Last updated: February 24, 2026
Case Overview
Anacor Pharmaceuticals filed suit against Mylan Pharmaceuticals in the U.S. District Court for the District of Delaware (D. Del.), case number 1:18-cv-01699, alleging patent infringement related to the drug Kerydin (tavaborole). The lawsuit centers on claims that Mylan’s generic version infringes on Anacor’s patents protecting Kerydin, which is used to treat toenail fungus.
Patent Claims
Anacor asserts infringement of U.S. Patent Nos. 8,618,208 and 9,013,878. The patents cover tavaborole, a boron-based antifungal compound, and its methods of treatment. Key patent features:
- '208 patent: Covering the compound's structure and its method of use.
- '878 patent: Broadens protection, including formulations and treatment methods.
The patents issued in 2015 and expire in 2030, with supplemental protections.
Alleged Infringement Details
Mylan’s generic tavaborole product seeks FDA approval via abbreviated new drug application (ANDA). Anacor claims that Mylan’s product infringes the patents by:
- Using the same active ingredient (tavaborole).
- Following the same method of treatment claimed in the patents.
Anacor filed a Paragraph IV certification asserting Mylan’s product infringes patents and requested patent invalidation or non-infringement.
Litigation Timeline
- August 23, 2018: Complaint filed by Anacor alleging patent infringement.
- September 2018: Mylan responds with a Paragraph IV certification.
- October 2018: Mylan files ANDA application.
- January 2019: District Court issues a preliminary injunction hearing, but no ruling published.
- February 2019–Present: Litigation proceeds with claim construction, fact discovery, and potential trial phases.
Key Legal Issues
1. Validity of the Patents
Anacor seeks to uphold the patents amidst challenges to their validity, including allegations that the patents are obvious or lacking novelty under 35 U.S.C. §§ 102, 103. Evidence includes prior art references and patent prosecution history.
2. Infringement Claims
The core issue is whether Mylan’s generic infringes the specific claims of the '208 and '878 patents. Mylan disputes infringement, asserting non-identity of claims and potential invalidity.
3. Patent Term and Duration
The patents have a standard 20-year term from filing, with some adjustments. Mylan’s ANDA submission triggers a 30-month stay provision, delaying market entry.
Legal Outcomes and Status
As of the latest update, the case remained in pre-trial stages:
- Claim construction hearings occurred in 2020.
- No summary judgment or final ruling available.
- Court has not issued a preliminary injunction, though discussions on market entry timing continue.
Competitive Dynamics
The case influences Mylan’s entry into the antifungal marketplace. A ruling in favor of Anacor could delay generic approval, maintaining market exclusivity for Kerydin. Conversely, invalidation of patents would allow rapid entry for Mylan.
Patent Litigation Landscape Context
This case exemplifies common tactics in biologic and pharmaceutical patent disputes, where generics challenge innovator patents through Paragraph IV certifications. Litigation duration typically extends 3-4 years, with potential settlement or patent challenge proceedings.
Financial and Business Implications
- A court ruling invalidating patents would open the market for generics, significantly affecting Anacor’s sales.
- If patents withstand challenge, Anacor maintains exclusive rights and revenue streams.
- Ongoing litigation presents risks for Mylan, including potential delays and legal costs.
Key Takeaways
- The lawsuit centers on patent validity and infringement of antifungal drug Kerydin.
- Court proceedings are in early stages; no final adjudication yet.
- The outcome impacts market exclusivity for Anacor and Mylan’s entry plans.
- Patent challenges are common in this sector, often extending over several years.
- Anacor’s patent portfolio remains critical in defending its market position.
FAQs
Q1: How long does patent litigation typically last in pharmaceutical cases?
A1: Usually 3 to 4 years from filing through resolution, depending on case complexity and court schedules.
Q2: What is a Paragraph IV certification?
A2: It is a legal declaration by a generic applicant asserting that the patent it seeks to challenge is invalid, unenforceable, or not infringed by the generic product.
Q3: What are common grounds for patent invalidation?
A3: Obviousness, lack of novelty, insufficient disclosure, or prior art invalidates patents.
Q4: How does patent litigation impact drug market entry?
A4: Litigation can delay generic entry until courts resolve validity and infringement issues or settlement agreements are reached.
Q5: Can a patent be invalidated during litigation?
A5: Yes, courts can declare patents invalid if the challenger proves invalidity by clear and convincing evidence.
Citations:
[1] U.S. District Court, District of Delaware. (2018). Anacor Pharmaceuticals, Inc. v. Mylan Pharmaceuticals Inc. No. 1:18-cv-01699.
