How to Build Smaller, Synthetic Antibody-Like Molecules for Medicine
This patent describes a way to create small, single-chain proteins that mimic the binding power of full-sized antibodies to deliver medicine more effectively.
Original patent title: “Immunotheraphy using single chain polypeptide binding molecules”
This patent describes a way to create small, single-chain proteins that mimic the binding power of full-sized antibodies to deliver medicine more effectively. Granted to Enzon Labs Inc in 1995 with 16 claims and 440 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
The patent details a method for creating a single-chain polypeptide that acts like an antibody but is much smaller. It achieves this by taking the two key binding parts of a natural antibody—the light chain variable region and the heavy chain variable region—and connecting them with a flexible peptide linker. This creates one continuous protein chain rather than the complex, multi-part structure of a natural antibody. In practice, this molecule can be conjugated to a therapeutic agent, such as a drug or toxin, to target specific cells, like cancer cells, while ignoring healthy ones.
The gap
What does this patent NOT cover?
- Does not cover full-sized, naturally occurring antibodies with two heavy and two light chains.
- Does not cover binding molecules that lack a peptide linker to connect the variable regions.
- Does not cover non-protein-based targeting molecules.
- Does not cover the specific therapeutic agents themselves, only the method of using the single-chain molecule as a delivery vehicle.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation lies in realizing that you can physically tether the two separate binding domains of an antibody into a single chain without losing their ability to lock onto a target, effectively creating a 'mini-antibody' that is easier to produce in bacteria or yeast.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Single-chain variable fragments (scFv)
Antibody-drug conjugates (ADCs)
Bispecific T-cell engagers (BiTEs)
Why it matters
The bigger picture
This technology was a foundational step toward modern antibody-based therapies. By shrinking the binding molecule, researchers could improve tissue penetration and simplify the manufacturing process using recombinant DNA technology. It paved the way for the development of bispecific antibodies and various antibody-drug conjugates used in oncology today.
Filed
April 1, 1993
Granted
October 3, 1995
Market context
Who's building on this
Companies in this space
Major pharmaceutical companies like Amgen, Roche, and AstraZeneca utilize variations of single-chain binding technology to develop targeted cancer therapies. The fundamental concepts established here are now standard tools in protein engineering labs globally.
Market impact
This patent helped ignite the field of protein engineering, enabling the creation of smaller, more modular therapeutic proteins. It shifted the industry focus from using whole, complex antibodies to designing custom, synthetic binding molecules, which is now a multi-billion dollar sector of the biopharmaceutical market.
Claim 1 — Plain English
What this patent covers
The patent details a method for creating a single-chain polypeptide that acts like an antibody but is much smaller. It achieves this by taking the two key binding parts of a natural antibody—the light chain variable region and the heavy chain variable region—and connecting them with a flexible peptide linker. This creates one continuous protein chain rather than the complex, multi-part structure of a natural antibody. In practice, this molecule can be conjugated to a therapeutic agent, such as a drug or toxin, to target specific cells, like cancer cells, while ignoring healthy ones.
The clever bit
The innovation lies in realizing that you can physically tether the two separate binding domains of an antibody into a single chain without losing their ability to lock onto a target, effectively creating a 'mini-antibody' that is easier to produce in bacteria or yeast.
What it does not cover
- Does not cover full-sized, naturally occurring antibodies with two heavy and two light chains.
- Does not cover binding molecules that lack a peptide linker to connect the variable regions.
- Does not cover non-protein-based targeting molecules.
- Does not cover the specific therapeutic agents themselves, only the method of using the single-chain molecule as a delivery vehicle.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
11/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$219K – $702K
Midpoint $439K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
0 independent claims · 1 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
16 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Ladner, R. C., Hardman, K., & Bird, R. E. (1995). How to Build Smaller, Synthetic Antibody-Like Molecules for Medicine (U.S. Patent No. 5,455,030). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/5455030/immunotheraphy-using-single-chain-polypeptide-binding-molecules
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Build Smaller, Synthetic Antibody-Like Molecules for Medicine cover?
This patent describes a way to create small, single-chain proteins that mimic the binding power of full-sized antibodies to deliver medicine more effectively.
Who owns patent US 5455030?
Enzon Labs Inc owns this patent, granted in 1995.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 5455030 cited by?
This patent has been cited by 440 later patents that build on its ideas.
What problem does this patent solve?
This technology was a foundational step toward modern antibody-based therapies. By shrinking the binding molecule, researchers could improve tissue penetration and simplify the manufacturing process using recombinant DNA technology. It paved the way for the development of bispecific antibodies and various antibody-drug conjugates used in oncology today.
What does this patent NOT cover?
Does not cover full-sized, naturally occurring antibodies with two heavy and two light chains.
Patent monitoring