US Patent 6,620,847: Copolymer-1 Manufacturing Claims, Expiration, Litigation and Generic Entry Risk

US Patent 6,620,847 protects a manufacturing approach for glatiramer acetate, historically called copolymer-1. The patent does not claim glatiramer acetate as a broad chemical composition. Its core coverage is directed to producing copolymer-1 within a defined molecular-weight range by deprotecting trifluoroacetyl copolymer-1 with aqueous piperidine and purifying the resulting polymer.

The patent’s practical value was tied to process control and product characterization. Its claims covered both the final polymer made by the claimed process and the upstream steps used to generate a predetermined molecular-weight profile. The patent is expired and no longer creates a current US patent barrier to generic glatiramer acetate entry.

What does US Patent 6,620,847 protect?

Patent 6,620,847 protects copolymer-1 having a molecular weight of approximately 4 to 9 kilodaltons when made through a specified deprotection and purification process. The patent also covers selected upstream process conditions involving hydrobromic acid, N-carboxyanhydride polymerization, diethylamine initiation, acetic acid addition and filtration.

The claims can be divided into two groups:

Claim group	Claims	Subject matter
Product-by-process claims	1-7	Copolymer-1 defined by molecular weight and the process used to make it
Manufacturing-method claims	8-9	Production of trifluoroacetyl copolymer-1 with a predetermined molecular-weight profile and conversion to copolymer-1

Copolymer-1 is the active synthetic polypeptide mixture in glatiramer acetate, marketed by Teva as Copaxone. It contains L-glutamic acid, L-alanine, L-tyrosine and L-lysine residues in a heterogeneous polymer distribution.

What is the scope of independent claim 1?

Claim 1 has four material limitations:

The product is copolymer-1.
The polymer has a molecular weight of about 4 to about 9 kilodaltons.
Trifluoroacetyl copolymer-1 is treated with aqueous piperidine to form a copolymer-1 solution.
The copolymer-1 is purified.

The claim is narrower than a claim to all glatiramer acetate. A competing manufacturer would face infringement risk only if its product and manufacturing route satisfied the relevant claim limitations.

The molecular-weight limitation is central. “About 4 to about 9 kilodaltons” creates a range rather than a single target value. Because glatiramer acetate is a heterogeneous polymer mixture, the legally relevant question would depend on how molecular weight is measured, what statistic is used, and whether the claimed range refers to a number-average, weight-average or other molecular-weight profile. The specification and prosecution history would be important in a claim-construction dispute.

The process language also matters. Claim 1 is written as a product-by-process claim. Under US patent law, a product-by-process claim generally requires the claimed product, but the process limitations can become material where the product cannot be adequately distinguished by structural or analytical characteristics. The Federal Circuit has treated product-by-process claims as product claims for infringement analysis, while recognizing that the process language may limit the claim in particular circumstances (U.S. Court of Appeals for the Federal Circuit, 2015).

How do claims 2 through 7 narrow the patent?

Claims 2 through 7 add manufacturing details that narrow the process pathway.

Claim	Added limitation	Commercial relevance
2	Protected copolymer-1 is reacted with hydrobromic acid to form trifluoroacetyl copolymer-1	Covers the deprotection route before piperidine treatment
3	Hydrobromic acid is about 33% hydrogen bromide in acetic acid	Narrows the acid composition
4	Protected copolymer-1 is made by polymerizing N-carboxyanhydride derivatives	Covers the protected-polymer synthesis route
5	Polymerization uses a diethylamine initiator	Narrows initiation chemistry
6	Acetic acid is added after piperidine treatment	Covers a specific post-deprotection operation
7	Purification includes filtration	Narrows the purification step

Claims 2 through 7 are dependent claims. They require compliance with all limitations of the underlying claim plus the added feature. Their narrower scope could have been useful against a manufacturer using the same process sequence, but they would not reach every process that produces glatiramer acetate in the 4-to-9-kilodalton range.

What does claim 8 protect?

Claim 8 is the principal process claim. It covers manufacturing trifluoroacetyl copolymer-1 with a predetermined molecular-weight profile by:

Selecting the desired molecular-weight profile.
Reacting protected copolymer-1 with hydrobromic acid.
Conducting the reaction at approximately 26 degrees Celsius.
Continuing the reaction for a time determined by a test reaction.
Producing trifluoroacetyl copolymer-1 with the selected profile.

This claim is directed to controlled molecular-weight manufacture rather than merely to a finished copolymer. Its potentially important limitation is the use of a test reaction to determine reaction time. A process that used fixed reaction times without a test reaction could present a stronger noninfringement position, although the complete process record and equivalents analysis would control.

Claim 8 also requires a predetermined profile. That language links the process to a selected target distribution rather than an uncontrolled reaction. The patent therefore addresses manufacturing reproducibility, a major technical issue for a heterogeneous synthetic polymer such as glatiramer acetate.

Does claim 9 cover piperidine treatment?

As supplied, claim 9 depends on claim 7 but recites a method. That dependency is internally inconsistent because claim 7 is a product-by-process claim directed to purification by filtration, while claim 9 adds piperidine treatment to a manufacturing method.

The issued patent should be read for the authoritative dependency. If the issued claim depends on claim 8, claim 9 would cover treating the trifluoroacetyl copolymer-1 produced under claim 8 with aqueous piperidine to form copolymer-1 having the predetermined molecular-weight profile. If the issued text actually depends on claim 7, the claim would present a substantial formal and construction issue under the statutory dependency rules.

What patents protect glatiramer acetate and Copaxone?

Glatiramer acetate historically had several distinct patent categories:

Patent category	Scope	Status of US 6,620,847
Basic composition patents	Copolymer-1 and related polypeptide compositions	Not the subject of 6,620,847
Manufacturing-process patents	Deprotection, molecular-weight control and purification	Core subject of 6,620,847
Formulation patents	Concentration, excipients, stability and delivery	Outside the principal claim scope of 6,620,847
Method-of-use patents	Treatment of multiple sclerosis and dosing regimens	Outside the principal claim scope of 6,620,847
Device patents	Syringe, autoinjector and administration systems	Outside the principal claim scope of 6,620,847

The patent should not be treated as a complete Copaxone estate. It is one process patent in a wider portfolio associated with glatiramer acetate.

Other Teva patents, including US Patent 6,939,962, were litigated in connection with generic Copaxone challenges. Those patents addressed related aspects of glatiramer acetate and its production or characterization, but they should be analyzed separately from 6,620,847. Patent expiration, claim scope and litigation outcomes were not identical across the portfolio.

When did US Patent 6,620,847 expire?

US Patent 6,620,847 is expired. Public patent records identify Teva Pharmaceutical Industries Ltd. as the patent owner or assignee and show a priority chain reaching back to the late 1990s. The patent’s nominal US term ended in approximately 2019 or 2020, depending on the applicable effective filing date and any patent-term adjustment reflected in the USPTO record (U.S. Patent and Trademark Office, 2003).

There is no current patent-term extension associated with this manufacturing patent that would restore an enforceable exclusivity period for glatiramer acetate. The patent therefore cannot presently block an ANDA applicant solely because the applicant uses a process that would once have fallen within the claims.

What was the Orange Book status of patent 6,620,847?

Patent 6,620,847 was associated with the Copaxone patent litigation and was relevant to Orange Book-listed patent disputes involving glatiramer acetate. Orange Book listing does not itself establish validity or infringement. It identifies patents submitted by an NDA holder as claiming the listed drug, its formulation or an approved method of use (U.S. Food and Drug Administration, 2024).

Because the patent is expired, its current Orange Book significance is historical rather than exclusionary. An expired listing does not create a live statutory stay against an ANDA applicant. Current entry analysis must focus on unexpired patents, regulatory exclusivity and any applicable settlement restrictions.

Which companies challenged the Copaxone patent estate?

The main generic challenges to Copaxone involved Sandoz, Mylan and other ANDA applicants. Teva brought Hatch-Waxman litigation concerning glatiramer acetate patents, including US 6,620,847 and related patents.

The Supreme Court’s 2015 decision in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc. addressed claim-construction standards in the dispute. The Federal Circuit proceedings then addressed the patent claims and the generic applicants’ defenses. The litigation established that the Copaxone estate could not be evaluated solely from the Orange Book listing; claim construction, validity, infringement and the specific generic process were all material (Supreme Court of the United States, 2015).

The principal commercial outcome was the erosion of Copaxone exclusivity and the subsequent entry of generic glatiramer acetate products. The expiration of 6,620,847 removed one process-based barrier, but generic applicants still had to address any remaining unexpired patents and FDA requirements.

Does patent 6,620,847 create biosimilar risk?

No. Glatiramer acetate is a synthetic polypeptide drug regulated through the abbreviated new drug application framework, not as a biologic requiring a biosimilar application under section 351(k) of the Public Health Service Act.

The relevant competitive pathway is generic substitution through an ANDA. Applicants must demonstrate pharmaceutical equivalence and bioequivalence under the FDA’s applicable standards. The principal risk is therefore generic competition, not biosimilar competition.

What formulation and method-of-use protection remains relevant?

Patent 6,620,847 does not materially protect Copaxone formulations, injection devices or dosing methods. Its claims focus on manufacturing copolymer-1.

A complete current freedom-to-operate review must separately examine:

20 mg/mL and 40 mg/mL injectable presentations;
prefilled syringes and autoinjector systems;
excipient and stability claims;
three-times-weekly dosing;
multiple-sclerosis treatment methods;
manufacturing and analytical methods;
patents owned by Teva, device suppliers and other licensors.

The existence of an expired process patent does not eliminate risk from a separate formulation or device patent. Conversely, a live formulation patent would not revive the expired claims of 6,620,847.

How strong was the patent estate for generic-entry defense?

The strength of 6,620,847 was moderate when considered as a standalone patent and stronger when combined with related Copaxone patents.

Its strengths were:

a defined molecular-weight range;
a detailed process sequence;
control of the HBr deprotection step;
a test-reaction concept for selecting reaction time;
coverage of both intermediate and final-product manufacturing.

Its limitations were:

no broad claim to all glatiramer acetate;
dependence on process-specific facts;
potential difficulty proving infringement from the final product alone;
vulnerability to alternative deprotection, polymerization or purification routes;
expiration of the patent term.

A generic manufacturer could pursue a noninfringing process that used different reaction conditions, a different initiator, a different deprotection reagent or a different molecular-weight-control strategy. The practical value of the patent was highest against manufacturers whose process closely followed the claimed sequence.

What generic launch scenarios existed after expiration?

After expiration, the principal launch scenarios were:

Scenario	Effect
Same active ingredient, different manufacturing process	Generic entry subject to ANDA approval and remaining patent barriers
Same molecular-weight range, noninfringing process	Reduced exposure to 6,620,847
Same process with expired patent	No infringement liability under the expired claims
Entry after Paragraph IV litigation	Launch timing controlled by litigation, settlement and regulatory status
At-risk launch before final judgment	Potential damages exposure under other unexpired patents

Generic glatiramer acetate products entered the US market after challenges to the Copaxone estate. Sandoz received FDA approval for generic glatiramer acetate, including 40 mg/mL and 20 mg/mL presentations, while Mylan also entered the market. The commercial consequence was price competition against Copaxone and erosion of Teva’s glatiramer-acetate revenue base (FDA, 2017).

What is the current commercial significance of patent 6,620,847?

The patent has no current blocking value because it is expired. Its continuing importance is historical and technical:

it describes a commercially relevant manufacturing route;
it helps explain Copaxone patent litigation;
it identifies molecular-weight control as a central product-quality issue;
it may remain relevant to validity, prosecution and freedom-to-operate analyses involving related patent families;
it does not prevent an ANDA applicant from manufacturing or selling generic glatiramer acetate today.

No active royalty or license obligation can be inferred from the claims alone. The patent record identifies ownership and prosecution information, but commercial licensing arrangements require separate transaction evidence. Teva’s historical rights and any underlying licenses should not be assumed to continue after patent expiration.

Key Takeaways

US Patent 6,620,847 covers process-defined copolymer-1, not all glatiramer acetate products.
Claim 1 requires copolymer-1 in an approximately 4-to-9-kilodalton range made through aqueous piperidine treatment and purification.
Claims 2 through 7 narrow the process through HBr concentration, polymerization chemistry, diethylamine initiation, acetic acid addition and filtration.
Claim 8 covers molecular-weight-profile control using HBr at approximately 26 degrees Celsius and a test reaction to select reaction time.
Claim 9, as supplied, has an apparent dependency inconsistency and should be checked against the issued patent.
The patent is expired, with its effective term ending approximately in 2019 or 2020.
The patent is no longer a live US barrier to generic glatiramer acetate entry.
Copaxone competition is governed by ANDA and Hatch-Waxman principles, not biosimilar law.
Current risk analysis must examine separate formulation, device, dosing and manufacturing patents.
The patent’s main historical value is its role in Copaxone litigation and its disclosure of molecular-weight control methods.

FAQs

Is US Patent 6,620,847 a composition patent for glatiramer acetate?

No. It is principally a process and product-by-process patent. It does not broadly claim every composition of glatiramer acetate.

Can an ANDA applicant use aqueous piperidine after patent expiration?

Yes. The expiration of the patent removes liability under its claims, subject to any separate unexpired patent covering the same product or process.

Does the 4-to-9-kilodalton range define the full molecular-weight distribution?

Not necessarily. The claim language must be interpreted with the specification, analytical method and prosecution history. The range alone does not resolve whether the patent uses number-average, weight-average or another measurement.

Are glatiramer acetate generics biosimilars?

No. They are generic drug products approved through the ANDA pathway rather than biosimilars approved under section 351(k).

Does an expired Orange Book patent continue a 30-month stay?

No. An expired patent does not independently create a current 30-month statutory stay for an ANDA applicant.

References

Food and Drug Administration. (2017). FDA approves first generic versions of Copaxone. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
Supreme Court of the United States. (2015). Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318.
U.S. Court of Appeals for the Federal Circuit. (2015). Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 789 F.3d 1335.
U.S. Patent and Trademark Office. (2003). U.S. Patent No. 6,620,847, Copolymer-1 and process for its preparation. U.S. Department of Commerce.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0762888	⤷ Start Trial	90987	Luxembourg	⤷ Start Trial
European Patent Office	0762888	⤷ Start Trial	C300096	Netherlands	⤷ Start Trial
European Patent Office	0762888	⤷ Start Trial	C300251	Netherlands	⤷ Start Trial
Austria	212857	⤷ Start Trial
Australia	1016102	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,620,847

Summary for Patent: 6,620,847