Details for Patent: 7,727,994

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Summary for Patent: 7,727,994

Title:	Methods of treating patients suffering from movement disorders
Abstract:	The present invention is directed to methods of treating movement disorders by administering an effective amount of one or more adenosine A2A receptor antagonists to a patient in need thereof. The present invention also provides methods of decreasing the adverse effects of L-DOPA in patients receiving L-DOPA therapy in the treatment of Parkinson's disease. The present invention further provides methods and compositions for treating Parkinson's disease patients with sub-clinically effective doses of L-DOPA by combining L-DOPA treatment with an effective amount of one or more adenosine A2A receptor antagonists (i.e., L-DOPA sparing effect). The present invention further provides methods of effective treatment of Parkinson's disease by co-administering at least one adenosine A2A receptor antagonist, L-DOPA and a dopamine agonist and/or a COMT inhibitor and/or a MAO inhibitor. The present invention further provides methods of prolonging effective treatment of Parkinson's disease by administering an adenosine A2A receptor antagonist singly or together with a dopamine agonist, and/or a COMT inhibitor, and/or a MAO inhibitor without prior or subsequent administration of L-DOPA, delaying or removing on-set of L-DOPA motor complication.
Inventor(s):	Hiroshi Kase, Akihisa Mori, Yutaka Waki, Yutaka Ohsawa, Akira Karasawa, Yoshihisa Kuwana
Assignee:	Kyowa Kirin Co Ltd
Application Number:	US11/326,516
Patent Claim Types: see list of patent claims	Use;

U.S. Patent 7,727,994: Scope, Claim Construction, Expiration, and Istradefylline Patent Landscape

U.S. Patent 7,727,994 covers a Parkinson's disease treatment method using istradefylline, the adenosine A2A receptor antagonist marketed as Nourianz. The central claim is a method-of-treatment claim requiring administration of istradefylline to a patient already receiving L-DOPA, with the objective of delaying the patient's need for additional L-DOPA therapy. The patent does not broadly claim istradefylline, all Parkinson's disease uses, or every combination of istradefylline and levodopa.

The patent's principal commercial relevance was the use of istradefylline as a levodopa-sparing or levodopa-delaying therapy. Based on the 20-year patent term calculated from the underlying U.S. filing, the patent reached its ordinary expiration in March 2025, subject to any patent-term adjustment reflected in the official USPTO record. It is therefore no longer a significant forward-looking barrier to generic istradefylline entry.

What drug and therapeutic use does U.S. Patent 7,727,994 cover?

The claimed compound is istradefylline, chemically identified as:

(E)-8-(3,4-dimethoxystyryl)-1,3-diethyl-7-methylxanthine

Istradefylline is a selective adenosine A2A receptor antagonist. FDA approved Nourianz tablets in 2019 as an adjunctive treatment to levodopa/carbidopa in patients with Parkinson's disease experiencing "off" episodes. The approved product is supplied in 20 mg and 40 mg tablets [2].

The patent's claimed clinical concept differs from the principal current FDA label. The patent focuses on delaying the need for add-on L-DOPA therapy and delaying motor complications. The approved indication focuses on reducing off episodes in patients already treated with levodopa/carbidopa.

Attribute	U.S. Patent 7,727,994
Active ingredient	Istradefylline
Chemical form	Defined E-isomer
Disease	Parkinson's disease
Claim category	Method of treatment
Required baseline therapy	Patient currently receives L-DOPA therapy
Primary outcome	Delay in need for add-on L-DOPA
Dependent outcome	Delay in motor complications
Special dependent limitation	No subsequent administration of L-DOPA
Dosage specified in claims	No fixed dose
Formulation specified in claims	No
Route specified in claims	No
Patent type	Utility patent
Commercial product	Nourianz
Applicant/assignee associated with patent	Kyowa Hakko group

What does claim 1 of U.S. Patent 7,727,994 require?

Claim 1 has several mandatory elements. A potentially infringing practice must satisfy each one.

1. A method of prolonging effective Parkinson's disease treatment

The preamble identifies the therapeutic objective: prolonging effective treatment of Parkinson's disease. The operative limitations are the administration, patient status, compound identity and treatment result.

The phrase "prolonging effective treatment" is not an independent right to claim any clinical benefit from istradefylline. It frames the claimed method and is read with the more specific requirement that treatment delay the patient's need for add-on L-DOPA therapy.

2. Administration to a patient with Parkinson's disease

The patient must have Parkinson's disease and must be a patient "in need thereof." The claim is directed to treatment of an identified disease state, not prophylactic administration to a healthy person or treatment of an unrelated movement disorder.

3. Administration of the specified E-isomer

The claim identifies the compound by chemical name and stereochemistry. The claimed product is the E-isomer of the dimethoxystyryl xanthine structure. This limitation excludes unrelated xanthine derivatives and raises potential claim-construction issues for:

• The Z-isomer;
• Racemic or geometrically mixed material;
• Metabolites;
• Prodrugs;
• Salts or solvates that contain the same active moiety;
• Formulations in which the active ingredient is present at an extremely low concentration.

A commercial product containing istradefylline would generally satisfy the compound limitation if the active ingredient is the claimed E-isomer. The patent does not require a particular crystalline form, particle size, excipient, tablet coating or release profile.

4. The patient must already receive L-DOPA therapy

This is a critical limitation. Claim 1 does not cover initial istradefylline treatment in a patient who has never received L-DOPA. It requires that the patient "currently receives L-DOPA therapy."

The wording also creates a distinction between:

• A patient receiving levodopa before istradefylline administration;
• A patient receiving levodopa and istradefylline concurrently;
• A patient who previously received levodopa but no longer receives it;
• A patient treated with istradefylline before levodopa is introduced.

Only the first two categories clearly align with the express current-treatment limitation.

The claim uses "L-DOPA" rather than expressly requiring carbidopa or benserazide. A product or regimen using levodopa/carbidopa would ordinarily fall within the ordinary clinical meaning of L-DOPA therapy. The claim does not state that the patient must receive a specific levodopa dose or formulation.

5. The amount must be effective to delay add-on L-DOPA therapy

The claim requires an amount "effective to delay the patient's need for add-on L-DOPA therapy." This is a functional limitation. It does not specify a numerical dose, treatment duration, response threshold or comparator.

The limitation creates two issues:

• The administered amount must be capable of producing the claimed delay.
• The delay concerns a subsequent need for add-on L-DOPA, not merely improvement in symptoms or reduction in off time.

FDA-approved istradefylline doses of 20 mg and 40 mg are commercially relevant, but the patent claims are not limited to those doses [2].

How do claims 2 and 3 narrow the patent scope?

Claim 2: delayed motor complications

Claim 2 depends on claim 1 and adds the limitation that development of motor complications is delayed. The claim therefore requires all limitations of claim 1 plus a delay in motor complications.

Motor complications may include dyskinesia, wearing-off, fluctuations, or other complications associated with chronic dopaminergic treatment. The claim does not define which motor complications qualify. That creates a potential dispute over whether the term is limited to clinically recognized levodopa-induced complications or includes broader Parkinson's disease motor progression.

Claim 2 is narrower than claim 1 because it requires a particular clinical outcome. A regimen that delays the need for additional L-DOPA but does not establish delayed motor complications could fall within claim 1 while failing claim 2.

Claim 3: no subsequent L-DOPA administration

Claim 3 requires the method of claim 1 and adds that the patient does not have subsequent administration of L-DOPA.

The claim appears directed to a treatment sequence in which:

1. The patient is currently receiving L-DOPA;
2. Istradefylline is administered;
3. The patient does not later receive L-DOPA.

This limitation is narrower than claim 1 and creates a temporal issue. Claim 1 requires current L-DOPA therapy, while claim 3 excludes later L-DOPA administration. The logical structure is not necessarily contradictory: a patient can be receiving L-DOPA when istradefylline begins and later discontinue or avoid further L-DOPA. The claim does, however, make infringement dependent on the patient's subsequent treatment history.

Claim 3 is commercially less aligned with the current Nourianz label, which describes istradefylline as adjunctive therapy to levodopa/carbidopa rather than as a treatment intended to eliminate later levodopa administration [2].

What formulations and dosage forms are protected by U.S. Patent 7,727,994?

The patent claims do not expressly require a particular formulation or dosage form. The method could theoretically be practiced using:

• Immediate-release tablets;
• Capsules;
• Oral suspensions;
• Other orally administered preparations;
• A formulation administered by a route capable of delivering effective istradefylline exposure.

The patent does not, based on the asserted claims, provide formulation-specific protection for:

• A particular tablet composition;
• A controlled-release system;
• A specific excipient combination;
• A defined dissolution profile;
• A particular polymorph;
• A particular particle-size distribution;
• A fixed 20 mg or 40 mg strength.

This distinction matters in generic competition. A generic manufacturer could avoid formulation-specific patents by changing excipients or release characteristics, but it would not avoid a broad method-of-treatment claim merely by changing the tablet formulation if the generic product still causes the claimed administration to patients.

When did U.S. Patent 7,727,994 expire?

The patent's ordinary term was tied to its underlying U.S. nonprovisional filing and ran approximately 20 years. Public patent records associate the patent with a March 2005 U.S. filing and a March 2025 term endpoint. The patent was issued on June 1, 2010, as U.S. Patent No. 7,727,994 [1].

The relevant commercial conclusion is that the patent reached the end of its ordinary enforceable term in 2025. Patent-term adjustment, terminal disclaimer information and the official USPTO maintenance record control the precise legal endpoint. Expiration removes the patent owner's ability to seek prospective infringement relief for post-expiration conduct, although expiration does not erase claims concerning conduct that occurred while the patent was enforceable.

Exclusivity timeline

Event	Date
Underlying U.S. filing period	March 2005
Patent issued	June 1, 2010
Approximate 20-year term endpoint	March 2025
FDA approval of Nourianz	August 2019
Current forward-looking patent value	Limited after patent expiration

FDA approval in 2019 occurred well after the patent issued. The patent therefore provided late-stage method-of-use protection during the commercial launch period rather than original compound exclusivity.

What is the Orange Book status of U.S. Patent 7,727,994?

The FDA Orange Book distinguishes listed patents from regulatory exclusivity. An NDA holder may list patents claiming the approved drug, its formulation, or an approved method of use. Listing does not extend the patent term and does not convert a method-of-use patent into a composition patent [3].

For Nourianz, U.S. Patent 7,727,994 was commercially relevant as a method-of-use patent associated with istradefylline. Its claim language is narrower than the approved indication because the patent centers on delaying additional L-DOPA therapy, while the label authorizes adjunctive treatment to levodopa/carbidopa for off episodes.

The practical Orange Book consequences were:

• A generic applicant could address the patent through a Paragraph IV certification if the patent was listed and not expired.
• A method-of-use carve-out could be relevant if the applicant did not seek approval for the patented use.
• A Paragraph IV notice could have triggered a 30-month stay if the NDA holder filed an infringement action within the statutory period.
• After patent expiration, the listed patent no longer creates an active patent obstacle to approval or launch.

An expired patent may remain visible in historical Orange Book records. Historical listing should not be confused with current enforceability.

What Paragraph IV challenges and generic launch risks apply?

A generic istradefylline applicant would face two separate questions:

1. Whether the product can be approved under an ANDA; and
2. Whether the proposed labeling and marketing would induce practice of an unexpired patented method.

A Paragraph IV certification would challenge validity, enforceability or infringement of a listed patent. For this patent, likely technical arguments would include:

• The proposed label does not include the patented delayed-add-on-L-DOPA use;
• The patient population in the proposed label does not require the claimed treatment sequence;
• The product is not administered in an amount shown to delay the claimed endpoint;
• The claims are anticipated or obvious in light of prior Parkinson's treatment and A2A-antagonist disclosures;
• The functional treatment result is not satisfied in the accused population;
• Claim 3 is not infringed because patients continue receiving L-DOPA.

The principal infringement risk during the patent term was not manufacture of istradefylline alone. It was induced infringement based on prescribing information, promotional materials, payer communications or other conduct encouraging the claimed use under 35 U.S.C. § 271(b) [4].

After expiration, those patent-based generic launch risks from U.S. Patent 7,727,994 fall away. Other unexpired patents, regulatory exclusivities, controlled-substance rules or non-patent commercial barriers would need separate analysis.

How strong is the patent estate around istradefylline?

The estate should be divided into four categories.

Compound patents

Earlier patents covering istradefylline or related xanthine compounds provided the original chemical protection. Those patents are substantially older than U.S. Patent 7,727,994 and were not the principal source of late-stage U.S. exclusivity when Nourianz was approved.

Method-of-use patents

U.S. Patent 7,727,994 is a method-of-use patent. Its value depended on proving that the accused product or prescribing behavior practiced the specified clinical sequence.

Method patents generally have narrower enforcement leverage than composition patents because infringement depends on the treatment actually performed and the scope of the label or inducement evidence.

Formulation and dosage patents

The asserted claims do not contain formulation limitations. Any separate formulation patents would need to be analyzed independently by claim number, listed indication, dosage strength, pharmaceutical composition and expiration date.

Regulatory exclusivity

FDA approval of Nourianz did not create biologic exclusivity because istradefylline is a small molecule, not a biologic. The relevant approval pathway was an NDA, not a biologics license application. Hatch-Waxman regulatory exclusivity and Orange Book patent listing are distinct from patent term [3].

Which companies are challenging or competing with Nourianz?

The relevant competitive set includes:

• Generic manufacturers developing or marketing istradefylline;
• Producers of levodopa/carbidopa;
• Manufacturers of dopamine agonists;
• Suppliers of MAO-B inhibitors;
• Suppliers of COMT inhibitors;
• Developers of other adjunctive therapies for Parkinson's disease off episodes.

Istradefylline competes clinically with adjunctive therapies rather than replacing levodopa. Its approved positioning is as an add-on treatment for patients experiencing off episodes despite levodopa/carbidopa therapy [2].

The patent at issue did not block competitors from marketing unrelated Parkinson's products. It also did not prevent use of levodopa, dopamine agonists or other adjunctive agents.

What litigation and settlement issues affect the patent?

The relevant litigation question is whether a generic applicant filed a Paragraph IV certification and whether the patent holder filed a timely infringement action. A final litigation assessment requires the specific ANDA number, notice letter, district court docket and any Federal Circuit disposition.

The patent's expiration materially reduces the value of any historical settlement. A settlement that restricted launch until a date before expiration would have had commercial value only during the remaining enforceable term. After expiration, the settlement could still contain non-patent provisions, but U.S. Patent 7,727,994 itself would not support continued exclusion.

What geographic coverage does U.S. Patent 7,727,994 provide?

The patent is enforceable only in the United States. It does not create rights in:

• The European Union;
• Japan;
• China;
• Canada;
• The United Kingdom;
• Other national markets.

International protection must be evaluated patent by patent. Foreign family members may have different claims, prosecution histories, expiration dates and legal status. A U.S. expiration does not determine foreign expiry.

Key Takeaways

• U.S. Patent 7,727,994 is a method-of-treatment patent for istradefylline in Parkinson's disease.
• Claim 1 requires a patient currently receiving L-DOPA and an amount of istradefylline effective to delay the need for add-on L-DOPA therapy.
• Claim 2 narrows the method to delaying motor complications.
• Claim 3 requires no subsequent administration of L-DOPA after the claimed treatment begins.
• The patent does not claim all istradefylline products, all Parkinson's uses, or a particular tablet formulation.
• The patent's ordinary U.S. term ended in March 2025.
• Its strongest commercial value was late-stage method-of-use protection for the Nourianz launch period.
• The patent was relevant to Paragraph IV analysis while unexpired, but it no longer presents a current U.S. patent barrier to generic entry.
• FDA Orange Book listing and patent enforceability are separate issues.
• No biosimilar pathway applies because istradefylline is a small-molecule drug.

FAQs

Does U.S. Patent 7,727,994 cover Nourianz 20 mg and 40 mg tablets?

The claims do not specify a strength. They can potentially read on administration of an approved 20 mg or 40 mg istradefylline product if all patient-status and treatment-outcome limitations are satisfied. The patent does not independently claim those tablet strengths.

Can a generic sell istradefylline for patients who have never used L-DOPA?

That use would not satisfy the express "currently receives L-DOPA therapy" limitation in claim 1. A generic label directed only to such patients would present a different infringement analysis from a label encouraging use in patients already receiving levodopa.

Is claim 3 a claim to replacing levodopa with istradefylline?

Not broadly. Claim 3 requires that the patient currently receive L-DOPA when the method begins, then adds the limitation that the patient does not have subsequent L-DOPA administration. It is a narrow treatment-sequence claim, not a general claim to istradefylline monotherapy.

Does the patent cover istradefylline's A2A receptor mechanism?

No. The claims are written as treatment methods and do not claim the receptor, receptor binding, or the pharmacological mechanism in isolation.

Does patent expiration eliminate FDA approval requirements for generic istradefylline?

No. Patent expiration removes the patent-based exclusion, but a generic applicant must still satisfy FDA approval requirements under the ANDA or another applicable pathway, including bioequivalence, manufacturing and labeling requirements.

References

1. United States Patent and Trademark Office. (2010). U.S. Patent No. 7,727,994, Treatment of Parkinson's disease.
2. U.S. Food and Drug Administration. (2019). Nourianz (istradefylline) prescribing information.
3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
4. 35 U.S.C. §§ 154, 271, 355(j).

Drugs Protected by US Patent 7,727,994

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 7,727,994

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003207734
Australia	2008200611
Brazil	0306919
Canada	2473864
Canada	2813048
China	101543497
China	101822676