US Patent 8,058,238: Daptomycin Purification Claims, Scope, Expiration and Patent Landscape

US Patent 8,058,238 is a process-linked composition patent covering highly purified daptomycin produced through aggregate or micelle formation, separation, dissociation and related chromatographic operations. Its practical value was concentrated in manufacturing-process control rather than in the basic daptomycin molecule, Cubicin formulation, dosage regimen or method of treating infection. Based on the claim set provided, the patent does not broadly block all daptomycin products. It targets daptomycin compositions made through specified purification pathways and meeting defined purity or impurity criteria.

The patent’s commercial relevance is now primarily historical and freedom-to-operate related. It is not an Orange Book-listed patent for the approved daptomycin drug product, and its enforceable term has expired or ended under the applicable US patent-term calculation. The underlying purification concepts remain relevant as manufacturing know-how and may overlap with later process patents.

What does US Patent 8,058,238 cover?

US 8,058,238 covers purified daptomycin compositions characterized by both product attributes and the process used to obtain them. The central technical concept is that daptomycin can form aggregates or micelles under selected solution conditions. Those larger assemblies can be retained or separated from contaminants, then converted back into monomeric daptomycin.

The principal claim families are:

Claim group	Primary subject matter	Representative claims
Aggregate-purified daptomycin	Essentially pure daptomycin obtained from an aggregate	1-9, 49-59
Micelle-based purification	Formation, retention, separation and dissociation of daptomycin micelles	10-24, 37-48, 99-112, 144-150, 165-182
Defined impurity profiles	Limits on impurities identified as peaks 1-14 in Figure 12	8-9, 21-36, 49-50, 92, 113-124, 151-162
Fermentation and chromatography	Streptomyces roseosporus fermentation followed by anion exchange and hydrophobic interaction chromatography	66-84
Pharmaceutical compositions	Purified daptomycin combined with a carrier, excipient, antibiotic or antifungal agent	52-65
Preparation of pharmaceutical compositions	Combining purified daptomycin with a carrier or excipient	85-91
Specific process conditions	pH, temperature, salt, critical micelle concentration and solvent conditions	20, 44-48, 111, 146-150, 168-182

The broadest technical theme is the use of a daptomycin aggregate as a purification vehicle. The claims repeatedly require one or more of the following:

Forming daptomycin aggregates or micelles.
Separating the aggregate from low-molecular-weight contaminants.
Dissociating the aggregate into monomeric daptomycin.
Separating monomeric daptomycin from high-molecular-weight contaminants.
Obtaining a product having at least approximately 93% purity.
Reducing anhydro-daptomycin, the beta-isomer and impurities identified in Figure 12.

How do the independent claims define patent scope?

The independent claims should be analyzed as product-by-process claims rather than as unrestricted product claims.

Claim 1: Essentially pure daptomycin from an aggregate

Claim 1 requires:

A composition.
Essentially pure daptomycin.
Daptomycin purified by forming a daptomycin aggregate.
Obtaining the purified daptomycin from that aggregate.

Claim 1 does not specify a numeric purity threshold. Its scope depends on the meaning of “essentially pure,” the disclosed analytical method and the requirement that the claimed composition be obtained through the recited aggregate-based process.

Claim 3: Reduced anhydro-daptomycin and beta-isomer

Claim 3 narrows the composition through impurity characteristics. It requires daptomycin that is substantially free of anhydro-daptomycin and substantially free of the beta-isomer, while also requiring aggregate-based purification.

Claims 4-7 further address anhydro-daptomycin reduction and purity of at least approximately 93%. These claims could be relevant to a competing manufacturer if its product specification identifies anhydro-daptomycin and beta-isomer levels but does not disclose the manufacturing process.

Claim 8: Figure 12 impurity profile

Claim 8 requires daptomycin substantially free of each of impurities 1 through 14 identified by chromatographic peaks in Figure 12. This limitation creates several proof issues:

The identity of each impurity depends on the patent disclosure and analytical method.
“Substantially free” may require a quantitative interpretation.
A product specification alone may not establish that the product was made through the claimed aggregate and monomerization sequence.
The chromatographic method, column, mobile phase and detection conditions may affect whether a peak corresponds to the claimed impurity.

Claim 10: Micelle-to-non-micellar purification

Claim 10 requires a pharmaceutical composition comprising essentially pure daptomycin purified by:

Forming daptomycin micelles.
Converting the micelles into a non-micellar daptomycin composition.
Obtaining purified daptomycin from the micellar, non-micellar or combined material.

Claims 14-20 add process conditions involving pH, electrolyte concentration, daptomycin concentration, temperature, filtration and lyophilization.

Claim 21: Purity threshold plus micelle formation

Claim 21 requires daptomycin of at least approximately 93% purity relative to fermentation or purification impurities and requires that the product be obtained through micelle formation. Claims 25-36 add limits for selected impurity peaks.

The threshold structure is important. A product with 98% total daptomycin purity may still fall outside a dependent claim if a specified impurity exceeds its individual limit. Conversely, a product below 98% may satisfy a 93% claim if the relevant impurity limits and process limitations are met.

Claim 49: Aggregate-derived purified daptomycin

Claim 49 is one of the more commercially significant composition claims. It requires purified daptomycin of at least approximately 93% purity relative to impurities 1-14, obtained by forming a daptomycin-containing aggregate.

Claims 50-65 extend that concept to specified impurity profiles and pharmaceutical compositions.

Claim 66: Integrated commercial manufacturing process

Claim 66 recites a complete production sequence:

Fermenting Streptomyces roseosporus.
Feeding n-decanoic acid.
Clarifying the fermentation broth.
Anion exchange chromatography.
Hydrophobic interaction chromatography.
A second anion exchange chromatography step.

Claims 67-84 add operational restrictions involving residual n-decanoic acid, filtration, resin chemistry, continuous-flow chromatography, radial-flow chromatography, ultrafiltration, depyrogenation and lyophilization.

This claim family is narrower than the aggregate and micelle claims but potentially more relevant to a manufacturer using a similar commercial-scale process.

Claims 176-192: Later-developed micelle and aggregate embodiments

The final claim group focuses on:

Daptomycin micelles.
pH of approximately 3.0 to 4.8.
Temperature of approximately 2-15°C.
Critical micelle concentration.
Organic solvents such as n-butanol, isopropyl alcohol and acetonitrile.
Hydrophobic interaction chromatography at approximately pH 6.0-7.5.
Aggregate filtration.
Fermentation followed by anion exchange, aggregate formation and filtration.

These claims provide the most technically specific coverage of the micelle-based process.

What purification conditions are claimed?

The patent claims several overlapping operating windows.

Parameter	Claimed range or condition
Acidic pH for micelle or aggregate formation	Approximately pH 2.5-5.0
More specific pH range	Approximately pH 3.0-4.8
Temperature for aggregate formation	Approximately 2-15°C
Sodium chloride concentration	Approximately 300-500 mM
Dissociation pH	Approximately 6.0 or higher
Neutralization condition	Approximately pH 6.5
Daptomycin concentration	At or above the critical micelle concentration for formation; below that concentration for dissociation
Organic solvents for dissociation	n-Butanol, isopropyl alcohol, acetonitrile or combinations
Purity threshold	Approximately 93%, 95%, 97%, 98% or 99%, depending on the claim
Chromatographic sequence	Anion exchange, hydrophobic interaction chromatography, then anion exchange

The process is designed to exploit size differences. Daptomycin in aggregate form is retained or separated differently from small contaminants, while monomeric daptomycin is treated differently from high-molecular-weight contaminants.

Are the claims product claims or process claims?

The claims are formally directed to compositions, but many are product-by-process claims. A product-by-process claim defines a product by the process used to make it. Under US patent law, the process limitation can be relevant to infringement and validity analysis, although the product itself generally must still satisfy the claimed structural or compositional characteristics. The Federal Circuit’s treatment of product-by-process claims is reflected in MPEP § 2113 and cases including Abbott Laboratories v. Sandoz, Inc. [USPTO, MPEP § 2113; Abbott Laboratories v. Sandoz, Inc., 566 F.3d 1282 (Fed. Cir. 2009)].

For this patent, a challenger would likely examine two separate issues:

Whether the accused daptomycin has the claimed purity or impurity profile.
Whether the accused composition was produced through the claimed aggregate, micelle, filtration or chromatography steps.

A manufacturer using a different purification route may have a noninfringement position even if its daptomycin has a similar purity profile. That position would depend on the construction of each claim and whether the claim’s process language is treated as limiting.

What are the principal claim vulnerabilities?

The patent’s claim breadth is constrained by several terms and analytical dependencies.

Ambiguous purity language

Terms such as “essentially pure,” “substantially free” and “essentially free” require construction against the specification. The claims do not apply one uniform numerical threshold. Some recite approximately 93% purity, while others use qualitative impurity language.

Dependence on Figure 12

Claims referring to impurities 1-14 depend on the identity and measurement of peaks in Figure 12. A dispute could focus on:

Whether the accused peak is the same impurity.
Whether the test method is sufficiently comparable.
Whether “substantially free” has a defined numerical meaning.
Whether the impurity profile is inherent to the product or merely associated with the disclosed process.

Process proof

The process limitations create evidence issues. A downstream purchaser normally may know the final product specification but not the supplier’s exact pH, temperature, salt concentration or micelle-handling conditions. Discovery of batch records, validation protocols, master production records and analytical data would be central in an infringement investigation.

Enablement and written description

The claims cover multiple aggregate-forming conditions, chromatographic systems, impurity profiles and manufacturing configurations. A validity challenge could test whether the specification enables the full breadth of claims, particularly claims extending across broad combinations of pH, temperature, salt, solvents, resins and purification sequences.

Obviousness

The individual operations, including ion exchange, hydrophobic interaction chromatography, ultrafiltration and pH adjustment, are conventional bioprocessing tools. The principal inventive argument would therefore focus on the specific use of daptomycin aggregation or micellization to separate impurities and improve product quality. Prior-art references concerning daptomycin purification, lipopeptide aggregation, micelle filtration and impurity control would be central to an obviousness analysis.

What is the patent expiration status?

The patent was issued on November 15, 2011. Its term is governed by the 20-year patent term measured from the earliest effective US nonprovisional filing date, subject to patent-term adjustment and any applicable terminal disclaimer. The patent is not a current Orange Book-listed patent for Cubicin or a generic daptomycin injection product.

The effective term should be confirmed against the USPTO Patent Center record and Patent Term Adjustment data before relying on a precise date in a transaction or litigation position. On the available patent-term framework and the age of the patent family, the enforceable term has ended by the current commercial period. Any expiration estimate should not be confused with the expiration of separate daptomycin patents, formulation patents or process patents in the same family.

Item	Assessment
Patent	US 8,058,238
Issue date	November 15, 2011
Technology	Purified daptomycin and aggregate/micelle purification
Orange Book status	Not identified as an Orange Book-listed patent for the approved daptomycin drug product
Current enforceability	Patent term has ended under the applicable US term calculation
Commercial significance	Historical process protection; potential relevance to legacy FTO and manufacturing records
Remaining risk	Later patents, trade secrets, process know-how and foreign counterparts

What is the Orange Book status of US 8,058,238?

US 8,058,238 is not the basic composition-of-matter patent for daptomycin and is not the principal patent listed for Cubicin in the FDA Orange Book. The Orange Book focuses on patents submitted for approved drug products, including patents covering the drug substance, drug product or approved method of use under FDA listing rules [FDA, Approved Drug Products with Therapeutic Equivalence Evaluations].

Because the patent concerns purification and product quality rather than the approved indication or dosage form, it would not ordinarily create a standard Paragraph IV certification issue unless it were listed for the relevant reference-listed drug. The absence of an Orange Book listing means that a generic applicant would not normally be required to certify Paragraph IV against this patent through the standard ANDA certification mechanism.

Were there Paragraph IV challenges or settlements involving this patent?

No public record cited here establishes a Paragraph IV challenge specifically directed to US 8,058,238. The better-known daptomycin generic disputes generally concerned Cubicin-related product, formulation, method-of-use or other listed patents rather than this purification patent.

A Paragraph IV certification to an Orange Book-listed patent can trigger a patent-infringement action under 35 U.S.C. § 271(e)(2). A non-listed process patent does not ordinarily generate the same automatic Hatch-Waxman litigation pathway. It could still support a conventional infringement action if a generic manufacturer practiced the claimed process or sold a composition falling within an enforceable claim.

No settlement agreement specifically resolving US 8,058,238 is identified in the materials provided.

Which companies are relevant to the daptomycin competitive landscape?

The principal commercial parties have been:

Company or group	Relevance
Cubist Pharmaceuticals	Original commercial developer of Cubicin and principal patent holder associated with daptomycin commercialization
Merck & Co.	Acquired Cubist and assumed Cubicin-related assets
Generic injectable manufacturers	Potential users of alternative fermentation and purification processes
Contract manufacturers	Relevant because process infringement may occur in outsourced API or drug-product manufacturing
API suppliers	Key targets for process mapping, impurity testing and supply-chain diligence

Daptomycin is a fermentation-derived cyclic lipopeptide. Unlike a conventional small-molecule API, its manufacturing risk includes strain performance, precursor feeding, fermentation impurities, closely related lipopeptide variants, anhydro-daptomycin, beta-isomer formation, endotoxin control and sterile injectable production.

How strong is the patent estate?

The estate was technically meaningful but claim strength varied by claim family.

Claim family	Relative strength	Reason
Broad aggregate-derived composition claims	Moderate	Broad concept, but dependent on product-by-process construction and purity proof
Micelle claims with pH and temperature limits	Moderate to strong historically	More concrete operating conditions and process evidence
Figure 12 impurity claims	Variable	Potentially useful if analytical identity and thresholds are clear
Detailed fermentation/chromatography claims	Stronger against a matching process	Specific resin, feed, pH and chromatography sequence limitations
Pharmaceutical-composition claims	Limited	Often depend on the underlying purified daptomycin and process limitations
Claims requiring specific solvents or HIC conditions	Narrow but potentially enforceable	Clearer technical boundaries, narrower coverage

The patent was stronger as a manufacturing-process patent than as a broad product patent. Its principal commercial effect would have been to increase the cost of designing and validating an alternative daptomycin purification route.

What generic launch risks existed?

Before expiration, generic manufacturers faced four principal risks:

Their process could form daptomycin micelles under the claimed pH, temperature or salt conditions.
Their process could retain micelles by ultrafiltration and later dissociate them.
Their final product could meet the claimed impurity profile.
Their supplier’s process could follow the claimed fermentation and chromatography sequence without the generic sponsor’s full visibility.

The practical design-around options included:

Avoiding the claimed aggregate or micelle formation conditions.
Using a different chromatographic sequence.
Selecting alternative resin chemistry.
Avoiding the claimed pH and temperature windows.
Demonstrating that the final composition does not satisfy the specified impurity profile.
Structuring supply agreements to obtain process representations and indemnities from API manufacturers.

These strategies do not address separate patents covering daptomycin formulations, dosage forms, treatment methods or sterile injectable manufacturing.

What geographic coverage matters?

US 8,058,238 provides US protection only. Commercial diligence should separately review:

PCT publications and national-phase filings.
European patent counterparts.
Canadian, Japanese, Chinese, Indian and Australian counterparts.
Continuations, divisionals and patents claiming related purification improvements.
Foreign expiry dates and local patent-term adjustments.
Regulatory data and manufacturing exclusivity independent of patent rights.

Patent expiry in the United States does not establish freedom to operate in Europe or other markets.

Key Takeaways

US 8,058,238 covers purified daptomycin made through aggregate or micelle-mediated purification.
Its claims combine product attributes with process limitations.
The main technical features are micelle formation, aggregate retention, contaminant separation, monomerization and high-purity daptomycin recovery.
The patent includes claims directed to anhydro-daptomycin, beta-isomer and impurities 1-14 identified in Figure 12.
Claims 66-84 cover a more specific commercial process involving Streptomyces roseosporus, n-decanoic acid, anion exchange and hydrophobic interaction chromatography.
The patent is not the basic daptomycin composition-of-matter patent.
It is not identified as an Orange Book-listed patent for the approved daptomycin product.
No specific Paragraph IV challenge or settlement involving this patent is established by the cited record.
The patent’s enforceable term has ended under the applicable US patent-term calculation.
Later daptomycin process patents, trade secrets and manufacturing know-how remain relevant to current freedom-to-operate analysis.

FAQs

Does US 8,058,238 cover all daptomycin API?

No. The claims require specified purification steps, aggregate or micelle formation, purity characteristics, impurity profiles or combinations of those limitations.

Can a manufacturer avoid the patent by making daptomycin below 93% purity?

That may avoid claims containing the approximately 93% threshold, but it would not automatically avoid claims using “essentially pure” or “substantially free” language. Each claim must be analyzed separately.

Does a daptomycin micelle automatically infringe US 8,058,238?

No. Micelle formation alone is insufficient for every claim. The relevant claim may also require pH, temperature, filtration, impurity, purity, dissociation or chromatography limitations.

Are daptomycin biosimilars relevant to this patent?

No. Daptomycin is a chemically defined fermentation-derived lipopeptide, not a biologic subject to the biosimilar pathway under the Public Health Service Act. Competition generally proceeds through abbreviated drug applications for generic injectable products rather than biosimilar applications.

Does patent expiration eliminate manufacturing risk?

It eliminates the patent’s prospective US infringement risk after the applicable expiration date, but it does not eliminate risks from later patents, confidential manufacturing information, regulatory requirements, contractual restrictions or foreign patent rights.

References

United States Patent and Trademark Office. (2011). U.S. Patent No. 8,058,238, Purification of daptomycin.
United States Patent and Trademark Office. (n.d.). Manual of Patent Examining Procedure § 2113: Product-by-process claims.
U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (2017). Cubicin (daptomycin for injection) prescribing information.
Abbott Laboratories v. Sandoz, Inc., 566 F.3d 1282 (Fed. Cir. 2009).
35 U.S.C. §§ 154, 271 and 271(e)(2).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	311405	⤷ Start Trial
Austria	449785	⤷ Start Trial
Australia	3097801	⤷ Start Trial
Australia	784937	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,058,238

Summary for Patent: 8,058,238