Kaken Pharmaceutical Co., Ltd. v. Iancu
952 F.3d 1346
Fed. Cir.2020Background
- The ’506 patent claims a topical method to treat onychomycosis (nail fungal infection) using efinaconazole (KP‑103), emphasizing the invention’s ability to penetrate and be retained in the nail plate.
- Acrux petitioned for inter partes review of claims 1–2, arguing obviousness over combinations of prior art; the PTAB found all claims unpatentable for obviousness and construed “treating a subject having onychomycosis” broadly to include infections of skin or visible mucosa around the nail.
- Kaken (patent owner) argued the claim phrase should be limited to treatment of infections where they primarily reside—i.e., within or under the keratinized nail plate (and underlying nail bed), because the patent stresses nail‑plate penetration.
- The prosecution history shows Kaken distinguished prior art by arguing onychomycosis specifically affects the nail plate and that the invention unexpectedly penetrates and is retained by the nail; the examiner withdrew a double‑patenting rejection and noted nail‑plate penetration in allowing the claims.
- The Federal Circuit reviewed claim construction de novo, held the Board’s construction unreasonable in light of the specification and prosecution history, reversed the construction, vacated the Board’s obviousness decision, and remanded for further proceedings.
Issues
| Issue | Kaken's Argument | Director/Board's Argument | Held |
|---|---|---|---|
| Proper construction of “treating a subject having onychomycosis” | Term requires treating infection inside the nail plate or in the nail bed beneath it (nail‑plate penetration is central) | Specification’s definitions of “nail” and “superficial mycosis” support a broader reading that includes skin or mucosa around the nail | Reversed: reasonable construction limits onychomycosis to treatment that penetrates the nail plate to treat infection inside the plate or underlying nail bed |
| Role of specification vs. definitions that include surrounding skin | The patent’s statements about required permeability/retention in the nail plate and the invention’s purpose support the nail‑penetration limitation | Board relied on express definitions (nail includes surrounding structures; superficial mycosis lies in skin) to allow treatment of surrounding skin alone | Court held the specification’s purpose and linked passages do not compel the Board’s broad reading; they support Kaken’s narrower construction |
| Weight of prosecution history and examiner statements | Kaken argued and relied on prosecution statements distinguishing prior art by emphasizing nail‑plate penetration; those statements bind claim scope | Board discounted those limitations, construing claims broadly | Court found prosecution statements decisive: applicant’s arguments and examiner’s withdrawal of rejection show claims require nail‑plate penetration; claim construction reversed |
| Effect on PTAB obviousness decision | Kaken argued Board’s obviousness findings depended on the erroneous broad construction and should be overturned or remanded | Board applied its broad construction and found motivation to combine prior art; it discounted objective indicia (e.g., Jublia®) as lacking nexus | Court vacated the obviousness decision and remanded because the Board’s analysis materially relied on the erroneous construction; did not decide obviousness on the merits |
Key Cases Cited
- Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831 (2015) (claim construction reviewed de novo with subsidiary factual findings reviewed for substantial evidence)
- Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (specification and prosecution history inform claim meaning)
- Standard Oil Co. v. American Cyanamid Co., 774 F.2d 448 (Fed. Cir. 1985) (applicant arguments to examiner can limit claim scope)
- In re Power Integrations, Inc., 884 F.3d 1370 (Fed. Cir. 2018) (patent purpose can inform claim construction under broadest reasonable interpretation)
- Microsoft Corp. v. Proxyconn, Inc., 789 F.3d 1292 (Fed. Cir. 2015) (prosecution history informs broadest‑reasonable‑interpretation analysis)
- Arista Networks, Inc. v. Cisco Sys., Inc., 908 F.3d 792 (Fed. Cir. 2018) (vacatur and remand appropriate where PTAB claim construction is reversed)
- Dell Inc. v. Acceleron, LLC, 818 F.3d 1293 (Fed. Cir. 2016) (same)