DCT
1:22-cv-00042
Eagle Pharma Inc v. Celerity Pharma LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Eagle Pharmaceuticals, Inc. (Delaware)
- Defendant: Celerity Pharmaceuticals, LLC (Delaware)
- Plaintiff’s Counsel: McCarter & English, LLP; Latham & Watkins LLP
- Case Identification: 1:22-cv-00042, D. Del., 03/18/2022
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because the Defendant is a Delaware corporation and therefore resides in the district.
- Core Dispute: Plaintiff alleges that Defendant’s New Drug Application for a generic bendamustine injection product constitutes an act of infringement of a patent directed to stable, ready-to-use liquid formulations of the chemotherapy drug.
- Technical Context: The technology involves creating long-term stable, liquid formulations of the drug bendamustine, which historically was supplied as a freeze-dried powder requiring a complex and potentially hazardous on-site reconstitution process before administration.
- Key Procedural History: The complaint describes an extensive prosecution history for the patent-in-suit, highlighting amendments and arguments made to distinguish the claimed invention from prior art that required reconstitution. Plaintiff emphasizes these arguments to support its proposed construction of the key claim term "ready to use." The complaint also notes that Plaintiff filed terminal disclaimers over other patents during prosecution and references a court-ordered construction of "ready to use" from a separate, parallel litigation involving the same patent.
Case Timeline
| Date | Event |
|---|---|
| 2010-01-28 | '483 Patent Priority Date |
| 2012-11-30 | Applicant Amendment and Remarks in parent application |
| 2019-07-12 | Filing of application that issued as the '483 Patent |
| 2020-05-27 | Non-Final Rejection issued by USPTO |
| 2020-12-21 | Final Rejection issued by USPTO |
| 2021-03-11 | Examiner Interview |
| 2021-05-20 | Applicant Response after Final Action |
| 2021-06-02 | Advisory Action issued by USPTO |
| 2021-07-12 | Examiner Interview |
| 2021-07-26 | Notice of Allowance issued by USPTO |
| 2021-08-31 | U.S. Patent No. 11,103,483 Issues |
| 2021-12-02 | Celerity Notifies Eagle of its New Drug Application Submission |
| 2022-03-18 | First Amended Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,103,483 - "Formulations of Bendamustine"
(the "’483 Patent," issued August 31, 2021)
The Invention Explained
- Problem Addressed: The patent's background section explains that prior to the invention, the chemotherapy drug bendamustine was primarily available as a lyophilized (freeze-dried) powder (Compl. ¶3). This powder required a "clinically inconvenient" reconstitution process that took 15-30 minutes and introduced risks of "chemical instability" ('483 Patent, col. 1:56-61). The reconstituted liquid was unstable in water and had to be used quickly (Compl. ¶4; '483 Patent, col. 1:56-58).
- The Patented Solution: The patent discloses "long term storage stable" liquid formulations of bendamustine that are described as "ready to use or ready for further dilution" ('483 Patent, col. 2:13-21). This solution avoids the reconstitution step required by the prior art (Compl. ¶6). Stability is achieved by formulating bendamustine in a specific non-aqueous fluid, such as polyethylene glycol (PEG), and including a "stabilizing amount of an antioxidant" ('483 Patent, Abstract). This allows the liquid formulation to be stored for extended periods (e.g., at least 15 months) with less than 5% total impurities ('483 Patent, Abstract).
- Technical Importance: The development of a stable, ready-to-use liquid formulation aimed to enhance safety for healthcare personnel by eliminating exposure to the cytotoxic powder and improve clinical efficiency by removing the time-consuming on-site reconstitution step (Compl. ¶¶3, 5).
Key Claims at a Glance
- The complaint asserts infringement of "one or more claims of the ’483 patent, including but not limited to claim 1" (Compl. ¶71).
- The essential elements of independent Claim 1 are:
- A ready to use liquid bendamustine-containing composition comprising
- bendamustine, or a pharmaceutically acceptable salt thereof, wherein the bendamustine concentration in the composition is from about 10 mg/mL to about 100 mg/mL;
- polyethylene glycol; and
- a stabilizing amount of an antioxidant;
- the composition having less than about 5% peak area response of total impurities resulting from the degradation of the bendamustine, as determined by HPLC as a wavelength of 223 nm after at least 15 months at a temperature of from about 5° C. to about 25° C.
III. The Accused Instrumentality
Product Identification
Celerity's proposed Bendamustine Hydrochloride Injection product, 100 mg/4 mL (25 mg/mL), which is the subject of New Drug Application ("NDA") No. 216078 (Compl. ¶58).
Functionality and Market Context
The accused product is alleged to be a generic, "ready to use liquid bendamustine product" intended to be sold as a substitute for Plaintiff's BELRAPZO® product (Compl. ¶8). The complaint alleges the product is a concentrated liquid that, like BELRAPZO®, can be "administered with minimal preparation through infusion with an appropriate diluent" (Compl. ¶8). It is alleged to contain bendamustine hydrochloride as the active ingredient (Compl. ¶63), polyethylene glycol, and a stabilizing amount of an antioxidant (Compl. ¶65), at a concentration of 25 mg/mL (Compl. ¶64).
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint.
Claim Chart Summary
The complaint alleges infringement under 35 U.S.C. § 271(e)(2) based on Celerity's submission of its NDA. The core infringement allegations for Claim 1 are summarized below.
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A ready to use liquid bendamustine-containing composition comprising | Celerity's NDA Product is a "ready to use liquid bendamustine-containing composition" and a "liquid bendamustine product." | ¶¶66, 67 | col. 12:21-22 |
| bendamustine, or a pharmaceutically acceptable salt thereof, wherein the bendamustine concentration... is from about 10 mg/mL to about 100 mg/mL | The product's active ingredient is bendamustine hydrochloride, and its proposed dosage strength is 100 mg/4 mL (25 mg/mL), which is within the claimed range. | ¶¶63, 64 | col. 12:23-26 |
| polyethylene glycol | Celerity's NDA Product "contains polyethylene glycol." | ¶65 | col. 12:27 |
| a stabilizing amount of an antioxidant | Celerity's NDA Product contains "a stabilizing amount of an antioxidant." | ¶65 | col. 12:28 |
| the composition having less than about 5% peak area response of total impurities... after at least 15 months at a temperature of from about 5° C. to about 25° C. | On information and belief, Celerity's product meets this stability limitation. The complaint notes Celerity's notification letter "does not dispute" this fact. | ¶68 | col. 12:29-34 |
Identified Points of Contention
- Scope Questions: A central dispute may arise over the proper construction of the preamble term "ready to use". The complaint dedicates significant attention to the prosecution history to argue that the term was understood by both the applicant and the examiner to mean a concentrated liquid that is "ready for further dilution" prior to infusion, distinguishing it from prior art that required reconstitution from a powder (Compl. ¶¶32-48). A potential defense could argue for a narrower construction, positing that "ready to use" implies no further preparation steps, including dilution.
- Technical Questions: While the complaint alleges Celerity's notification did not dispute the composition's stability, the question of whether the accused product actually has "less than about 5% peak area response of total impurities" after 15 months of storage remains an evidentiary issue for the court. The specific identity and quantity of the "antioxidant" in the accused product will also be a key factual point of comparison.
V. Key Claim Terms for Construction
- The Term: "ready to use"
- Context and Importance: This term, appearing in the preamble of the independent claim, is critical to the scope of the patent. The infringement analysis may depend entirely on whether this term is construed to cover concentrated liquid formulations that require dilution before administration, such as Plaintiff's BELRAPZO® and the accused generic product. Practitioners may focus on this term because the complaint's extensive recitation of the prosecution history indicates Plaintiff anticipates a dispute over its meaning.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation (encompassing dilution): The complaint points to prosecution history where the applicant allegedly distinguished the invention from prior art by describing the claimed compositions as "concentrated, bendamustine-containing liquids for administration through infusion with an appropriate diluent" (Compl. ¶43). The specification states that the "inventive formulations are advantageously ready to use or ready for further dilution" ('483 Patent, col. 2:13-14). The complaint also quotes the examiner as stating, "the 'ready to use' appears to infer 'ready for further dilution'" (Compl. ¶45).
- Evidence for a Narrower Interpretation (precluding dilution): A defendant may argue that the plain and ordinary meaning of "ready to use" implies that no further preparative steps are needed. The disjunctive "or" in the specification's phrase "ready to use or ready for further dilution" ('483 Patent, col. 2:13-14) could be argued to delineate two distinct, mutually exclusive types of formulations, with the claim preamble only reciting the former.
VI. Other Allegations
Indirect Infringement
The complaint alleges that Celerity will induce infringement because its proposed product labeling will direct healthcare professionals to use the product in an infringing manner (i.e., by diluting and administering it) (Compl. ¶73). It also alleges contributory infringement, stating the product is especially made for infringing use and not suitable for substantial noninfringing use (Compl. ¶74).
Willful Infringement
Willfulness is alleged based on Celerity's "full knowledge of the '483 patent and/or the application leading to the '483 patent," as evidenced by its submission of a Paragraph IV certification, allegedly without a reasonable basis for believing it would not be liable for infringement (Compl. ¶75).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of "definitional scope": can the claim term "ready to use", as defined by the patent's specification and its detailed prosecution history, be properly construed to cover a concentrated liquid formulation that is not reconstituted from a powder but still requires dilution before being infused into a patient?
- A key evidentiary question will be one of "factual compliance": assuming a favorable claim construction for the Plaintiff, what evidence will demonstrate that Celerity’s proposed commercial product actually meets the specific quantitative stability limitation of having "less than about 5% peak area response of total impurities" after 15 months of storage as required by Claim 1?