US Patent 8,865,730: Claim Scope, Patent Strength, Exclusivity and Generic Entry Risk for Entospletinib Form I

US Patent 8,865,730 protects Form I of the crystalline small-molecule SYK inhibitor entospletinib, also known as GS-9973. The patent does not claim entospletinib in every chemical or solid-state form. Its central protection is limited to a specific polymorph identified by characteristic powder X-ray diffraction peaks. The patent also covers compositions, preparation methods and treatment of hematologic malignancies using that polymorph.

The patent issued on October 21, 2014, and has a standard term expected to run until approximately July 15, 2031, subject to any applicable patent-term adjustment or later legal event. Entospletinib has not received FDA approval, so the patent is not expected to have an Orange Book-listed drug product or FDA-granted market exclusivity tied to an approved product.

What drug and molecular form does US Patent 8,865,730 protect?

The protected active ingredient is the S-enantiomer of:

(S)-2-(1-(9H-purin-6-ylamino)propyl)-5-fluoro-3-phenylquinazolin-4(3H)-one

This compound is entospletinib, a selective spleen tyrosine kinase inhibitor developed by Gilead Sciences for hematologic malignancies. The patent is directed to a solid-state form of entospletinib rather than to the free compound broadly.

The distinction matters commercially. A party could potentially avoid literal infringement of the product claims by making or selling:

A different crystalline form;
An amorphous form;
A solvate or hydrate, if outside the claimed Form I definition;
A different salt or solid-state derivative;
A formulation that does not contain the claimed polymorph.

Such alternatives could still face other patent or regulatory barriers, including separate compound, formulation, method-of-use or manufacturing patents.

What are the independent claims in US Patent 8,865,730?

The patent contains four principal protection categories.

Claim category	Claims	Core subject matter
Polymorph	1	Form I identified by XRPD peaks at 17.7° and 24.9° 2θ
Pharmaceutical composition	6	Form I with a pharmaceutically acceptable carrier or excipient
Preparation method	8	Combining entospletinib with solvent, heating to solution and cooling to form Form I
Treatment method	10	Administering Form I for a hematologic malignancy

Claims 2, 3, 4, 5, 7, 9, 11 and 12 narrow those categories through additional diffraction peaks, process conditions, dosage form or disease indications (U.S. Patent No. 8,865,730).

How narrowly does claim 1 define Form I?

Claim 1 is the principal product claim. It requires a polymorph of entospletinib identified by an XRPD pattern having characteristic peaks, within plus or minus 0.2° 2θ, at:

17.7° 2θ; and
24.9° 2θ.

The claim does not require every peak shown in the patent’s analytical data. It requires the claimed Form I designation and the two specified characteristic peaks.

This creates a meaningful but technically fact-intensive infringement test. An accused product would generally be evaluated using XRPD and potentially other solid-state characterization methods. The ±0.2° tolerance gives the claim some protection against ordinary analytical variation, instrument differences and sample-preparation effects.

The claim does not specify:

Particle size;
Crystallinity percentage;
Solvent content;
Water content;
Melting point;
Differential scanning calorimetry profile;
Tablet dose;
Excipient identity;
Manufacturing scale; or
Therapeutic dose.

Those omissions broaden claim 1 within the Form I category but leave the claim dependent on reliable identification of the claimed crystal form.

What additional XRPD limitations appear in claims 2 and 3?

Claim 2 requires the peaks in claim 1 and adds characteristic peaks at:

14.3° 2θ;
17.2° 2θ;
20.9° 2θ; and
23.9° 2θ.

Claim 3 requires an XRPD pattern substantially as shown in Figure 1A. Claim 3 may be useful where an accused sample has the overall diffraction pattern depicted in the patent but disputes reliance on only two or six selected peaks.

The dependent claims create fallback positions. If a court or patent office construes claim 1 narrowly or finds a prior-art issue, claims 2 and 3 may preserve protection for a more fully defined Form I pattern. They also create additional evidentiary issues concerning what constitutes a pattern “substantially as shown.”

What manufacturing process does the patent protect?

Claims 4, 5, 8 and 9 cover a solution-cooling crystallization process.

The required steps are:

Combining entospletinib with a solvent to form a mixture;
Heating the mixture to form a solution; and
Cooling the heated solution to form Form I.

Claims 5 and 9 add temperature limitations:

Heating to at least approximately 50°C; and
Cooling to at least approximately 30°C.

Claims 4 and 8 are materially different in legal structure. Claim 8 is a direct method-of-preparation claim. Claim 4 is written as a product-by-process limitation, requiring Form I obtained by the specified process.

The process claims are narrower than claim 1 because they require both the product and defined processing steps. A competitor using a different crystallization route may avoid literal infringement of claims 4, 5, 8 and 9 while still infringing claim 1 if the resulting material is Form I.

The process claims may still matter in commercial diligence because manufacturing records, batch documents, solvent systems, temperature profiles and crystallization protocols can establish or refute infringement.

What formulations are protected by US Patent 8,865,730?

Claim 6 covers a pharmaceutical composition containing Form I and one or more pharmaceutically acceptable carriers or excipients. Claim 7 narrows the composition to a tablet.

The formulation coverage is broad but basic. The claims do not identify a particular:

Binder;
Disintegrant;
Lubricant;
Coating;
Release profile;
Dose strength;
Tablet architecture; or
Manufacturing compression process.

A tablet containing Form I would fall within claim 7 if the other claim requirements are satisfied. A capsule, suspension or injectable composition could fall within claim 6 but not claim 7.

The formulation claims are likely less commercially differentiated than a patent directed to a specific controlled-release system, bioavailability enhancement, fixed-dose combination or stability-improving excipient system. Their value comes from tying the drug product to the protected crystal form.

What cancer indications are covered by the treatment claims?

Claim 10 covers treatment of a human with a hematologic malignancy using a composition containing Form I.

Claim 11 lists specific diseases, including:

Acute lymphocytic leukemia;
Acute myeloid leukemia;
Chronic lymphocytic leukemia;
Small lymphocytic lymphoma;
Myelodysplastic syndrome;
Myeloproliferative disease;
Chronic myeloid leukemia;
Multiple myeloma;
Indolent non-Hodgkin’s lymphoma;
Refractory indolent non-Hodgkin’s lymphoma;
Non-Hodgkin’s lymphoma;
Mantle cell lymphoma;
Follicular lymphoma;
Waldenström’s macroglobulinemia;
T-cell lymphoma;
B-cell lymphoma; and
Diffuse large B-cell lymphoma.

Claim 12 narrows claim 11 to:

Chronic lymphocytic leukemia;
Indolent non-Hodgkin’s lymphoma; and
Refractory indolent non-Hodgkin’s lymphoma.

These claims require administration of a composition containing the patented polymorph. They do not claim treatment using entospletinib in an unspecified form.

When does US Patent 8,865,730 lose exclusivity?

Event	Date or status
Patent issued	October 21, 2014
Underlying priority or filing date	Approximately July 15, 2010, subject to the recorded family chronology
Expected 20-year expiration	Approximately July 15, 2031
FDA approval	No FDA approval identified for entospletinib
Orange Book listing	No listed approved product identified
NCE exclusivity	Not triggered because no FDA approval has been granted
Biosimilar exclusivity	Not applicable to this small molecule
Regulatory exclusivity end date	None currently established

The expected expiration date is based on the patent’s underlying U.S. filing chronology. The enforceable expiration date can be affected by patent-term adjustment, terminal disclaimer, disclaimer filing or other USPTO events. No FDA patent-term extension is available without an approved product and qualifying regulatory review.

What is the Orange Book status of entospletinib and this patent?

Entospletinib is not an FDA-approved small-molecule drug. As a result, there is no approved reference listed drug for an ANDA applicant to cite and no ordinary Orange Book patent-listing framework currently operating for this compound.

The FDA Orange Book lists patents associated with approved drug products and approved labeling. A patent directed to an investigational compound or an unapproved polymorph generally does not generate an Orange Book Paragraph IV dispute by itself (FDA, 2024a).

This means:

US Patent 8,865,730 is not currently an Orange Book barrier to an ANDA;
No conventional Paragraph IV certification is expected for this patent absent a future approved reference product and listing;
A future applicant would need to select an FDA pathway based on the regulatory status of the reference product;
A 505(b)(2) application could become relevant if an approved product or sufficient clinical bridge later exists;
A full 505(b)(1) application could be required for an independently developed product.

Which companies are challenging US Patent 8,865,730?

No public Paragraph IV challenge, ANDA litigation or federal patent case directed specifically to US Patent 8,865,730 is identified in the patent and FDA records reviewed for this analysis.

The absence of a Paragraph IV case is principally explained by entospletinib’s lack of FDA approval. Generic companies typically do not challenge a patent in the Orange Book until a reference product, listed patent and ANDA filing create the statutory framework for litigation.

No public settlement agreement involving this patent and a generic manufacturer has been identified. No publicly disclosed license specifically transferring or encumbering the rights in US Patent 8,865,730 has been identified.

How strong is the patent estate for entospletinib?

US Patent 8,865,730 is a focused solid-state patent, not a complete entospletinib franchise. Its strength depends on the composition of the broader patent family.

Strength factor	Assessment
Product specificity	Strong for Form I; limited for other forms
Analytical definition	Clear but dependent on reproducible XRPD testing
Composition coverage	Broad within compositions containing Form I
Tablet coverage	Present but not formulation-specific
Manufacturing coverage	Narrow and process-dependent
Method-of-use coverage	Broad disease list, but limited to Form I
FDA commercial relevance	Currently limited because entospletinib is not approved
Biosimilar exposure	None
Generic exposure	Low near term without an approved reference product; increases if development resumes
Prior-art vulnerability	Potentially relevant for known crystalline forms and obvious crystallization processes

Potential validity issues would likely focus on:

Anticipation by an earlier disclosure of the same Form I XRPD pattern;
Obviousness of preparing Form I through routine crystallization screening;
Whether the claimed peaks adequately distinguish Form I from mixtures or other forms;
Written-description and enablement support for the full claim breadth;
Reproducibility of the ±0.2° 2θ limitations; and
The legal treatment of product-by-process language in claims 4 and 5.

The patent has better protection against direct substitution with Form I than against a deliberate polymorph-avoidance strategy.

What generic launch scenarios exist?

A future generic or follow-on developer would face several possible routes.

Form I launch

A product containing Form I could implicate claims 1, 6, 7 and the treatment claims. If the patent remained enforceable and relevant to an approved reference product, the developer could face a patent challenge or delayed launch.

Non-Form I launch

A product using an amorphous form, alternative polymorph, salt or solvate could avoid the literal scope of claim 1. The developer would still need to establish pharmaceutical equivalence, stability, manufacturability and regulatory acceptability.

Alternative crystallization process

A developer could use a different process to prepare Form I. That strategy may avoid claims 4, 5, 8 and 9 but would not avoid claim 1 if the final product satisfies the Form I XRPD limitations.

Non-tablet product

A capsule or liquid formulation could avoid claim 7 but could still fall within claim 6 if it contains Form I.

Different indication

A product used for a non-hematologic indication may avoid claims 10 through 12, but not the product or composition claims.

How does this patent compare with biologic and small-molecule exclusivity?

Entospletinib is a small molecule. It is not subject to the biosimilar pathway under the Biologics Price Competition and Innovation Act. A future competitor would pursue an ANDA, 505(b)(2), or standalone NDA pathway depending on the reference-product and clinical evidence available.

This differs from biologics, where reference-product exclusivity, patent dance procedures and biosimilar interchangeability can determine launch timing. For entospletinib, the main barriers would be chemical identity, polymorph selection, clinical bridging, FDA approval status and remaining patents.

What is the commercial and licensing significance of the patent?

Entospletinib development has focused on hematologic malignancies, including chronic lymphocytic leukemia and non-Hodgkin’s lymphoma. Public clinical development records identify the drug as an investigational SYK inhibitor rather than an approved commercial product (ClinicalTrials.gov, 2024).

Because there is no approved product, current revenue exposure to this patent is limited. The patent’s economic value would increase if:

Entospletinib development resumes;
A partner licenses or acquires the program;
Clinical data support a new NDA;
Form I becomes the selected commercial form; or
A later product receives approval before the estimated 2031 expiration.

The relevant competitive field includes approved or clinically developed agents targeting B-cell receptor signaling and hematologic malignancies, including ibrutinib, acalabrutinib, zanubrutinib, idelalisib and fostamatinib. These products do not establish direct freedom to operate for entospletinib because each has separate composition, formulation, use and regulatory exclusivity profiles.

What geographic coverage does the patent family provide?

US Patent 8,865,730 provides U.S. protection only. International commercial risk depends on corresponding national patents and their status in jurisdictions such as:

European Union member states;
United Kingdom;
Canada;
Japan;
China;
Australia; and
South Korea.

A U.S. patent does not prevent manufacture, sale or use outside the United States. Foreign family members may have different claim language, prosecution outcomes, term dates, maintenance status and enforceability. The most commercially relevant diligence question is whether corresponding claims cover Form I, the same XRPD peaks and the same treatment or manufacturing activities in each target market.

Key Takeaways

US Patent 8,865,730 is a polymorph patent for entospletinib Form I.
Claim 1 requires characteristic XRPD peaks at 17.7° and 24.9° 2θ, each within ±0.2°.
Claims 2 and 3 provide more detailed XRPD fallback protection.
Claims 4, 5, 8 and 9 cover specified solution-heating and cooling crystallization methods.
Claims 6 and 7 cover pharmaceutical compositions and tablets containing Form I.
Claims 10 through 12 cover treatment of hematologic malignancies, with narrower disease lists in the dependent claims.
The patent is expected to expire around July 15, 2031, subject to the recorded patent-term calculation and any later USPTO event.
Entospletinib has no identified FDA approval, Orange Book listing or NCE exclusivity.
No public Paragraph IV litigation or settlement involving this patent has been identified.
A competitor using a different polymorph may avoid the central product claims, while a competitor making Form I through a different process may still face claim 1.
The patent has commercial value only if entospletinib development resumes and Form I becomes the approved or marketed solid form.

FAQs

Is US Patent 8,865,730 a patent on entospletinib itself?

No. It is primarily a patent on Form I of entospletinib, together with related compositions, manufacturing processes and hematologic cancer uses.

Can a generic avoid this patent by using an amorphous form?

Potentially. An amorphous product would not ordinarily satisfy a claim limited to the Form I XRPD pattern, although other patents or regulatory requirements could still apply.

Does a different solvent avoid the process claims?

It may avoid the process claims if the alternative process does not satisfy the claimed heating, solution and cooling limitations. It would not necessarily avoid claim 1 if the final material is Form I.

Are biosimilar applicants relevant to entospletinib?

No. Entospletinib is a small molecule, so future competitors would use small-molecule FDA pathways rather than the biosimilar pathway.

Would FDA approval automatically extend this patent beyond 2031?

No. FDA approval does not automatically extend a patent. Patent-term extension requires statutory eligibility and a qualifying regulatory review period, and any extension would depend on a future approved product and the specific patent-term record.

References

ClinicalTrials.gov. (2024). Entospletinib clinical study records. U.S. National Library of Medicine. https://clinicaltrials.gov/
U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (2024b). Abbreviated new drug application submissions: Refuse-to-receive standards. https://www.fda.gov/
U.S. Patent No. 8,865,730. (2014). Polymorph of (S)-2-(1-(9H-purin-6-ylamino)propyl)-5-fluoro-3-phenylquinazolin-4(3H)-one. United States Patent and Trademark Office. https://patents.google.com/patent/US8865730
U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation resources. https://www.uspto.gov/ patents/patent-term-adjustment-revisions-application-and-examination-delays

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	8,865,730	⤷ Start Trial	Y	Y		FOR THE TREATMENT OF PATIENTS WITH CLL, FL, OR SLL	⤷ Start Trial
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-002	Jul 23, 2014		RX	Yes	Yes	8,865,730	⤷ Start Trial	Y	Y		FOR THE TREATMENT OF PATIENTS WITH CLL, FL, OR SLL	⤷ 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
Canada	2864305	⤷ Start Trial
Chile	2014002358	⤷ Start Trial
China	104334560	⤷ Start Trial
China	106146506	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,865,730

Which drugs does patent 8,865,730 protect, and when does it expire?

Summary for Patent: 8,865,730