Last updated: September 24, 2026
Aragon Pharmaceuticals, Inc. v. Eugia Pharma Specialities Limited, No. 1:22-cv-00688, was a Hatch-Waxman patent action in the U.S. District Court for the District of Delaware concerning generic apalutamide tablets, the active ingredient in Janssen’s Erleada. Aragon sued after Eugia filed an abbreviated new drug application containing a Paragraph IV certification against U.S. Patent No. 9,266,951. The case did not produce a reported merits decision on patent validity or infringement. The principal commercial issue was whether Eugia could launch generic apalutamide before the patent’s expected 2027 expiration date.
What drug and patent were at issue in Aragon Pharmaceuticals v. Eugia?
The litigation involved apalutamide, an androgen-receptor inhibitor marketed as Erleada.
| Item |
Detail |
| Brand drug |
Erleada |
| Active ingredient |
Apalutamide |
| Dosage form |
Oral tablets |
| Brand sponsor |
Janssen Research & Development, LLC / Johnson & Johnson |
| Patent plaintiff |
Aragon Pharmaceuticals, Inc. |
| Generic applicant |
Eugia Pharma Specialities Limited |
| Court |
U.S. District Court for the District of Delaware |
| Case number |
1:22-cv-00688 |
| Filing date |
May 26, 2022 |
| Litigation type |
Hatch-Waxman patent infringement action |
| Primary patent |
U.S. Patent No. 9,266,951 |
| Patent expiration |
August 2027, subject to applicable patent-term calculations |
| Regulatory pathway |
ANDA with Paragraph IV certification |
The asserted patent is part of Aragon’s androgen-receptor-modulator patent estate. The patent covers apalutamide-related pharmaceutical subject matter and supported Erleada’s protection in the generic approval process.[1]
What patent did Aragon assert against Eugia?
Aragon asserted U.S. Patent No. 9,266,951, titled “Androgen Receptor Modulators and Methods of Use Thereof.” The patent issued in February 2016 and claims subject matter directed to androgen-receptor modulators, including apalutamide-related compounds and their therapeutic use.
The patent’s expected expiration is in August 2027. That date was commercially important because Erleada’s principal small-molecule patent protection extended beyond the end of the product’s five-year new chemical entity exclusivity period.
U.S. Patent No. 9,266,951
| Patent attribute |
Detail |
| Patent number |
9,266,951 |
| Title |
Androgen Receptor Modulators and Methods of Use Thereof |
| Assignee history |
Aragon Pharmaceuticals, Inc. and related successors |
| Issue date |
February 23, 2016 |
| Relevant product |
Apalutamide / Erleada |
| Expected expiration |
August 2027 |
| Litigation role |
Asserted against Eugia’s ANDA |
| Patent type |
Active pharmaceutical ingredient and therapeutic-use protection |
The case record should be distinguished from broader Erleada patent listings. A product may have multiple Orange Book patents, but a particular ANDA case depends on the patents specifically asserted against the applicant.
Why did Aragon sue Eugia?
Eugia’s ANDA included a Paragraph IV certification stating that the asserted patent was invalid, unenforceable, or would not be infringed by the proposed generic product. Under the Hatch-Waxman Act, that certification gave Aragon a statutory basis to bring an infringement action under 35 U.S.C. § 271(e)(2).
Aragon’s complaint sought the standard relief available in a Paragraph IV case:
- A declaration that Eugia’s proposed generic apalutamide would infringe the asserted patent.
- An order preventing FDA approval of the ANDA until patent protection expired.
- A 30-month regulatory stay under 21 U.S.C. § 355(j)(5)(B)(iii).
- Costs and other relief available under the patent laws.
The lawsuit did not require Eugia to have launched a product. Hatch-Waxman litigation is triggered by the ANDA certification itself.
What was the FDA and Orange Book status of Erleada?
The FDA approved Erleada in February 2018 for patients with nonmetastatic castration-resistant prostate cancer. The FDA later expanded the indication to metastatic castration-sensitive prostate cancer in combination with androgen-deprivation therapy.[2]
Erleada received five years of new chemical entity exclusivity. That exclusivity ended in February 2023, allowing ANDA applicants to pursue approval subject to listed-patent challenges and any applicable regulatory stay.
Erleada exclusivity timeline
| Milestone |
Date |
| FDA approval for nonmetastatic CRPC |
February 2018 |
| Five-year NCE exclusivity |
Through approximately February 2023 |
| Aragon v. Eugia filed |
May 26, 2022 |
| Expected expiration of asserted patent |
August 2027 |
| Earliest ordinary post-patent generic entry |
After patent expiry, absent settlement or successful challenge |
The Orange Book listing of U.S. Patent No. 9,266,951 created the basis for the Paragraph IV dispute. FDA approval of Eugia’s ANDA would have been subject to the statutory stay and the outcome or resolution of the litigation.[3]
How did the 30-month stay affect Eugia’s generic launch?
Aragon’s timely infringement action triggered the Hatch-Waxman 30-month stay, which generally prevents FDA approval of the challenged ANDA for 30 months from the date the patent holder received notice of the Paragraph IV certification, unless the court resolves the case earlier.
The stay does not automatically prevent a generic company from preparing its product, manufacturing commercial inventory, or pursuing approval-related activities. It primarily delays FDA approval. A generic launch before patent expiration would require one of the following:
- A successful invalidity or noninfringement judgment.
- A settlement permitting an earlier launch.
- A statutory or judicial termination of the stay.
- A later court decision that removes the patent-based approval barrier.
The case therefore created a regulatory delay risk for Eugia rather than an absolute prohibition on product development.
What was the litigation status and outcome?
Aragon Pharmaceuticals v. Eugia was a Delaware Hatch-Waxman case and did not result in a publicly reported trial judgment establishing that the asserted patent was valid, infringed, or enforceable.
The public case record does not establish a merits ruling that would invalidate U.S. Patent No. 9,266,951 across the market. Any termination by dismissal or resolution must be treated separately from a judgment following claim construction, summary judgment, or trial.
Litigation posture
| Issue |
Assessment |
| Paragraph IV case |
Yes |
| Preliminary injunction |
No publicly reported merits injunction |
| Claim construction ruling |
No reported final construction affecting market-wide rights |
| Summary judgment |
No publicly reported final merits judgment |
| Trial verdict |
None publicly reported |
| Patent invalidated |
No |
| Patent held infringed |
No reported final merits holding |
| Settlement terms |
Not publicly disclosed in the case record |
| Generic launch date |
Not established by the public docket |
A dismissal without prejudice or pursuant to a settlement would not constitute a judicial determination that the patent was valid or invalid. It also would not, by itself, establish the date on which Eugia could launch.
Was there a Paragraph IV settlement?
The public record does not disclose commercially complete settlement terms for the Aragon-Eugia dispute. In pharmaceutical patent cases, settlement agreements often include:
- A licensed entry date before patent expiration.
- An authorized-generic arrangement.
- A royalty or supply provision.
- Restrictions on formulation, indication, or manufacturing source.
- A covenant not to sue.
- Confidential business terms.
Without a public settlement agreement or court order describing the launch date, the case cannot be used to establish that Eugia received a specific early-entry right.
The absence of a reported merits opinion indicates that the litigation did not generate a judicial precedent resolving the validity or scope of the asserted apalutamide patent.
How strong was Aragon’s patent position?
Aragon’s position was commercially meaningful because the asserted patent covered the branded product and extended several years beyond FDA’s NCE exclusivity period. The principal strengths were:
- The patent was listed in the Orange Book for Erleada.
- The patent had an expected term through 2027.
- The ANDA challenge occurred before patent expiration.
- A timely infringement action could delay FDA approval.
- The patent was part of the originating innovator’s apalutamide development program.
The principal risks were equally clear:
- A Paragraph IV challenge placed validity and infringement directly at issue.
- The asserted claims could face written-description, enablement, obviousness, or claim-construction attacks.
- The strength of the case depended on Eugia’s proposed product and the precise ANDA certification.
- A settlement could reduce the practical value of the remaining patent term.
- A successful challenge by one ANDA filer could weaken the barrier for other generic applicants.
Because the case ended without a public merits decision, the docket does not support assigning a court-tested probability of validity or infringement.
What generic entry risks existed for Erleada?
The main risk was a coordinated wave of ANDA filings after the February 2023 end of NCE exclusivity. Once the NCE exclusivity period ended, generic applicants could seek FDA approval by challenging the remaining Orange Book patents.
Generic launch scenarios
| Scenario |
Commercial effect |
| Patent upheld through 2027 |
No ordinary full generic approval based on the challenged patent before expiry |
| Eugia wins on invalidity |
Potential approval and launch before 2027, subject to other listed patents |
| Eugia wins on noninfringement |
Same potential, subject to remaining patent barriers |
| Settlement with licensed entry |
Launch occurs on the negotiated date |
| Settlement with patent expiry entry |
Generic launch remains delayed until the agreed or statutory date |
| Authorized generic launch |
Brand owner may reduce price erosion before independent generic entry |
| Multiple generic approvals after expiry |
Rapid price erosion and share loss are likely |
The most important analytical point is that the case concerned one filer and one asserted patent. It did not eliminate the possibility of separate litigation involving other ANDA applicants or other Erleada patents.
Are biosimilars relevant to apalutamide?
No. Apalutamide is a chemically synthesized small molecule, not a biologic. The relevant competitive pathway is the ANDA process for generic drugs, not the biosimilar pathway under the Public Health Service Act.
The relevant risks are:
- Paragraph IV patent challenges.
- 30-month FDA approval stays.
- ANDA approval timing.
- Authorized-generic competition.
- Formulation and manufacturing differences.
- Potential settlement-based launch dates.
Biosimilar interchangeability, reference-product exclusivity under the biologics statute, and patent dance procedures do not apply to Erleada.
What manufacturing and formulation barriers could remain?
A generic applicant must demonstrate pharmaceutical equivalence and bioequivalence for its apalutamide product. Manufacturing barriers may include:
- Control of apalutamide particle characteristics.
- Tablet dissolution and bioavailability.
- Stability and impurity control.
- Scale-up and process validation.
- Consistency of the active pharmaceutical ingredient.
- Compliance with FDA manufacturing requirements.
These barriers are regulatory and technical. They do not necessarily create independent patent protection. A formulation or process patent would need to be separately listed, asserted, or otherwise enforceable against the proposed product.
For this case, the publicly reported dispute centered on the listed patent identified in the Paragraph IV action. The record does not establish a separate adjudicated formulation or manufacturing patent barrier.
How does Aragon v. Eugia compare with other Erleada patent risks?
| Category |
Aragon v. Eugia |
Broader Erleada risk |
| Product |
Apalutamide tablets |
Same |
| Legal pathway |
Hatch-Waxman |
Hatch-Waxman |
| Challenged patent |
U.S. 9,266,951 |
May include additional listed patents |
| Plaintiff |
Aragon Pharmaceuticals |
Aragon/Janssen-related entities |
| Defendant |
Eugia |
Other ANDA applicants may file separately |
| Public merits ruling |
None reported |
Must be assessed case by case |
| Biosimilar exposure |
None |
None |
| Key launch variable |
Case resolution and patent term |
Full Orange Book and settlement landscape |
A single dismissal or settlement does not resolve all potential Erleada patent disputes. Each ANDA applicant may present different invalidity, noninfringement, or formulation arguments.
What was the commercial exposure for Johnson & Johnson?
Erleada is a prostate-cancer product in Johnson & Johnson’s oncology and urology portfolio. Generic entry would expose the product to the standard small-molecule erosion pattern:
- Price reductions after generic approval.
- Rapid substitution in pharmacy channels.
- Payer pressure before patent expiry.
- Loss of share to multiple ANDA-approved products.
- Reduced net sales even if branded demand remains stable.
The precise revenue exposure from this case cannot be separated from the broader Erleada patent estate without a disclosed settlement, launch date, and product-level sales forecast. The case nevertheless represented a direct challenge to the period between NCE exclusivity expiry in 2023 and the expected expiration of the asserted patent in 2027.
Key Takeaways
- Aragon sued Eugia in Delaware after Eugia filed a Paragraph IV ANDA challenge for generic apalutamide.
- The principal asserted patent was U.S. Patent No. 9,266,951.
- The patent was expected to remain in force through August 2027.
- Erleada’s five-year NCE exclusivity ended in approximately February 2023.
- The case did not produce a publicly reported merits judgment invalidating or enforcing the patent.
- Publicly undisclosed settlement terms prevent confirmation of any specific Eugia launch date.
- Apalutamide faces generic, not biosimilar, competition.
- The commercial outcome depends on the full Orange Book listing, other ANDA litigations, settlement terms, and the final FDA approval path.
FAQs
When can generic apalutamide enter the U.S. market?
Generic apalutamide may enter after all applicable patents and regulatory stays are resolved, or earlier if an applicant wins its Paragraph IV litigation or obtains a negotiated license.
Does dismissal of the Eugia case invalidate Erleada’s patent?
No. A dismissal is not equivalent to a judgment that the patent is invalid or not infringed.
Is U.S. Patent No. 9,266,951 the only patent protecting Erleada?
Not necessarily. Erleada’s regulatory and commercial protection must be assessed against the complete FDA Orange Book listing and any unlisted or non-Orange-Book patent rights.
Can Eugia launch generic apalutamide before August 2027?
Only if it is permitted by a settlement, obtains a favorable patent ruling, or avoids other enforceable patent barriers. The public case record does not establish a confirmed early-launch date.
Does this case create a biosimilar threat to Erleada?
No. Apalutamide is a small-molecule drug. The relevant threat is ANDA-based generic entry.
References
- U.S. Patent No. 9,266,951, “Androgen Receptor Modulators and Methods of Use Thereof,” issued Feb. 23, 2016.
- U.S. Food and Drug Administration. (2018). FDA approves apalutamide for non-metastatic castration-resistant prostate cancer.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- Aragon Pharmaceuticals, Inc. v. Eugia Pharma Specialities Limited, No. 1:22-cv-00688, U.S. District Court for the District of Delaware.
- Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j); 35 U.S.C. § 271(e)(2).
