US Patent 9,572,857: Leuprolide Mesylate Injectable Depot Patent Scope and Patent Landscape

US Patent No. 9,572,857 protects injectable depot compositions containing leuprolide mesylate, a biodegradable lactide-based polymer, and N-methyl-2-pyrrolidone (NMP). The central limitation is the absence of excess strong acid beyond the acid used to create the mesylate salt. The claims cover polymeric in situ depot systems used for sustained release after subcutaneous or intramuscular injection.

The patent is highly relevant to leuprolide mesylate products using poly(lactic acid), polylactide, PLGA, or related polymers dissolved or dispersed in NMP. It does not, based on the supplied claims, cover every leuprolide depot, every PLGA formulation, or every injectable GnRH agonist product.

What does US Patent 9,572,857 claim?

The patent has one broad independent composition claim and six dependent claims. The claim architecture is as follows:

Claim	Principal limitation	Scope
1	Leuprolide mesylate, specified biodegradable polymer, NMP, and no excess strong acid	Broad composition claim
2	Claim 1 polymer molecular weight of about 2,000-100,000 Da	Molecular-weight limitation
3	0.01-40% leuprolide mesylate, 40-60% polylactide or PLA, 30-80% NMP	Narrow PLA formulation
4	Claim 3 polymer molecular weight of about 8,000-50,000 Da	Narrow molecular-weight limitation
5	0.01-40% leuprolide mesylate, 30-60% PLGA or related copolymer, 30-80% NMP	Narrow PLGA formulation
6	Claim 5 copolymer ratio of about 85:15 lactide:glycolide	Specific PLGA ratio
7	Claim 5 polymer molecular weight of about 15,000-50,000 Da	Narrow PLGA molecular-weight limitation

Claim 1 is the commercial significance of the patent. Claims 3 and 5 provide narrower fallback positions directed to PLA and PLGA formulation families.

What elements must be present for literal infringement?

A product would need to satisfy every limitation of at least one asserted claim. For claim 1, the relevant elements are:

An injectable polymeric composition.
Leuprolide in the mesylate salt form.
A biodegradable polymer selected from:
- polylactide;
- poly(lactic acid);
- poly(lactic acid-co-glycolic acid); or
- poly(lactide-co-glycolide).
NMP.
No excess strong acid beyond the acid used to form leuprolide mesylate.

The claim is composition-based. It does not expressly require a particular release duration, injection site, particle size, syringe presentation, dose, pH, polymer concentration, or commercial indication.

The phrase "does not contain excess strong acid" is a material limitation. A formulation containing hydrochloric acid, sulfuric acid, methanesulfonic acid, or another strong acid in an amount beyond that used to form the mesylate salt could fall outside literal claim scope, depending on the claim construction and formulation chemistry.

How broad is the polymer coverage?

The polymer Markush language covers both homopolymers and lactide-glycolide copolymers.

Polylactide and poly(lactic acid)

Claims 1 through 4 cover polylactide and poly(lactic acid). Claims 3 and 4 narrow this group by requiring:

0.01-40% w/w leuprolide mesylate;
40-60% w/w polymer;
30-80% w/w NMP; and
a polymer molecular weight of about 8,000-50,000 Da.

The terms polylactide and poly(lactic acid) may create nomenclature overlap, but they do not automatically make every PLA product infringing. Composition concentration and molecular-weight limitations remain relevant for the dependent claims.

PLGA and related copolymers

Claims 1, 5, 6, and 7 cover PLGA and poly(lactic acid-co-glycolic acid). Claim 5 requires a lactide:glycolide or lactic-acid:glycolic-acid ratio from 50:50 to about 100:0.

Claim 6 specifically identifies an approximately 85:15 ratio. This limitation is commercially important because 85:15 PLGA is a common controlled-release polymer grade. A product using 50:50, 75:25, 85:15, or 100:0 polymer may implicate different dependent claims, subject to the precise polymer nomenclature and formulation composition.

What formulations are protected by US 9,572,857?

The practical claim coverage can be summarized as follows:

Formulation characteristic	Claim 1	Claims 3-4	Claims 5-7
Leuprolide mesylate	Required	Required	Required
NMP	Required	Required	Required
PLA or polylactide	Covered	Required	Excluded
PLGA	Covered	Excluded	Required
0.01-40% leuprolide mesylate	Not required	Required	Required
30-60% polymer	Not required	40-60%	30-60%
30-80% NMP	Not required	Required	Required
85:15 PLGA	Not required	Not applicable	Required by claim 6
Polymer molecular weight	2,000-100,000 Da under claim 2	8,000-50,000 Da	15,000-50,000 Da under claim 7
No excess strong acid	Required	Required	Required

The concentration ranges are written independently and can mathematically overlap above 100% when read as separate open ranges. They should be interpreted in the context of a complete formulation and the specification’s disclosed embodiments rather than as permission to exceed a physically meaningful total composition.

Does the patent cover Eligard or Camcevi?

Eligard

Eligard contains leuprolide acetate and uses an Atrigel-based depot system with biodegradable polymer and NMP. The supplied claims require leuprolide mesylate, not leuprolide acetate. A leuprolide acetate product therefore does not literally satisfy the salt limitation of claims 1-7.

The distinction between acetate and mesylate is central. A formulation that uses leuprolide acetate rather than leuprolide mesylate would require a doctrine-of-equivalents analysis, if asserted, rather than straightforward literal infringement. Salt-form differences can create substantial prosecution-history and claim-construction issues.

Camcevi

Camcevi is a leuprolide mesylate injectable emulsion approved by the FDA for six-month treatment of advanced prostate cancer. Its formulation uses a biodegradable polymeric depot technology and NMP-related delivery system. The product is therefore technically aligned with the claim theme of US 9,572,857. The commercial formulation must be compared against the patent’s polymer identity, polymer molecular weight, NMP concentration, leuprolide mesylate content, and acid profile to determine claim coverage.

The strongest potential overlap would be with:

claim 1, if the product contains one of the listed polymers and NMP without excess strong acid;
claim 5, if the product uses PLGA within the stated concentration and copolymer-ratio ranges;
claim 6, if the PLGA is approximately 85:15;
claim 7, if the polymer molecular weight is approximately 15,000-50,000 Da.

The product label alone may not disclose every parameter needed for a complete infringement determination. Regulatory labeling commonly omits exact polymer molecular weight, residual acid content, and detailed formulation percentages. Those facts are generally controlled by the sponsor’s chemistry, manufacturing, and controls records.

What is the Orange Book relevance?

For an FDA-approved drug, Orange Book relevance depends on whether the patent is listed by the NDA holder and whether the claims cover the approved drug or an approved method of use.

US 9,572,857 is a drug-product formulation patent rather than a pure method-of-use patent. If listed against a leuprolide mesylate NDA, it could create a Paragraph IV certification issue for an abbreviated new drug application seeking approval of the same or therapeutically equivalent formulation.

The commercial effect depends on:

the NDA to which the patent is listed;
the patent’s listed expiration date;
whether the patent is listed for the drug product or only a particular use;
whether a generic applicant certifies Paragraph IV;
whether the NDA holder files suit within 45 days;
whether a 30-month stay applies; and
whether the generic product uses the claimed mesylate-polymer-NMP combination.

A patent claiming the formulation does not automatically block a generic using a materially different salt, solvent, polymer, or delivery mechanism.

When does US Patent 9,572,857 lose exclusivity?

The patent issued on February 21, 2017. Its enforceable expiration date depends on the patent’s earliest effective nonprovisional filing date, patent-term adjustment, terminal disclaimers, and any patent-term extension.

The ordinary US patent term is generally 20 years from the earliest effective US nonprovisional or international filing date, subject to statutory adjustments (35 U.S.C. § 154). The issue date does not establish the expiration date.

The patent’s exclusivity should therefore be separated into three dates:

Date type	Meaning
Filing-based nominal expiry	20 years from the applicable earliest effective filing date
Adjusted expiry	Nominal expiry plus any patent-term adjustment
Drug-specific expiry	Adjusted expiry plus any available patent-term extension, if granted

No patent-term-extension conclusion follows from the claims alone. The controlling source is the USPTO patent-term data and, for a drug-specific extension, the FDA and USPTO regulatory records.

What is the strongest claim?

Claim 1 is the strongest claim for broad product coverage because it does not impose the concentration or molecular-weight limits appearing in claims 3-7. Its principal narrowing features are:

mesylate rather than another leuprolide salt;
one of the listed biodegradable polymers;
NMP; and
no excess strong acid.

Claims 3 and 5 are narrower but may be more useful in litigation because they provide detailed formulation positions. Claim 6 is particularly specific and may be valuable if the accused product uses 85:15 PLGA. Claim 7 adds a polymer molecular-weight range that may be difficult for a patentee to prove without discovery or analytical testing.

What are the principal design-around strategies?

A competitor could seek to avoid literal infringement through one or more of the following approaches:

Use a different leuprolide salt

Leuprolide acetate, leuprolide pamoate, or another salt would not satisfy the express mesylate limitation. The commercial and pharmaceutical consequences of changing the salt would require separate stability, bioavailability, toxicology, and regulatory analysis.

Replace NMP

A solvent other than NMP could avoid the express solvent limitation. Candidate systems would need to preserve injectability, polymer solubility, depot formation, release control, and local tolerability.

Use a different polymer

A polymer outside the listed PLA, polylactide, PLGA, and poly(lactic acid-co-glycolic acid) categories could avoid the Markush limitation. Polycaprolactone, polyanhydrides, or alternative in situ depot polymers may raise separate patent issues.

Add or alter strong-acid content

The no-excess-strong-acid limitation may create a formulation distinction, but deliberately adding acid can produce separate safety, stability, and regulatory problems. The relevant question is the amount and function of acid in the final product, not merely whether an acid appears in the manufacturing process.

Change the delivery format

A microsphere, implant, preformed depot, aqueous suspension, or solid implant may avoid an injectable polymeric composition containing NMP. Each alternative can implicate different patent families.

What patent litigation or Paragraph IV risk exists?

The supplied claims establish technical infringement risk but do not establish a litigation outcome, settlement, or Paragraph IV filing. A Paragraph IV challenge would likely focus on one or more of the following issues:

Lack of anticipation by earlier leuprolide acetate or leuprolide mesylate depot formulations.
Obviousness based on combining leuprolide mesylate with known PLA or PLGA/NMP in situ depot technology.
Written-description support for the broad polymer and concentration ranges.
Enablement of the full polymer, molecular-weight, and concentration scope.
Construction of "excess strong acid."
Whether the accused commercial product actually contains the claimed salt and polymer.
Whether the asserted claims are listed against the relevant NDA.

The formulation technology was known before the patent, particularly for leuprolide acetate depot products. The patent’s potentially differentiating technical position is the use of leuprolide mesylate in the specified polymer-NMP system without excess strong acid.

How strong is the patent estate?

US 9,572,857 appears strongest as a formulation patent when the accused product closely matches the mesylate, polymer, NMP, and acid limitations. Its strength is lower against:

leuprolide acetate products;
non-NMP systems;
products using non-PLA/non-PLGA polymers;
formulations with materially different acid chemistry;
delivery systems that do not form an injectable polymeric depot.

The patent does not, from the supplied claims, independently protect:

leuprolide mesylate as a molecule;
treatment of prostate cancer with leuprolide;
every dose or dosing interval;
manufacturing of the polymer;
manufacture of leuprolide mesylate;
a specific syringe or vial;
a specific release profile; or
all depot formulations containing NMP.

Competitive landscape for leuprolide depot products

Product or technology	Leuprolide form	Depot technology	Relevance to US 9,572,857
Eligard	Acetate	Polymer/NMP in situ depot	Salt limitation creates a potential distinction
Camcevi	Mesylate	Injectable polymeric depot	Technically closest product profile
Lupron Depot	Acetate	Microsphere depot	Different salt and delivery architecture
Other GnRH depot products	Varies	Microspheres, implants, or suspensions	Generally outside the claim unless all limitations are met

The most direct competitive issue is not the broad prostate-cancer market. It is whether a competing leuprolide mesylate product uses the same polymeric NMP depot architecture.

Key Takeaways

US 9,572,857 is a composition patent covering leuprolide mesylate with specified biodegradable polymers and NMP.
The no-excess-strong-acid limitation is a central claim feature.
Claim 1 provides the broadest coverage; claims 3-7 narrow the invention by polymer type, concentration, polymer ratio, and molecular weight.
Eligard’s leuprolide acetate formulation does not literally satisfy the mesylate limitation based on the supplied claims.
Camcevi is technically aligned with the patent’s claimed formulation category and presents the most direct product-overlap issue.
Exact infringement requires formulation data not ordinarily disclosed in the FDA label.
A competing product could reduce risk by changing the leuprolide salt, solvent, polymer, acid chemistry, or delivery format.
The patent’s expiration must be determined from USPTO patent-term records, including any patent-term adjustment or extension.
The claims do not independently cover leuprolide, prostate-cancer treatment, all depot formulations, or all manufacturing methods.

FAQs

Does US 9,572,857 cover leuprolide acetate?

No, not literally based on the supplied claims. The claims require leuprolide mesylate. Leuprolide acetate could raise a separate doctrine-of-equivalents question.

Does every PLGA and NMP leuprolide formulation infringe?

No. The formulation must also contain leuprolide mesylate and satisfy the injectable polymeric-composition and no-excess-strong-acid limitations. Claims 5-7 add concentration, polymer-ratio, and molecular-weight requirements.

Does the patent cover a leuprolide implant?

Not necessarily. The claims require an injectable polymeric composition. A preformed implant may fall outside the literal scope, depending on how it is made and administered.

Can a generic avoid the patent by using another solvent?

Potentially. Replacing NMP removes an express claim element, but the alternative formulation may implicate other patents and would require separate pharmaceutical and regulatory development.

Is an 85:15 PLGA formulation automatically covered?

No. An 85:15 ratio aligns with claim 6, but the product must also satisfy claim 5’s leuprolide, concentration, polymer, NMP, and acid limitations, as well as claim 6’s ratio requirement.

References

United States Patent No. 9,572,857. (2017). Injectable polymeric compositions comprising leuprolide mesylate. United States Patent and Trademark Office.
United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term information. https://www.uspto.gov/
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov/drugsatfda
U.S. Food and Drug Administration. (n.d.). Camcevi prescribing information. https://www.accessdata.fda.gov/
U.S. Food and Drug Administration. (n.d.). Eligard prescribing information. https://www.accessdata.fda.gov/
35 U.S.C. § 154. Patent term. (2024). United States Code.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Accord	CAMCEVI ETM	leuprolide mesylate	EMULSION;SUBCUTANEOUS	219745-001	Aug 25, 2025		RX	Yes	Yes	9,572,857	⤷ Start Trial	Y				⤷ Start Trial
Accord	CAMCEVI KIT	leuprolide mesylate	EMULSION;SUBCUTANEOUS	211488-001	May 25, 2021		RX	Yes	Yes	9,572,857	⤷ 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
Australia	2007207618	⤷ Start Trial
Brazil	PI0706558	⤷ Start Trial
Canada	2637569	⤷ Start Trial
China	101400363	⤷ Start Trial
Denmark	1984009	⤷ Start Trial
European Patent Office	1984009	⤷ Start Trial
Spain	2397712	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,572,857

Which drugs does patent 9,572,857 protect, and when does it expire?

Summary for Patent: 9,572,857