US Patent 10,391,094: Pacritinib Capsule Formulation Claims, Expiration, and Patent Landscape

US Patent No. 10,391,094 protects specific oral capsule formulations of pacritinib, the active ingredient in VONJO. Its independent claims cover the capsule product, treatment of myelofibrosis, manufacturing, and a labeled article of manufacture. The central formulation limitations are a pacritinib-to-microcrystalline-cellulose ratio of about 1:1.5 to 1:9 and sodium stearyl fumarate at about 1% by weight. The patent is directed to formulation and use of pacritinib, not the underlying pacritinib molecule itself.

The patent creates a potential formulation barrier for generic or alternative manufacturers seeking to reproduce the commercial VONJO capsule, particularly the 100-mg and 200-mg dose presentations using silicified microcrystalline cellulose.

What drug does US Patent 10,391,094 protect?

US 10,391,094 protects formulations containing the compound commonly known as pacritinib. The claimed compound is pacritinib dihydrochloride monohydrate, while the key ratio is expressed using the free-base mass of pacritinib.

Item	Description
Active ingredient	Pacritinib
Claimed salt	Pacritinib dihydrochloride monohydrate
Brand product	VONJO
Sponsor	CTI BioPharma Corp., now part of Sobi
FDA indication	Intermediate- or high-risk primary or secondary myelofibrosis in adults with platelet count below 50 × 10^9/L
Dosage form	Oral hard capsule
Commercial strengths	100 mg and 200 mg pacritinib
FDA approval	February 28, 2022
Patent at issue	US 10,391,094 B2

The 117-mg and 235-mg quantities in the claims correspond approximately to the 100-mg and 200-mg commercial strengths after accounting for the molecular weight of the dihydrochloride monohydrate salt.

What are the independent claims of US 10,391,094?

The patent has four principal independent claim categories.

Claim 1: Capsule formulation

Claim 1 requires a capsule containing:

Pacritinib dihydrochloride monohydrate;
Microcrystalline cellulose; and
Sodium stearyl fumarate.

The formulation must also meet two quantitative limitations:

A pacritinib-to-microcrystalline-cellulose weight ratio of about 1:1.5 to about 1:9; and
Sodium stearyl fumarate at about 1% by weight of the formulation.

The claim is drafted using “comprising.” That open-ended transition permits additional excipients, provided the claimed ingredients and quantitative limitations are present.

Claim 6: Method of treating myelofibrosis

Claim 6 covers administering the claimed capsule to treat myelofibrosis. A potentially infringing product would need to satisfy both the formulation requirements and the claimed treatment use.

The claim is narrower than a general pacritinib treatment claim because it requires the specified capsule composition. It does not cover every pacritinib product used for myelofibrosis.

Claim 7: Manufacturing method

Claim 7 covers blending microcrystalline cellulose and sodium stearyl fumarate with pacritinib dihydrochloride monohydrate within the specified ratio and lubricant concentration.

The claim focuses on the blending operation and resulting formulation parameters. A manufacturer could face process infringement risk even if its product is not marketed under the VONJO name.

Claim 8: Article of manufacture

Claim 8 covers an article containing:

The claimed pacritinib capsule; and
A package insert or label stating that the formulation is useful for treating myelofibrosis.

This claim links the physical product to labeling or promotional material. It is relevant to branded and generic products carrying myelofibrosis instructions.

What formulation limitations control infringement?

The patent’s practical scope is concentrated in four limitations.

Limitation	Commercial significance
Pacritinib dihydrochloride monohydrate	Excludes products using a materially different active form unless claim construction treats the alternative as equivalent
Microcrystalline cellulose	Covers the principal diluent class
Pacritinib-to-cellulose ratio of about 1:1.5 to 1:9	Defines the formulation window
Sodium stearyl fumarate at about 1% by weight	Protects the selected lubricant level

The claims do not require every VONJO excipient. A product could fall within claim 1 even if it uses additional ingredients, such as a capsule colorant or other processing aid.

The use of “about” creates a numerical claim-construction issue. Courts typically evaluate the term in light of the specification, examples, measurement methods, manufacturing tolerances, and technical meaning. A formulation just outside the stated ratio or lubricant percentage may still present risk if the difference is viewed as insubstantial.

What narrower claims protect silicified microcrystalline cellulose?

Claims 2, 9, 10, 11, 15, 18, 20, 22, 25, and 26 narrow the formulation to silicified microcrystalline cellulose.

Silicified microcrystalline cellulose is a composite excipient combining microcrystalline cellulose with colloidal silicon dioxide. It can improve powder flow, compressibility, and manufacturing performance. The narrower claims are commercially important because they correspond more closely to the disclosed and commercially relevant formulation than the broad microcrystalline-cellulose language in claim 1.

A generic capsule that uses ordinary microcrystalline cellulose rather than silicified microcrystalline cellulose may avoid these narrower claims, but it would remain exposed to claim 1 if the other limitations are met.

Which claims cover the 100-mg and 200-mg doses?

The patent expressly covers formulations corresponding to the two VONJO dose strengths.

Claim set	Pacritinib dihydrochloride monohydrate	Other specified limitations
Claim 3	About 117 mg	Broad microcrystalline-cellulose formulation
Claim 4	About 235 mg	About 357 mg silicified microcrystalline cellulose and about 6 mg sodium stearyl fumarate
Claim 13	About 117 mg	Pacritinib-to-cellulose ratio of about 1:1.5 to 1:2
Claim 14	About 235 mg	Pacritinib-to-cellulose ratio of about 1:1.5 to 1:2
Claim 16	About 117 mg	Silicified microcrystalline cellulose and 1:1.5 to 1:2 ratio
Claim 17	About 235 mg	Silicified microcrystalline cellulose and 1:1.5 to 1:2 ratio
Claims 19 and 23	About 117 mg	Labeled article of manufacture
Claims 24 and 25	About 235 mg	Labeled article of manufacture; claim 25 also requires silicified microcrystalline cellulose

Claim 4 is particularly concrete. It identifies approximately 235 mg of the salt, 357 mg of silicified microcrystalline cellulose, and 6 mg of sodium stearyl fumarate. The 6-mg lubricant quantity is approximately 1% of the stated formulation weight.

How broad is the patent’s formulation scope?

The broadest formulation protection is in claim 1. Its effective scope includes capsules containing pacritinib, microcrystalline cellulose, and approximately 1% sodium stearyl fumarate across a wide cellulose ratio of 1:1.5 to 1:9.

The patent becomes materially narrower in the dependent claims:

Claims 2 and 9-11 require silicified microcrystalline cellulose.
Claims 3, 4, 13, 14, 16, 17, and 19-26 require specific dose quantities.
Claims 12-18 and 21-26 narrow the ratio to approximately 1:1.5 to 1:2.
Claims 5 and related product configurations require a hard gelatin capsule.
Claims 6 and 8 require a myelofibrosis treatment use or a label indicating that use.

The formulation estate is therefore layered. A competitor may avoid an individual dependent claim by changing the capsule shell, excipient grade, dose fill, or cellulose ratio, while still needing to avoid the broader independent claim.

What is the patent expiration date for US 10,391,094?

US 10,391,094 has a listed patent expiration date in 2033 based on its underlying priority and filing chronology. The exact enforceable term must be determined from the USPTO patent-term-adjustment calculation and any terminal disclaimer recorded against the patent. The patent is not a short-term formulation patent expiring near the 2022 VONJO launch.

Milestone	Date or period
Patent grant	August 27, 2019
VONJO FDA approval	February 28, 2022
Expected patent-term period	Through approximately 2033
FDA orphan-drug exclusivity	Through approximately February 28, 2029

The patent term and FDA orphan exclusivity are separate. FDA orphan exclusivity blocks approval of the same drug for the same orphan indication during the exclusivity period, while the patent can restrict making, using, selling, offering for sale, or importing the claimed formulation for the longer patent term. (U.S. Food and Drug Administration, 2022; U.S. Patent and Trademark Office, 2019)

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

VONJO is approved under NDA 215596. FDA product information identifies pacritinib capsules in 100-mg and 200-mg strengths for the treatment of adults with intermediate- or high-risk primary or secondary myelofibrosis with platelet counts below 50 × 10^9/L. (FDA, 2022)

US 10,391,094 is relevant to the FDA-listed VONJO product because its claims correspond to the capsule formulation and myelofibrosis labeling. The Orange Book listing determines whether an ANDA applicant must make a Paragraph I, II, III, or IV certification for the patent.

A Paragraph III certification would defer approval until patent expiration. A Paragraph IV certification would assert that the patent is invalid, unenforceable, or not infringed and could trigger Hatch-Waxman litigation if the patent owner brings suit within the statutory period.

When does VONJO lose regulatory exclusivity?

VONJO received orphan-drug designation for myelofibrosis and has seven years of orphan exclusivity from approval for the approved orphan indication, subject to statutory exceptions. The exclusivity period runs approximately through February 28, 2029.

The regulatory timeline is:

Event	Date
FDA approval of VONJO	February 28, 2022
Orphan exclusivity period	Approximately seven years
Approximate orphan-exclusivity end	February 28, 2029
Patent protection under US 10,391,094	Approximately through 2033

Orphan exclusivity does not prevent a generic applicant from filing an ANDA or submitting a Paragraph IV certification before 2029. It generally prevents FDA approval for the protected orphan indication during the exclusivity period unless an exception applies.

Are there Paragraph IV challenges to US 10,391,094?

A public patent-risk assessment must distinguish between an ANDA filing, a Paragraph IV certification, and litigation. The existence of a listed patent does not establish that a generic company has challenged it.

The available patent and FDA records do not establish a publicly adjudicated Paragraph IV challenge, final judgment, or settlement involving US 10,391,094. No litigation outcome has been identified that invalidates, narrows, or renders the patent unenforceable.

A future ANDA applicant could challenge the patent on several grounds:

The claims lack novelty over earlier pacritinib formulations.
The selected excipient combination and ratios would have been obvious.
The term “about” is indefinite.
The patent specification does not enable the full 1:1.5 to 1:9 ratio range.
The commercial product does not meet one or more quantitative limitations.
The asserted claim is not infringed because of a different salt, excipient, lubricant level, or manufacturing process.

The strongest noninfringement strategy would likely involve changing multiple formulation variables rather than relying on a minor deviation from the 1% sodium stearyl fumarate limitation.

What earlier patents protect pacritinib itself?

US 10,391,094 should be separated from patents directed to pacritinib’s chemical structure, kinase activity, salts, crystalline forms, treatment methods, and formulation.

Patent category	Typical protected subject matter	Relevance to US 10,391,094
Composition of matter	Pacritinib chemical structure	May have expired earlier or have a separate term
Salt and solid form	Dihydrochloride monohydrate, polymorphs, hydrates	Can create separate API and manufacturing barriers
Treatment method	Myelofibrosis, myeloproliferative neoplasms, kinase inhibition	May overlap with claim 6 but requires different claim elements
Formulation	Capsule excipients, ratios, lubricant concentration	Primary subject of US 10,391,094
Manufacturing	Blending, granulation, encapsulation, scale-up	Claim 7 and related process protection
Regulatory labeling	Myelofibrosis indication	Claim 8 and Orange Book use-code relevance

The patent is therefore one layer in a broader pacritinib estate. Its commercial importance comes from protecting the finished dosage form after a generic manufacturer has potentially designed around earlier active-ingredient patents.

How strong is the patent estate for VONJO?

The patent has moderate-to-strong commercial relevance but a narrower technical scope than a composition-of-matter patent.

Strengths

It targets the marketed oral capsule rather than an experimental formulation.
It claims both product and manufacturing categories.
It covers a broad cellulose ratio range in claim 1.
It includes both 100-mg and 200-mg dose-related claims.
It protects silicified microcrystalline cellulose in multiple dependent claims.
It links the product to the approved myelofibrosis use through claims 6 and 8.
The apparent 2033 term extends well beyond the 2029 orphan-exclusivity date.

Vulnerabilities

The active pharmaceutical ingredient is identified precisely, limiting the patent to pacritinib formulations.
The excipient requirements may be designed around.
Sodium stearyl fumarate is a specific lubricant, not a broad class of lubricants.
The ratio limitations require proof of formulation composition.
“About” creates potential claim-construction and invalidity disputes.
Claims 6 and 8 require additional treatment or labeling facts that may not be present in every infringement scenario.
A generic product could use a different salt, lubricant, diluent, or manufacturing sequence.

The patent is strongest against a product that reproduces the VONJO formulation closely. It is weaker against a substantially redesigned capsule using a different lubricant system or diluent profile.

What generic launch scenarios exist for VONJO?

Launch after patent expiry

A generic applicant could pursue Paragraph III certification and defer approval until the listed patent expires. This approach reduces litigation exposure but delays market entry.

Paragraph IV launch

A Paragraph IV applicant could argue invalidity or noninfringement and seek approval before the 2033 patent expiration. The filing could trigger litigation and a 30-month FDA approval stay if statutory requirements are met.

Formulation design-around

A design-around could alter one or more of the following:

Use lactose, dibasic calcium phosphate, or another diluent instead of microcrystalline cellulose.
Use magnesium stearate, sodium lauryl sulfate, or another lubricant instead of sodium stearyl fumarate.
Use a lubricant concentration materially outside approximately 1%.
Change the pacritinib-to-cellulose ratio.
Use a different salt or solid form, subject to separate API and solid-form rights.
Use a manufacturing process that does not blend the claimed components as required by claim 7.

The design-around must be evaluated against the full patent family and FDA pharmaceutical-equivalence requirements. A formulation that avoids US 10,391,094 may still infringe another patent or fail to qualify as pharmaceutically equivalent to VONJO.

What litigation and settlement issues affect the patent?

No final court decision or publicly documented settlement has been identified that changes the scope of US 10,391,094. The key future litigation questions would include:

Whether the commercial VONJO formulation falls within every limitation of the asserted claim.
Whether the disclosed formulation examples support the full 1:1.5 to 1:9 range.
Whether the claimed excipient selection would have been obvious.
Whether a generic formulation’s lubricant concentration is within the meaning of “about 1%.”
Whether the claimed manufacturing method is practiced by the generic manufacturer.
Whether a package insert directed to myelofibrosis satisfies the article-of-manufacture claims.

A settlement could permit a generic launch before patent expiry, but no such settlement is established for this patent in the cited record.

Does biosimilar risk apply to pacritinib?

No. Pacritinib is a chemically synthesized small molecule, not a biologic. The relevant competitive pathway is an abbreviated new drug application, not a biosimilar application under the Biologics Price Competition and Innovation Act.

The principal entry risks are:

ANDA patent certifications;
Paragraph IV litigation;
Formulation design-around;
Separate API, salt, solid-form, and method-of-use patents;
FDA requirements for bioequivalence and pharmaceutical equivalence.

What is the competitive landscape for VONJO?

VONJO competes in myelofibrosis with other JAK-pathway products, but the approved populations differ.

Product	Active ingredient	Sponsor	General positioning
VONJO	Pacritinib	Sobi/CTI BioPharma	Myelofibrosis with severe thrombocytopenia
Jakafi	Ruxolitinib	Incyte	Broad myelofibrosis and related indications
Ojjaara	Momelotinib	GlaxoSmithKline	Myelofibrosis, including anemia-related treatment considerations

VONJO’s commercial exposure is concentrated in patients with platelet counts below 50 × 10^9/L, the population addressed by its FDA indication. That narrower population reduces total market breadth but increases the importance of maintaining formulation and regulatory exclusivity in the severe-thrombocytopenia segment.

Key Takeaways

US 10,391,094 is a pacritinib formulation patent covering capsules with microcrystalline cellulose and approximately 1% sodium stearyl fumarate.
The broadest ratio is approximately 1:1.5 to 1:9 pacritinib free base to microcrystalline cellulose.
Multiple dependent claims specifically cover silicified microcrystalline cellulose.
The patent covers formulation, myelofibrosis treatment, manufacturing, and labeled-product claims.
The 117-mg and 235-mg salt quantities correspond to the commercial 100-mg and 200-mg VONJO strengths.
The patent has an apparent term extending to approximately 2033, beyond VONJO’s approximately 2029 orphan-exclusivity endpoint.
Pacritinib is a small molecule, so generic ANDA litigation, not biosimilar litigation, is the relevant entry pathway.
The principal design-around options involve the diluent, lubricant, formulation ratio, salt form, and manufacturing process.
No final invalidity decision, infringement judgment, or settlement affecting US 10,391,094 is established in the cited record.

FAQs About US Patent 10,391,094 and Pacritinib

Does US 10,391,094 cover all pacritinib products?

No. It covers pacritinib products containing the specified excipients and quantitative formulation limitations. Pacritinib products using materially different excipients or ratios may fall outside the claims.

Does the patent cover the VONJO active ingredient itself?

No. The patent is primarily directed to the finished capsule formulation and related use, manufacturing, and labeling. Separate patents may address pacritinib’s chemical structure, salts, solid forms, or therapeutic uses.

Can a generic use microcrystalline cellulose and avoid the patent?

Possibly, but only if the complete formulation falls outside the claimed ratio and all other claim limitations. Switching to a different grade or excipient does not automatically avoid infringement.

Is a 200-mg VONJO generic exposed to more claims than a 100-mg product?

The 200-mg presentation is expressly identified in claims 4, 14, 17, 24, and 25. The 100-mg presentation is expressly identified in claims 3, 13, 16, 19, and 23. Both strengths face layered claim coverage.

Does orphan-drug exclusivity replace patent protection?

No. Orphan exclusivity and patent protection operate independently. Orphan exclusivity is a regulatory restriction on approval for the protected indication, while the patent creates enforceable rights against qualifying acts of infringement.

References

U.S. Food and Drug Administration. (2022). VONJO (pacritinib) capsules: Prescribing information. FDA.
U.S. Patent and Trademark Office. (2019). U.S. Patent No. 10,391,094 B2, pharmaceutical compositions comprising pacritinib. USPTO.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2024). Orphan drug designation and exclusivity. FDA.
U.S. Food and Drug Administration. (2024). ANDA submissions: Content and format. FDA.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Bristol-myers	INREBIC	fedratinib hydrochloride	CAPSULE;ORAL	212327-001	Aug 16, 2019		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y			TREATMENT OF ADULT PATIENTS WITH INTERMEDIATE-2 OR HIGH-RISK PRIMARY OR SECONDARY MYELOFIBROSIS	⤷ 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
Australia	2010363329	⤷ Start Trial
Australia	2011323108	⤷ Start Trial
Brazil	112013011184	⤷ Start Trial
Canada	2816710	⤷ Start Trial
Canada	2816957	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,391,094

Which drugs does patent 10,391,094 protect, and when does it expire?

Summary for Patent: 10,391,094