Key Takeaways: Recent Federal Circuit decision draws a meaningful distinction between patents that claim a broad genus as the invention itself and those that claim a novel therapeutic method using a well‑known genus, signaling that method‑of‑use claims tied to specific treatments may face a narrower written‑description and enablement burden.
Three years after Amgen Inc. v. Sanofi[1], courts continue to sort out its impact. Recent decisions reveal a developing pattern: courts applying Amgen to invalidate claims directed to a broad functionally defined genus of compounds where the specification allegedly discloses only a fraction of what is claimed (Seagen v. Daiichi Sankyo[2]; OssiFi-Mab v. Amgen[3]; Brita v. ITC[4]), while simultaneously drawing a meaningful boundary that protects claims directed to a novel application of a well-known genus of compounds (Teva v. Lilly5[5]). The takeaway is that Amgen is a context-sensitive doctrine where the difference between surviving and failing may turn on whether the genus is claimed as the invention, or merely serves as a well-known input used to achieve a specific downstream therapeutic result. The court in Teva v. Lilly held that when the underlying genus is well-known, isolating specific working embodiments for a targeted treatment may be considered a routine exercise akin to “extra credit,” rather than a “research assignment”
requiring undue experimentation.[6] It thus appears that when a patent claims a novel method of using a well-known genus, the required scope
of enablement is narrower than what Amgen may suggest.
For IP counsel in the life sciences, this evolving body of case law has at least two implications. First, for portfolios containing broad composition-of-matter claims, recent decisions highlight the potential risk of defining antibodies, ADCs, or biologics primarily by what they do rather than what they are. Seagen and OssiFi-Mab demonstrate that even commercially successful, FDA-approved products cannot insulate a patent if a court determines that the specification leaves skilled artisans to perform trial-and-error discovery across the full claimed scope, making proactive portfolio audits against the Wands factors an important consideration. Second, the Teva v. Lilly decision, if it is not reversed, delivers an actionable drafting and enforcement signal: claims framed as novel methods of using a well-known genus for a distinct therapeutic purpose may have lower enablement and written-description thresholds than broad composition claims directed to a novel genus of compounds, potentially providing an easier path to securing and enforcing patent protection for key biotech innovations.
Editor: Brenden S. Gingrich, Ph.D.
[1] Amgen Inc. v. Sanofi, 598 U.S. 594 (2023)
[2] Seagen Inc. v. Daiichi Sankyo Co., Ltd., 160 F.4th 1322 (Fed. Cir. 2025).
[3] OssiFi-Mab LLC v. Amgen Inc., No. 23-cv-10861, 2026 WL 942085 (D. Mass. Feb. 24, 2026)
[4] Brita LP v. Int’l Trade Comm’n, 156 F.4th 1326 (Fed. Cir. 2025)
[5] Teva Pharms. Int’l GmbH v. Eli Lilly & Co., — F.4th —, 2026 WL 1025802 (Fed. Cir. Apr. 16, 2026)
[6] Id. at *10
This article was reposted with permission.
Original post: April 20, 2026
