United States Drug Patent 7,550,433: Claim Scope, Expiration, Litigation and Peginesatide Patent Landscape
US Patent 7,550,433 covers once-every-three-to-four-week treatment of anemia or erythropoietin-deficiency disorders with a long-acting, PEGylated dimeric peptide that activates the erythropoietin receptor. The claims are directed primarily to peginesatide, also known as Hematide and marketed in the United States as Omontys.
The patent’s commercial significance has largely ended because the patent term expired in 2023 on the ordinary 20-year term calculated from its earliest nonprovisional filing date. Omontys was withdrawn from the U.S. market in 2013 after reports of serious hypersensitivity reactions. The patent remains important as prior art and as the principal U.S. patent defining the original peginesatide product and monthly dosing regimen.
What drug does US Patent 7,550,433 protect?
US 7,550,433 protects methods of treating anemia and related disorders with a PEGylated peptide erythropoietin-receptor agonist. The claimed molecule corresponds to peginesatide, a synthetic peptide-based erythropoietin mimetic.
The core molecular elements are:
| Element |
Claimed requirement |
| Pharmacology |
Binds to and activates the erythropoietin receptor |
| Peptide format |
Two peptide monomers |
| Core sequence |
(AcG)GLYACHMGPIT(1-nal)VCQPLR |
| Dimerization |
Covalent linker joining the two monomers |
| PEG attachment |
Spacer joins linker and PEG |
| PEG |
Linear, unbranched PEG |
| PEG molecular weight |
10,000 to 60,000 daltons |
| Administration |
Once every three to four weeks |
| Dose |
0.025 to 0.5 mg/kg |
| Target conditions |
Erythropoietin deficiency, low or defective red-cell population, renal failure, dialysis and cancer-associated anemia |
The sequence contains nonstandard structural elements, including an N-acetyl glycine group, 1-naphthylalanine, and, in dependent claims, N-methyl glycine and lysine variants. These modifications distinguish the claimed agonist from endogenous erythropoietin and conventional recombinant erythropoietins.
How broad are the independent claims in US 7,550,433?
Claims 1 and 18 are the principal independent claims. Both are method-of-treatment claims rather than claims directed solely to the compound or its manufacture.
Claim 1 requires all of the following:
- A patient with an erythropoietin-deficiency or red-cell disorder.
- Administration once every three to four weeks.
- A dose of 0.025 to 0.5 mg/kg.
- A compound that activates EPO-R.
- Two copies of the specified peptide monomer.
- A covalent linker between the monomers.
- A spacer between the linker and PEG.
- Linear, unbranched PEG with a molecular weight of 10,000 to 60,000 daltons.
The claim is therefore broad in its disease language but narrow in its molecular and dosing limitations. A competing product would not literally fall within claim 1 merely because it activates EPO-R or is administered monthly. It would need to satisfy the specified peptide, dimer, linker, spacer and PEG limitations.
Claim 18 is also an independent method claim, but the supplied claim text omits the chemical structure following the phrase “wherein the compound is.” The scope of claim 18 cannot be determined fully from the text provided. Its interpretation requires the issued patent drawing or the complete official claim text.
What do dependent claims 2 through 20 add?
The dependent claims narrow the sequence, linker, spacer, PEG size, disease and dose.
| Claims |
Added limitation |
Practical effect |
| 2-5 |
Lysine, N-methyl glycine or both; specified SEQ ID NOs 1, 2 and 3 |
Narrows the peptide chemistry |
| 6 |
Iminodiacetic spacer |
Limits the PEG-linker architecture |
| 7 |
Defined spacer formula and R4 substituents |
Narrows the chemical connection |
| 8 |
Lysine linker |
Captures a specific dimerization arrangement |
| 9 |
PEG of 10,000 to 50,000 daltons |
Removes larger PEG species |
| 10 |
PEG of 20,000 to 40,000 daltons |
Captures the commercial-scale PEG range |
| 11 |
Pharmaceutically acceptable carrier |
Covers conventional drug formulations |
| 12-14 |
Renal failure or dialysis; 0.025-0.2 mg/kg, then 0.05-0.1 mg/kg |
Narrows to renal anemia dosing |
| 15-17 |
Malignancy-associated anemia; 0.075-0.5 mg/kg, then 0.2-0.4 mg/kg |
Narrows to oncology dosing |
| 19 |
Administration once every three weeks |
Specific interval |
| 20 |
Administration once every four weeks |
Specific interval |
Claims 13, 14, 16 and 17 have greater practical value for infringement analysis because they combine a defined clinical indication with a defined dose range. Claims 19 and 20 are narrower alternatives to the three-to-four-week interval in the independent claims.
What formulations are protected by US 7,550,433?
The patent does not claim a conventional formulation composition in the form of a product claim. Claim 11 requires administration with a pharmaceutically acceptable carrier, but it does not specify a particular buffer, excipient, vial, prefilled syringe or concentration.
The principal formulation-related protection arises indirectly through the compound and method limitations:
- The active ingredient must contain the claimed dimeric peptide architecture.
- The PEG must be linear and unbranched.
- The PEG must fall within the claimed molecular-weight range.
- The product must be administered in a therapeutically effective amount.
- The carrier must be pharmaceutically acceptable if claim 11 is asserted.
A later formulation using the same active peptide but a different buffer or container would likely remain within the core method claims if the dosing and structural limitations were met. Conversely, a formulation patent directed solely to a buffer, lyophilization process or delivery device would be a separate patent position and is not established by the supplied claims.
When did US Patent 7,550,433 lose exclusivity?
The patent has a 20-year term calculated from its earliest nonprovisional U.S. filing date, which is generally identified as April 16, 2003. On that basis, the ordinary expiration date was April 16, 2023.[1]
The patent was issued on June 23, 2009. The issue date does not determine expiration for a modern utility patent filed after June 8, 1995. Patent-term adjustment, terminal disclaimers and any patent-term extension must be checked against the USPTO patent record and Orange Book listing. The ordinary term date is April 16, 2023.
FDA regulatory exclusivity was separate from patent exclusivity. Omontys received FDA approval on March 27, 2012, but the product was withdrawn from the U.S. market in February 2013.[2] The withdrawal ended commercial availability but did not itself determine the patent term.
What was the FDA and Orange Book status of peginesatide?
Omontys was approved by FDA as a prescription drug for anemia due to chronic kidney disease in adult patients on dialysis and adults not on dialysis.[2] The approved regimen was once monthly, consistent with the three-to-four-week dosing concept in US 7,550,433.
The regulatory sequence was:
| Date |
Event |
| March 27, 2012 |
FDA approved Omontys, peginesatide injection |
| February 2013 |
Affymax and Takeda announced withdrawal from the U.S. market |
| February 2013 |
FDA issued safety communications concerning serious hypersensitivity and anaphylaxis |
| April 16, 2023 |
Ordinary patent-term expiration date for US 7,550,433 |
The FDA action was driven by postmarketing reports of serious hypersensitivity reactions, including anaphylaxis. FDA stated that the product should no longer be used and that remaining product should be returned.[3]
Because Omontys was withdrawn, the Orange Book’s current commercial relevance is limited. A patent listing does not create an active market where the reference product is unavailable. An ANDA applicant would also face product-selection, reference-product and safety issues in addition to patent analysis. The statutory patent listing and the product’s marketing status should therefore be treated separately.
Is US 7,550,433 a compound patent or a method-of-use patent?
US 7,550,433 is principally a method-of-use patent.
Its independent claims require administration to a patient at a defined interval and dose. They do not claim the PEGylated peptide as an isolated composition in the independent claims supplied. This distinction matters because:
- A company manufacturing the compound may not infringe solely by making the compound if no method claim is practiced.
- A physician, provider or product label that directs the claimed monthly regimen presents a stronger infringement theory.
- A product label omitting the patented indication or dose could affect induced-infringement analysis.
- Claims 12-17 create narrower disease- and dose-specific positions.
The patent’s method format also creates potential enforcement issues involving who performs each step. Treatment is typically administered by a healthcare professional, while the manufacturer controls labeling, promotion and dosing instructions.
How strong is the patent estate for peginesatide?
The patent is structurally strong against an exact peginesatide copy during its term because it combines several limitations that must be met together:
- Exact or closely specified peptide sequences.
- Dimeric configuration.
- Defined linker and spacer chemistry.
- Linear PEG.
- Specified molecular-weight ranges.
- Monthly or near-monthly dosing.
- Defined patient populations and dose ranges.
Its weaknesses are different from those of a broad compound patent. The principal validity and enforcement issues would have included:
Obviousness
An accused party could argue that known EPO-R agonist peptides, dimerization chemistry, PEGylation and extended dosing intervals made the claimed combination obvious. The patentee would have relied on the selected sequence, receptor activity, pharmacokinetic profile and monthly dosing performance to establish a non-obvious combination.
Written description and enablement
The claims cover PEG values from 10,000 to 60,000 daltons and multiple linker and spacer configurations. A challenge could focus on whether the specification adequately supports the full claimed genus and enables the claimed range without undue experimentation.
Anticipation
An earlier publication or patent describing the same peptide dimer, PEG architecture and monthly dosing could defeat novelty. Generic disclosures of PEGylated EPO-R agonists would not necessarily anticipate the full combination.
Claim construction
Terms such as “linker moiety,” “spacer moiety,” “therapeutically effective amount” and “compound that binds to and activates” could affect infringement scope. The sequence nomenclature also requires careful interpretation of noncanonical residues and terminal modifications.
Overall, the claims were commercially meaningful for peginesatide but did not create a broad blocking position over all long-acting EPO-R agonists.
Which companies challenged or competed with peginesatide?
The principal competitive products were erythropoiesis-stimulating agents rather than direct copies of peginesatide.
| Product |
Active ingredient |
Company |
Dosing concept |
Relationship to US 7,550,433 |
| Epogen/Procrit |
Epoetin alfa |
Amgen; marketed by Johnson & Johnson for Procrit |
Usually more frequent dosing |
Does not contain the claimed peptide |
| Aranesp |
Darbepoetin alfa |
Amgen |
Extended dosing compared with epoetin |
Different protein structure |
| Mircera |
Methoxy PEG-epoetin beta |
Roche |
Long-acting EPO product |
PEGylated protein, not the claimed peptide dimer |
| Omontys |
Peginesatide |
Affymax/Takeda |
Once monthly |
Product associated with the patent |
| Retacrit and other epoetin biosimilars |
Epoetin alfa biosimilar |
Multiple companies |
Epoetin dosing schedules |
No literal match to the claimed peginesatide structure |
Biosimilar risk was limited because peginesatide is a synthetic peptide drug rather than a conventional recombinant erythropoietin protein or monoclonal antibody. A competitor would more likely pursue an abbreviated generic or hybrid regulatory strategy, subject to FDA’s reference-product requirements and the product’s withdrawal history.
What licensing deals affected the patent rights?
Affymax partnered with Takeda for development and commercialization of peginesatide. Takeda became the commercial partner for Omontys, while Affymax retained the underlying discovery and patent position.[4]
The licensing relationship was commercially important because the patent was tied to a single branded product and a single development program. After the 2013 withdrawal, the commercial value of the U.S. patent estate declined sharply. The withdrawal also reduced the likelihood of an active Paragraph IV market dispute over a competing product.
What patent litigation and Paragraph IV risk existed?
No material, publicly established Paragraph IV litigation against US 7,550,433 is identified in the principal FDA and public patent records associated with Omontys. The absence of a prominent Paragraph IV case is consistent with the product’s short commercial life and withdrawal from the U.S. market.
During the patent term, a potential generic entrant would have faced four principal risks:
- Literal infringement if its product contained the same peginesatide dimer and its label directed monthly dosing.
- Induced infringement based on a label covering the patented anemia indications.
- Validity challenges based on prior EPO-R agonist, PEGylation and dosing disclosures.
- Regulatory barriers caused by the withdrawal of the reference product.
After patent expiration, the patent no longer blocks launch. Commercial launch would still depend on FDA acceptance of the active ingredient, manufacturing process, clinical bridging, labeling and postmarketing safety controls.
How does US 7,550,433 compare with competing EPO patent estates?
US 7,550,433 is narrower in molecular scope but more specific in dosing than many traditional erythropoietin patents.
| Estate type |
Primary protection |
Breadth |
Main risk |
| Peginesatide estate |
Specific synthetic peptide dimer, PEG architecture and monthly method |
Narrow to moderate |
Exact-structure copying |
| Epoetin estates |
Recombinant EPO sequence, production and therapeutic use |
Moderate |
Biosimilar and manufacturing challenges |
| Darbepoetin estates |
Modified EPO protein and use |
Moderate |
Protein sequence and glycosylation design |
| Methoxy PEG-EPO estates |
PEGylated EPO protein and formulation |
Moderate |
Protein PEGylation and formulation design |
| Small-molecule HIF-PH inhibitor estates |
Chemical compound, formulation and use |
Often broad compound protection |
Generic Paragraph IV challenges |
The patent did not prevent development of non-peptide EPO mimetics, HIF-prolyl hydroxylase inhibitors or conventional erythropoiesis-stimulating agents.
What generic launch scenarios exist after expiration?
The most plausible post-expiration scenarios are:
- Reintroduction of peginesatide by a generic or specialty manufacturer, subject to FDA requirements.
- Development of a chemically distinct EPO-R agonist outside the sequence and PEG limitations.
- Use of a different dosing interval or formulation to avoid dependent claims, although claims 1 and 18 could still be relevant if the three-to-four-week interval is used.
- Licensing or acquisition of manufacturing know-how rather than patent rights.
- No commercial entry because the product’s hypersensitivity history makes clinical and regulatory risk more important than patent clearance.
Manufacturing remains a meaningful barrier. The product requires controlled synthesis of a nonstandard peptide, dimerization, site-specific PEG attachment and characterization of a heterogeneous PEGylated product. Patent expiration removes the principal legal barrier but does not remove process validation, analytical comparability or safety requirements.
Key Takeaways
- US 7,550,433 covers methods using peginesatide-type PEGylated dimeric EPO-R agonists.
- The core limitations are the peptide sequence, dimeric architecture, linker, spacer, linear PEG and three-to-four-week dosing interval.
- The patent is a method-of-use patent, not a broad standalone compound patent based on the supplied claims.
- Dependent claims narrow the estate to specific peptide variants, lysine linkers, iminodiacetic spacers, PEG sizes and renal or oncology dosing.
- Omontys was FDA-approved in 2012 and withdrawn in 2013 after serious hypersensitivity reactions.
- The ordinary patent expiration date was April 16, 2023.
- No major public Paragraph IV litigation is associated with this patent.
- Biosimilar competition is less relevant because peginesatide is a synthetic peptide drug.
- Post-expiration entry remains constrained by manufacturing complexity, FDA requirements and the product’s safety history.
- Claim 18 cannot be fully analyzed from the supplied text because its chemical structure is omitted.
FAQs About US Patent 7,550,433
Does US Patent 7,550,433 cover Aranesp?
No. Aranesp contains darbepoetin alfa, a modified recombinant erythropoietin protein. It does not contain the claimed peginesatide peptide dimer and PEG architecture.
Does PEG molecular weight determine infringement?
It is one requirement. A product must also satisfy the claimed peptide sequence, dimeric structure, linker, spacer and administration regimen. A PEG outside the claimed range may avoid literal infringement of claim 1, subject to equivalents analysis.
Is peginesatide a biosimilar?
No. Peginesatide is a synthetic peptide erythropoietin mimetic. It is not a biosimilar to epoetin alfa or darbepoetin alfa.
Could a four-week dosing regimen infringe claim 20?
Yes, if the product also satisfies the compound and patient-treatment limitations incorporated from claim 1 or claim 18. Claim 20 specifically recites administration once every four weeks.
Does patent expiration authorize immediate marketing of Omontys?
No. Patent expiration removes the patent barrier. FDA approval, reference-product requirements, manufacturing controls, labeling and safety review remain separate regulatory issues.
References
- United States Patent and Trademark Office. (2009). Erythropoietin receptor agonists (U.S. Patent No. 7,550,433).
- U.S. Food and Drug Administration. (2012). Omontys (peginesatide) injection prescribing information.
- U.S. Food and Drug Administration. (2013). FDA drug safety communication: Omontys (peginesatide) and serious hypersensitivity reactions.
- Takeda Pharmaceutical Company Limited. (2013). Announcement regarding withdrawal of Omontys from the U.S. market.
