Xeris Pharma Inc v. Somerset Therap LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Xeris Pharmaceuticals, Inc. (Delaware) and Strongbridge Dublin Limited (Ireland)
  • Defendant: Somerset Therapeutics, LLC, et al. (Delaware, New Jersey, India); Torrent Pharma Inc., et al. (Delaware, New Jersey, India)
  • Plaintiff's Counsel: FBT Gibbons LLP; Latham & Watkins LLP
• Case Identification: 2:26-cv-02044, D.N.J., 02/26/2026
• Venue Allegations: Venue is alleged to be proper in the District of New Jersey because the defendant entities maintain principal places of business and regular and established places of business in the district, and committed acts of infringement, including the submission of their Abbreviated New Drug Applications (ANDAs), from their New Jersey locations.
• Core Dispute: Plaintiffs allege that Defendants' proposed generic versions of the drug RECORLEV® will infringe four patents covering methods of treating Cushing's syndrome with the active ingredient levoketoconazole, particularly in patients with certain co-morbidities or co-administered medications.
• Technical Context: The technology relates to pharmaceutical methods for managing Cushing's syndrome, a serious endocrine disorder caused by excess cortisol, by using a specific, purified enantiomer of ketoconazole and managing its drug-drug interactions.
• Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendants' submissions of ANDAs seeking FDA approval to market generic levoketoconazole tablets. Plaintiffs allege the filing was made within 45 days of receiving Defendants' Paragraph IV certification notice letters, which would trigger a 30-month statutory stay on FDA approval of the ANDAs.

Case Timeline

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

U.S. Patent No. 11,020,393 - "Methods of Treating Disease With Levoketoconazole", issued June 1, 2021

The Invention Explained

• Problem Addressed: The patent background describes Cushing's disease as a rare and serious condition caused by excessive cortisol U.S. Patent 11,020,393, col. 1:10-13 It notes that ketoconazole, an existing off-label treatment, has known risks including liver toxicity and significant drug-drug interactions U.S. Patent 11,020,393, col. 1:41-47 A specific challenge arises when treating patients who are also taking other medications, such as metformin for type 2 diabetes, that are substrates for drug transporters like MATE1 and OCT2.
• The Patented Solution: The invention is a method of treatment using levoketoconazole, the 2S,4R enantiomer of ketoconazole, which is described as a more potent inhibitor of cortisol synthesis compared to the other enantiomer U.S. Patent 11,020,393, col. 1:51-60 The patented method addresses drug-drug interactions by claiming a specific protocol for treating Cushing's patients who are also being co-administered metformin. The method involves administering levoketoconazole according to a titration scheme, monitoring for specific dose-limiting events related to metformin (e.g., low vitamin B-12, abnormal kidney function), and reducing the metformin dosage if such an event occurs U.S. Patent 11,020,393, claim 1 The specification notes that co-administration of levoketoconazole can increase systemic exposure to metformin by approximately two-fold U.S. Patent 11,020,393, col. 3:10-14
• Technical Importance: This patented method provides a specific treatment protocol for managing drug-drug interactions in a complex patient population (Cushing's syndrome with comorbid type 2 diabetes), potentially enabling safer and more effective therapy.

Key Claims at a Glance

• The complaint asserts at least independent claim 1 Compl. ¶88 Compl. ¶160
• Claim 1 of the '393 Patent includes the following essential elements:
  • A method of treating persistent or recurrent Cushing's syndrome in a subject who has type 2 diabetes mellitus and is being co-administered metformin.
  • Administering a therapeutically effective amount of levoketoconazole, determined via a titration scheme.
  • During the titration, monitoring the subject for a dose-limiting event, which is defined as a decreased fasting glucose level, abnormal kidney function, and/or a low Vitamin B-12 level.
  • If the subject experiences such a dose-limiting event, reducing the amount of metformin administered to the subject.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 11,278,547 - "Methods of Treating Disease With Levoketoconazole", issued March 22, 2022

The Invention Explained

• Problem Addressed: The patent addresses the same general problem as the '393 Patent: the safe and effective treatment of Cushing's syndrome with levoketoconazole in patients with co-morbidities requiring co-administered drugs like metformin U.S. Patent 11,278,547, col. 1:10-13 U.S. Patent 11,278,547, col. 1:41-47
• The Patented Solution: The '547 Patent claims a method of treatment that is substantially similar to that of the '393 Patent, involving the titrated administration of levoketoconazole with concurrent monitoring and potential dose reduction of co-administered metformin U.S. Patent 11,278,547, claim 1 The key distinction in the asserted independent claim is the addition of a limitation that narrows the patient population to only those who have "had previous surgery or radiation to treat the subject's Cushing syndrome" U.S. Patent 11,278,547, claim 1
• Technical Importance: This invention provides method-of-use protection for a specific subgroup of the Cushing's patient population-those who have not found success with first-line treatments like surgery or radiation.

Key Claims at a Glance

• The complaint asserts at least independent claim 1 Compl. ¶106 Compl. ¶178
• Claim 1 of the '547 Patent includes the following essential elements:
  • A method of treating Cushing's syndrome in a subject who has type 2 diabetes mellitus and is being co-administered metformin.
  • The subject has had previous surgery or radiation to treat the Cushing's syndrome.
  • Administering a therapeutically effective amount of levoketoconazole, determined via a titration scheme.
  • During the titration, monitoring the subject for a dose-limiting event (defined as decreased fasting glucose, abnormal kidney function, and/or low Vitamin B-12).
  • If a dose-limiting event occurs, reducing the amount of metformin administered to the subject.
• The complaint does not explicitly reserve the right to assert dependent claims.

Multi-Patent Capsule: U.S. Patent No. 11,903,940

• Patent Identification: U.S. Patent No. 11,903,940, "Methods of Treating Disease With Levoketoconazole", issued February 20, 2024.
• Technology Synopsis: This patent claims a method for treating Cushing's syndrome in patients who are also being treated with an organic cation transporter 2 (OCT2) substrate. The method involves administering levoketoconazole via a titration scheme, monitoring for a dose-limiting event caused by increased exposure to the OCT2 substrate, and reducing the dosage of the OCT2 substrate if such an event is observed U.S. Patent 11,903,940, claim 1 This patent generalizes the drug-drug interaction management method beyond just metformin to a broader class of drugs.
• Asserted Claims: At least independent claim 1 Compl. ¶124 Compl. ¶196
• Accused Features: The complaint alleges that the proposed labels for the generic products will instruct physicians to co-administer levoketoconazole with OCT2 substrates (such as metformin), monitor for dose-limiting events, and adjust the substrate dosage, thereby directing infringement of the claimed method (Compl. ¶124; Compl. ¶125).

Multi-Patent Capsule: U.S. Patent No. 12,377,096

• Patent Identification: U.S. Patent No. 12,377,096, "Methods of Treating Disease With Levoketoconazole", issued August 5, 2025.
• Technology Synopsis: This patent claims a method similar to the '940 Patent but focuses on the co-administration of levoketoconazole with a multidrug and toxin extrusion transporter 1 (MATE1) substrate. The method requires titrating levoketoconazole, monitoring for dose-limiting events due to increased MATE1 substrate exposure, and reducing the MATE1 substrate's dosage if an event occurs U.S. Patent 12,377,096, claim 1
• Asserted Claims: At least independent claim 1 Compl. ¶142 Compl. ¶214
• Accused Features: The complaint alleges the proposed generic product labels will instruct for co-administration with MATE1 substrates (such as metformin), monitoring for related adverse events, and adjusting the MATE1 substrate dosage accordingly, thus directing infringement (Compl. ¶142; Compl. ¶143).

III. The Accused Instrumentality

Product Identification

• The accused instrumentalities are the "Somerset ANDA Product" (from ANDA No. 221137) and the "Torrent ANDA Product" (from ANDA No. 220357) Compl. ¶66 Compl. ¶76

Functionality and Market Context

• The products are identified as 150 mg oral tablets of levoketoconazole, the active ingredient in Plaintiffs' RECORLEV® product Compl. ¶66 Compl. ¶73 Compl. ¶76 Compl. ¶83 The complaint alleges that these are purported generic versions of RECORLEV® intended for the treatment of Cushing's syndrome Compl. ¶1 Compl. ¶66 The core of the infringement allegation is not the composition of the tablets themselves, but rather the methods of use that will be instructed by the proposed product labeling that will accompany the generic products upon FDA approval Compl. ¶88 Compl. ¶90 Compl. ¶106 Compl. ¶108 The complaint alleges that these labels will instruct healthcare providers to prescribe the drug in a manner that directly infringes the steps of the asserted method claims Compl. ¶89 Compl. ¶107

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

11,020,393 Patent Infringement Allegations

11,278,547 Patent Infringement Allegations

• Identified Points of Contention:
  • Label Language and Inducement: As this is an ANDA case based on induced infringement, the central dispute will likely concern whether the specific language in the Defendants' proposed product labels will be found to encourage, recommend, or promote infringement. A key question for the court will be whether the label instructs physicians to perform each and every step of the claimed methods.
  • Specificity of Monitoring: A potential point of contention may be whether the proposed labels' instructions to monitor for general "adverse events" Compl. ¶89 Compl. ¶107 satisfy the claims' requirement to monitor for a specific, defined "dose limiting event" (e.g., "decreased fasting glucose level, abnormal kidney function, and/or a low Vitamin B-12 level").
  • Specificity of Action: It raises a question whether a label's instruction to "adjust the metformin dosage accordingly" Compl. ¶89 Compl. ¶107 is sufficiently specific to meet the claim limitation requiring "reducing the amount of metformin" if a dose-limiting event occurs.
  • Patient Subgroup for the '547 Patent: For the '547 Patent, a key issue may be whether the proposed labels specifically direct use in the claimed sub-population of patients who have "had previous surgery or radiation." Defendants may argue that because the label does not explicitly single out this group, they are not inducing infringement of this narrower claim.

V. Key Claim Terms for Construction

• The Term: "titration scheme"

  • Context and Importance: This term is a core element of the administration step in all asserted patents. The definition will be critical, as the infringement allegation hinges on the Defendants' proposed labels instructing a method that constitutes a "titration scheme." Practitioners may focus on this term to dispute whether the dosing instructions on the generic labels describe the specific, iterative process contemplated by the patents.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The term is used generally in the specification to mean a process of dose adjustment to find a therapeutic effect while managing tolerability U.S. Patent 11,020,393, col. 6:6-9 This could support a construction covering any stepped-dose increase.
    • Evidence for a Narrower Interpretation: Claim 8 of the '393 Patent recites a specific titration cycle: "administering a first dose... increasing the dose by an amount equal to an incremental value of 150 mg daily; and determining whether the subject tolerates the increased dose." A defendant may argue that "titration scheme" should be limited to this or similarly detailed examples in the specification.

• The Term: "dose limiting event"

  • Context and Importance: This term triggers the monitoring and dosage-reduction steps of the claims. Its construction is central to determining whether the adverse events mentioned in the accused labels fall within the scope of the claims.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The term is explicitly defined within claim 1 of the '393 and '547 Patents as "a decreased fasting glucose level, abnormal kidney function, and/or a low Vitamin B-12 level." Plaintiffs will likely argue that any instruction to monitor for these specific outcomes, regardless of the terminology used on the label, meets this limitation.
    • Evidence for a Narrower Interpretation: The specifications of the '940 and '096 patents further specify that the event is "due to increased exposure to the OCT2 [or MATE1] substrate." Defendants may argue that a general warning of side effects on their labels does not establish this required causal link, and therefore does not instruct monitoring for the claimed "dose limiting event."

VI. Other Allegations

• Indirect Infringement: The complaint is centered on allegations of induced infringement under 35 U.S.C. § 271(b) Compl. ¶99 Compl. ¶117 Plaintiffs allege that Defendants, with knowledge of the asserted patents (e.g., from their listing in the FDA's Orange Book), will sell their generic products with labels that instruct healthcare providers and patients to perform the steps of the patented methods, thereby intending to cause infringement Compl. ¶97 Compl. ¶99 Compl. ¶115 Compl. ¶117
• Willful Infringement: The complaint does not explicitly allege "willful infringement." However, it alleges that the Defendants' filing of their ANDAs "without adequate justification" for their non-infringement and/or invalidity assertions renders the case "exceptional" under 35 U.S.C. § 285, entitling Plaintiffs to attorneys' fees Compl. ¶102 Compl. ¶120 This allegation is based on Defendants' alleged pre-suit knowledge of the patents.

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

• A central issue will be one of induced infringement: does the specific language of the Defendants' proposed generic drug labels contain instructions that are specific enough to lead a healthcare provider to perform each and every limitation of the asserted method claims, or is the guidance too general to meet the legal standard for inducement?
• A key question of claim scope will be whether general label instructions to "monitor for adverse events" and "adjust... dosage accordingly" can be mapped directly onto the patents' specific requirements to monitor for a "dose limiting event" (defined by a list of specific clinical outcomes) and to perform the responsive step of "reducing the amount" of the co-administered drug.
• For the '547 patent, the case may turn on a question of patient population targeting: does the infringement allegation require proof that the accused label specifically directs use in the narrow sub-population of patients who have "had previous surgery or radiation," and if so, does the general nature of an ANDA label satisfy that requirement?