Key Points

• In patent litigation, courts may read a "mental intent" element into method claims, and proof of infringement can depend on what the physician knew about the patient's condition.
• A method-of-treatment preamble that states the claim's therapeutic purpose can limit the claim even when the claim body partly repeats that purpose.
• District courts can revisit and clarify earlier claim constructions before final judgment, so construction disputes can reopen mid-case.

Method-of-treatment claims often turn on what a physician knew, not just what the physician did. In a significant clarification of pharmaceutical patent claim construction, a visiting judge in the District of New Jersey held that a treatment purpose stated in a claim's preamble is a binding limitation, and that the claim itself requires the practitioner to intend to treat the specific patient population the patent describes.

There is no bright-line rule for whether a preamble will be treated as a claim limitation. It depends on the facts of the case, including the claims and the invention described in the patent. But the decision shows that under Federal Circuit precedent in Eli Lilly, "intended purpose" language may generally be treated as limiting, even where the claim body already partly recites that purpose.

For patent owners and generic challengers alike, the lesson is plain: the words that frame a method claim can redefine the battlefield for both validity and infringement.

Background

On September 21, 2026, Judge Jennifer Choe-Groves of the U.S. Court of International Trade, sitting by designation in the District of New Jersey, issued an opinion in Hatch-Waxman litigation over generic LYNPARZA® (olaparib) that clarified an earlier claim construction ruling. The court held that the preamble of the asserted method-of-treatment claim is limiting. It also held that the claim includes a "mental intent" element, meaning the person practicing the claim must intend to treat a particular patient population. The decision is useful reading for pharmaceutical patent owners and ANDA filers, because it shows how courts apply the Federal Circuit's decision in Eli Lilly & Co. v. Teva to method-of-treatment claims.

AstraZeneca, KuDOS Pharmaceuticals, the University of Sheffield, and MSD International sued Natco, Cipla, and Zydus after each company filed an ANDA seeking FDA approval to market generic olaparib tablets in 100 mg and 150 mg strengths. One of the asserted patents is U.S. Patent No. 8,859,562, which covers the use of agents that inhibit the PARP DNA-repair enzyme to treat certain cancers.

The ’562 patent has a single claim, which recites:

[a] method of treatment of cancer cells defective in homologous recombination (HR), the method comprising:

• identifying a human patient with a familial predisposition to gene-linked hereditary cancer, wherein said cancer comprises cancer cells defective in homologous recombination;
• identifying a compound which inhibits PARP-1, and
• administering to said human patient a therapeutically effective amount of said compound.

The parties disputed the term “the method comprising” found in the preamble. Plaintiffs’ proposed meaning was “the claimed method is not limited to administering a PARP-1 inhibitor in a monotherapy.” In addition, plaintiffs urged, the two “identifying” steps must be performed before the “administering” step. Plaintiffs also argued a physician must have a particular intent, specifically that the physician “must understand that the patient has HR-defective cancer and that the compound is a PARP-1 inhibitor in order to possess the requisite intent to practice the claim.”

Defendants proposed defining the term as “the claimed method is not limited to administering a PARP-1 inhibitor in a monotherapy, and the claimed method steps may be performed in any order.” Defendants also argued that the preamble provided no antecedent basis for any claim terms and thus provided no limitations.

The judge previously assigned to the case held a Markman hearing in July 2025 and issued a claim construction opinion that held “the method comprising” to require “[t]he two ‘identifying’ steps (i.e., ‘identifying a human patient with a familial predisposition to gene-linked hereditary cancer’ and ‘identifying a compound which inhibits PARP-1’) be performed prior to the ‘administering’ step (i.e., administering to said human patient a therapeutically effective amount of said compound).”

The case was reassigned in April 2026. The parties then disputed how the Markman opinion applied to the defendants' prior art disclosures, and the plaintiffs asked for clarification.

The Court evaluated the request under Federal Rule of Civil Procedure 54(b). It relied on Federal Circuit precedent holding that a district court "may (and sometimes must) revisit, alter, or supplement its claim constructions" so that they genuinely clarify claim scope.

The Preamble Is Limiting

Defendants argued that the preamble did not limit the claim because it provides no antecedent basis for any claim term. Plaintiffs argued that the preamble was limiting.

The Court started from the general rule that preambles do not limit claims. It then reviewed a decision “rel[ied] heavily” upon by plaintiffs, Eli Lilly & Co. v. Teva Pharmaceuticals International GmbH, 8 F.4th 1331 (Fed. Cir. 2021).

In that case, the Federal Circuit held that the "method for treating" preambles at issue were limiting where the purpose of the methods (“to treat vasomotor symptoms such as migraines”) was incorporated “in every section of the patents’ written description” yet only mentioned in the preambles of the claims. The Federal Circuit further found that claim references to administer an “effective amount” weighed in favor of the preamble being limiting “because the amount of the antibody needed to treat vasomotor symptoms could differ from the amount needed to treat other conditions.”

Turning to the single claim of the ’562 patent, the Court found that the purpose recited in the preamble, “treat[] cancer cells defective in homologous recombination,” was consistently described in the specification. The Court thus found “[r]eading the specification as a whole and considering all portions of the written description to be internally consistent requires that a person practicing the claimed method must intend to treat cancer cells defective in homologous recombination.”

Although unlike in Eli Lilly the “purpose of the method here is not confined to the preamble” because the claim language also was limited to ”wherein said cancer comprises cancer cells defective in homologous recombination,” the Court still concluded the preamble is "necessary to give meaning and life to Claim 1" and limits the claim.

Order and Mental Intent Element

The Court declined to revisit the prior ruling that the method steps must be performed in order. The Court concluded the opinion by clarifying that the claim includes a “mental intent element for a person to practice the claim.”

The step of “identifying a human patient with a familial predisposition to gene-linked hereditary cancer, wherein said cancer comprises cancer cells defective in homologous recombination,” the Court observed, incorporates an intent to treat a patient with cancer cells defective in homologous recombination.

The Court explained that “[a]xiomatically, without knowledge that a patient is suffering from cancer with cancer cells defective in homologous recombination, a physician cannot practice the claimed method.”

Paul W. Kalish and Jonathan J. Madara are members of the IP Litigation team in Fox Rothschild’s Princeton, NJ office and write about patent litigation decisions in the District of New Jersey. Contact Paul at pkalish@foxrothschild.com or 609.895.6751 and Jonathan at jmadara@foxrothschild.com or 609.844.7428.

This information is intended to inform firm clients and friends about legal developments, including the decisions of courts and administrative bodies. Nothing in this alert should be construed as legal advice or a legal opinion. Readers should not act upon the information contained in this alert without seeking the advice of legal counsel. Views expressed are those of the authors and not necessarily this law firm or its clients.