ACADIA Pharmaceuticals v. MSN Laboratories: Pimavanserin ANDA Patent Win After 1,260 Days
ACADIA Pharmaceuticals secured final judgment against MSN Laboratories and MSN Pharmaceuticals in the Delaware District Court, defending claim 26 of US7601740 covering pimavanserin tartrate formulations. MSN’s ANDA submission was ruled an act of infringement, and its invalidity counterclaims were rejected — a full plaintiff win across 1,260 days of litigation.
ACADIA defends pimavanserin ANDA exclusivity in full Delaware trial win
ACADIA Pharmaceuticals, Inc. filed suit on 30 July 2020 in the District of Delaware against MSN Laboratories Private Limited and MSN Pharmaceuticals, Inc. (collectively MSN), asserting infringement of US Patent No. 7,601,740 and two related patents covering pimavanserin tartrate — the active ingredient in Nuplazid, ACADIA’s FDA-approved treatment for Parkinson’s disease psychosis. The trigger was MSN’s submission of Abbreviated New Drug Application (ANDA) No. 214925, a paragraph IV challenge seeking regulatory approval to market a generic equivalent before patent expiry.
After more than three years of litigation, the court entered final judgment on 11 January 2024 in favour of ACADIA on all remaining issues. The critical ruling, issued by Judge Gregory B. Williams in a Memorandum Order dated 13 December 2023, denied MSN’s Motion for Summary Judgment of Invalidity of claim 26 of the ‘740 patent on double-patenting grounds, and simultaneously granted ACADIA’s cross-motion for summary judgment of no invalidity. Final judgment was then entered under Fed. R. Civ. P. 58, confirming that MSN’s ANDA filing constituted an act of infringement under 35 U.S.C. § 271(e)(2) and rejecting MSN’s counterclaims of non-infringement and invalidity.
The case resolved through full adjudication rather than settlement, which is relatively uncommon in ANDA patent disputes and signals ACADIA’s confidence in the strength of claim 26. The double-patenting challenge — a frequently litigated invalidity theory in pharmaceutical cases — was disposed of on summary judgment, avoiding trial on that issue. Attorneys’ fees remain unresolved pending any appeal, meaning the financial terms of the dispute are not yet final. The public record does not disclose whether MSN intends to appeal.
Filing to settlement in 1260 days
1,260 days — over 3.4 years from filing to final judgment in Delaware District Court
Final judgment entered for ACADIA across infringement and invalidity claims
ANDA filing as an act of infringement under § 271(e)(2)
Under 35 U.S.C. § 271(e)(2), the submission of an ANDA containing a paragraph IV certification is deemed an act of infringement even before a generic product enters the market. This Hatch-Waxman mechanism allows branded pharmaceutical companies to seek injunctive relief pre-launch. Here, MSN’s ANDA No. 214925 was the infringing act — the court’s judgment blocks MSN from launching until the ‘740 patent expires absent a successful appeal.
Hatch-Waxman § 271(e)(2) rulingDouble-patenting challenge defeated at summary judgment
MSN argued claim 26 of the ‘740 patent was invalid for double patenting — a doctrine that prevents a patentee from obtaining two patents covering the same invention or obvious variations, potentially extending exclusivity improperly. The court rejected this on summary judgment, granting ACADIA’s cross-motion. This outcome suggests the court found claim 26 sufficiently distinct from ACADIA’s other patents to survive the challenge without a full evidentiary hearing.
Double patenting — MSN motion deniedClaim 26 of US7601740 — the pivotal claim
US7601740B2 covers pimavanserin, its tartrate salt, and crystalline forms — the formulation chemistry underlying Nuplazid. Claim 26 specifically was the focus of the invalidity and infringement dispute. The court’s ruling that this specific claim is both valid and infringed by MSN’s ANDA provides ACADIA with continued market protection for its branded formulation. The two additional patents in suit (US7732615 and US10646480) were not the focus of the final judgment narrative.
US7601740 claim 26 — valid and infringedAttorneys’ fees deferred — exceptional case motion still possible
The judgment preserves ACADIA’s right to seek attorneys’ fees under 35 U.S.C. § 285 and costs under Fed. R. Civ. P. 54, but only after any appeal is resolved. A § 285 motion requires the court to find the case ‘exceptional’ — a high bar typically met by litigation misconduct or objectively unreasonable legal positions. Whether ACADIA pursues this after appeal will be a signal of how it characterises MSN’s litigation conduct.
§ 285 exceptional case — post-appealFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | ACADIA Pharmaceuticals, Inc. | Company | CNS-focused biopharmaceutical company — holder of US7601740B2 covering pimavanserin tartrateSearch in Eureka ↗ |
| Defendant | MSN Laboratories Private Limited | Company | Indian generic pharmaceutical manufacturer and its US subsidiary, ANDA filer for pimavanserin genericSearch in Eureka ↗ |
| Plaintiff counsel | Bruce M. Wexler | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Chad J. Peterman | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Charles E. Davis | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | James Darlington Taylor , Jr. | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Jessica Marie Jones | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Scott F. Peachman | Attorney | Counsel for ACADIA Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Brent A. Batzer | Attorney | Counsel for MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Defendant counsel | James S. Green , Jr. | Attorney | Counsel for MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Defendant counsel | Shashank D. Upadhye | Attorney | Counsel for MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Defendant counsel | Yixin H. Tang | Attorney | Counsel for MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Presiding judge | Judge Gregory B. Williams | Chief Judge | Delaware District Court — Chief JudgeSearch in Eureka ↗ |
Stipulation of dismissal — official text
The final judgment is unusually comprehensive in scope: it enters judgment for ACADIA on both the affirmative infringement claim under § 271(e)(2) and against MSN on every counterclaim — non-infringement and invalidity — in a single order. This dual entry leaves MSN with no surviving legal basis to justify its ANDA. The deferral of attorneys’ fees until after any appeal is standard Hatch-Waxman practice but preserves meaningful financial exposure for MSN if the judgment is affirmed and ACADIA elects to pursue a § 285 exceptional case motion.
US7601740B2 — Pimavanserin tartrate salt and crystalline forms
US7601740B2, corrected application number US10/759561, covers N-(4-fluorobenzyl)-N-(1-methylpiperidin-4-yl)-N′-(4-(2-methylpropyloxy)phenylmethyl)carbamide — better known as pimavanserin — including its tartrate salt and distinct crystalline forms. The patent sits at the foundation of ACADIA’s Nuplazid franchise, the first FDA-approved therapy for hallucinations and delusions associated with Parkinson’s disease psychosis. As a selective serotonin 5-HT2A/2C inverse agonist, pimavanserin represents a mechanistically distinct approach to CNS psychosis treatment, avoiding dopamine pathway interference common to older antipsychotics.
The ‘740 patent’s commercial significance is substantial: Nuplazid generated hundreds of millions in annual revenue, making it a high-value generic target. The fact that ACADIA filed suit on three patents — including US10646480, filed in 2019 — signals a layered exclusivity strategy designed to maintain market protection well beyond the original ‘740 expiry. The confirmed validity of claim 26 post-litigation reinforces the durability of this estate and makes any future generic challenge more expensive and legally uncertain for ANDA filers.
Should your team run an FTO analysis against US7601740 and the pimavanserin family?
Any company developing formulations of pimavanserin, serotonin 2A/2C inverse agonists, or related piperidinyl carbamide derivatives for neurological or psychiatric indications should treat the ‘740 patent family as a live risk. This litigation has now confirmed that claim 26 is valid and enforceable, and that ACADIA will litigate aggressively to protect it. The two additional patents in suit — US7732615 and US10646480 — extend coverage across formulation and compound dimensions that a narrow FTO focused only on the ‘740 would miss.
PatSnap Eureka’s FTO Search Agent can map your compound or formulation against the full pimavanserin patent family, identify claim-level overlap, and surface prosecution history that may constrain claim scope. For pipeline teams working in CNS psychosis or neurodegenerative disease therapeutics, Eureka’s claim monitoring alerts will flag any new continuations or divisionals ACADIA files — giving you advance warning before an ANDA or IND filing triggers Hatch-Waxman exposure.
Run a freedom-to-operate analysis on US7601740B2 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA patent cases in CNS and serotonin receptor therapeutics
PatSnap Eureka tracks related litigation across truck body equipment, vehicle accessories, and comparable infringement actions in the Georgia district system.
What this case signals for the CNS generic drug IP landscape
ACADIA’s full trial win reinforces how branded pharma can use Hatch-Waxman mechanics and summary judgment to shut down generic entry.
Double-patenting challenges on CNS patents face high summary judgment risk
MSN’s failed double-patenting motion is consistent with a broader pattern where courts dispose of this invalidity theory at summary judgment when the patentee can demonstrate meaningful claim differentiation. Generic challengers in CNS-adjacent ANDA cases should expect robust cross-motions and should front-load claim differentiation analysis before filing paragraph IV certifications.
Pimavanserin’s patent estate remains formidable post-judgment
With claim 26 of the ‘740 patent validated and US10646480 (filed 2019) still in the portfolio, ACADIA’s pimavanserin exclusivity window extends well beyond the ‘740 base patent. Companies assessing generic entry timelines for Nuplazid should model around the full patent family, not just the earliest filing, since later-generation patents covering formulation and crystalline forms are now confirmed to be live.
ACADIA v MSN — key questions answered
Final judgment was entered in favour of ACADIA Pharmaceuticals on 11 January 2024. The court ruled that MSN’s ANDA No. 214925 infringed claim 26 of US7601740 under 35 U.S.C. § 271(e)(2), and rejected MSN’s counterclaims of non-infringement and invalidity in their entirety.
The primary disputed patent was US7601740B2, covering pimavanserin, its tartrate salt, and crystalline forms. Claim 26 was specifically at issue. Two further patents — US7732615B2 and US10646480B2 — were also listed in the case. The final judgment focused on the ‘740 patent.
MSN argued claim 26 of the ‘740 patent was invalid for double patenting — a doctrine that bars a patentee from securing overlapping patent protection to extend exclusivity. The court denied MSN’s motion for summary judgment on this ground and granted ACADIA’s cross-motion for summary judgment of no invalidity in a Memorandum Order dated 13 December 2023.
Under § 271(e)(2) of the Hatch-Waxman Act, the mere filing of an ANDA with a paragraph IV patent certification constitutes an act of patent infringement. This allows the branded patent holder to seek an injunction before any generic product reaches market. In this case, MSN’s ANDA No. 214925 was found to be an infringing act under this provision.
No attorneys’ fees were awarded at the time of the final judgment. The court’s order preserves the right for either party to file a fees motion under 35 U.S.C. § 285 or Fed. R. Civ. P. 54, but only within 14 days after final disposition of any appeal. The cost outcome remains unresolved as of the judgment date.
PatSnap Eureka searches patents and litigation data to answer instantly.