DCT
1:24-cv-00065
Eagle Pharma Inc v. Slayback Pharma LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Eagle Pharmaceuticals, Inc. (Delaware)
- Defendant: Slayback Pharma LLC (Delaware)
- Plaintiff’s Counsel: McCarter & English, LLP (with Latham & Watkins LLP as Of Counsel)
- Case Identification: 1:24-cv-00065, D. Del., 04/22/2024
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because the defendant, Slayback Pharma LLC, is a Delaware corporation and therefore resides in the district.
- Core Dispute: Plaintiff alleges that Defendant’s VIVIMUSTA® product, a liquid bendamustine hydrochloride injection, infringes two patents related to stable, long-shelf-life liquid formulations of the drug.
- Technical Context: The technology addresses the chemical instability of bendamustine, a widely used cancer therapy, by providing ready-to-use liquid formulations that avoid the need for time-sensitive reconstitution of a lyophilized powder.
- Key Procedural History: The complaint notes that the parties have been involved in prior patent litigation concerning related patents, suggesting Defendant's awareness of Plaintiff's patent portfolio in this technology area.
Case Timeline
| Date | Event |
|---|---|
| 2010-01-28 | Earliest Priority Date for ’783 and ’214 Patents |
| 2022-12-07 | FDA grants approval for Defendant's VIVIMUSTA® NDA |
| 2023-12-19 | U.S. Patent No. 11,844,783 Issues |
| 2023-12-20 | Plaintiff sends letter to Defendant regarding '783 patent |
| 2024-01-16 | U.S. Patent No. 11,872,214 Issues |
| 2024-01-16 | Plaintiff sends letter to Defendant regarding '214 patent |
| 2024-04-22 | First Amended Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,844,783 - Formulations of Bendamustine
- Patent Identification: U.S. Patent No. 11,844,783, "Formulations of Bendamustine," issued December 19, 2023. (Compl. ¶18).
The Invention Explained
- Problem Addressed: The patent’s background describes that bendamustine exhibits rapid degradation upon reconstitution from its conventional lyophilized (freeze-dried powder) form, making it unsuitable for long-term storage in a liquid state and creating clinical inconvenience. (’783 Patent, col. 1:50-65).
- The Patented Solution: The invention provides a long-term, storage-stable liquid bendamustine composition by using a specific pharmaceutically acceptable fluid, such as polyethylene glycol (PEG) and/or propylene glycol (PG), combined with a stabilizing amount of an antioxidant. (’783 Patent, Abstract; col. 3:1-5). This creates a "ready to use" formulation that avoids the instability and handling challenges of reconstitution. (’783 Patent, col. 1:63-65).
- Technical Importance: This approach provides a significant clinical advantage by improving the stability and ease of use for an important chemotherapy agent. (’783 Patent, col. 1:63-65).
Key Claims at a Glance
- The complaint asserts infringement of at least Claim 1. (Compl. ¶46).
- The essential elements of independent Claim 1, a method claim, are:
- Providing a liquid bendamustine-containing composition with a specific concentration (20-60 mg/mL) and impurity profile (less than 5% after 15 months).
- The composition includes a "pharmaceutically acceptable fluid consisting of" polyethylene glycol and other optional solvents like ethanol.
- The composition also includes "a stabilizing amount of an antioxidant."
- The method concludes with the steps of "diluting" the composition and "intravenously administering" it to a human to treat leukemia. (Compl. ¶19).
U.S. Patent No. 11,872,214 - Formulations of Bendamustine
- Patent Identification: U.S. Patent No. 11,872,214, "Formulations of Bendamustine," issued January 16, 2024. (Compl. ¶22).
The Invention Explained
- Problem Addressed: The ’214 Patent addresses the same technical problem as the ’783 Patent: the rapid degradation of bendamustine in liquid solutions, which has historically necessitated the use of inconvenient lyophilized powder formulations. (’214 Patent, col. 1:50-65).
- The Patented Solution: The invention claims the stable liquid formulation itself, packaged in a sterile vial. The solution uses a specific fluid containing polyethylene glycol and an antioxidant to achieve long-term stability, with total impurities remaining below 5% after at least 15 months of storage. (’214 Patent, Abstract; col. 3:1-5).
- Technical Importance: This patented product provides a commercially valuable, ready-to-use alternative to the traditional powder form of bendamustine, enhancing safety and efficiency in clinical settings. (’214 Patent, col. 1:63-65).
Key Claims at a Glance
- The complaint asserts infringement of at least Claim 1. (Compl. ¶57).
- The essential elements of independent Claim 1, a product claim, are:
- A sterile vial containing a liquid bendamustine-containing composition.
- The composition contains about 100 mg of bendamustine at a concentration from about 25 mg/mL.
- The composition includes a "pharmaceutically acceptable fluid consisting of" polyethylene glycol and other optional solvents.
- The composition also includes "a stabilizing amount of antioxidant."
- The composition meets a stability requirement where total impurities are less than 5% after at least 15 months of storage. (Compl. ¶23).
III. The Accused Instrumentality
Product Identification
- The accused product is Slayback Pharma LLC's VIVIMUSTA® (bendamustine hydrochloride injection), supplied at a concentration of 100 mg/4 mL (25 mg/mL). (Compl. ¶3).
Functionality and Market Context
- VIVIMUSTA® is a liquid, injectable formulation of the chemotherapy drug bendamustine hydrochloride. (Compl. ¶3). The complaint alleges that VIVIMUSTA®’s Approved Labeling identifies its key components as bendamustine hydrochloride (25 mg/mL), polyethylene glycol ("PEG"), "absolute alcohol" (ethanol), and monothioglycerol (an antioxidant). (Compl. ¶30-33, ¶41). The product is positioned as a generic or follow-on competitor to Plaintiff's BELRAPZO® product, with its FDA approval allegedly relying on data from BELRAPZO®. (Compl. ¶2, ¶28). No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
U.S. Patent No. 11,844,783 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| providing a liquid bendamustine-containing composition comprising bendamustine... wherein the bendamustine concentration... is from about 20 mg/mL to about 60 mg/mL... | Slayback provides VIVIMUSTA®, a liquid product with a bendamustine hydrochloride concentration of 25 mg/mL. | ¶31, ¶48 | col. 3:20-25 |
| a pharmaceutically acceptable fluid consisting of polyethylene glycol and optionally one or more of propylene glycol, ethanol, benzyl alcohol and glycofurol... | The Approved Labeling for VIVIMUSTA® states that it contains polyethylene glycol and "absolute alcohol," which is a grade of ethanol. | ¶32, ¶33 | col. 4:47-52 |
| and a stabilizing amount of an antioxidant... | VIVIMUSTA®'s label recites that it contains 5 mg of monothioglycerol, which the patent specification identifies as an antioxidant. | ¶33, ¶41 | col. 4:13-25 |
| wherein the total impurities... is less than about 5% peak area response... after at least about 15 months at a temperature of about 5 °C. to about 25 °C... | The complaint alleges, based on FDA review documents supporting a 24-month expiry and prior litigation, that VIVIMUSTA® satisfies the claimed stability limitations. | ¶29, ¶42 | col. 3:6-14 |
| diluting the liquid bendamustine containing composition; and intravenously administering the diluted composition to the human. | The Approved Labeling for VIVIMUSTA® allegedly instructs and encourages healthcare professionals to dilute the product in an infusion bag and administer it intravenously to patients for the treatment of chronic lymphocytic leukemia. | ¶47, ¶48 | col. 5:26-36 |
U.S. Patent No. 11,872,214 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A sterile vial containing a liquid bendamustine-containing composition comprising about 100 mg of bendamustine... wherein the bendamustine concentration... is from about 25 mg/mL... | Slayback allegedly markets and sells VIVIMUSTA® in a sterile 100 mg/4 mL vial, which corresponds to a concentration of 25 mg/mL. | ¶58 | col. 3:20-25 |
| a pharmaceutically acceptable fluid consisting of polyethylene glycol and optionally one or more of propylene glycol, ethanol, benzyl alcohol and glycofurol... | The Approved Labeling for VIVIMUSTA® states that it contains polyethylene glycol and "absolute alcohol" (ethanol). | ¶32, ¶33 | col. 4:47-52 |
| and a stabilizing amount of antioxidant... | VIVIMUSTA®'s label recites that it contains 5 mg of monothioglycerol. The patent specification identifies monothioglycerol as a suitable antioxidant. | ¶33, ¶41 | col. 4:13-25 |
| wherein the total impurities... is less than about 5% peak area response... after at least about 15 months at a temperature of about 5 °C. to about 25 °C. | The complaint alleges, based on FDA review documents and prior litigation, that VIVIMUSTA® satisfies the claimed stability limitations. | ¶29, ¶42 | col. 3:6-14 |
- Identified Points of Contention:
- Scope Questions: The complaint anticipates a dispute over the claim term "consisting of," which defines the components of the "pharmaceutically acceptable fluid." (Compl. ¶33-40). The core question is whether the alleged use of sodium hydroxide as a pH adjuster during the manufacturing of the polyethylene glycol component (Compl. ¶34) introduces an unrecited element into the fluid, thereby placing the accused product outside the scope of this restrictive term. The complaint argues it does not, characterizing the sodium hydroxide as a processing aid that is not a component of the final fluid. (Compl. ¶38).
- Technical Questions: A central factual question for discovery will be whether sodium hydroxide or its reaction products are present in the final VIVIMUSTA® product as sold and imported. The complaint's allegation that it is "consumed by such use and/or is otherwise not a component of VIVIMUSTA®" will require technical evidence to substantiate. (Compl. ¶38).
V. Key Claim Terms for Construction
- The Term: "a pharmaceutically acceptable fluid consisting of"
- Context and Importance: This term is critical to the infringement analysis. The transitional phrase "consisting of" is legally interpreted as closed-ended, meaning the claimed fluid must not contain any materials other than those explicitly recited. Practitioners may focus on this term because Defendant will likely argue that its alleged use of sodium hydroxide to adjust the pH of a raw material (PEG) adds an unrecited substance to the fluid, thereby avoiding infringement. Plaintiff’s case hinges on construing this term to permit the use of such processing aids that are not present as components in the final formulation. (Compl. ¶34, ¶38-39).
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The complaint argues that a person of ordinary skill would understand that using a pH adjuster like sodium hydroxide on a standard excipient like PEG does not alter the fundamental identity of the PEG as a "pharmaceutically acceptable fluid" component, especially if it is consumed or removed. (Compl. ¶39-40). The patent specification's focus is on the final composition's long-term stability, suggesting that incidental processing aids not present in the final product may fall outside the scope of what the claim intends to exclude.
- Evidence for a Narrower Interpretation: The plain language of "consisting of" creates a strong presumption of exclusion. The claims in both patents explicitly list several optional components for the fluid (e.g., "optionally one or more of propylene glycol, ethanol..."). The express inclusion of some optional elements may strengthen the argument that any other unlisted substance, including a pH adjuster or its remnants, is excluded.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Slayback induces infringement of the method claims of the ’783 Patent. The basis for this allegation is VIVIMUSTA®'s Approved Labeling and marketing website, which allegedly instruct and encourage healthcare professionals to dilute and intravenously administer the product for treating leukemia, thereby directing them to perform the claimed method steps. (Compl. ¶47, ¶49-50).
- Willful Infringement: Willfulness is alleged for both patents based on Defendant’s alleged long-standing awareness of Plaintiff’s patent portfolio from prior litigation. (Compl. ¶51, ¶60). More specifically, the complaint alleges Plaintiff provided Defendant with actual notice of infringement by sending letters on the exact day each patent-in-suit was issued. (Compl. ¶51, ¶60).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of claim construction: does the restrictive term "consisting of," as used to define the claimed fluid, foreclose infringement if an unrecited substance (sodium hydroxide) is used as a processing aid during manufacturing, even if, as Plaintiff alleges, it is not a component of the final marketed product?
- A key evidentiary question will be one of compositional fact: what is the actual chemical composition of the accused VIVIMUSTA® product as sold? The dispute may turn on sensitive analytical tests to determine whether sodium hydroxide or its byproducts are present in the final formulation, potentially moving the central issue from a legal one of claim scope to a technical one of detectable presence.