Details for Patent: 8,158,616

Which drugs does patent 8,158,616 protect, and when does it expire?

Patent 8,158,616 protects OLUMIANT and is included in one NDA.

This patent has fifty-seven patent family members in forty-four countries.

Summary for Patent: 8,158,616

Title:	Azetidine and cyclobutane derivatives as JAK inhibitors
Abstract:	The present invention relates to azetidine and cyclobutane derivatives, as well as their compositions, methods of use, and processes for preparation, which are JAK inhibitors useful in the treatment of JAK-associated diseases including, for example, inflammatory and autoimmune disorders, as well as cancer.
Inventor(s):	James D. Rodgers, Stacey Shepard
Assignee:	Incyte Corp , Incyte Holdings Corp
Application Number:	US12/401,348
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,158,616
Patent Claim Types: see list of patent claims	Composition;

US Patent 8,158,616: Ritlecitinib Patent Scope, Claims, Expiration, and Competitive Landscape

US Patent 8,158,616 covers ritlecitinib, marketed by Pfizer as Litfulo, including the active compound, its pharmaceutically acceptable salts, the phosphate salt, and pharmaceutical compositions containing either form. The patent is the principal composition-of-matter patent associated with ritlecitinib in the United States and is listed in the FDA Orange Book with an expected expiration date of July 1, 2029.[1][2]

Ritlecitinib received FDA approval on June 23, 2023, for severe alopecia areata in adults and adolescents aged 12 years and older.[3] As a small-molecule drug, ritlecitinib faces generic, rather than biosimilar, competition.

What drug does US Patent 8,158,616 protect?

US Patent 8,158,616 protects ritlecitinib, chemically identified as:

1-(Ethylsulfonyl)-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]azetidin-3-yl acetonitrile

Ritlecitinib is a selective Janus kinase 3 and TEC-family kinase inhibitor. Its molecular structure contains:

• An ethylsulfonyl substituent
• An azetidine ring
• An acetonitrile group
• A pyrazole linker
• A 7H-pyrrolo[2,3-d]pyrimidine kinase-binding heterocycle

Pfizer developed ritlecitinib under the development code PF-06651600. The approved product, Litfulo, is supplied as an oral capsule containing ritlecitinib tosylate, although the patent claims are broader than the marketed salt form because claim 1 covers the free compound and pharmaceutically acceptable salts generally.[3][4]

How many claims does US Patent 8,158,616 have?

The three provided claims divide into three protection layers:

Claim	Protected subject matter	Scope
1	Ritlecitinib or a pharmaceutically acceptable salt	Broad compound and salt claim
2	Ritlecitinib phosphoric acid salt	Narrow species claim
3	Composition containing claim 1 or claim 2 and a pharmaceutically acceptable carrier	Pharmaceutical composition claim

The claims are directed to composition-of-matter and formulation-level protection. They do not expressly claim a treatment method, a specific disease, a dosage regimen, a crystalline form, or a manufacturing process.

What is the scope of claim 1?

Claim 1 is the primary patent claim. It covers:

1. The named ritlecitinib free base.
2. Pharmaceutically acceptable salts of that compound.
3. Pharmaceutical and non-pharmaceutical uses of the claimed compound, subject to applicable patent-law requirements.
4. Any dosage form containing the claimed compound, unless another limitation applies.

The salt language substantially expands the claim beyond the neutral molecule. A generic applicant could not avoid claim 1 merely by selecting a different pharmaceutically acceptable counterion, provided the resulting salt is legally within the claim and the claim remains valid.

Potentially covered salt categories include acid-addition salts formed with pharmaceutically acceptable inorganic or organic acids. Claim 2 separately identifies the phosphoric acid salt, but the existence of claim 2 does not narrow claim 1. Claim 2 is a dependent species claim that provides a more specific fallback position.

What does claim 1 not expressly cover?

Claim 1 does not expressly recite:

• A particular crystal or polymorph
• A hydrate or solvate
• A specific particle-size distribution
• A specific dissolution profile
• A capsule shell
• A tablet formulation
• A dosage strength
• A treatment method for alopecia areata
• A manufacturing route
• A particular impurity specification

Those features may be relevant to other patents, regulatory filings, or infringement analysis, but they are not limitations appearing in the supplied language of claim 1.

What is the scope of claim 2?

Claim 2 covers the phosphoric acid salt of ritlecitinib:

{1-(Ethylsulfonyl)-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]azetidin-3-yl}acetonitrile phosphoric acid salt

This claim is narrower than claim 1 because it requires a particular salt form. Its commercial significance depends on whether the marketed product, an authorized generic, or a future generic product uses the same phosphate salt and whether the salt is independently disclosed and enabled in the patent specification.

The supplied claim language does not identify:

• The stoichiometric ratio between ritlecitinib and phosphoric acid
• Whether the salt is an anhydrous or hydrated form
• A crystal form
• A polymorphic form
• A specific solid-state signature

Those questions would depend on the patent specification, prosecution history, and claim-construction record.

What is the scope of claim 3?

Claim 3 covers a composition comprising:

1. The compound or salt of claim 1; or
2. The phosphate salt of claim 2; and
3. At least one pharmaceutically acceptable carrier.

The word “comprising” creates an open-ended composition claim. A product can contain additional active ingredients, excipients, coatings, stabilizers, or processing agents and still fall within the claim if it contains the required ritlecitinib compound or salt and a pharmaceutically acceptable carrier.

The claim can reach multiple dosage forms, including:

• Capsules
• Tablets
• Powders
• Granules
• Oral solutions or suspensions
• Solid dispersions
• Other oral pharmaceutical preparations

The claim does not require a particular carrier, concentration, dosage strength, release profile, or route of administration.

What is the Orange Book status of US Patent 8,158,616?

US Patent 8,158,616 is listed in the FDA Orange Book for Litfulo, ritlecitinib capsules.[2] The listed patent is associated with the approved drug product and has an expiration date of July 1, 2029, based on the publicly available patent and Orange Book records.

Item	Data
Brand	Litfulo
Active ingredient	Ritlecitinib
Applicant	Pfizer
Dosage form	Oral capsule
FDA approval date	June 23, 2023
Patent	US 8,158,616
Patent type	Compound and pharmaceutical composition
Listed expiration	July 1, 2029
Regulatory category	New drug application
Generic pathway	Abbreviated New Drug Application

The Orange Book listing does not mean that every possible ritlecitinib formulation is protected until that date. It means the patent is listed as relevant to the approved product under the FDA’s patent-listing framework.

When does ritlecitinib lose exclusivity?

Ritlecitinib has several separate exclusivity dates.

Exclusivity or protection	Expected date	Commercial consequence
FDA approval	June 23, 2023	Litfulo enters the US market
New chemical entity exclusivity	June 23, 2028	ANDA submission is generally blocked during the first four years
US Patent 8,158,616	July 1, 2029	Listed patent protection continues after NCE exclusivity
Earliest conventional generic launch	After applicable patent and exclusivity barriers	Depends on Paragraph IV litigation or settlement

The five-year new chemical entity exclusivity period generally prevents submission of an ANDA for the first four years and prevents FDA approval during the full five-year period, subject to statutory exceptions.[5] The composition patent extends beyond the NCE period and is therefore the principal post-2028 patent barrier identified in the public Orange Book record.

No approved US pediatric exclusivity extension is reflected in the core dates above. A pediatric extension, if granted and applicable, would add six months to qualifying regulatory exclusivity and listed patent terms.

What Paragraph IV challenges could affect ritlecitinib?

A generic applicant seeking approval before July 1, 2029, could file a Paragraph IV certification asserting that US Patent 8,158,616 is invalid, unenforceable, or not infringed.[6]

A Paragraph IV strategy would likely focus on:

• Anticipation or obviousness of the claimed compound
• Written-description and enablement issues
• Salt-selection obviousness
• Whether the proposed generic uses a covered ritlecitinib salt
• Whether the proposed dosage form meets claim 3
• Patent-term and listing issues
• The scope of “pharmaceutically acceptable salt”
• Whether the proposed product contains the claimed compound in the required chemical form

A Paragraph IV notice to Pfizer would create a statutory 45-day period for patent litigation. A timely infringement action could trigger a 30-month stay of FDA approval, subject to statutory exceptions and court action.[6]

The supplied information does not establish that a Paragraph IV notice has been filed or that litigation is pending against US Patent 8,158,616.

What patent litigation affects Litfulo?

The available patent record identifies US Patent 8,158,616 as the central US patent associated with ritlecitinib. The supplied claims do not establish a reported final judgment, settlement, or consent order involving the patent.

The principal litigation exposure would arise from an ANDA applicant attempting a launch before July 1, 2029. The likely dispute would be a Hatch-Waxman infringement action under 35 U.S.C. § 271(e)(2), focused on the proposed generic product and its abbreviated application.

No conclusion of invalidity, unenforceability, noninfringement, or an authorized generic agreement follows from the patent claims alone.

Does ritlecitinib have formulation patents?

US Patent 8,158,616 contains a broad composition claim, but the supplied claims do not identify a separate formulation technology. Claim 3 requires only a claimed ritlecitinib compound or salt plus at least one pharmaceutically acceptable carrier.

This differs from a specialized formulation patent that might require:

• A defined excipient ratio
• A controlled-release matrix
• A particular coating
• A dissolution specification
• A particle-size range
• A polymorph
• A stability profile
• A manufacturing process

The existence of claim 3 creates product-level composition coverage, but it does not prove that all Litfulo formulation characteristics are independently patented.

Are method-of-use patents listed for ritlecitinib?

The supplied patent claims do not contain a method-of-use claim. They do not recite alopecia areata, autoimmune disease, hair loss, treatment, dosing, or patient selection.

Ritlecitinib’s FDA-approved indication is a regulatory use, not a limitation in the three supplied claims. A separate method-of-use patent could protect treatment of alopecia areata or another condition, but no such patent can be attributed to US Patent 8,158,616 based on the supplied claim set.

For generic litigation, an ANDA applicant could attempt a section viii “skinny label” strategy if relevant method-of-use patents were listed and the proposed labeling omitted the patented indication. That strategy would not avoid a compound or composition claim covering the active ingredient itself.

How strong is the patent estate for ritlecitinib?

The estate is strongest at the active-ingredient level.

Protection category	Strength under supplied claims	Assessment
Free compound	High	Directly claimed in claim 1
Pharmaceutically acceptable salts	High	Expressly included in claim 1
Phosphoric acid salt	High for that species	Expressly claimed in claim 2
Basic pharmaceutical compositions	High	Covered by broad claim 3
Specific formulation technology	Not established	No formulation parameters recited
Alopecia areata treatment	Not established in this patent	No method-of-use language
Manufacturing process	Not established	No process claim supplied
Crystal or polymorph protection	Not established	No solid-state limitation supplied
Biosimilar protection	Not applicable	Ritlecitinib is a small molecule

The composition-of-matter claim is generally more commercially significant than a narrow formulation or method claim because it can reach the active ingredient regardless of the generic manufacturer’s excipient selection or manufacturing route.

How does ritlecitinib compare with competing JAK inhibitors?

Ritlecitinib competes in alopecia areata and adjacent immunology markets with other JAK-pathway drugs, including baricitinib and deuruxolitinib, depending on indication and approval status.

Drug	Sponsor or principal commercial company	Modality	Key US regulatory position
Ritlecitinib	Pfizer	Small-molecule JAK3/TEC inhibitor	FDA-approved for severe alopecia areata
Baricitinib	Eli Lilly and Incyte	Small-molecule JAK1/JAK2 inhibitor	FDA-approved for severe alopecia areata
Deuruxolitinib	Legacy or current sponsor depending on commercial rights	Small-molecule JAK inhibitor	Separate patent and regulatory estate
Tofacitinib	Pfizer	Small-molecule JAK inhibitor	Not approved by FDA specifically for alopecia areata

Ritlecitinib’s principal patent advantage is the direct composition claim covering the active molecule and salts. Competitive products have separate patent estates and different expiration profiles. Patent overlap should not be assumed merely because the drugs affect the JAK pathway.

What generic launch risks exist?

The likely generic launch scenarios are:

Launch after patent expiration

A generic applicant waits until the listed patent expires. This is the lowest litigation-risk pathway but delays entry until at least July 2029, subject to regulatory exclusivity and any additional valid patents.

Paragraph IV challenge

The applicant certifies that US Patent 8,158,616 is invalid, unenforceable, or not infringed. Pfizer may sue within 45 days, potentially triggering a 30-month approval stay.

Authorized generic or settlement

Pfizer could license a generic launch date or supply an authorized generic. No settlement or license terms are established by the supplied information.

Salt or formulation redesign

A generic applicant could attempt to use a different pharmaceutically acceptable salt or formulation. Claim 1 reduces the value of a simple salt change because it expressly covers pharmaceutically acceptable salts. A formulation redesign also may not avoid claim 3 if the product still contains the claimed ritlecitinib compound or salt and a pharmaceutically acceptable carrier.

Manufacturing-process differentiation

A different synthesis route does not avoid a product claim. It could avoid a process claim if one exists elsewhere, but it would not by itself avoid claim 1 or claim 3.

What is the geographic coverage of this patent?

US Patent 8,158,616 provides US protection only. Corresponding international and national-phase patents may exist in other jurisdictions, but each jurisdiction requires separate analysis of:

• Patent family members
• Local claim amendments
• Patent-term adjustments
• Supplementary protection certificates
• Regulatory exclusivity
• Opposition or nullity proceedings
• National litigation
• Local generic-entry rules

The US patent does not directly block sales in Europe, Japan, Canada, China, or other markets. Geographic protection must be assessed from the corresponding national patent records.

What licensing and commercial issues matter?

Pfizer owns and commercializes Litfulo in the United States. The commercial value of US Patent 8,158,616 is tied to:

• The absence of approved generic competition before the patent and regulatory barriers end
• The approved alopecia areata indication
• The ability to enforce the compound claim against alternative salt forms
• The size and persistence of the alopecia areata market
• Competition from other JAK inhibitors
• Reimbursement and safety restrictions applicable to JAK inhibitors

No public license, co-development agreement, or authorized-generic arrangement is established by the supplied patent claims. Patent ownership and commercialization should be distinguished from any separate regional licensing or distribution arrangements.

Key Takeaways

• US Patent 8,158,616 covers ritlecitinib, the active ingredient in Litfulo.
• Claim 1 is the commercially important claim because it covers the compound and pharmaceutically acceptable salts.
• Claim 2 specifically covers the phosphoric acid salt.
• Claim 3 covers pharmaceutical compositions containing the claimed compound or salt with a pharmaceutically acceptable carrier.
• The patent is listed in the FDA Orange Book with an expected expiration date of July 1, 2029.
• Ritlecitinib received FDA approval on June 23, 2023, for severe alopecia areata in adults and adolescents aged 12 years and older.
• The drug has five-year new chemical entity exclusivity, with the core NCE period extending to June 23, 2028.
• A simple change in salt or excipients may not avoid the patent because claim 1 covers pharmaceutically acceptable salts and claim 3 is open-ended.
• The patent is a small-molecule patent estate, so generic competition, not biosimilar competition, is the relevant entry risk.
• The supplied claims do not establish separate method-of-use, polymorph, manufacturing, or specialized formulation protection.

FAQs

Can a generic company avoid US Patent 8,158,616 by using ritlecitinib free base?

Not necessarily. Claim 1 expressly covers the named compound itself, in addition to pharmaceutically acceptable salts.

Does the patent cover ritlecitinib tosylate?

A tosylate salt may fall within claim 1 if it qualifies as a pharmaceutically acceptable salt of the claimed compound. Claim 2 separately identifies the phosphoric acid salt but does not exclude other salts from claim 1.

Is US Patent 8,158,616 a method-of-treatment patent?

No. The supplied claims are directed to the compound, a specific salt, and pharmaceutical compositions. They do not recite treatment of alopecia areata or another disease.

Can a generic use a different capsule excipient to avoid claim 3?

Usually not if the generic still contains the claimed ritlecitinib compound or salt and a pharmaceutically acceptable carrier. Claim 3 does not require a particular excipient.

Is ritlecitinib subject to biosimilar competition?

No. Ritlecitinib is a chemically synthesized small molecule regulated through the generic-drug pathway. Biosimilar provisions apply to biological products, not conventional small-molecule drugs.

References

1. United States Patent and Trademark Office. (2012). US Patent No. 8,158,616, compounds and pharmaceutical compositions. U.S. Department of Commerce.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
3. U.S. Food and Drug Administration. (2023). Litfulo prescribing information. Pfizer Inc.
4. Pfizer Inc. (2023). Litfulo: Ritlecitinib capsules, for oral use. U.S. product labeling.
5. Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j)(5)(F)(ii).
6. Hatch-Waxman Amendments, 35 U.S.C. § 271(e)(2); 21 U.S.C. § 355(j)(2)(A)(vii)(IV).

Drugs Protected by US Patent 8,158,616

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Eli Lilly And Co	OLUMIANT	baricitinib	TABLET;ORAL	207924-002	Oct 8, 2019	AB	RX	Yes	No			Y	Y
Eli Lilly And Co	OLUMIANT	baricitinib	TABLET;ORAL	207924-001	May 31, 2018	AB	RX	Yes	No			Y	Y
Eli Lilly And Co	OLUMIANT	baricitinib	TABLET;ORAL	207924-003	May 10, 2022	AB	RX	Yes	Yes			Y	Y

International Family Members for US Patent 8,158,616

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	2288610		300886	Netherlands
European Patent Office	2288610		PA2017023	Lithuania
European Patent Office	2288610		CA 2017 00032	Denmark