing enough examples to enable claims has always been a challenge. And we have been already progressively honing our strategy likewise along with the USPTO’s progressively stringent requirements. Meanwhile, patent practitioners typically do not describe small molecules in functional terms anyway.
Imagine Amgen’s claim 1 of U.S. 8,829,165 (the ’165 patent) being written for a small molecule.
1. A small molecule that binds to PCSK9, wherein the small molecule binds an epitope on PCSK9 comprising at least one of residues 237 or 238 of SEQ ID NO: 3, and wherein the small molecule blocks binding of PCSK9 t
Regarding enablement of small molecules, the law still stands from the Federal Circuit’s decision in Idenix Pharmaceuticals LLC v. Gilead Sciences Inc. (Fed. Cir. 2019); 941 F.3d 1149 (2018 WL 922125). Prior to Amgen, the U.S. Supreme Court refused to hear Idenix’s appeal. [cert. denied, 141 S. Ct. 1234 (2021) No. 20-380]. See below.
Even prior to Amgen, chemical patent practitioners have been keen to include so-called common qualities in core aspects of generic structure formulas. Skilled patent practitioners draft intermediate and narrow sub-generic formulas for embodiments in case broad generic formulas are challenged. Such intermediate formulas often surround a preferred set of species. The preferred set of species often have a common quality that may make them more active or stable than other series of compounds. Seek out your favorite medicinal chemist. They can explain it better than I can.
Examples
For example, a patent application may include a generic formula that recites the broad term “aromatic group.” Meanwhile, the patent application should also include backup provisions such as a sub-generic formula that narrows the term “aromatic” to “heteroaromatic.” Furthermore, the application should include an even narrower backup embodiment wherein the “heterocyclic group can be a specific heterocycle such as pyridine, pyrimidine or pyrazine. The scope of the generic formula would be guided by the compounds exemplified in the application.
In one hypothetical scenario, a claim to any aromatic group may fail if only heteroaromatic groups are shown in examples. In a further scenario, a claim to a heteroaromatic group may fail if only pyridines are exemplified. Perhaps pyrimidines or pyrazines, with two nitrogens, may have significantly different functional properties than a pyridine having only one nitrogen.
As before Amgen v. Sanofi, a greater variety of exemplary compounds provides a stronger argument for enablement.
Enablement Opinions from the U.S. Court of Appeals for the Federal Circuit
Wyeth and Cordis Corp. v. Abbott Laboratories, 2012-1223, -1224 (Fed. Cir. June 26, 2013)
“Rapamycin” method-of-treament claims are invalid for lack of enablement when only sirolimus (one such rapamycin compound) is disclosed.
CAFC affirmed the district court’s grant of summary judgment in favor of the defendants, holding method of treatment claims invalid under 35 U.S.C. § 112(a) (2012) as not being enabled for their full scope.
- Abbott sells vascular stents coated with everolimus and zotarolimus, which are analogs of sirolimus.
- Wyeth’s patents claim methods of treatment using rapamycin.
- Rapamycin can be refered to as a single compound, sirolimus, or a class of compounds.
- Wyeth’s patents only disclose sirolimus. Wyeth appears to use the term rapamycin as refering only to sirolimus and not any other analogs.
- When Abbott began selling stents with sirloimus analogs, everolimus and zotarolimus, Wyeth then pivoted arguing that its patent claims meant rapamycin as a class, rather than rapamycin as a compound (i.e., sirolimius).
- The District Court and the CAFC agreed that Wyeth only enabled sirolimus and did not enable any other analog of sirolimus such as everolimus and zotarolimus.
- The CAFC took their reasoning further stating that enabling rapamycin ─ as a whole class of compounds ─ would require synthesising and testing every possible analog of sirolimus.
Idenix Pharmaceuticals LLC v. Gilead Sciences Inc. (Fed. Cir. 2019); 941 F.3d 1149 (2018 WL 922125)
Idenix’s sued Gilead claiming Gilead’s sofosbuvir (Solvadi®) HCV treatment would infringe U.S. Patent No. 7,608,597, directed to methods for treating hepatitis C virus (HCV). CAFC Panel Split: Chief Judge Prost and Circuit Judges Wallach agreed that Idenix’s ‘597 patent claims were not enabled. Circuit Judge Newman dissented, arguing that the ‘597 patent, although having overly broad claims, was still valid. However, while still valid, the claims should be interpreted narrowly, allowing Gilead to avoid liability anyway.
Claim 1. A method for the treatment of a hepatitis C virus infection, comprising administering an effective amount of a purine or pyrimidine β-D-2′-methyl-ribofuranosyl nucleoside or a phosphate thereof, or a pharmaceutically acceptable salt or ester thereof.
The CAFC opinion illustrates the structure of the purine or pyrimidine β-D-2′-methyl-ribofuranosyl nucleoside as disclosed in the ‘759 patent:
Idenix’s patent does not disclose sofosbuvir. But the claims generically cover sofubir as a “purine or pyrimidine β-D-2′-methyl-ribofuranosyl nucleoside or a phosphate thereof.” As illustrated a β-D-2′-methyl-ribofuranosyl nucleoside has a methyl group in the
“up” configuration. The opinion asserted that the claims were not enabled because “Claim 1 requires more than just an identification of 2′-methyl-up: it requires identification of which 2′-methyl-up nucleosides will effectively treat HCV” and that “[w]ithout specific guidance on that point, the specification provides “only a starting point, a direction for further research,” citing ALZA Corp. v. Andrx Pharm., LLC, 03 F.3d 935, 941 (Fed. Cir. 2010).
