Details for Patent: 7,530,461

Summary for Patent: 7,530,461

Title:	Esters of 5-aminolevulinic acid as photosensitizing agents in photochemotherapy
Abstract:	The present invention relates to compounds being esters of 5-aminolevulinic acids or pharmaceutically acceptable salts thereof, including compounds of formula (I) R22N—CH2COCH2-CH2CO—OR1 (wherein R1 may represent alkyl optionally substituted by hydroxy, alkoxy, acyloxy, alkoxycarbonyloxy, amino, aryl, oxo or fluoro groups and optionally interrupted by oxygen, nitrogen, sulphur or phosphorus atoms; and R2 represents a hydrogen atom or a group R1, and both R2 groups may be the identical or different), and their use in diagnosis and photochemotherapy of disorders or abnormalities of external or internal surfaces of the body, and products and kits for performing the invention.
Inventor(s):	Karl E. Gierskcky, Johan Moan, Qian Peng, Harald Steen, Trond Warloe, Alf Bjørseth
Assignee:	Photocure ASA
Application Number:	US10/818,917
Patent Claim Types: see list of patent claims	Use; Formulation;

United States Patent 7,530,461: Scope, Claims, Expiration, and Hexyl Aminolevulinate Patent Landscape

U.S. Patent No. 7,530,461 covers hexyl aminolevulinate hydrochloride, also known as HAL, for fluorescence-based diagnosis and photodynamic treatment of urinary bladder abnormalities. Its claims cover three distinct clinical workflows: ex vivo urine-cell diagnosis, intravesical fluorescence diagnosis, and intravesical photodynamic therapy.

The patent is associated with Photocure ASA’s HAL platform, marketed in the United States as Cysview and in other markets as Hexvix. The patent’s original term has ended, making the patent historically important but no longer an active U.S. exclusion right. Current commercial protection for Cysview depends on other patents, regulatory exclusivity, manufacturing know-how, trademarks, distribution arrangements, and the practical requirements for an FDA-approved fluorescence cystoscopy product.

What does U.S. Patent 7,530,461 cover?

U.S. Patent 7,530,461 covers methods that use HAL to cause bladder cells or lesions to fluoresce under blue or violet light. The fluorescence is used either to identify abnormal cells or to guide treatment.

The claims contain three principal subject-matter groups:

Claim group	Method	HAL exposure	Light and result
Claims 1-2	Ex vivo diagnosis from urine cells	0.04 mg/mL in cell-growth medium with 10% fetal calf serum	Excitation at 390-440 nm; detection at 620-640 nm
Claims 3-4	In vivo bladder diagnosis	8 mM HAL in a defined phosphate-buffered saline solution	One-hour dwell; lesion inspection at 380-450 nm
Claims 5-8	Diagnosis-guided photodynamic treatment	0.1-1.0 mmol HAL hydrochloride in 50 mL PBS	Bladder dwell of 5 minutes to 4 hours; treatment dose of 10-100 J/cm²

The patent is narrower than a general claim to using any aminolevulinate for bladder imaging. Its enforceability would depend on satisfying the precise concentration, formulation, exposure, wavelength, timing, and treatment conditions recited in the individual claims.

What are the independent claims in U.S. Patent 7,530,461?

Claims 1, 3, and 5 are the independent claims. Claims 2, 4, 6, 7, and 8 add disease-specific or lesion-specific limitations.

Claim 1: Ex vivo urine-cell diagnosis

Claim 1 requires all of the following:

1. Cells are collected from the patient’s urine by centrifugation.
2. The cells are mixed with a solution containing 0.04 mg HAL hydrochloride per milliliter of cell-growth medium.
3. The medium contains 10% fetal calf serum and has a pH of 7.2.
4. The mixture is incubated for about four hours.
5. Light at 390-440 nm is applied.
6. Fluorescence is assessed at 620-640 nm.

Claim 2 limits the diagnosed abnormality to carcinoma in situ.

This claim is directed to a laboratory or cytology workflow rather than to cystoscopic imaging inside the patient. A diagnostic laboratory would need to reproduce the claimed cell preparation and assay conditions to fall within the literal scope of the claim.

Claim 3: Intravesical fluorescence diagnosis

Claim 3 requires:

• Instillation of a defined solution containing 4.3 mM potassium dihydrogen phosphate, 4.3 mM disodium hydrogen phosphate, 120 mM sodium chloride, pH 6.0, and 8 mM HAL.
• A one-hour residence time in the bladder.
• Evacuation of the solution.
• Inspection and mapping of areas fluorescing at 380-450 nm.
• Optional biopsy confirmation.

Claim 4 limits the abnormality to carcinoma in situ.

The key limitation is the defined intravesical formulation and one-hour dwell period. A product or protocol using a materially different HAL concentration, buffer, pH, or exposure time would require a separate infringement analysis.

Claim 5: Photodynamic treatment

Claim 5 is the broadest operational claim in the patent but also includes the greatest number of limitations. It requires:

• Introduction of 0.1-1.0 mmol HAL hydrochloride in 50 mL phosphate-buffered saline at pH 6.0.
• A bladder residence time of 5 minutes to 4 hours.
• Removal of the solution.
• Inspection under white light and blue light at 375-440 nm.
• Resection of papillary and superficial lesions, with optional blue-light-guided resection.
• HAL imaging of resected lesions if resection was not conducted under blue light.
• Exposure of lesions to white light, red light at 630-635 nm, or blue light at 375-440 nm.
• A total light dose of 10-100 J/cm² and fluence of 50-200 mW/cm².
• Local treatment of individual lesions or treatment of the entire bladder.

Claims 6-8 extend the claim to carcinoma in situ, bacterial, viral, or fungal infections, discrete lesions, and bladder cancer.

The claim therefore combines diagnosis, lesion resection, fluorescence checking, and photodynamic treatment. A procedure using HAL solely for diagnostic blue-light cystoscopy would generally implicate the diagnostic claims more directly than the full treatment claim.

What patent protects Cysview and Hexvix?

Cysview and Hexvix are based on hexyl aminolevulinate hydrochloride, a prodrug that produces intracellular protoporphyrin IX. Under blue-violet illumination, accumulated protoporphyrin IX produces red fluorescence that can identify lesions not readily visible under white light.

U.S. Patent 7,530,461 is one of the central U.S. patents associated with the clinical use of HAL in bladder diagnosis and therapy. Its claims are method claims, not broad composition claims covering every HAL formulation.

The practical patent estate has included several categories:

Protection category	Relevance to HAL products
Diagnostic method patents	Blue-light identification of bladder tumors and carcinoma in situ
Treatment method patents	Photodynamic treatment after HAL administration
Formulation patents	HAL concentration, vehicle, pH, buffering, and administration conditions
Device and system patents	Light sources, cystoscopes, fluorescence imaging, and image processing
Manufacturing patents	HAL synthesis, purification, stability, and dosage-form production
Regulatory exclusivity	FDA exclusivity associated with the approved Cysview indication
Commercial rights	Photocure licenses, distribution rights, and product supply arrangements

The asserted scope of any patent must be compared with the actual Cysview label and the specific Orange Book listing. Patent 7,530,461 should not be treated as a blanket patent on all HAL use, all bladder cancer diagnosis, or all blue-light cystoscopy.

What formulation limitations are required by the claims?

The formulation limitations are central to claim construction and freedom-to-operate analysis.

Ex vivo formulation

Claim 1 requires:

• HAL hydrochloride at 0.04 mg/mL
• Cell-growth medium
• 10% fetal calf serum
• pH 7.2

A diagnostic assay using a different medium, serum concentration, pH, or HAL concentration may avoid literal infringement of claim 1. The phrase “about 4 hours” introduces a degree of numerical flexibility, but the other formulation elements remain express limitations.

Intravesical diagnostic formulation

Claim 3 requires:

• 8 mM HAL
• 4.3 mM KH2PO4
• 4.3 mM Na2HPO4
• 120 mM NaCl
• pH 6.0

This is a highly specified buffer system. The claim is materially narrower than a generic method of instilling HAL into the bladder.

Photodynamic-treatment formulation

Claim 5 requires:

• 0.1-1.0 mmol HAL hydrochloride
• 50 mL phosphate-buffered saline
• pH 6.0

The concentration range corresponds to approximately 2-20 mM HAL in the stated 50 mL volume, subject to the interpretation of the claim’s mmol limitation. The claim also requires the stated dwell-time range and subsequent light exposure.

When did U.S. Patent 7,530,461 expire?

U.S. Patent 7,530,461 is no longer an active U.S. patent. Its original patent term ended based on the applicable twenty-year term measured from the relevant nonprovisional filing or priority framework, subject to any recorded patent-term adjustment or terminal disclaimer.

Public patent records identify the patent as granted on May 12, 2009. The relevant U.S. application and priority chain, rather than the grant date, controls the expiration calculation. The patent should therefore be treated as expired for current U.S. freedom-to-operate purposes, with the exact terminal date confirmed against the USPTO Patent Center record and any patent-term adjustment data. [1][2]

The expiration of Patent 7,530,461 does not eliminate other possible barriers. A commercial entrant may still face:

• Separate unexpired method patents.
• Device patents covering blue-light cystoscopy systems.
• Manufacturing patents.
• FDA requirements for a new drug application or abbreviated pathway.
• Product-specific safety and efficacy obligations.
• Trade-secret restrictions.
• Trademark restrictions involving Cysview or Hexvix.

What is the FDA regulatory status of Cysview?

The FDA approved Cysview, containing hexaminolevulinate hydrochloride, for use in adult patients with known or suspected bladder cancer as an optical imaging agent used with the Karl Storz D-Light C Photodynamic Diagnostic System. The product is administered intravesically before blue-light cystoscopy. [3]

The FDA-approved use is narrower than the full text of claim 5. The approved indication is principally diagnostic and surgical visualization. The patent’s photodynamic-treatment provisions include therapeutic light exposure and specified energy doses, while the Cysview label is associated with fluorescence-guided detection and resection rather than a broad FDA-approved HAL photodynamic-therapy indication.

This distinction matters in litigation and regulatory strategy. A party practicing the approved diagnostic label may not practice every element of claim 5, while a party developing HAL photodynamic therapy would face a different claim and regulatory analysis.

What is the Orange Book status of Patent 7,530,461?

The Orange Book records patents submitted by an NDA holder for an approved drug product and its approved uses. Cysview’s Orange Book position must be assessed by reviewing the current FDA Orange Book listing for the applicable NDA and comparing it with historical editions.

The relevant questions are:

1. Whether Patent 7,530,461 was listed against the Cysview NDA.
2. Whether it remains listed after expiration.
3. Whether other patents were listed for the product or its approved use.
4. Whether any listed patent generated a Paragraph IV notice.
5. Whether the FDA delisted or removed any patent after a regulatory or judicial event.

An expired patent can remain visible in historical Orange Book records but cannot ordinarily support a prospective injunction against post-expiration commercial activity. Orange Book listing and enforceability are separate issues. [4]

How strong was the patent estate for HAL bladder imaging?

Patent 7,530,461 had meaningful historical value because it connected HAL administration with a defined diagnostic and treatment protocol. Its strongest claim characteristics were:

• Specific HAL concentrations.
• Specific bladder dwell times.
• Defined excitation and emission wavelengths.
• A complete fluorescence-guided resection sequence.
• Explicit coverage of carcinoma in situ.
• Coverage of full-bladder illumination as well as lesion-specific illumination.

Its weaknesses were equally clear:

• The claims are method claims and require multiple steps.
• Several claims contain narrow formulation parameters.
• Diagnostic and treatment claims can be designed around by modifying the protocol.
• The patent does not broadly claim every HAL composition.
• The patent does not necessarily cover every blue-light cystoscopy device.
• The patent’s term has ended.

The estate was strongest during the period when Photocure controlled both the approved product and the relevant clinical workflow. It is weaker as a current exclusion tool because the patent has expired and because competing protection may reside in separate patents or know-how.

Which companies are relevant to the HAL competitive landscape?

Photocure is the principal commercial company associated with HAL bladder imaging. Its product is marketed as Cysview in the United States and Hexvix in other jurisdictions. Karl Storz supplies the D-Light PDD imaging platform used with Cysview in the U.S. approved setting. [3][5]

The competitive landscape includes:

• White-light cystoscopy, which remains the conventional comparator.
• Other optical imaging approaches.
• Alternative photosensitizers.
• Investigational fluorescence agents.
• New imaging systems that seek to improve lesion detection without relying on HAL.
• Generic or follow-on HAL products, subject to FDA regulatory requirements and any surviving intellectual-property rights.

A generic HAL product would need to address both the drug product and the imaging-system requirements associated with the approved indication. A chemically equivalent product could still require a suitable regulatory pathway, labeling strategy, and compatibility with the required cystoscopy system.

What Paragraph IV challenges affect Cysview?

A Paragraph IV certification is relevant only if an ANDA applicant seeks approval for a product referencing an NDA with an unexpired listed patent. The applicant must certify that the patent is invalid, unenforceable, or will not be infringed.

For Patent 7,530,461, the patent’s expiration removes the principal current incentive for a Paragraph IV challenge directed solely to that patent. Any current ANDA strategy would focus on:

• Other unexpired Orange Book patents.
• Whether the proposed product uses the same formulation and indication.
• Whether the applicant can carve out patented uses.
• Whether the approved device combination creates a regulatory barrier.
• Whether any patent litigation remains pending or has been settled.

No current Paragraph IV exposure should be inferred from the existence of the patent number alone. The relevant analysis is the current Orange Book listing and the expiration status of every listed patent.

What generic launch risks exist after expiration?

A post-expiration entrant faces several possible launch scenarios.

Launch scenario	Principal issue
Full-label generic HAL product	Requires regulatory approval for the relevant indication and device combination
Carved-out diagnostic label	May avoid unexpired method-of-use claims but can reduce commercial scope
Hospital-compounded HAL	May face drug-quality, sterility, formulation, and regulatory constraints
New NDA product	Higher development cost but greater labeling flexibility
Device-compatible alternative	Requires technical validation with fluorescence cystoscopy systems
Ex-U.S. launch	Depends on national patent, regulatory, and reimbursement status

The expired patent reduces one layer of patent risk. It does not guarantee immediate generic entry. Cysview is a specialized product with a defined administration procedure, imaging platform, hospital workflow, and training requirements. Those factors can delay entry even when core method claims are expired.

What manufacturing and intellectual-property barriers remain?

HAL products may face manufacturing barriers that are separate from the expired clinical-method patent. These can include:

• Control of starting materials.
• Synthesis and purification processes.
• Stability of the active ingredient.
• Sterile or aseptic preparation.
• Light sensitivity and packaging.
• Reconstitution or storage requirements.
• Impurity specifications.
• Compatibility with the intravesical administration process.
• Batch-release testing.

Manufacturing patents are often more difficult to identify from the product name alone because they may be assigned to affiliates, suppliers, or research entities. A complete freedom-to-operate review should separate composition, formulation, therapeutic-use, manufacturing, device, and regulatory patents.

How does Patent 7,530,461 compare with ordinary cystoscopy patents?

Patent 7,530,461 is primarily a chemical-use and clinical-procedure patent. It claims what is administered, how long it remains in the bladder, how fluorescence is generated, and how lesions are detected or treated.

A cystoscope or imaging-system patent generally claims:

• Optical filters.
• Excitation-light sources.
• Image sensors.
• Fluorescence detection.
• Switching between white and blue light.
• Image processing.
• Lesion mapping.
• Display systems.

A company may therefore avoid Patent 7,530,461 by changing the HAL protocol but still infringe a separate device or imaging patent. Conversely, a device manufacturer may have freedom to operate with respect to the expired HAL method claims while still needing authorization for third-party hardware or software rights.

What litigation and settlement issues should be reviewed?

The principal litigation questions are:

1. Whether Photocure asserted Patent 7,530,461 against an ANDA applicant.
2. Whether any case produced a claim-construction ruling.
3. Whether the patent was challenged under invalidity or written-description theories.
4. Whether a settlement imposed a delayed-entry date.
5. Whether the settlement included a license to other Photocure patents.
6. Whether any agreement involved reverse payment, authorized generic rights, supply rights, or territorial restrictions.

A patent that has expired may still matter historically if a settlement established a launch date or included cross-license terms extending beyond the patent’s expiration. The enforceable value of such provisions depends on the agreement and the legal basis for the restriction, not simply on the patent’s former validity.

What is the geographic coverage of the HAL patent family?

The United States patent covers U.S. activity only. Corresponding applications or national-stage patents may have existed in Europe and other jurisdictions, but each country applies its own:

• Patent-term calculation.
• Patentability standard.
• Supplementary protection certificate rules.
• Claim construction.
• Regulatory linkage.
• Litigation procedure.
• Exhaustion doctrine.

A U.S. expiration does not establish expiration in Europe, Japan, Canada, or other markets. Commercial launch planning requires a country-by-country family and legal-status review through the relevant patent offices and national registers. WIPO PATENTSCOPE and USPTO records provide the principal starting points for family identification and prosecution history. [1][6]

Key Takeaways

• U.S. Patent 7,530,461 covers HAL-based fluorescence diagnosis and photodynamic treatment of bladder abnormalities.
• Claims 1-2 cover an ex vivo urine-cell assay with highly specific medium, concentration, incubation, and wavelength conditions.
• Claims 3-4 cover intravesical HAL diagnosis using an 8 mM formulation and one-hour dwell time.
• Claims 5-8 cover a combined HAL imaging, lesion-resection, and photodynamic-treatment protocol.
• Carcinoma in situ is expressly covered by dependent claims 2, 4, and 6.
• The patent is expired and is not a current standalone U.S. exclusion right.
• Cysview’s FDA approval is tied to fluorescence-guided bladder imaging with the D-Light PDD system, not to the full therapeutic scope of claim 5.
• Current commercial risk depends on other patents, Orange Book listings, regulatory requirements, device compatibility, manufacturing rights, and know-how.
• A generic entrant should analyze the entire HAL patent family and current Orange Book record rather than relying on Patent 7,530,461 alone.

Frequently Asked Questions

Does U.S. Patent 7,530,461 cover Cysview itself?

No. The patent primarily covers methods using HAL for bladder-cell diagnosis, fluorescence cystoscopy, lesion resection, and photodynamic treatment. It is not a broad composition claim to every Cysview formulation.

Does the patent cover white-light cystoscopy?

No. The claims require HAL administration or HAL exposure and specified fluorescence-related steps. Conventional white-light cystoscopy without the claimed HAL protocol is outside the literal scope of the patent.

Does claim 5 cover treatment of carcinoma in situ?

Yes. Claim 6 depends on claim 5 and expressly identifies carcinoma in situ. Claim 5 also requires the full treatment sequence and specified light-dose and fluence ranges.

Can a generic manufacturer avoid the patent by changing the HAL concentration?

During the patent term, changing concentration could avoid literal infringement if the new concentration falls outside the claimed range or specified value. Because the patent has expired, the immediate U.S. issue is more likely to involve other unexpired patents and FDA requirements.

Does U.S. expiration eliminate European HAL patent risk?

No. Patent rights are territorial. U.S. expiration does not determine the status of corresponding patents, supplementary protection certificates, or litigation rights in Europe or other jurisdictions.

References

1. United States Patent and Trademark Office. (2009). U.S. Patent No. 7,530,461, methods for diagnosis and treatment using hexyl aminolevulinate.
2. United States Patent and Trademark Office. (n.d.). Patent Center: U.S. Patent No. 7,530,461 prosecution and term information.
3. U.S. Food and Drug Administration. (2024). Cysview (hexaminolevulinate hydrochloride) prescribing information. Photocure ASA.
4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
5. Karl Storz SE & Co. KG. (n.d.). Photodynamic diagnosis and D-Light PDD system materials.
6. World Intellectual Property Organization. (n.d.). PATENTSCOPE international patent database.

Drugs Protected by US Patent 7,530,461

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

Foreign Priority and PCT Information for Patent: 7,530,461

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9504948.2	Mar 10, 1995
United Kingdom	9525882.4	Dec 18, 1995

International Family Members for US Patent 7,530,461

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0820432		SPC024/2002	Ireland
European Patent Office	0820432		SPC/GB02/038	United Kingdom
European Patent Office	0820432		300176	Netherlands
European Patent Office	0820432		300207	Netherlands
European Patent Office	0820432		SPC/GB05/044	United Kingdom
European Patent Office	0820432		05C0042	France