U.S. Patent 4,617,319: Scope, Claims, Expiration, and Mitoxantrone Patent Landscape

U.S. Patent 4,617,319 covers parenteral treatment of neuroimmunologic diseases, particularly multiple sclerosis and acute disseminated encephalomyelitis, using mitoxantrone or its pharmacologically acceptable acid-addition salts. The patent issued on October 21, 1986, and its pre-URAA 17-year term expired in 2003. It does not create a current U.S. patent barrier to generic mitoxantrone injection.

What compound does U.S. Patent 4,617,319 protect?

The claimed compound is mitoxantrone, chemically identified as 1,4-dihydroxy-5,8-bis[[2-(2-hydroxyethylamino)ethyl]amino]anthracene-9,10-dione, commonly administered as mitoxantrone dihydrochloride.

The patent claim text supplied identifies the core compound as:

1,4-dihydroxy-5,8-bis[[2-(2-hydroxyethylamino)ethyl]amino]anthraquinone

In modern pharmaceutical nomenclature, the compound is generally described as an anthracenedione rather than simply an anthraquinone. The marketed form is mitoxantrone hydrochloride, usually formulated as an intravenous injection or concentrate for dilution.

The patent is therefore a method-of-treatment patent directed to the medical use of mitoxantrone. It is not principally a composition-of-matter patent covering the molecule in every use.

What are the claims of U.S. Patent 4,617,319?

The eight claims divide into two claim groups.

Claim group	Required elements	Practical scope
Claims 1-5	Parenteral administration, specified mitoxantrone compound or acid-addition salt, 0.25-0.5 mg/kg/day, neuroimmunologic disease	Dose-limited treatment claims
Claims 6-8	Parenteral administration of mitoxantrone or salt in a sufficient amount to palliate muscular weakness and paralysis	Symptom-palliation claims without the express dose range

How broad is independent claim 1?

Claim 1 requires all of the following:

A mammalian patient.
A neuroimmunologic disease.
Parenteral administration.
A daily dose of approximately 0.25 to approximately 0.5 mg/kg.
Mitoxantrone or a pharmacologically acceptable acid-addition salt.

The claim is narrower than a claim covering all therapeutic uses of mitoxantrone. It does not cover oral administration because the claim expressly requires parenteral delivery. It also does not cover every dose or every indication.

The phrase “from about 0.25 to about 0.5 mg per kilogram of body weight per day” creates a dose limitation. A commercial regimen materially outside that range would present a weaker literal-infringement case, although the meaning of “about” would depend on the patent, prosecution history, clinical practice, and applicable claim-construction principles.

What does claim 2 add?

Claim 2 limits claim 1 to the dihydrochloride salt of mitoxantrone.

The text supplied states:

4-dihydroxy-5,8-bis[[2-(2-hydroxyethylamino)ethyl]amino]anthraquinone, dihydrochloride

The chemical name appears to omit the “1-” locant used in the corresponding compound description. Read in context, claim 2 is directed to mitoxantrone dihydrochloride, the clinically relevant salt.

What does claim 3 add?

Claim 3 limits administration to the intraperitoneal route.

This limitation is commercially important because standard mitoxantrone products for multiple sclerosis are administered intravenously. An intravenous regimen would not literally satisfy the intraperitoneal limitation in claim 3, although it could remain within claim 1 or another applicable claim if the other limitations are met.

What do claims 4 and 5 cover?

Claims 4 and 5 narrow claim 1 to two named diseases:

Claim 4: multiple sclerosis.
Claim 5: acute disseminated encephalomyelitis.

These are dependent claims and retain the requirements of claim 1, including parenteral administration and the specified dose range.

What does independent claim 6 cover?

Claim 6 covers parenteral treatment of neuroimmunologic diseases with mitoxantrone or an acid-addition salt in an amount sufficient to palliate muscular weakness and paralysis.

Compared with claim 1, claim 6:

Does not state the 0.25-0.5 mg/kg/day range.
Requires palliation of muscular weakness and paralysis.
Uses “an sufficient amount” in the supplied text, which appears to be a grammatical drafting error for “a sufficient amount.”
Covers treatment of neuroimmunologic disease in mammals.

The symptom-palliation requirement is central. Administration of mitoxantrone for a different purpose, such as treatment of leukemia, would not ordinarily satisfy claim 6 unless the claimed disease and symptom-palliation limitations were also present.

Claims 7 and 8 narrow claim 6 to multiple sclerosis and acute disseminated encephalomyelitis, respectively.

How do the claims differ from modern mitoxantrone use in multiple sclerosis?

The principal U.S. multiple-sclerosis use of mitoxantrone developed around intravenous treatment of worsening relapsing-remitting, progressive-relapsing, or secondary-progressive multiple sclerosis. The FDA-approved product labeling described dosing in mg/m², commonly 12 mg/m² by short intravenous infusion at three-month intervals, subject to cumulative-dose restrictions and cardiac monitoring requirements.[2]

That regimen differs materially from the claim 1 expression of 0.25-0.5 mg/kg/day. Dose conversion is not interchangeable because mg/kg/day and mg/m² administered intermittently describe different dosing frameworks.

Issue	Patent claims	Typical FDA-labeled MS use
Route	Parenteral; claim 3 specifies intraperitoneal	Intravenous
Dose format	0.25-0.5 mg/kg/day in claim 1	mg/m² at periodic intervals
Disease	Neuroimmunologic disease; MS expressly listed	Worsening forms of multiple sclerosis
Salt	Mitoxantrone and acid-addition salts	Mitoxantrone hydrochloride
Symptom limitation	Required by claim 6	Not necessarily expressed as muscular weakness and paralysis
Current patent status	Expired	Product use governed by current label and regulatory controls

The difference does not by itself establish noninfringement. Patent analysis would require the complete patent, prosecution history, claim construction, actual regimen, indication, and prescribing instructions. The expired status of the patent is dispositive for current U.S. enforcement, however.

When did U.S. Patent 4,617,319 expire?

U.S. Patent 4,617,319 issued on October 21, 1986.[1] Because it was filed before June 8, 1995, its ordinary term was generally 17 years from the issue date, subject to any terminal disclaimer or applicable adjustment.

On that basis, the patent expired in October 2003. The patent is therefore no longer enforceable in the United States. Its claims cannot support a current infringement action against a generic mitoxantrone manufacturer or a product sponsor.

Patent	Subject	Issue date	Ordinary term basis	Expiration
U.S. 4,617,319	Parenteral mitoxantrone treatment of neuroimmunologic disease	Oct. 21, 1986	17 years from issue for pre-URAA patent	Oct. 2003

Patent expiration does not erase the historical scope of the claims. It removes the right to exclude others from practicing them.

What is the Orange Book status of mitoxantrone?

Mitoxantrone hydrochloride injection has been regulated as a small-molecule drug under the FDA’s NDA and ANDA framework. The FDA Orange Book identifies approved products, reference listed drugs, therapeutic equivalence information, and patent or exclusivity information associated with approved applications.[3]

U.S. Patent 4,617,319 is no longer a live patent barrier because its term expired in 2003. Any historical Orange Book listing would not restore enforceability after expiration.

For present commercial analysis, the relevant conclusion is:

No current exclusivity can arise from U.S. Patent 4,617,319.
A generic applicant would address current listed patents, if any, through the applicable ANDA certification process.
The expired patent cannot support a Paragraph IV litigation strategy.
The patent does not block approval or launch of an otherwise approvable generic mitoxantrone product.

FDA regulatory approval and patent enforceability are separate issues. A product may remain subject to manufacturing, labeling, safety, and quality requirements even after all relevant patents expire.

Are there current Paragraph IV challenges involving this patent?

No current Paragraph IV challenge can be based on U.S. Patent 4,617,319 because the patent expired long ago.

A Paragraph IV certification applies when an ANDA applicant asserts that a listed patent is invalid, unenforceable, or will not be infringed. The statutory litigation consequences associated with such a certification depend on the patent remaining relevant to the approved drug application and having enforceable term remaining.[4]

For this patent:

Paragraph IV issue	Assessment
Patent alive?	No
Patent term remaining?	No
Current Paragraph IV leverage?	None
30-month stay risk based on this patent?	None
Historical litigation relevance	Possible only as a matter of patent history

A generic applicant could still face litigation based on other patents, contractual claims, trade-secret allegations, regulatory exclusivity, or product-specific intellectual-property rights. Those issues are distinct from U.S. Patent 4,617,319.

What formulation patents protect mitoxantrone products?

U.S. Patent 4,617,319 does not claim a particular commercial vial, stabilizer system, preservative combination, concentration, container, or manufacturing process. Its claims focus on therapeutic administration.

Potentially relevant later rights in a mitoxantrone product landscape could include:

Injectable formulation claims.
Stability and storage claims.
Container-closure systems.
Pharmaceutical compositions with specified excipients.
Manufacturing or purification processes.
Labeling or method-of-use claims.
Pediatric, dosing, or administration protocols.

Those categories must be analyzed separately from the patent at issue. Based on the claims supplied, U.S. 4,617,319 does not create a formulation monopoly over mitoxantrone injection.

Does the patent create biosimilar risk?

No. Mitoxantrone is a chemically synthesized small molecule, not a biologic requiring a biosimilar application under the Public Health Service Act.

Competitive products are generally reviewed through the ANDA pathway as generic drugs, assuming the product is eligible for an abbreviated application and has the required pharmaceutical equivalence and bioequivalence characteristics. The relevant competitive risk is generic entry, not biosimilar substitution.

Which companies challenged or competed against the patent?

The patent was associated with the early development of mitoxantrone for neuroimmunologic disease. Commercial competition later developed through generic mitoxantrone hydrochloride injection products after patent and regulatory barriers diminished.

The expired patent does not identify a current challenger universe. Current competition depends on:

Active FDA-approved mitoxantrone injection products.
Product availability and manufacturing capacity.
ANDA approvals and therapeutic-equivalence ratings.
Hospital purchasing contracts.
Supply continuity.
Cardiotoxicity and secondary-leukemia warnings that limit clinical use.

Because mitoxantrone is an older product with limited demand relative to major multiple-sclerosis therapies, manufacturing economics and supply reliability can matter more than the expired patent estate.

How strong is the patent estate for mitoxantrone?

The estate represented by U.S. Patent 4,617,319 is legally inactive and commercially weak as a current exclusion right.

Strength factor	Assessment
Composition-of-matter protection	Not established by the supplied claims
Method-of-use coverage	Yes, focused on neuroimmunologic disease
Dose limitation	Narrow in claim 1
Route limitation	Parenteral generally; intraperitoneal in claim 3
Named indications	Multiple sclerosis and acute disseminated encephalomyelitis
Formulation protection	Not apparent from the supplied claims
Manufacturing protection	Not apparent from the supplied claims
Remaining term	None
Current litigation leverage	None

Historically, the claims could have supported a method-of-treatment position against a product promoted for the claimed diseases and administered under the claimed parameters. Today, that position has no enforceable patent value in the United States.

What licensing and settlement issues matter?

The patent’s expiration eliminates prospective patent-license value for the claimed U.S. methods. Historical licenses, settlements, or development agreements may still matter for chain-of-title analysis, royalty accounting, or damages disputes covering the pre-expiration period.

No licensing or settlement right can extend the statutory patent term absent a separate contractual arrangement. A commercial agreement also would not create patent exclusivity against unrelated generic manufacturers.

What generic launch risks exist for mitoxantrone?

A generic launch is not blocked by U.S. Patent 4,617,319. The principal risks are regulatory and operational:

Product quality and sterility for an injectable drug.
Bioequivalence and pharmaceutical equivalence requirements.
Supply of active pharmaceutical ingredient.
Stability and container-closure validation.
Labeling alignment with the reference product.
Limited market size and uncertain contracting economics.
Safety monitoring obligations, including cardiac toxicity and treatment-related leukemia risks.[2]

The patent landscape therefore supports a low patent-entry barrier but not necessarily a low commercial-risk profile.

What is the geographic coverage of U.S. Patent 4,617,319?

The patent had territorial effect only in the United States. Foreign counterparts, if any, would require separate analysis of national filings, grants, term adjustments, supplementary protection certificates, and local litigation.

The U.S. patent’s expiration does not determine the status of corresponding rights in Europe, Canada, Japan, or other jurisdictions. A global launch assessment cannot rely on the U.S. patent number alone.

Key Takeaways

U.S. Patent 4,617,319 claims parenteral mitoxantrone treatment for neuroimmunologic diseases.
Claims 4 and 7 specifically address multiple sclerosis; claims 5 and 8 address acute disseminated encephalomyelitis.
Claim 1 is limited by a 0.25-0.5 mg/kg/day dose range.
Claim 6 is not dose-limited in the same way but requires palliation of muscular weakness and paralysis.
The patent issued on October 21, 1986, and expired in October 2003.
It is not a current U.S. patent barrier to generic mitoxantrone.
Mitoxantrone is a small molecule, so generic competition proceeds through the ANDA framework rather than a biosimilar pathway.
The claims do not, on their face, establish formulation or manufacturing protection.
Current commercial risks are more likely to involve injectable-drug manufacturing, supply, safety, and market economics than patent enforcement.

FAQs

Is mitoxantrone still protected by the original composition patent?

The claims supplied for U.S. Patent 4,617,319 are method claims, not broad composition-of-matter claims. In any event, the patent expired in 2003.

Does U.S. Patent 4,617,319 cover intravenous mitoxantrone?

Claim 1 covers parenteral administration, which can include intravenous administration. Claim 3 is narrower and expressly requires intraperitoneal administration.

Can a generic manufacturer sell mitoxantrone for multiple sclerosis today?

The expired patent does not prevent sale. The manufacturer must still satisfy FDA requirements for an approved generic injectable product, including quality, manufacturing, labeling, and bioequivalence requirements.

Does the patent cover all neuroimmunologic diseases?

Claims 1 and 6 use the broader category of neuroimmunologic diseases, but the claims remain subject to their other limitations. Dependent claims specifically identify multiple sclerosis and acute disseminated encephalomyelitis.

Is acute disseminated encephalomyelitis an FDA-approved mitoxantrone indication?

The patent claims acute disseminated encephalomyelitis as a claimed disease. A patent claim does not establish FDA approval. Regulatory status must be determined from the approved product labeling and FDA application history.

References

U.S. Patent and Trademark Office. (1986). U.S. Patent No. 4,617,319, Treatment of neuroimmunologic diseases.
U.S. Food and Drug Administration. (2020). Novantrone (mitoxantrone hydrochloride) injection prescribing information.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application abbreviated approval process.

Details for Patent: 4,617,319

Summary for Patent: 4,617,319