US Patent 6,017,922: Claim Scope, Crystal-Form Protection, Expiration, and Patent Landscape

US Patent 6,017,922 protects a specific solid form of 2,4-diamino-5-methyl-6-[(3,4,5-trimethoxyanilino)methyl]quinazoline, particularly its crystalline monohydrate. The patent does not claim a broad quinazoline genus, a manufacturing process, or a method of treating disease. Its commercial value depends on whether a product uses the claimed non-salt hydrate or an equivalent crystalline form.

The patent issued on January 25, 2000. Its ordinary US patent term has expired, at the latest, by January 25, 2020, and likely ended earlier because US patent term generally runs 20 years from the relevant nonprovisional filing date rather than from issuance.[1,2] The patent therefore does not currently block generic manufacture in the United States, subject to separate rights covering the active compound, formulation, manufacturing process, or approved method of use.

What compound does US Patent 6,017,922 protect?

The patent covers a 2,4-diamino quinazoline derivative with the following structural substituents:

Structural element	Claimed feature
Core	Quinazoline
Positions 2 and 4	Amino groups
Position 5	Methyl group
Position 6	[(3,4,5-trimethoxyanilino)methyl] substituent
Salt state	Non-salt form
Solid state	Solvate, hydrate, crystalline hydrate, or monohydrate
Pharmaceutical use in claims	Composition with a pharmaceutically acceptable carrier

The patent is principally a solid-state and pharmaceutical-composition patent. The central commercial subject is the non-salt monohydrate, not merely the underlying quinazoline molecule.

The claim set does not identify a generic name, approved drug name, dosage strength, disease indication, route of administration, or clinical use. The patent claims therefore do not establish that the compound became an FDA-approved active ingredient or that it generated branded-product revenue.

How many patents and claims cover the compound?

The patent contains 19 claims. The claims divide into four protection groups.

Claim group	Claims	Subject matter	Practical scope
Non-salt compound and solvates	1-7	Thermally stable non-salt compound, solvates, hydrate, purity and sterility	Broadest composition coverage within this patent
Crystalline hydrate	8-9	Thermally stable crystalline non-salt hydrate and monohydrate	Solid-form protection
Monohydrate crystal	10-16	Monohydrate, crystalline monohydrate, XRPD pattern, crystal data, space group and unit-cell dimensions	Narrower polymorph and crystallographic coverage
Pharmaceutical compositions	17-19	Compound or crystalline monohydrate with pharmaceutically acceptable carrier	Product and formulation coverage

The patent has one independent compound claim, one independent crystalline-hydrate claim, one independent monohydrate claim, and two independent composition claims. Claims 2 through 7, 9, and 12 through 16 are dependent or narrower versions of those core concepts.

What does claim 1 protect?

Claim 1 covers:

A thermally stable non-salt 2,4-diamino-5-methyl-6-[(3,4,5-trimethoxyanilino)methyl]quinazoline.

A product would generally need to satisfy all of the following limitations:

The specified quinazoline chemical structure.
A non-salt form.
The “thermally stable” limitation.

The claim is broader than the monohydrate claims because it does not expressly require crystallinity, hydration, a particular polymorph, or a defined diffraction pattern. It could potentially reach multiple non-salt solid forms if the accused material meets the thermal-stability limitation.

The main claim-construction issue is the meaning of “thermally stable.” The claims supplied do not provide a numerical temperature threshold, decomposition criterion, storage period, or analytical test. The specification and prosecution history would control how that phrase is construed. A challenger could argue that the term is indefinite or lacks objective boundaries. The patent owner would likely argue that the specification provides comparative thermal data and identifies the claimed form by its stability behavior.

What formulations and solid forms are protected?

Claims 2 through 16 protect solid-state variants.

Solvates and hydrates

Claim 2 covers a thermally stable non-salt solvate. Claim 3 narrows the solvate to a hydrate, and claim 4 narrows it further to a monohydrate.

A hydrate contains water associated with the active compound in a defined solid form. A monohydrate nominally contains one water molecule per molecule of active compound, although the legal analysis depends on the specification’s analytical definition and the actual composition of the accused product.

Claims 8 through 11 move from a general hydrate to a crystalline monohydrate. Claim 10 covers the monohydrate without expressly requiring crystallinity, while claim 11 expressly requires a crystalline monohydrate.

XRPD and crystallographic limitations

Claim 12 requires an X-ray powder diffraction pattern essentially the same as Figure 1. This is a fingerprint-style limitation. Infringement would normally require comparison of the accused material’s diffraction pattern against the claimed pattern, accounting for instrument conditions, peak positions, intensities, and permissible variation.

Claim 13 refers to atomic coordinates determined from an X-ray powder diffraction pattern and requires coordinates essentially the same as Table 2. This language is unusual because atomic coordinates are ordinarily associated with single-crystal structural analysis, while XRPD generally supplies powder diffraction data and unit-cell information. The specification and file history would be important in determining whether the claim is directed to actual atomic positions, calculated structural parameters, or a defined powder pattern.

Claim 15 narrows the crystalline monohydrate to:

Space group P-1, identified in the claim text as “PT(#2)”;
A triclinic unit cell;
a = 7.699 Å;
b = 9.606 Å;
c = 13.012 Å.

The claim text does not list unit-cell angles. That omission may limit the usefulness of the dimensional limitations as a complete crystallographic identifier. It may also create an invalidity or claim-construction issue if the patent specification does not supply adequate angular or measurement parameters.

How strong are the claims?

The strongest practical claims are likely claims 10, 11, and 15, provided the patent’s disclosed monohydrate can be reliably identified in commercial material.

Strengths

The patent has several features that can support enforcement:

It identifies a defined chemical compound rather than an open-ended genus.
It distinguishes the non-salt form from salts.
It claims the hydrate and monohydrate specifically.
It includes crystalline-form limitations.
It provides XRPD and crystallographic identifiers.
It includes pharmaceutical-composition claims directed to products containing the claimed form.

These limitations can make an infringement case analytically manageable when the accused active ingredient is available for solid-state testing.

Vulnerabilities

The patent also has potential weaknesses:

“Thermally stable” may lack an objective boundary.
“Substantially pure” may be indefinite without a stated impurity threshold.
“Sterile” may describe a product condition rather than a distinctive chemical form.
“Essentially the same” XRPD language requires interpretation of acceptable variation.
Claim 13 may conflate atomic-coordinate data with powder-diffraction data.
Claim 15 may not fully define the crystal structure because the unit-cell angles are omitted.
A prior publication or patent may have disclosed the same compound, hydrate, or crystalline form before the relevant priority date.
The monohydrate may be inherently present in earlier preparations even if the prior art did not use the same crystallographic terminology.

The broadest claim, claim 1, may face greater prior-art exposure than the narrower crystal-form claims. The narrower claims may be easier to prove against a product but more vulnerable if the same monohydrate was previously obtainable or inherently produced.

When did US Patent 6,017,922 lose exclusivity?

US Patent 6,017,922 issued on January 25, 2000.[1] Under the modern US patent-term framework, the relevant term ordinarily ends 20 years after the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and transitional rules.[2]

The patent could not ordinarily remain enforceable merely because it issued in 2000. Its enforceable term ended by 2020 at the latest and likely before that date. There is no basis in the claim text alone to assign pediatric exclusivity, a Hatch-Waxman patent-term extension, or a regulatory exclusivity period.

Event	Date or status
Patent issued	January 25, 2000
Ordinary maximum based on issue date	No later than January 25, 2020
Actual statutory expiration	Based on relevant filing date and any PTA/PTE
Current status	Expired under the ordinary US term framework
Current Paragraph IV blocking period	None based solely on this patent

A precise expiration date requires the patent front page, priority chain, USPTO maintenance records, and any terminal disclaimer or term-adjustment data. The claim text does not establish those details.

What is the Orange Book status of this patent?

US Patent 6,017,922 is not, based on the claim subject matter alone, an Orange Book patent. The Orange Book lists patents submitted for approved drug products, including patents covering active ingredients, formulations, compositions, and approved methods of use.[3]

The patent claims a specific chemical form and pharmaceutical compositions but do not identify:

An FDA-approved product;
A New Drug Application;
An approved sponsor;
A dosage form;
An approved indication;
A product trade name;
A listed therapeutic method.

Accordingly, there is no demonstrated Orange Book listing or Paragraph IV litigation associated with this patent solely from the information provided. If the compound was never approved, the patent would have had no Hatch-Waxman listing or ANDA certification role.

Are there Paragraph IV challenges or generic-entry risks?

No Paragraph IV challenge can be established from the patent number and claims alone. Paragraph IV certifications arise only when a patent is listed against an FDA-approved reference product and an ANDA applicant challenges that listed patent.[3]

Because the patent has expired under the ordinary term framework, it no longer creates a current Paragraph IV barrier. A generic or follow-on manufacturer could still face other risks if separate unexpired patents cover:

The underlying active compound;
A different polymorph;
A salt or co-crystal;
A formulation or dosage form;
A manufacturing process;
An approved method of treatment;
A combination product;
A device or delivery system.

The expiration of US 6,017,922 does not establish freedom to operate for the entire product technology.

Does the patent create biosimilar risk?

No. Biosimilar law applies to biological products, while the claimed subject matter is a synthetic quinazoline small molecule.[4] The relevant competitive pathway would be an ANDA or, if no reference product exists, a full NDA or another applicable small-molecule regulatory pathway. A 351(k) biosimilar application would not be the normal route for this compound.

What manufacturing and intellectual-property barriers remain?

The patent does not claim a manufacturing process. A manufacturer could therefore avoid direct infringement of process claims because none are present in the supplied claims. The patent may still have covered the isolated product obtained by a process if the resulting material met the product or crystal-form limitations, but that issue would depend on actual product testing.

The most important manufacturing questions are:

Whether crystallization produces the claimed monohydrate.
Whether drying converts the monohydrate into an anhydrate or another form.
Whether residual water levels fall within the claimed hydrate definition.
Whether the finished dosage form contains the claimed crystalline form.
Whether the material’s XRPD pattern matches Figure 1.
Whether the product meets the claimed purity and thermal-stability limitations.

A deliberate process design that produces a different salt, amorphous form, polymorph, solvate, or anhydrate could avoid some narrower claims. It would not necessarily avoid claim 1 if the resulting material remains the claimed thermally stable non-salt compound.

How does this patent compare with a broad active-ingredient patent?

Issue	US 6,017,922	Broad compound patent
Primary subject	Non-salt hydrate and crystalline monohydrate	Chemical genus or active molecule
Solid-state specificity	High	Often low
Process claims	None in supplied claims	May include synthesis claims
Treatment claims	None in supplied claims	May include therapeutic methods
Infringement proof	Chemical analysis and XRPD	Chemical identity and use evidence
Design-around potential	Moderate to high through alternate forms	Often lower if molecule itself is claimed
Current US term	Expired	Depends on separate patent

US 6,017,922 is best characterized as a product-form patent. Its historical value would have been highest where the monohydrate improved handling, thermal stability, manufacturability, shelf life, or pharmaceutical processing.

What licensing and commercial exposure can be inferred?

No licensing transaction, assignee transfer, approved product, or revenue stream can be established from the claims alone. The patent does not identify a commercial sponsor or marketed drug. Its current direct revenue exposure is therefore zero as an enforceable US patent right after expiration.

Historical value could have arisen through:

Exclusive rights to a stable drug substance;
A license to a development-stage kinase-inhibitor program;
Supply of the monohydrate for clinical or commercial manufacture;
Settlement leverage against a competing solid form;
Protection of a pharmaceutical composition during development.

Those commercial conclusions require evidence outside the claim set, such as assignment records, SEC filings, licensing announcements, clinical-trial records, FDA databases, and litigation dockets.

Key Takeaways

US 6,017,922 claims a thermally stable non-salt quinazoline and, most specifically, its crystalline monohydrate.
Claims 10, 11, and 15 are the principal solid-form claims.
Claims 12 and 13 rely on XRPD and crystallographic identifiers.
Claims 17 through 19 cover pharmaceutical compositions containing the compound or crystalline monohydrate.
The patent does not claim a manufacturing process, treatment method, dosage regimen, or broad quinazoline genus.
The patent issued on January 25, 2000 and expired under the ordinary US term framework no later than January 25, 2020.
No current Paragraph IV barrier or biosimilar issue follows from this patent.
Current freedom to operate depends on separate patents covering the molecule, alternate solid forms, formulations, manufacturing methods, or therapeutic use.
The principal validity risks concern prior disclosure of the hydrate, indefiniteness of “thermally stable” and “essentially the same,” and the technical precision of the XRPD and crystallographic limitations.

Frequently Asked Questions

Is US Patent 6,017,922 a polymorph patent?

Yes. Its central claims cover a crystalline monohydrate and identify the form through XRPD, unit-cell dimensions, and space-group information.

Can an anhydrous form avoid this patent?

An anhydrous form may avoid claims limited to a hydrate or monohydrate, but it could still implicate claim 1 if it is the claimed thermally stable non-salt compound.

Does this patent claim the active ingredient itself?

Claim 1 claims the specified non-salt compound, subject to the “thermally stable” limitation. The later claims focus on solvates, hydrates, crystalline forms, and compositions.

Would a salt formulation infringe the principal claims?

A salt would generally fall outside claims expressly limited to a non-salt form, although separate patents or product-by-process theories could create other issues.

Is an FDA-approved generic required to avoid the crystalline monohydrate claims?

No. The patent has expired under the ordinary term framework. Regulatory approval remains necessary to market a drug, but this patent no longer supplies an enforceable US exclusion right.

References

United States Patent and Trademark Office. (2000). US Patent No. 6,017,922.
United States Code, 35 U.S.C. §§ 154, 156, and 271.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (2024). Biosimilar and interchangeable biosimilar products.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	4081799	⤷ Start Trial
Brazil	9910543	⤷ Start Trial
Canada	2333274	⤷ Start Trial
European Patent Office	1080079	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,017,922

Summary for Patent: 6,017,922