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 to LDLR.

I am confident that most chemical patent agents and attorneys would expect such a claim to fail as not enabled.  No quantity of exemplary compounds can enable the full scope of covering any small molecule.

Idenix v. Gilead

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]. 

Please see my earlier post: Idenix v. Gilead: Split CAFC Panel at Least Agrees – Valid or Not, Either Way it’s Idenix Loss – Claims Too Broad.

Recall in Idenix, all three justices– including Justice Newman – agreed that Idenix did not enable the claims with regard to the claim’s infringed elements. Justice Newman disagreed, however, with the majority’s ruling that the claims were invalid. Instead, she argued that the claims should have been ruled to be unenforceable over the infringing product rather than be draconianly ruled as invalid as a whole.  I would tend to agree with Justice Newman. Idenix should be at least able to enforce their claims on some other competing product that would be covered by the enabled embodiments. However, I would tend agree with the majority if there were a broad claim to any small molecule defined by functionality alone, without a structure. I don’t believe such a claim should be valid, if not for enablement, perhaps for insufficient written description requirement.

Idenix claimed a method for the treatment of a hepatitis C virus infection by administering an effective amount of a purine or pyrimidine β-D-2′-methyl-ribofuranosyl nucleoside or a phosphate thereof. However, none of their examples included a 2′-methyl “up” / 2’- fluoro “down” analog like Gilead’s sofosbuvir (Solvadi®). Rather, most examples showed 2′-methyl “up” / 2’- hydroxyl “down” analogs.

As Justice Gorsuch opined, “in some cases, disclosing that general quality may reliably enable a person skilled in the art to make and use all of what is claimed, not merely a subset.” Channeling SCOTUS’s preference for seeing a common-quality within the claims, the common quality for Idenix would probably have been the 2’- fluoro “down” element, and not just the broad 2′-methyl element.

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.

[ I intend to add more discussion soon. Check back. Thank you for reading! ]