Pfizer Inc. v. TEVA PHARMACEUTICALS USA, INC.

Citations: 803 F. Supp. 2d 397; 2011 U.S. Dist. LEXIS 27886; 2011 WL 996794Docket: Civil 2:10cv128

Court: District Court, E.D. Virginia; March 17, 2011; Federal District Court

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The legal proceedings involve Pfizer Inc., Pfizer Ltd., and Pfizer Ireland Pharmaceuticals (collectively "Pfizer") suing Teva Pharmaceuticals USA, Inc. ("Teva") for alleged infringement of U.S. Patent No. 6,469,012, which pertains to chemical compounds for treating erectile dysfunction, including the active ingredient in Viagra. Pfizer filed the suit on March 24, 2010, seeking injunctive and declaratory relief against Teva's potential production of a generic Viagra. In response, Teva counterclaimed on April 29, 2010, asserting the invalidity of the patent and claiming its drug would not infringe any patentable claims.

The court conducted a claim construction hearing on December 13, 2010, under the precedent of Markman v. Westview Instruments, Inc. The parties submitted various briefs regarding claim construction and the validity of the patent prior to the hearing. Teva sought to amend its counterclaim on November 12, 2010, to include allegations of inequitable conduct, which Pfizer opposed. On December 8, 2010, Pfizer notified the court of a covenant not to sue Teva regarding certain claims of the patent that related to Teva's assertion of inequitable conduct.

Following the Markman hearing, the court took the issues of claim construction and Teva's motion to amend under advisement. On January 18, 2011, the court granted Teva's motion to amend, instructing it to file a revised answer focusing only on the claims relevant to the court’s considerations. Teva complied by submitting a revised counterclaim on January 26, 2011, which Pfizer answered on February 2, 2011. The Memorandum Opinion provides detailed reasoning on the court's claim construction and procedural history of the case.

The '012 patent, titled "Pyrazolopyrimidinones for the Treatment of Impotence," includes twenty-six claims, specifically focusing on certain chemical compounds for treating erectile dysfunction (ED). Claims 25 and 26, which are under scrutiny, detail a method for treating ED in males by orally administering an effective amount of specified compounds, including sildenafil, the active ingredient in Viagra. The patent is set to expire on October 22, 2019.

The patent's development traces back to Pfizer's research in the late 1980s aimed at treating angina. During initial human trials in 1992, male participants reported erections as a side effect, leading Pfizer to explore sildenafil for ED treatment. Sildenafil was subsequently approved by the FDA in March 1998 as Viagra, which works by inhibiting the enzyme PDE5, allowing for increased blood flow necessary for an erection.

Claim construction is identified as a legal issue for the court, aiming to determine the meaning of terms in the context of the invention and its field. Courts are tasked with construing only the terms of disputed claims as needed to resolve the controversy, guided by the perspective of a person of ordinary skill in the relevant art at the patent's effective filing date. The Federal Circuit emphasizes that ordinary meanings of terms may be clear even to non-experts, simplifying the construction process in such cases.

When the meaning of patent claim terms is unclear, courts should consult public sources reflecting what a skilled person in the art would understand those terms to mean. These sources include intrinsic evidence (claims, specifications, prosecution history) and extrinsic evidence (technical dictionaries, treatises, expert testimony). Intrinsic evidence is deemed more reliable and should be the primary focus for determining the ordinary and customary meaning of terms. The claim construction process starts with the claims' wording, considering their context, as the claims define the invention to which the patentee holds exclusive rights. Each disputed term should be assigned its ordinary meaning, emphasizing fair notice to the public regarding the claims' scope. Consistency in term usage across claims can illuminate their meanings, and distinctions among claims can clarify their relationships. The claims are interconnected with the specification, which encompasses the abstract, summary, and preferred embodiment, and is crucial for claim construction. If the specification provides a specific definition for a term that differs from its general meaning, that definition prevails, provided the patentee clearly articulates this in the written description. The specification may also limit the invention's scope through disclaimers. However, courts should be cautious not to impose limitations from the specification onto the claims, as skilled artisans might not restrict definitions to specific embodiments. Additionally, prosecution history can be considered, though it often lacks clarity and is less useful for claim construction due to its nature as a negotiation record between the PTO and the applicant.

The court has discretion to consider extrinsic evidence to clarify the understanding of claim terms, provided it does not contradict unambiguous meanings derived from intrinsic evidence. The court is set to construe five key terms from Claims 25 and 26 of the patent related to treating erectile dysfunction (ED). The primary dispute centers on the scope of the '012 patent; Pfizer claims it encompasses all dosing regimens for the listed compounds, while Teva argues it only covers daily prophylactic use akin to Cialis, asserting that a generic version of Viagra for as-needed use would not infringe the patent.

The first term for construction is "erectile dysfunction." Pfizer defines it as "an inability to obtain or sustain an erection adequate for intercourse," based on the patent's specification. Teva agrees with this definition but argues for an expansion to include the necessity of sexual stimulation, referencing the understanding within the scientific community at the time of the patent's filing. Teva also notes that "erectile dysfunction" was often used interchangeably with "impotence." However, the court supports Pfizer's definition, emphasizing the importance of the explicit language provided in the patent, consistent with the Federal Circuit's precedent that an inventor's defined terms in the specification take precedence.

The patentee has clearly established a specialized definition of erectile dysfunction (ED) as "an inability to obtain or sustain an erection adequate for intercourse" in the '012 patent, specifically indicated by the phrase "more specifically" in the text. This definition is supported by the patent's language, which distinguishes between the broader term "impotence" and the specific condition of ED. The patent defines impotence as encompassing both an inability to achieve erection and ejaculation, whereas ED is specifically defined. The court holds that the term "erectile dysfunction" should be interpreted strictly as stated in the patent.

Regarding the term "treating erectile dysfunction," Pfizer argues it is clear and requires no construction, asserting that it means "medically caring for or dealing with erectile dysfunction." Conversely, Teva proposes a definition focused on preventing ED from recurring when sexually stimulated, citing a 1996 submission by Pfizer to the PTO that suggested "treating" meant preventing the return of ED. However, Pfizer contends this submission was merely a reservation of rights and that the final patent claims only addressed treatment, not prevention. The court finds that Teva's argument does not demonstrate an intent by the patentee to assign a special meaning to "treating," thus supporting Pfizer's position that the term should maintain its ordinary meaning.

A patentee's understanding of a term in a pre-approval submission to the PTO that is not reflected in the final patent cannot create a "special definition" for that term. The court emphasizes that communications with the PTO are part of an ongoing negotiation process, and there is insufficient evidence to support Teva's claim that Pfizer intended "treating" to have a specialized meaning. The patent specifies that its compounds are useful for treating erectile dysfunction and outlines their purpose, but does not clarify the terms "curative or prophylactic treatment." Teva argues that the specification's preferred embodiment, which prescribes a dosing regimen, implies that "treating" means administering multiple daily doses to prevent erectile dysfunction. However, according to Federal Circuit precedent, a single embodiment cannot limit the broader claim language unless the patentee has explicitly restricted the claim scope. The court concludes that "treating erectile dysfunction" does not require further construction due to its ordinary meaning, which would be clear to a skilled person in the field. 

Regarding the term "a male human [animal] in need of such treatment," Pfizer proposes it means "a male human in need of treatment for erectile dysfunction," while Teva's definition relies on its earlier interpretations. Since "treating erectile dysfunction" has been determined to need no construction, "such treatment" naturally refers back to it and also requires no further clarification. The court adopts Pfizer's definition as clear. Lastly, for "an effective amount," Pfizer argues that the term's plain meaning is sufficient, indicating that no construction is necessary.

Pfizer and Teva have differing interpretations of the term "an effective amount" in relation to treating erectile dysfunction (ED). Pfizer suggests it means "an amount sufficient to produce the desired effect," while Teva argues for a definition that includes preventing the return of ED whenever sexually stimulated. Both parties agree on the general meaning of "an effective amount," but they dispute how it should relate to the desired effect, with Teva emphasizing that an effective amount must prevent ED consistently. The court has previously dismissed Teva’s arguments and asserts that "an effective amount" requires no construction, as its meaning is understood by a person skilled in the art.

Regarding the term "a method of treating erectile dysfunction in a male human in need of such treatment," Pfizer defines it as "a method practiced for the purpose of treating erectile dysfunction," a point Teva appears to agree with, despite claiming Pfizer's definition is not a claim term. Teva proposes a similar definition focused on preventing ED during sexual stimulation. Pfizer cites precedent, asserting that the claim language reflects the invention's purpose. The court finds merit in this purposive interpretation, particularly given the context of method claims, and concludes that the term means "a method practiced for the purpose of treating erectile dysfunction."

Consequently, the court finalizes the language of Claims 25 and 26 as a method for treating ED in males, specifying the administration of an effective amount of certain compounds. The Clerk is directed to send a copy of the Memorandum Opinion to the parties' counsel, and the order concludes with notes on the procedural history of the case, including the dismissal of claims against one Teva entity and details about the FDA's tentative approval of a generic drug application.

Pfizer holds United States Patent No. 5,250,534 for sildenafil, which expires on March 27, 2012. This patent differs from the '012 patent, which is a method patent for treating erectile dysfunction (ED) with various compounds, while the '534 patent claims sildenafil as a specific chemical compound. Clinical testing for sildenafil began in 1993, with FDA-approved dosages of Viagra being 25 mg, 50 mg, or 100 mg taken prior to sexual activity. ED can arise from both psychological and physical causes; when not due to specific physical injuries, it often results from a cellular imbalance between PDE5 and cGMP, making Viagra effective in these cases. 

The court excludes FDA approval of Viagra from claim term construction because the '012 patent application predates the approval process, focusing instead on the state of the art at the time of filing. The relevance of FDA information may emerge at trial concerning secondary considerations of non-obviousness. Claim 26 relies on Claim 25, necessitating the same construction approach, as established in precedent. Disagreement exists between Pfizer and Teva over which language constitutes a "term" for claim construction, with both parties proposing constructions for certain disputed terms.

Cialis is mentioned as a comparative example but is not involved in this suit. The court clarifies that sexual stimulation is not included in the definition of ED in the patent. The discussion primarily centers on the term "treating," as "erectile dysfunction" has already been defined. Teva's argument that "treating" equates to "preventing" ED when sexually stimulated is unsupported by Pfizer's submissions, which indicate that "cure" and "prevent" were not intended to imply permanent solutions. The court notes that Teva does not propose a specific effective dosage for the treatment. Pfizer also highlights the prosecution history, asserting that the uniqueness of the '012 patent lies in its method claims for treating ED, despite the prior patent for sildenafil.