Pfizer Inc v. Torrent Pharma Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Pfizer Inc. (Delaware) and UCB Pharma GmbH (Germany)
  • Defendant: Torrent Pharmaceuticals Limited (India) and Torrent Pharma Inc. (Delaware)
  • Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP
• Case Identification: 1:17-cv-00112, D. Del., 02/02/2017
• Venue Allegations: Venue is alleged to be proper in the District of Delaware based on Defendant Torrent Pharma Inc.'s incorporation in Delaware and Defendant Torrent Pharmaceuticals Limited's distribution of products within the state and previous submissions to the court's jurisdiction.
• Core Dispute: This is a Hatch-Waxman action in which Plaintiffs allege that Defendants' filing of an Abbreviated New Drug Application (ANDA) to market a generic version of the drug Toviaz® constitutes an act of infringement of a patent covering stable salt forms of the active ingredient.
• Technical Context: The technology concerns creating highly pure and stable salt forms of 3,3-diphenylpropylamine derivatives, compounds used as antimuscarinic agents for treating conditions such as overactive bladder, to improve their suitability for pharmaceutical formulation and oral bioavailability.
• Key Procedural History: The complaint states that Plaintiffs have previously filed fourteen lawsuits in the same district against other generic drug manufacturers asserting infringement of the same patent-in-suit. The complaint notes that in several of these prior cases, including a consolidated action, the court found the patent to be valid and infringed. It further alleges that the Defendant was aware of these prior litigations before filing its ANDA.

Case Timeline

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

U.S. Patent No. 6,858,650 - "Stable Salts of Novel Derivatives of 3,3-Diphenylpropylamines"

The Invention Explained

• Problem Addressed: The patent describes precursor compounds that are useful as prodrugs but possess technical drawbacks. Specifically, these compounds have low water solubility, which limits oral bioavailability, and a tendency to undergo "intermolecular transesterification" during storage, which degrades the product. Furthermore, salts made from these precursors could be "altogether amorphous and/or hygroscopic," making them chemically unstable and difficult to process into pharmaceutical tablets ('650 Patent, col. 2:47-62).
• The Patented Solution: The invention provides "highly pure, crystalline, stable compounds" in the form of specific salts of the 3,3-diphenylpropylamine derivatives ('650 Patent, Abstract). By converting the base compound into a salt using a "physiologically compatible inorganic or organic acid," the invention claims to overcome the prior art’s solubility and stability problems, yielding a product that is "well suited to use in pharmaceutical-technical formulations" ('650 Patent, col. 2:18-22). The specification details a specific reaction process to obtain these stable salts ('650 Patent, col. 9:1-26).
• Technical Importance: This technology provided a method for creating a stable, crystalline, and orally deliverable form of a pharmaceutically active compound for treating urinary incontinence, thereby enabling its development as a commercial drug product ('650 Patent, col. 2:16-18).

Key Claims at a Glance

• The complaint does not identify specific claims asserted, but Claim 1 is the broadest independent compound claim.
• The essential elements of independent Claim 1 are:
  • Compounds of general formula I, which chemically defines a genus of 3,3-diphenylpropylamine salts.
  • The "R" substituent is defined as C1-C6-alkyl, C3-C10-cycloalkyl, or substituted/unsubstituted phenyl.
  • The "X-" counter-ion is defined as "the acid residue of a physiologically compatible inorganic or organic acid."
• The complaint does not explicitly reserve the right to assert dependent claims, but this is standard practice in such litigation.

III. The Accused Instrumentality

Product Identification

The accused instrumentality is "Torrent's Product," identified as a generic version of fesoterodine fumarate extended-release tablets in 4 mg and 8 mg dosage strengths. This product is the subject of Torrent's ANDA No. 209783 filed with the FDA (Compl. ¶9).

Functionality and Market Context

The accused product is a generic drug intended to be therapeutically equivalent to Pfizer's brand-name drug, Toviaz® (Compl. ¶1, ¶10). Fesoterodine fumarate is an antimuscarinic agent used to treat the symptoms of overactive bladder. The complaint alleges that Torrent's ANDA contains data demonstrating the bioequivalence of its product to Toviaz® (Compl. ¶10).

IV. Analysis of Infringement Allegations

The complaint does not contain a claim chart or detailed infringement allegations mapping specific product features to claim limitations. The infringement theory is based on 35 U.S.C. § 271(e)(2)(A), which defines the submission of an ANDA seeking approval to market a patented drug prior to patent expiration as an act of infringement (Compl. ¶19).

The core of the infringement allegation is that Torrent's Product, fesoterodine fumarate, is a chemical compound that falls within the scope of the claims of the '650 patent. Fesoterodine is the isobutyrate ester of a 3,3-diphenylpropylamine derivative, where the ester group (isobutyrate) corresponds to an "R" group of "isopropyl" as recited in the claims ('650 Patent, col. 9:14-15). The product is a "fumarate" salt, and "fumaric acid" is explicitly listed in the specification as a "physiologically compatible... organic acid" suitable for forming the claimed salts ('650 Patent, col. 3:56). Dependent Claim 5 specifically recites the hydrogen fumarate salt ('650 Patent, col. 24:15-20). Therefore, the infringement allegation rests on the chemical identity of the accused product matching the claimed subject matter.

No probative visual evidence provided in complaint.

• Identified Points of Contention:
  • Scope Questions: As the chemical structure of the accused product appears to fall within the patent's claims, disputes over claim scope may be limited. However, a potential question for the court could be: Does Claim 1, when interpreted in light of the specification's repeated emphasis on creating "highly pure, crystalline, stable compounds," implicitly require a particular level of purity or a specific crystalline form that might not be present in the accused product? ('650 Patent, col. 2:18-19).
  • Technical Questions: The primary technical question in an ANDA case of this nature is whether the product for which approval is sought is, in fact, the claimed invention. The key evidentiary question will be: What evidence from Torrent's ANDA confirms that the proposed generic "fesoterodine fumarate" possesses the exact chemical structure and salt form of a compound encompassed by Claim 1 of the '650 patent?

V. Key Claim Terms for Construction

• The Term: "compounds"
• Context and Importance: This term, appearing at the start of Claim 1, is fundamental. While seemingly straightforward, its construction could be pivotal for validity and infringement. Practitioners may focus on this term because the specification heavily qualifies the invention as pertaining to "highly pure, crystalline, stable compounds" ('650 Patent, col. 2:18-19, Abstract). The outcome of this construction could determine whether properties like crystallinity and purity are claim limitations.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim itself simply recites "Compounds of general formula I" without any express purity or crystallinity limitations ('650 Patent, col. 23:14). An argument could be made that the plain language of the claim covers the chemical structure regardless of its physical form.
  • Evidence for a Narrower Interpretation: The patent repeatedly frames the invention as a solution to the problem of amorphous, unstable, and impure prior art substances ('650 Patent, col. 2:50-62). A party could argue that the specification defines the invention by its properties, thereby implicitly limiting the term "compounds" to only those that are in the highly pure, crystalline, and stable forms described as the invention's key advantage.

VI. Other Allegations

• Indirect Infringement: The complaint makes a general allegation that the future commercial manufacture, use, or sale of Torrent's Product would constitute induced and/or contributory infringement under 35 U.S.C. § 271(b) and (c) (Compl. ¶20). The basis for this would likely be the product's label, which would instruct physicians and patients to administer the drug for its patented use.
• Willful Infringement: The complaint does not use the word "willful" but does allege that the case is "exceptional" and seeks attorneys' fees under 35 U.S.C. § 285 (Compl. ¶23; Prayer for Relief ¶E). The factual basis for this claim appears to be the allegation that Torrent was aware of fourteen prior patent infringement lawsuits against other generic companies on the '650 patent, including court decisions upholding the patent's validity and finding infringement, before it sent its Paragraph IV certification letter (Compl. ¶12, ¶16).

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

• A core issue will be one of patent resilience: Given that the '650 patent has reportedly survived numerous prior challenges in the same court, a central question is whether the Defendant can introduce a new and compelling invalidity argument (e.g., based on previously unconsidered prior art or a novel claim construction theory) sufficient to overcome the patent's significant litigation history and presumption of validity.
• A key question for damages and fees will be one of litigation conduct: Will the court find that the Defendant's decision to proceed with its ANDA filing, in the face of alleged awareness of multiple prior judicial determinations that the '650 patent is valid and infringed, was objectively reckless, thereby rendering this an "exceptional case" that justifies an award of attorneys' fees?