United States Patent 6,753,006: Paclitaxel Formulation Scope, Claim Analysis, and Patent Landscape

U.S. Patent No. 6,753,006 protects specified unit-dose and formulation presentations of non-crystalline, Cremophor-free paclitaxel. Its claims focus on the drug product’s physical state, absence of Cremophor, sealed-vial presentation, sterility characteristics, and dose or treatment schedule. The patent does not broadly claim every Cremophor-free paclitaxel formulation or every use of paclitaxel.

The patent issued on June 22, 2004. Its patent term ended in December 2021, subject to the official USPTO term calculation and any applicable adjustment. It therefore does not currently create an enforceable U.S. patent barrier for new commercial products. Its historical importance is linked to albumin-bound paclitaxel products, including Abraxane, although claim coverage must be assessed against the specific formulation and product presentation rather than the brand name alone.

What does U.S. Patent 6,753,006 claim?

The patent has two principal claim groups:

Claims 1-10 cover a unit dosage form or article of manufacture.
Claims 11-14 cover a stable, sterile, nonpyrogenic, nonaqueous paclitaxel formulation.

The independent claims require the following core elements:

Claim group	Product form	Paclitaxel state	Cremophor	Dose range	Additional limitation
Claims 1-3	Sealed vial	Non-crystalline	Free of Cremophor	30-1,000 mg/m²	Administration period no greater than about three hours
Claims 4-6	Sealed vial	Non-crystalline	Free of Cremophor	30-1,000 mg/m²	Treatment cycle less than about three weeks
Claims 7-10	Article of manufacture with sealed vial	Non-crystalline	Free of Cremophor	30-1,000 mg/m²	Administration period no greater than about three hours
Claims 11-14	Formulation	Non-crystalline	Free of Cremophor	30-1,000 mg/m²	Stable, sterile, nonpyrogenic, nonaqueous
Dependent claims	Same as parent claim	Same	Same	50-300 or 175-700 mg/m²	Single-dose administration in claims 10 and 14

The broadest practical claim is claim 11 because it does not expressly require a sealed vial. It does, however, require a stable, sterile, nonpyrogenic, nonaqueous formulation containing sufficient non-crystalline, Cremophor-free paclitaxel for systemic administration within the stated dose range.

What technical features limit the patent’s scope?

Non-crystalline paclitaxel

“Non-crystalline” is a central limitation. A product containing paclitaxel in a crystalline form would not meet the literal claim language. The limitation is directed to the physical form of the paclitaxel, not merely the absence of visible crystals in a final product.

A competing product could attempt to avoid the claims by using:

Crystalline paclitaxel;
A different solid-state form;
A molecularly complexed paclitaxel presentation;
A formulation in which the claimed non-crystalline state is not present in the finished dosage form.

The practical legal analysis would depend on how the claim term is construed and where the physical state is measured, including whether it refers to the drug before reconstitution, after reconstitution, or throughout the product lifecycle.

Cremophor-free composition

Cremophor EL is the principal solubilizing excipient associated with conventional paclitaxel injection. The claims require the formulation or vial contents to be “cremophor-free.”

This limitation excludes conventional paclitaxel injections that use polyoxyethylated castor oil. A product using polysorbate, ethanol, albumin, lipids, polymers, cyclodextrins, or another delivery vehicle could still fall within the claims if it also contains non-crystalline paclitaxel and satisfies the other limitations.

“Cremophor-free” does not mean excipient-free. The claims permit other excipients unless another claim limitation or the specification narrows the formulation.

Sealed vial

Claims 1 and 4 require a sealed vial. Claims 7-10 require an article of manufacture comprising a sealed vial. A bulk drug substance, open container, prefilled syringe, or non-vial presentation may avoid literal infringement of those claims if the presentation does not include the claimed sealed vial.

Claim 11 does not expressly require a vial. A non-vial product can therefore remain within the scope of claim 11 if it satisfies the formulation requirements.

Dose expressed in mg/m²

The claims define the dose by body-surface-area dosing:

Broad range: 30-1,000 mg/m²;
Intermediate range: 50-300 mg/m²;
Higher range: 175-700 mg/m².

The claims do not state a fixed milligram quantity per vial. A product must contain a quantity suitable to deliver the relevant dose to a human patient. The “suitable” language creates a functional limitation tied to administration, patient dosing, and the quantity in the vial.

A 100 mg vial, for example, cannot be assessed solely by its nominal fill weight. The relevant question is whether the vial contains a quantity suitable to deliver a claimed mg/m² dose under the claimed administration conditions.

Administration period and treatment cycle

Claims 1-3 and 7-10 require administration over a period of no more than approximately three hours. Claims 4-6 instead require a treatment cycle of less than approximately three weeks.

These are separate claim pathways. A product could potentially satisfy the formulation and dose limitations but avoid claims 1-3 if its labeled administration period exceeds three hours. It could still implicate claims 4-6 if the treatment cycle is less than three weeks.

The term “about” provides tolerance around the three-hour and three-week thresholds. The scope would depend on ordinary clinical practice, the patent specification, prosecution history, and the evidence used to establish the relevant administration period or treatment interval.

How do claims 1-10 differ from claims 11-14?

Claims 1-10 are presentation and dosing claims. They require a sealed vial or article of manufacture and tie the product to a specific administration period or treatment cycle.

Claims 11-14 are formulation claims. They require the formulation to be:

Stable;
Sterile;
Nonpyrogenic;
Nonaqueous;
Cremophor-free;
Non-crystalline with respect to paclitaxel;
Suitable for systemic administration within the claimed dose range.

The formulation claims may be more difficult to design around because they do not depend on the use of a sealed vial. They may cover a broader range of commercial presentations, provided the formulation itself satisfies all limitations.

The dependent claims do not introduce a new delivery technology. They narrow the dose range or specify single-dose administration.

What products are most likely to fall within the patent’s historical scope?

A product was most likely to fall within the claims if it had the following profile:

Product characteristic	Relevance
Paclitaxel as the active ingredient	Required
Paclitaxel in non-crystalline form	Required
No Cremophor EL	Required
Sterile presentation	Required for claims 11-14
Nonpyrogenic presentation	Required for claims 11-14
Nonaqueous formulation	Required for claims 11-14
Sealed vial	Required for claims 1-10
Dose of 30-1,000 mg/m²	Required by independent claims
Administration within three hours	Required by claims 1-3 and 7-10
Treatment cycle under three weeks	Required by claims 4-6

Albumin-bound paclitaxel products are the most commercially relevant comparison. Abraxane is supplied as a lyophilized powder for reconstitution and contains paclitaxel formulated with human albumin. Its labeling identifies a 100 mg single-dose vial and administration schedules that vary by indication. The product is free of Cremophor EL and is administered intravenously. FDA’s product labeling and regulatory records should be read with the patent claims when evaluating historical product coverage.[1]

The presence of albumin alone does not decide infringement. The analysis turns on whether the paclitaxel is non-crystalline, whether the finished product is nonaqueous before reconstitution, whether the vial contents satisfy the dose language, and whether the labeled administration regimen meets the relevant limitations.

What does the patent not claim?

The patent does not expressly claim:

A particular cancer indication;
Breast, lung, pancreatic, ovarian, or other cancer treatment;
Human serum albumin as a required excipient;
Nanoparticle size;
A specific albumin-to-paclitaxel ratio;
A particular manufacturing process;
A specific lyophilization cycle;
A particular vial fill weight;
A specific infusion device;
A specific brand or trade name;
A biosimilar or biologic product.

Those limitations may appear in other patents in the paclitaxel or albumin-bound paclitaxel landscape, but they are not present in the claims supplied for Patent 6,753,006.

When did U.S. Patent 6,753,006 lose exclusivity?

The patent term ended in December 2021. The U.S. term for a post-June 8, 1995 utility patent generally runs 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and other statutory rules.[2]

The relevant commercial consequence is that Patent 6,753,006 no longer provides an active U.S. patent exclusion right. Historical Orange Book listings may continue to appear in archived regulatory records, but an expired listing does not create a current right to block an ANDA or commercial launch.

The patent’s expiration did not necessarily eliminate every patent issue involving albumin-bound paclitaxel. Other patents may have covered later formulations, manufacturing steps, dosing regimens, or product-specific improvements.

What was the Orange Book status of Patent 6,753,006?

Patent 6,753,006 was associated with the U.S. regulatory and patent history of Abraxane, the FDA-approved albumin-bound paclitaxel product. Orange Book analysis must distinguish:

Whether a patent was listed for the NDA;
Whether the patent was unexpired at the relevant time;
Whether the listed claims covered the approved product;
Whether a generic applicant made a Paragraph IV certification;
Whether litigation triggered a 30-month stay;
Whether the patent later expired.

The Orange Book does not determine infringement. It records patents submitted by an NDA holder and accepted for listing under FDA rules. The scope of a listed patent remains a matter of claim construction and infringement analysis.[3]

Because Patent 6,753,006 expired in 2021, its current Orange Book relevance is historical rather than exclusionary.

Which companies challenged or could challenge the product?

Paclitaxel is a small-molecule drug, so the relevant abbreviated pathway is generally an ANDA under section 505(j), not a biosimilar application under section 351(k). A generic applicant seeking approval of a conventional paclitaxel injection is not automatically a competitor to Abraxane because conventional paclitaxel and albumin-bound paclitaxel differ in formulation, excipients, administration requirements, labeling, and regulatory product characteristics.

A product intended to compete directly with Abraxane could require a more complex regulatory and clinical strategy. Potential pathways depend on whether the product is considered pharmaceutically equivalent, therapeutically equivalent, or sufficiently different to require a new drug application.

A Paragraph IV challenge would have been relevant only while an unexpired listed patent remained in force. For Patent 6,753,006, the expiration date removed the patent-specific basis for a current Paragraph IV injunction claim. The commercial risk would instead turn on other active patents, regulatory exclusivity, product-specific requirements, and the ability of the applicant to establish substitutability.

Are biosimilars relevant to Patent 6,753,006?

No. Paclitaxel is a chemically synthesized small molecule, not a biologic. The relevant competitors are generic or follow-on paclitaxel products, not biosimilars.

The distinction matters commercially:

Issue	Paclitaxel	Biosimilar
Regulatory pathway	Usually ANDA or NDA	351(k) biosimilar application
Active ingredient	Small molecule	Biologic
Patent certification	Paragraph I-IV framework	Patent dance and biologic patent framework
Substitution	Based on therapeutic equivalence and state law	Based on biosimilarity and interchangeability
Primary patent risk	Formulation, method, manufacturing, device	Biologic composition, cell line, process, formulation

What generic-entry risks existed after patent expiration?

After expiration of Patent 6,753,006, a commercial entrant could avoid the patent by using a product that does not contain the claimed combination of limitations. The principal design-around options include:

Use crystalline paclitaxel rather than non-crystalline paclitaxel.
Use a formulation containing Cremophor, although that would sacrifice the claimed Cremophor-free profile.
Use a non-vial presentation for claims 1-10.
Use an aqueous formulation to avoid claims 11-14, subject to other patent and regulatory risks.
Use an administration period longer than approximately three hours.
Use a treatment cycle of three weeks or longer.
Develop a product outside the claimed dose ranges.
Use a different active ingredient or taxane.

These options are not equivalent from a commercial perspective. Conventional Cremophor-containing paclitaxel has known tolerability and premedication requirements. A formulation design-around may therefore create clinical or regulatory disadvantages even if it avoids the patent.

How strong was the patent estate?

Patent 6,753,006 had meaningful historical coverage because it combined product presentation, physical-state, excipient, sterility, dosing, and administration limitations. Its weaknesses were equally clear:

The claims were narrow compared with a composition claim covering all paclitaxel nanoparticles.
“Non-crystalline” could require technical characterization and expert evidence.
“Cremophor-free” was relatively straightforward to test but left alternative excipient systems open.
“Suitable to deliver” and “about” introduced factual questions.
Sealed-vial requirements limited some claims to particular presentations.
Dose and schedule limitations created potential design-around routes.
The patent’s term ended before many later product and manufacturing patents.

The strongest historical claims were likely claims 11-14 against a stable, sterile, nonpyrogenic, nonaqueous, Cremophor-free formulation meeting the non-crystalline and dose requirements. Claims 1-10 added more product-specific limitations and were more vulnerable to presentation or regimen-based design-arounds.

What patent landscape remains relevant for albumin-bound paclitaxel?

The relevant landscape extends beyond Patent 6,753,006 and should be divided into five categories:

Core composition patents

These cover albumin-bound or nanoparticle paclitaxel compositions and may include particle-size, protein-binding, or composition limitations. Earlier foundational patents may have expired before Patent 6,753,006.

Formulation patents

These may cover lyophilized powders, reconstitution media, stabilizers, excipient ratios, pH, residual moisture, and storage stability.

Manufacturing patents

These may cover high-pressure homogenization, nanoparticle formation, drying, aseptic processing, vial filling, and control of particle-size distribution.

Method-of-use patents

These may cover dosing schedules, specific indications, combination therapy, first-line treatment, metastatic disease, or administration without premedication.

Product-specific and regulatory patents

These may cover later improvements, alternate strengths, delivery systems, or additional approved indications. Their expiration dates can extend beyond the 2021 expiration of Patent 6,753,006.

A freedom-to-operate review should therefore search the complete U.S. family, continuations, divisionals, reissues, terminal disclaimers, and later patents assigned to the original patent owner and subsequent commercial licensees.

What licensing and ownership issues matter?

The commercial history of albumin-bound paclitaxel involved American Bioscience, Abraxis BioScience, Celgene, and later Bristol Myers Squibb through corporate transactions. Patent ownership and licensing should be traced through recorded assignments, merger documents, security interests, and any license agreements filed with the USPTO.

A patent assignment does not establish that every related patent was licensed on the same terms. Patent-by-patent ownership and field-of-use provisions must be verified. Patent 6,753,006’s expiration means that historical licenses may retain royalty or dispute significance but cannot restore the expired exclusion right.

Key Takeaways

Patent 6,753,006 covers non-crystalline, Cremophor-free paclitaxel in specified vial and formulation presentations.
Claims 1-10 focus on sealed-vial dosage forms, administration timing, treatment cycles, and dose ranges.
Claims 11-14 focus on stable, sterile, nonpyrogenic, nonaqueous formulations.
The broad dose range is 30-1,000 mg/m², with dependent ranges of 50-300 mg/m² and 175-700 mg/m².
Albumin-bound paclitaxel is the primary commercial comparator, but infringement requires satisfaction of every claim limitation.
Paclitaxel is a small molecule; biosimilar analysis does not apply.
The patent expired in December 2021 and no longer provides a current U.S. exclusion right.
Current generic-entry risk depends on later-expiring formulation, manufacturing, method-of-use, and product-specific patents.
The most important technical questions are the physical state of paclitaxel, the presence or absence of Cremophor, the formulation’s aqueous status, and the labeled administration regimen.

FAQs About U.S. Patent 6,753,006

Does Patent 6,753,006 cover conventional Taxol?

No. Conventional paclitaxel injection generally uses Cremophor EL and therefore does not satisfy the Cremophor-free limitation in the claims supplied.

Does the patent require albumin-bound paclitaxel?

No. The claims do not expressly require albumin. An albumin-bound product may fall within the claims, but albumin is not itself a claim limitation.

Does the patent cover every Cremophor-free paclitaxel product?

No. The product must also satisfy the non-crystalline, dose, presentation, administration, or formulation limitations applicable to the particular claim.

Can a new product avoid the vial claims by using a prefilled syringe?

Potentially. A prefilled syringe may avoid claims requiring a sealed vial, but claim 11 could still be relevant if the formulation satisfies its independent limitations.

Is Patent 6,753,006 still a launch barrier in the United States?

No. Its U.S. patent term ended in December 2021. Other active patents and FDA requirements may still affect a competing albumin-bound paclitaxel product.

References

U.S. Food and Drug Administration. (2023). Abraxane (paclitaxel protein-bound particles for injectable suspension) prescribing information. FDA.
United States Patent and Trademark Office. (2004). U.S. Patent No. 6,753,006, Paclitaxel dosage forms and formulations. USPTO.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0961612	⤷ Start Trial	CA 2009 00036	Denmark	⤷ Start Trial
European Patent Office	0961612	⤷ Start Trial	91613	Luxembourg	⤷ Start Trial
European Patent Office	0961612	⤷ Start Trial	09C0050	France	⤷ Start Trial
European Patent Office	0961612	⤷ Start Trial	C00961612/01	Switzerland	⤷ Start Trial
European Patent Office	0961612	⤷ Start Trial	SZ 41/2009	Austria	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,753,006

Summary for Patent: 6,753,006