US Patent 9,469,643: Scope, Claim Construction, Patent Strength, and Generic Entry Risk

US Patent 9,469,643 claims a specific crystalline form, Form II, of the small-molecule compound (S)-2-(1-(9H-purin-6-ylamino)propyl)-5-fluoro-3-phenylquinazolin-4(3H)-one. The patent does not, based on the supplied claims, broadly claim the active compound, all solid forms, formulations, therapeutic uses, or manufacturing routes. Its principal value is protection of Form II and selected processes that convert Form I into Form II.

The claim set is narrow in chemical subject matter but potentially meaningful commercially if Form II is the drug substance used in an approved product or is required for acceptable stability, purity, dissolution, or manufacturing performance.

What compound and solid form does US 9,469,643 protect?

The patent protects Form II of a defined stereochemically pure quinazolinone-purine compound. Claim 1 identifies Form II through three characteristic powder X-ray diffraction peaks:

Claim element	Limitation
Chemical entity	(S)-2-(1-(9H-purin-6-ylamino)propyl)-5-fluoro-3-phenylquinazolin-4(3H)-one
Solid-state form	Polymorph Form II
Analytical definition	XRPD peaks at 14.0°, 18.6°, and 24.3° 2θ
Tolerance	Plus or minus 0.2° 2θ
Claim type	Product claim defined partly by physical characteristics

Claim 1 is the principal composition-of-matter claim. It does not require a particular particle size, purity, solvent content, water content, crystal habit, or pharmaceutical formulation based on the text supplied.

The claim is limited to the specified enantiomer. A racemate, the opposite enantiomer, or a different stereochemical mixture would not meet the literal stereochemical limitation unless another legal theory applied.

How broad is claim 1 for Form II?

Claim 1 is broader than claim 2 because it requires only the three recited characteristic XRPD peaks, within the stated angular tolerance, rather than an XRPD pattern substantially as shown in Figure 2A.

The main infringement questions would be:

Whether the accused material contains the claimed chemical compound.
Whether the material is Form II rather than Form I, an amorphous solid, a hydrate, a solvate, or another polymorph.
Whether the accused XRPD pattern includes the claimed peaks at the required positions.
Whether the peaks are characteristic peaks of the relevant crystalline phase rather than incidental or mixed-phase signals.

A material may contain Form II without being entirely Form II. Claim 1 does not expressly require a minimum percentage of Form II. Claim 6 also expressly contemplates conversion of only “at least a portion” of Form I into Form II. The interpretation of claim 1 in a mixed-polymorph situation would depend on the full specification, prosecution history, expert evidence, and the court’s construction of “polymorph.”

What does the plus-or-minus 0.2° limitation mean?

The three peak positions are subject to a numerical tolerance of 0.2° 2θ. A tested peak at approximately 13.9°, 18.7°, or 24.4° could fall within the literal range, subject to the applicable measurement method and instrument conditions.

XRPD peak positions can vary with instrument calibration, sample preparation, radiation source, crystallinity, preferred orientation, temperature, and residual solvent. Peak intensity is not recited in claim 1. A potentially infringing sample therefore cannot be cleared solely by comparing relative peak intensities.

What additional protection does claim 2 provide?

Claim 2 requires the Form II polymorph of claim 1 to have an XRPD pattern “substantially as shown in FIG. 2A.”

This claim is narrower than claim 1 in practical terms, although “substantially as shown” may create construction issues. The claim potentially captures the full diffraction fingerprint associated with Form II, including peaks not individually listed in claim 1.

Claim 2 may be useful where an accused product has the three claim 1 peaks but differs in other diffraction characteristics. It also creates a potential evidentiary issue because the legal meaning of “substantially” must be determined from the specification and Figure 2A.

How do claims 3 through 6 protect Form II manufacturing?

Claims 3 through 6 are product-by-process claims. They identify Form II by reference to the process used to obtain it.

Claim	Process limitation	Commercial significance
3	Grind Form I, then stir the ground Form I in a solvent	Covers a conversion route from Form I
4	Stir at about 10°C to 25°C	Narrows claim 3 to near-ambient conditions
5	Grinding with listed equipment or combinations	Defines permitted milling and grinding methods
6	Compress Form I at about 500 to 5,000 psi	Covers pressure-induced conversion to Form II

Claim 3 requires both grinding and solvent stirring. A process that only stirs unground Form I, or only grinds without the solvent-stirring step, would not literally satisfy claim 3.

Claim 4 adds a temperature range. “Between about 10°C and 25°C” may raise questions concerning the scope of “about,” particularly at the endpoints and under manufacturing tolerances.

Claim 5 identifies a broad set of equipment:

Mortar and pestle
High-shear wet mill
High-shear dry mixer
Jet mill
Ball mill
Combinations of those devices

The equipment limitation may be important in process litigation but does not necessarily expand the underlying Form II product claim.

Claim 6 is distinct because it covers compression of Form I at 500 to 5,000 psi, with conversion of at least part of Form I into Form II. It does not require solvent stirring. A tablet-compression, roller-compaction, or other pressure operation could be relevant if it falls within the claim’s construction of “compressing” and produces the claimed polymorph.

What does the patent not claim?

Based on the supplied claims, US 9,469,643 does not expressly claim:

The compound in every crystalline or amorphous form
Form I as a standalone product
Other polymorphs
Hydrates or solvates unless they also satisfy the Form II limitations
Pharmaceutical compositions
Tablets, capsules, injectables, or other dosage forms
Specific excipients
Therapeutic treatment methods
Dosage regimens
Combination therapy
The active compound’s salt forms
A broad synthetic route to the compound
A generic process for producing any polymorph
Analytical methods other than the XRPD-defined product limitations

This distinction is central. A competitor that produces the same active compound in Form I or an unrelated solid form may avoid these claims, provided the product does not contain or convert into the claimed Form II and does not practice one of the claimed conversion processes.

How strong is the patent estate for this compound?

The supplied claim set indicates a focused solid-state patent rather than a complete life-cycle patent estate.

Protection category	Covered by supplied claims?	Assessment
New chemical entity	No	No broad compound claim is supplied
Stereoisomer	Indirectly, as part of Form II	Limited to the claimed Form II
Form II polymorph	Yes	Core protection
Form I polymorph	No	Used as a starting material in process claims
Other polymorphs	No	Not expressly covered
Manufacturing process	Yes, for selected conversions	Narrow route-specific protection
Formulation	No	No composition claim supplied
Method of use	No	No therapeutic-use claim supplied
Commercial product	Potentially, if it contains Form II	Depends on product composition
Generic drug substance	Potentially	Only if the generic uses or produces Form II

The patent can be commercially strong even with narrow claims if Form II is the selected development form and alternative forms have inferior properties. Its practical strength depends on whether Form II is necessary for the reference product and whether competitors can develop a noninfringing polymorph or amorphous form.

What patent expiration date applies to US 9,469,643?

The expiration date cannot be calculated reliably from the patent number and supplied claims alone. US pharmaceutical patent term generally runs 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory limits.[1][2]

The relevant commercial date may differ from the nominal patent expiration date because:

Patent-term adjustment may extend the term.
Patent-term extension under 35 U.S.C. § 156 may apply to an approved product.
A terminal disclaimer may shorten the term.
Regulatory exclusivity may expire before or after the patent.
Related continuation, divisional, or reissue patents may create separate expiration dates.

The patent number itself does not establish the term end date.

What is the Orange Book status of the compound and patent?

The supplied claims do not establish whether the compound is an FDA-approved drug or whether US 9,469,643 is listed in the FDA Orange Book.[3]

Orange Book listing requires an approved NDA product and a patent submission accepted under FDA listing rules. A polymorph patent may be listed if it claims the drug substance, drug product, or an approved method of use in a manner meeting the statutory and regulatory requirements. A patent directed only to a manufacturing process generally has a different listing analysis from a patent claiming the active ingredient or drug product.[3][4]

The relevant Orange Book questions are:

Issue	Effect
Approved NDA exists	Enables Orange Book patent listing
Form II is the approved drug substance	Makes drug-substance listing more commercially relevant
Patent claims the approved drug substance	Supports potential listing analysis
Patent claims only a manufacturing process	May not create the same ANDA certification position
Patent claims a method of use	Could support a use-patent listing
Patent listed before ANDA filing	May trigger a certification requirement

Nothing in the supplied claims identifies an NDA, product name, sponsor, listed patent use code, or Orange Book entry.

What Paragraph IV risks exist for a generic applicant?

A generic applicant could challenge the patent through a Paragraph IV certification if the patent is listed in the Orange Book and the applicant contends that the patent is invalid, unenforceable, or not infringed.[4]

The most plausible generic strategies are:

Form I or non-Form II product

A generic could seek approval using Form I, an amorphous form, a different polymorph, or a formulation that does not contain Form II. This strategy targets noninfringement rather than invalidity.

The risk is that Form I could partially convert to Form II during milling, compression, granulation, drying, storage, or formulation. Claims 3 through 6 are directed to precisely those types of transformations.

Polymorph identification challenge

A challenger could argue that Form II is anticipated or obvious in view of prior disclosures of the compound, Form I, crystallization conditions, solid-state screening, or known polymorph-selection techniques.

Potential validity issues include:

Anticipation by an earlier disclosure of Form II
Obviousness based on routine polymorph screening
Insufficient written description
Lack of enablement
Indefiniteness in terms such as “characteristic peaks” or “substantially as shown”
Ambiguity in product-by-process limitations

The validity analysis requires the patent specification, priority documents, prosecution history, and cited prior art.

Process avoidance

A generic may avoid claims 3 through 6 by using a different conversion route. That does not avoid claim 1 if the resulting drug substance is Form II. Conversely, using a different process may reduce process-claim exposure while leaving product-claim exposure unchanged.

Which manufacturing and IP barriers matter most?

The highest operational risk is unintended conversion into Form II. Solid-state conversion can occur during:

Dry milling
Wet granulation
Compression
Thermal treatment
Solvent exposure
Drying
Storage under humidity or temperature stress

A generic development program would typically need XRPD controls at multiple stages. A process that begins with Form I may still create an infringement issue if the final product contains the claimed Form II or if the process meets claim 6.

The strongest noninfringement position would generally involve a demonstrably different solid form, validated through XRPD and complementary solid-state testing. XRPD alone may not resolve all issues where mixtures, low-level conversion, solvates, or amorphous content are present.

Does this patent create biosimilar risk?

No conventional biosimilar pathway is implicated by the supplied claims. The claimed subject matter is a small-molecule polymorph, not a biologic. Any competitive entry would more likely proceed through an ANDA or another small-molecule pathway rather than a biosimilar application under the Public Health Service Act.

How does US 9,469,643 compare with a compound patent?

A compound patent generally protects the active molecule across multiple solid forms, formulations, and uses, depending on its claims. US 9,469,643 is narrower because it focuses on one polymorph and selected methods of producing it.

Patent type	Typical scope	Relative impact
Compound patent	Broad molecule and sometimes salts, stereoisomers, and uses	Usually highest barrier
Polymorph patent	Specific crystalline form	High if the form is commercially required
Formulation patent	Drug product and excipient system	Relevant to finished-dose competition
Method-of-use patent	Treatment indication or regimen	Can delay approval for protected uses
Process patent	Specific synthesis or conversion route	Avoidable through process redesign

The commercial importance of US 9,469,643 therefore depends less on claim breadth than on whether Form II is the only viable development form.

What litigation and settlement issues should be monitored?

The supplied information does not identify litigation, Paragraph IV notices, ANDA filers, settlements, licensees, or covenant-not-to-sue agreements involving US 9,469,643.

For market-entry analysis, the relevant events would include:

A patent-listing dispute involving the FDA.
An ANDA Paragraph IV notice.
A Hatch-Waxman infringement action under 35 U.S.C. § 271(e)(2).
A district-court claim-construction ruling on “polymorph,” “characteristic peaks,” or “substantially as shown.”
A settlement with a licensed or authorized generic.
A continuation or divisional patent with overlapping solid-state claims.
A reexamination, post-grant review, or inter partes review.
A license or assignment affecting enforcement rights.

What is the likely generic launch scenario?

Three launch scenarios are commercially plausible:

Scenario	Product strategy	Patent exposure
Form II launch	Generic matches the reference drug substance	Highest risk under claim 1
Alternative-form launch	Generic uses Form I, another polymorph, or amorphous material	Lower product-claim risk, but conversion must be controlled
At-risk launch	Generic launches after Paragraph IV certification before final judgment	Litigation and damages exposure

A Form II generic would face the clearest infringement risk. An alternative-form generic could enter earlier if it establishes noninfringement and avoids conversion during manufacture and storage. A process redesign alone would not protect a generic that still markets Form II.

Key Takeaways

US 9,469,643 is a solid-state patent focused on Form II of a defined chiral quinazolinone-purine compound.
Claim 1 is the core product claim and requires the compound, Form II, and three specified XRPD peaks.
Claim 2 narrows the protection to an XRPD pattern substantially corresponding to Figure 2A.
Claims 3 through 6 protect selected Form I-to-Form II conversion processes involving solvent stirring, grinding equipment, temperature, or compression pressure.
The supplied claims do not cover the compound broadly, pharmaceutical formulations, therapeutic uses, or all manufacturing routes.
Generic risk is highest when the proposed product contains Form II or when manufacturing converts Form I into Form II.
A non-Form II product may offer a noninfringing route, but solid-state conversion must be controlled and documented.
Orange Book status, patent term, ownership, litigation, licensing, and settlement status are not established by the supplied claim text.

FAQs

Can a generic use Form I instead of Form II?

Potentially. Form I is not claimed as a standalone product in the supplied claims. The generic would still need to ensure that manufacturing, compression, storage, or formulation does not convert part of the product into Form II.

Does claim 6 cover ordinary tablet compression?

It may, if the operation qualifies as compressing Form I at 500 to 5,000 psi and converts at least part of Form I into Form II. The construction would depend on the full patent record and technical evidence.

Can an XRPD test alone determine infringement?

Not necessarily. XRPD is central to the claims, but testing may also need to address mixed phases, amorphous content, solvates, instrument variation, sample preparation, and the identity of the chemical compound.

Is a patent on a polymorph automatically Orange Book listable?

No. Listing depends on the approved product, the patent claims, FDA listing rules, and the statutory category into which the patent falls. A polymorph claim directed to the drug substance may receive different treatment from a process-only claim.[3][4]

Could a different solvent avoid claims 3 and 4?

Possibly, if the altered process does not satisfy the required grinding and stirring limitations or falls outside the temperature limitation. A different solvent would not by itself avoid claim 1 if the resulting product is Form II.

References

United States Code, 35 U.S.C. § 154. Patent term.
United States Code, 35 U.S.C. § 156. Patent term restoration.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.
United States Code, 21 U.S.C. § 355(j); 35 U.S.C. § 271(e)(2). Abbreviated new drug applications and patent litigation.
United States Patent No. 9,469,643. Claims 1-6.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-001	Jul 23, 2014		RX	Yes	No	9,469,643	⤷ Start Trial		Y			⤷ Start Trial
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-002	Jul 23, 2014		RX	Yes	Yes	9,469,643	⤷ Start Trial		Y			⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	090253	⤷ Start Trial
Australia	2013203620	⤷ Start Trial
Brazil	112014021935	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,469,643

Which drugs does patent 9,469,643 protect, and when does it expire?

Summary for Patent: 9,469,643