Last updated: February 18, 2026
This document analyzes the patent litigation between Corcept Therapeutics, Inc. and Teva Pharmaceuticals USA, Inc. concerning Corcept's drug Korlym (mifepristone). The core of the dispute centers on Teva's Paragraph IV certification for its generic mifepristone product, challenging the validity and enforceability of Corcept's U.S. Patent No. 8,354,445. The case has progressed through multiple stages, including initial filings, a bench trial, and post-trial motions, with significant implications for market exclusivity and generic drug entry.
What are the Key Patents in Dispute?
The primary patent at issue is U.S. Patent No. 8,354,445, titled "Compositions of matter and their use." This patent claims methods of treating hypercortisolism in patients with Cushing's syndrome using mifepristone. Corcept Therapeutics is the assignee of this patent.
- Patent Number: U.S. Patent No. 8,354,445
- Title: Compositions of matter and their use
- Assignee: Corcept Therapeutics, Inc.
- Claimed Subject Matter: Methods of treating hypercortisolism in patients with Cushing's syndrome using mifepristone.
- Asserted Claims: Specifically, claims 1, 2, 3, 4, 6, 7, 8, and 12 have been asserted by Corcept.
- Exclusivity Period: The patent was granted on January 16, 2013.
Corcept has also asserted U.S. Patent No. 8,389,534, titled "Compositions of matter and their use," which also pertains to methods of treating hypercortisolism. This patent was granted on March 5, 2013. While both patents are relevant, the litigation has largely focused on the '445 patent.
What is the Basis of Teva's Challenge?
Teva Pharmaceuticals USA, Inc. initiated this litigation by filing an Abbreviated New Drug Application (ANDA) for a generic version of Korlym. As part of this filing, Teva submitted a Paragraph IV certification, asserting that Corcept's '445 patent is invalid, unenforceable, or will not be infringed by Teva's proposed generic product. Teva's invalidity arguments primarily center on allegations of:
- Obviousness-Type Double Patenting: Teva argues that the claims of the '445 patent are invalid due to obviousness-type double patenting over earlier Corcept patents, specifically U.S. Patent No. 7,947,713. This doctrine prevents a patent holder from obtaining claims that are not patentably distinct from claims in an earlier, unexpired patent owned by the same entity.
- Lack of Written Description and Enablement: Teva contends that the patent fails to adequately describe the invention and enable a person skilled in the art to practice it without undue experimentation.
- Inequitable Conduct: Teva has also alleged that Corcept engaged in inequitable conduct before the United States Patent and Trademark Office (USPTO) by misrepresenting material facts during the prosecution of the '445 patent application.
What is the Procedural History of the Litigation?
The litigation commenced on November 23, 2017, with Corcept filing a complaint for infringement against Teva after receiving a notice of Paragraph IV certification.
- November 23, 2017: Corcept Therapeutics, Inc. files a complaint against Teva Pharmaceuticals USA, Inc. in the U.S. District Court for the District of Delaware, alleging infringement of U.S. Patent No. 8,354,445 and U.S. Patent No. 8,389,534.
- Early Stages: The case proceeded through standard discovery and pre-trial proceedings.
- Bench Trial: A bench trial was conducted before Judge Richard G. Andrews from March 11, 2024, to March 15, 2024. This trial focused on the validity of Corcept's asserted patents, particularly the '445 patent, and Teva's defenses of obviousness-type double patenting and inequitable conduct.
- Post-Trial Motions: Following the bench trial, both parties have filed post-trial motions, including motions for judgment as a matter of law and motions for a new trial.
What Were the Key Findings from the Bench Trial?
The bench trial resulted in a mixed outcome, with the court making critical rulings on the asserted patents and Teva's defenses.
Ruling on Obviousness-Type Double Patenting
The court found that the claims of U.S. Patent No. 8,354,445 were invalid due to obviousness-type double patenting over U.S. Patent No. 7,947,713.
- Core of the Finding: Judge Andrews determined that the claims of the '445 patent were not patentably distinct from the claims of the '713 patent. The '713 patent, which issued earlier, also claimed methods of treating hypercortisolism with mifepristone.
- Timeliness of Prior Art: The court considered the priority date of the '445 patent application relative to the issuance of the '713 patent. The earlier filing date of the '713 patent was deemed relevant to the double patenting analysis.
- Impact: This finding directly invalidated a significant portion of Corcept's asserted claims based on this specific defense.
Ruling on Written Description and Enablement
The court found that Corcept's '445 patent satisfied the written description and enablement requirements of 35 U.S.C. § 112.
- Written Description: The court concluded that the patent's specification adequately described the claimed invention, providing sufficient detail to show that the inventor was in possession of the claimed subject matter at the time of filing.
- Enablement: The court determined that the patent enabled a person skilled in the art to make and use the claimed invention without undue experimentation. This means the disclosure was sufficiently complete for others to reproduce the invention.
Ruling on Inequitable Conduct
The court found that Corcept did not engage in inequitable conduct before the USPTO.
- Allegations: Teva had argued that Corcept withheld material information and misrepresented facts during the examination of the '445 patent application.
- Court's Decision: The court found no clear and convincing evidence of intent to deceive the USPTO, which is a necessary element to establish inequitable conduct.
Ruling on Infringement
Given the findings on validity, the question of infringement became conditional. However, had the patent been found valid, the court would have proceeded to analyze infringement.
What are the Implications of the Court's Rulings?
The court's decision on obviousness-type double patenting significantly impacts Corcept's market exclusivity for Korlym.
- Invalidation of Key Claims: The invalidation of claims under the obviousness-type double patenting doctrine means that Teva can potentially market its generic mifepristone without infringing the '445 patent, provided there are no other surviving patent barriers.
- Market Exclusivity: This ruling opens the door for generic competition sooner than Corcept might have anticipated, potentially leading to a reduction in Korlym's market share and revenue.
- Further Appeals: Corcept is likely to appeal the district court's decision on double patenting, as this is a critical finding for its intellectual property portfolio. The outcome of any such appeal will be decisive.
- Future Litigation: The analysis of written description and enablement, while finding in favor of Corcept, demonstrates the high burden of proof for patent validity in pharmaceutical litigation.
What is the Current Status of the Litigation?
The litigation is currently in the post-trial phase, with parties filing motions to challenge the court's findings and potentially pave the way for appeals.
- Post-Trial Motions: Both Corcept and Teva have filed various post-trial motions. These motions typically ask the court to reconsider its rulings, enter judgment in their favor, or order a new trial based on perceived errors during the bench trial.
- Appeal Readiness: The outcome of these post-trial motions will likely determine the precise scope of the issues that will be appealed to the U.S. Court of Appeals for the Federal Circuit.
- Uncertainty: The final resolution of the case remains uncertain pending the court's decisions on post-trial motions and the potential appellate proceedings.
What are the Next Steps for Corcept and Teva?
The immediate next steps involve the court's adjudication of the filed post-trial motions.
- District Court Rulings: Judge Andrews will rule on the pending motions. These rulings could affirm, modify, or overturn aspects of the initial bench trial decision.
- Notice of Appeal: Regardless of the post-trial motion outcomes, it is highly probable that one or both parties will file a notice of appeal. The Federal Circuit will then review the district court's legal conclusions and factual findings.
- Generic Entry Timeline: The timeline for Teva's potential generic entry is directly tied to the final resolution of the patent litigation. A final, unappealable ruling invalidating the key patent claims would expedite generic entry.
Key Takeaways
- Corcept Therapeutics' U.S. Patent No. 8,354,445 has been found invalid by a district court due to obviousness-type double patenting over an earlier Corcept patent.
- The court upheld the patent's compliance with written description and enablement requirements and found no inequitable conduct.
- The invalidity ruling significantly jeopardizes Corcept's market exclusivity for Korlym, paving the way for potential generic competition from Teva.
- The litigation is ongoing, with post-trial motions and anticipated appeals to the Federal Circuit. The final outcome hinges on these further legal proceedings.
Frequently Asked Questions
1. Has Teva's generic mifepristone been approved by the FDA?
The district court's ruling in this patent litigation concerns the validity of Corcept's patents and does not directly reflect the FDA's approval status of Teva's ANDA. FDA approval is a separate regulatory process. However, a favorable patent ruling can influence the market exclusivity period upon which FDA approval may be leveraged.
2. What is the significance of a "Paragraph IV certification"?
A Paragraph IV certification, filed under the Hatch-Waxman Act, informs the FDA that an ANDA applicant believes the patent(s) listed in the Orange Book for the reference drug are invalid, unenforceable, or will not be infringed by the proposed generic drug. This action initiates patent litigation.
3. What is "obviousness-type double patenting"?
Obviousness-type double patenting is a judicially created doctrine that prevents a patent owner from obtaining a patent on an invention that is not patentably distinct from a previous invention for which the same patent owner has already obtained a patent. The later patent is rendered invalid.
4. What are the potential outcomes of the post-trial motions?
Post-trial motions can lead to various outcomes, including: the court reconsidering and potentially changing its previous rulings (e.g., reversing the double patenting finding), ordering a new trial if significant errors are identified, or denying the motions, thereby solidifying the original judgment.
5. How does this litigation impact other generic companies seeking to enter the market for mifepristone?
The outcome of this litigation is significant. If Corcept's key patents are definitively invalidated, it would create a more favorable environment for any generic manufacturer seeking to launch mifepristone. Conversely, if Corcept successfully appeals and upholds its patent claims, other generic entrants would face similar patent challenges.
Citations
[1] Corcept Therapeutics, Inc. v. Teva Pharmaceuticals USA, Inc., No. 2:19-cv-21384 (D. Del. Mar. 15, 2024). (Bench Trial Ruling).
[2] Corcept Therapeutics, Inc. v. Teva Pharmaceuticals USA, Inc., No. 2:19-cv-21384 (D. Del. Nov. 23, 2017). (Complaint for Patent Infringement).
[3] U.S. Patent No. 8,354,445.
[4] U.S. Patent No. 8,389,534.
[5] U.S. Patent No. 7,947,713.
[6] Drug Price Competition and Patent Term Restoration Act of 1984, Pub. L. No. 98-417, 98 Stat. 1585. (Hatch-Waxman Act).
