DCT

2:25-cv-08609

Ionis Pharma Inc v. Arrowhead Pharma Inc

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Key Events
Amended Complaint
complaint Intelligence

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:25-cv-08609, C.D. Cal., 10/01/2026
  • Venue Allegations: Venue is asserted in the Central District of California on the basis that Defendant resides in the district, maintains a regular and established place of business there, and a substantial part of the events giving rise to the claims occurred in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s forthcoming drug, plozasiran, for treating familial chylomicronemia syndrome (FCS) will infringe a patent related to methods of treating lipoprotein lipase deficiency (LPLD) by inhibiting the ApoCIII protein.
  • Technical Context: The technology lies in the field of RNA-targeted therapeutics, specifically those designed to treat rare genetic metabolic disorders characterized by severely elevated triglyceride levels.
  • Key Procedural History: The complaint alleges that the patent-in-suit is listed in the FDA's Orange Book for Plaintiff’s approved drug, Tryngolza®, for the same indication targeted by Defendant. The complaint also references a pre-suit notice letter sent to Defendant and a subsequent, allegedly improper, anticipatory Declaratory Judgment action filed by Defendant in the District of Delaware. A second count in the complaint seeks to correct the inventorship of the patent-in-suit to add Dr. Daniel Gaudet.

Case Timeline

Date Event
2013-02-14 ’333 Patent Priority Date
2014 Ionis's research on volanesorsen published in New England Journal of Medicine
2017-03-14 U.S. Patent No. 9,593,333 Issued
2018-12 Arrowhead announces clinical trials for its ApoCIII inhibitor for FCS
2024-12 Ionis's drug Tryngolza® (olezarsen) approved and launched in the U.S. for FCS
2025-01-17 Arrowhead's New Drug Application for plozasiran accepted by FDA
2025-09-03 Ionis sends letter to Arrowhead alleging future infringement of the ’333 Patent
2025-09-10 Arrowhead files Declaratory Judgment action against Ionis in Delaware
2025-11-18 Expected FDA decision (PDUFA) date for plozasiran
2026-10-01 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,593,333 - "Modulation of apolipoprotein C-III (ApoCIII) expression in lipoprotein lipase deficient (LPLD) populations"

  • Patent Identification: U.S. Patent No. 9,593,333 (“the ’333 Patent”), “Modulation of apolipoprotein C-III (ApoCIII) expression in lipoprotein lipase deficient (LPLD) populations,” issued March 14, 2017. Compl. ¶4 Compl. ¶40

The Invention Explained

  • Problem Addressed: The patent addresses the treatment of individuals with lipoprotein lipase deficiency (LPLD), a rare genetic condition also known as familial chylomicronemia syndrome (FCS) ’333 Patent, col. 5:5-9 Compl. ¶22 These patients lack functionally active lipoprotein lipase (LPL), an enzyme critical for breaking down triglycerides (TGs), leading to severely elevated TG levels and risk of life-threatening pancreatitis (Compl. ¶¶1; Compl. ¶18). Conventional wisdom suggested that inhibiting apolipoprotein C-III (ApoCIII)—a protein that itself inhibits LPL—would be ineffective in patients who already lack functional LPL ’333 Patent, col. 5:1-4 Compl. ¶¶5-6 Compl. ¶23
  • The Patented Solution: The invention is a method for treating LPLD by administering an inhibitor of ApoCIII ’333 Patent, abstract The inventors discovered, contrary to expectations, that reducing ApoCIII production in LPL-deficient patients leads to a significant reduction in triglyceride levels ’333 Patent, col. 5:1-4 Compl. ¶6 The patent describes using an antisense oligonucleotide to target and reduce ApoCIII mRNA, thereby preventing the protein from being made and unexpectedly lowering TG levels even in the absence of functional LPL ’333 Patent, abstract ’333 Patent, col. 6:3-10
  • Technical Importance: This discovery provided the first viable pharmacological treatment paradigm for LPLD/FCS, a severe condition for which other lipid-lowering therapies were ineffective and whose only management option was an extremely restrictive diet (Compl. ¶¶6; Compl. ¶15; Compl. ¶22).

Key Claims at a Glance

  • The complaint asserts independent claim 1, along with dependent claims 2-7, 9, 10, 14, 15, 18, and 20-23 Compl. ¶47
  • Independent claim 1 is broken down as follows:
    • A method of treating or ameliorating lipoprotein lipase deficiency (LPLD) in an animal
    • comprising administering a therapeutically effective amount of a compound comprising an ApoCIII specific inhibitor to the animal,
    • wherein: administering the compound reduces a triglyceride level by at least 10%, thereby treating or ameliorating LPLD.
  • The complaint states that infringement will be alleged for the listed claims, but does not foreclose assertion of other claims ’333 Patent, claim 1 Compl. ¶¶47-48

III. The Accused Instrumentality

Product Identification

  • The accused instrumentality is plozasiran, an investigational drug developed by Arrowhead Compl. ¶9

Functionality and Market Context

  • Plozasiran is described as an "investigational RNA interference (RNAi) therapeutic" and a type of "small-interfering RNA ("siRNA")" Compl. ¶¶52 Compl. ¶55
  • Its function is to inhibit the synthesis of ApoCIII, thereby acting as an ApoCIII-specific inhibitor (Compl. ¶52).
  • Arrowhead is seeking FDA approval to market plozasiran for the treatment of familial chylomicronemia syndrome (FCS), the same patient population as that covered by the ’333 Patent Compl. ¶50 The complaint alleges that data from Arrowhead's Phase 3 clinical trial showed that plozasiran achieved an 80% median reduction in triglycerides from baseline Compl. ¶54
  • The complaint characterizes plozasiran as a "copycat product" intended to compete directly with Ionis's approved FCS treatment, Tryngolza® Compl. ¶¶7 Compl. ¶10

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

  • Claim Chart Summary: The complaint alleges that the intended and approved use of plozasiran will infringe at least claim 1 of the ’333 Patent.

’333 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of treating or ameliorating lipoprotein lipase deficiency (LPLD) in an animal Arrowhead is seeking FDA approval to market plozasiran for the treatment of familial chylomicronemia syndrome (FCS), which is another name for LPLD. Its labeling, once approved, will allegedly instruct physicians to use it for this purpose. ¶50; ¶51 col. 19:60-64
comprising administering a therapeutically effective amount of a compound comprising an ApoCIII specific inhibitor to the animal, Plozasiran is an RNAi therapeutic designed to reduce the production of ApoCIII, thus functioning as an ApoCIII-specific inhibitor. Arrowhead's proposed labeling will allegedly direct administration of a therapeutically effective amount. ¶52; ¶53; ¶55 col. 7:62-68
wherein: administering the compound reduces a triglyceride level by at least 10%, thereby treating or ameliorating LPLD. Arrowhead’s clinical trial data for plozasiran allegedly demonstrated a median triglyceride reduction of 80%. The complaint alleges that administering plozasiran per its label will reduce triglyceride levels by at least 10%. ¶54 col. 21:26-42
  • Identified Points of Contention:
    • Scope Questions: A central issue may be whether the claim term "ApoCIII specific inhibitor" (from claim 1) and "antisense compound" (from dependent claim 3, also asserted) can be construed to cover plozasiran. The complaint alleges plozasiran is an siRNA-based RNAi therapeutic Compl. ¶¶52 Compl. ¶55 The court will have to determine if these terms, as defined and used in the ’333 Patent, are broad enough in scope to read on siRNA technology, especially given that the patent's own examples are based on a single-stranded antisense oligonucleotide.
    • Technical Questions: While both Ionis's disclosed antisense oligonucleotide and Arrowhead's siRNA target ApoCIII mRNA, they operate through different biological mechanisms (e.g., RNase H-mediated cleavage vs. RISC-mediated cleavage). This raises the question of whether the patent's specification provides sufficient written description and enablement to support a claim scope covering both modalities.

V. Key Claim Terms for Construction

  • The Term: "ApoCIII specific inhibitor"

    • Context and Importance: This term in independent claim 1 defines the therapeutic agent. Its construction is critical because the accused product, plozasiran, is an siRNA, and the parties will likely dispute whether it falls within the scope of this term as understood in the context of the ’333 Patent.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification provides a broad definition: "any agent capable of specifically inhibiting the expression of ApoCIII mRNA and/or the expression or activity of ApoCIII protein at the molecular level." It further lists "nucleic acids (including antisense compounds), peptides, antibodies, small molecules, and other agents" as examples (’333 Patent, col. 7:62-68). This language may support a construction covering a wide range of modalities, including siRNAs.
      • Evidence for a Narrower Interpretation: The detailed description and examples in the patent are focused exclusively on a specific type of antisense oligonucleotide (a 5-10-5 MOE gapmer) ’333 Patent, col. 38:55-69:3 A party may argue that the invention is limited to the technology actually invented and disclosed, and that the broad definitional language is not commensurate with the scope of the actual disclosure.

  • The Term: "antisense compound"

    • Context and Importance: Dependent claim 3, which the complaint asserts, narrows the inhibitor to an "antisense compound." The complaint alleges plozasiran is an "antisense compound" Compl. ¶56 Therefore, the construction of this term is fundamental to the infringement analysis of claim 3.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent specification defines "Antisense compound" to include "single-stranded and double-stranded compounds, such as, antisense oligonucleotides, siRNAs, shRNAs, ssRNAi and occupancy-based compounds" ’333 Patent, col. 7:31-39 The explicit inclusion of "siRNAs" provides strong intrinsic evidence for a construction that covers plozasiran.
      • Evidence for a Narrower Interpretation: A party might argue that despite the explicit mention of siRNAs in the definition, the specification lacks any working examples, technical details, or data related to siRNAs, potentially raising issues of written description and enablement for that modality under the "antisense compound" umbrella.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced infringement under § 271(b) and contributory infringement under § 271(c) Compl. ¶¶10-11 Inducement is based on the allegation that Arrowhead's future product labeling will actively instruct physicians and patients to use plozasiran in an infringing manner—specifically, to treat FCS/LPLD Compl. ¶¶51 Compl. ¶60 Contributory infringement is based on the allegation that plozasiran has no substantial non-infringing use Compl. ¶61
  • Willful Infringement: The complaint alleges willful infringement based on pre- and post-suit knowledge. Pre-suit knowledge is alleged from Arrowhead's citation of Ionis's scientific publication (which disclosed the pending patent), the listing of the ’333 Patent in the FDA's Orange Book for a competing drug, Arrowhead's own securities filings acknowledging third-party patent risks, and a direct notice letter sent by Ionis Compl. ¶¶30-32 Compl. ¶37 Post-suit knowledge is based on the filing of the complaint itself Compl. ¶58

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of definitional scope: can the term "antisense compound," as used in the ’333 Patent, be construed to cover plozasiran, an siRNA-based therapeutic? While the patent’s glossary explicitly includes siRNAs, the specification’s focus is exclusively on a different type of antisense technology, setting up a potential dispute over claim breadth versus the scope of the actual disclosure.
  • A second key question will relate to inventorship and standing. The complaint includes a count to correct the inventorship of the ’333 Patent. The outcome of this claim could affect ownership rights and Ionis’s standing to enforce the patent, making it a pivotal procedural and substantive issue for the court to resolve.
  • A third issue is one of intent and knowledge for the claims of indirect and willful infringement. The court will need to evaluate the evidence presented by Ionis—including Arrowhead's awareness of Ionis's scientific publications, the Orange Book listing, and its own securities filings—to determine whether Arrowhead possessed the requisite knowledge and specific intent to encourage infringement.