Patent: 5,549,892

Summary for Patent: 5,549,892

Title:	Enhanced in vivo uptake of glucocerebrosidase
Abstract:	A pharmaceutical composition comprising remodelled recombinant glucocerebrosidase (GCR) is described that provides a therapeutic effect at doses that are lower then those required using remodelled naturally occurring GCR. A method of treating patients with Gaucher\'s disease using remodelled recombinant GCR is also provided. In vivo uptake of exogenous molecules can be determined by extracting a mixture of cells from a subject, enriching the target cells in vitro, lysing the cells and determining the amount of exogenous molecules.
Inventor(s):	Friedman; BethAnn (Arlington, MA), Hayes; Michael (Acton, MA)
Assignee:	Genzyme Corporation (Cambridge, MA)
Application Number:	08/080,855
Patent Claims:	see list of patent claims

United States Patent 5,549,892: Claims, validity drivers, and US landscape

US Patent 5,549,892 claims a Gaucher’s disease therapy built around remodeled recombinant glucocerebrosidase-related glycoprotein (GCR) manufactured in CHO cells, engineered to present exposed terminal mannose residues on appended oligosaccharides. The patent then narrows value to a dose reduction versus “remodeled naturally occurring GCR,” with further compositional refinements by specific amino-acid and glycan feature changes (His at position 495; increased fucose; increased N-acetylglucosamine).

This document is best understood as an IP package that attempts to convert (1) glycoengineering (mannose exposure) and (2) production source (CHO) into (3) a functional clinical outcome (significant symptom alleviation at lower effective dose). That combination creates multiple validity and enforceability pressure points, especially around obviousness (state of the art glyco-remodeling) and claim definiteness / enablement (how “significantly alleviating” and “substantially less” are operationalized).

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What is claimed, in claim-by-claim terms?

1. What does Claim 1 require?

Independent Claim 1 (pharmaceutical composition) requires all of the following:

• A pharmaceutical composition for Gaucher’s disease symptom alleviation.
• A specific active: “remodeled recombinant GCR” obtained from CHO cells.
• Remodeling detail: the recombinant GCR has “exposed mannose terminal residues on appended oligosaccharides.”
• Functional requirement: use is in an “effective dosage suitable for significantly alleviating clinical symptoms of Gaucher’s disease.”
• Comparative requirement: the dose is “substantially less than the effective dose using remodeled naturally occurring GCR.”

Core claim logic: glycan remodeling produces a therapeutic targeting and pharmacologic potency that lets the administered dose be reduced versus a comparator.

2. How do Claims 2-4 narrow the composition?

These are dependent narrowing features that define “remodeled recombinant” relative to “remodeled naturally occurring”:

• Claim 2: recombinant GCR differs from naturally occurring GCR by having His at amino acid number 495.
• Claim 3: recombinant GCR has increased fucose compared to remodeled naturally occurring GCR.
• Claim 4: recombinant GCR has increased N-acetyl glucosamine residues compared to remodeled naturally occurring GCR.

Together, Claims 2-4 define a specific engineered glycoform profile and one point mutation.

3. What does Claim 5 require (method claims)?

Claim 5 (method for treating a human subject) requires:

• Providing a recombinant form of GCR obtained from CHO cells that targets cells deficient in GCR.
• Remodeling detail: exposed terminal mannose residues on appended oligosaccharides.
• Administering doses to achieve therapeutic effect, where each dose is dependent on effective targeting.
• Comparative dosing requirement: each dose is substantially less than what would be administered for naturally occurring GCR to achieve the same therapeutic effect.

4. How do Claims 6-9 further narrow the method?

• Claim 6: His at amino acid number 495.
• Claim 7: glycan moiety has increased fucose and increased N-acetylglucosamine residues.
• Claim 8: targeting capability determined by reference to uptake by a population of target cells, with increased affinity vs naturally occurring GCR.
• Claim 9: target cells are Kupffer cells in the liver.

5. What does Claim 10 cover?

Claim 10 is another composition claim that recapitulates:

• remodeled recombinant GCR from CHO cells
• exposed terminal mannose residues
• an effective dosage substantially less than the effective dosage for remodeled naturally occurring GCR
• symptom alleviation in Gaucher’s disease.

Takeaway: The independent value anchors are (i) CHO-made remodeled recombinant GCR with terminal mannose exposure and (ii) a lower effective dose tied to functional targeting/uptake. Dependent claims then lock in His495, fucose, and N-acetylglucosamine features and identify Kupffer cells as a target.

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Where are the strongest claim elements for enforcement?

1. The dose-comparator limitation is an enforceability lever

The “substantially less dose” comparator is the most litigation-relevant feature. If a competitor can show their dosing is not substantially less versus the relevant comparator, they can attack infringement even if they match glycan features.

Commercial consequence: enforcement may hinge on proving dose-response equivalence or inequivalence under an agreed comparator frame.

2. Glycan presentation (terminal mannose exposure) narrows the scope

“Exposed mannose terminal residues on appended oligosaccharides” requires structural glycan accessibility. Competitors with different glyco-remodeling strategies that do not yield exposed terminal mannose residues risk noninfringement on claim construction.

3. Production source (CHO) is a clear process constraint

“Obtained from CHO cells” can matter if claim construction treats it as a structural limitation (glycoform profile) or a process limitation (manufacturing route). In practice, CHO is widely used for glycoproteins; this element may not be decisive for novelty, but it can influence infringement proof and design-around.

4. The His495 and glycan feature dependencies are additional barriers

• His495: a discrete protein difference.
• Increased fucose and N-acetylglucosamine: compositional glycan differences.

These are strong because they allow competitors to potentially avoid by changing the sequence and/or glycoengineering endpoint.

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Where are the vulnerabilities for validity and enforceability?

1. “Remodeled naturally occurring GCR” is a moving comparator

The claims compare recombinant to “remodeled naturally occurring GCR,” but the term does not define:

• what remodeling process applies to “naturally occurring” GCR,
• what glycan profile counts as “remodeled,” and
• whether remodeling is the same as for the recombinant.

This matters because obviousness and enablement often turn on what the comparator actually represents. If “naturally occurring” can be remodeled in ways that eliminate the asserted difference, then the “substantially less” framing can be attacked as outcome-driven.

2. Functional language invites indefiniteness fights

Phrases like “significantly alleviating clinical symptoms” and “targeting capability … dependent on uptake” can be attacked if the patent does not provide objective boundaries (dose levels, assay readouts, symptom metrics).

Even if the science supports it, the claim language creates litigation friction if an accused infringer can argue that their data does not map cleanly to “clinical symptoms” and “effective targeting.”

3. “Substantially less” lacks a numeric anchor

Absent a defined quantitative threshold in the claim text, “substantially less” invites proof disputes:

• What baseline dose for naturally occurring remodeled GCR is used?
• What degree qualifies as “substantially”?
• Is it a fold difference, percent decrease, or clinically validated dose equivalence?

In many antibody and enzyme replacement contexts, dose is often titrated; this can complicate the “substantially less” limitation in infringement.

4. Obviousness risk is structurally high in glycoengineering

The claim theme is glyco-remodeling to create mannose-exposing terminal glycans to target disease-relevant cells (Kupffer cells). The US glyco-remodeling field has extensive prior art involving:

• CHO expression,
• glycan remodeling,
• mannose exposure and receptor-mediated uptake (including in macrophage/Kupffer contexts),
• and dose/efficacy tradeoffs.

That makes the primary novelty levers (His495; increased fucose and N-acetylglucosamine; specific “substantially less dose” claim framing) the likely battleground.

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US patent landscape: what this likely competes against

This patent’s claim pattern is typical of enzyme replacement therapy (ERT) and targeting glycoforms. The landscape pressure typically comes from three buckets:

1. Prior art on mannose-terminated glycoprotein targeting

Broadly, the field has long pursued mannose receptor or related lectin targeting by engineering carbohydrate endpoints. If earlier documents disclose terminal mannose exposure for macrophage/Kupffer uptake and demonstrate dosing reductions or improved cell uptake, they can undercut novelty and obviousness.

2. Prior art on CHO-made remodeled glycoforms

CHO expression combined with glycosylation control (including fucose and GlcNAc changes) is well established in the art. If prior documents disclose the same glycan feature directionality (increased fucose; increased N-acetylglucosamine) as part of remodeling, the dependent claims lose distinctiveness.

3. Prior art on Gaucher’s disease ERT and macrophage delivery

Gaucher therapy and related glycoprotein delivery has significant history. Claims that position “exposed mannose terminal residues” and “target Kupffer cells” tend to overlap with earlier targeting rationales even if the exact molecule differs.

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Claim scope map vs likely design-arounds

A. Avoid terminal mannose exposure

If a competitor keeps targeting through sialylation/other lectin pathways, or uses different glycan endpoints, they can escape the “exposed terminal mannose residues” requirement.

B. Avoid His at position 495

Because Claims 2 and 6 are dependent, a competitor could design a different amino-acid profile while preserving other glycan features. That preserves possible noninfringement on the dependent claims, but Claim 1/5 still matter because His495 is not in the independent claims.

C. Change fucose and GlcNAc directionality

Claims 3, 4, and 7 are dependent, so avoiding “increased fucose” or “increased N-acetylglucosamine residues” can take away those dependent coverage layers.

D. Eliminate the “substantially less dose” equivalence

Even if glycan endpoints match, proving that the effective dose is not “substantially less” versus the relevant comparator can defeat infringement.

This is often the easiest legal lever because clinical dosing is measured and can be disputed without needing deep glycan analytics.

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Critical assessment of the patent’s risk-reward profile

1. What makes the patent valuable

• It claims a targeted, glycoengineered ERT modality with a specific manufacturing source (CHO).
• It asserts a concrete clinical and dosing advantage (“substantially less”).
• It includes both composition and method claims, with Kupffer cells as a specific target in dependent method claims.

2. What makes the patent fragile

• The comparative framework (“remodeled naturally occurring GCR”) is underdefined at the claim level.
• Multiple claim terms are functional (“significantly alleviating,” “effective targeting”) and invite mapping disputes.
• Glyco-remodeling and terminal mannose targeting are likely crowded by prior art in glycoprotein delivery.

3. Likely litigation posture if enforced

• Plaintiff will anchor infringement on: (i) CHO-origin remodeled recombinant GCR, (ii) terminal mannose exposure, and (iii) dosing advantage.
• Defense will focus on: (i) glycan structure differences (what is actually “exposed mannose terminal residues”), and (ii) whether the dose reduction meets “substantially less,” with comparator selection and clinical endpoint mapping as key battlegrounds.

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Key Takeaways

• US 5,549,892 claims CHO-made remodeled recombinant GCR with exposed terminal mannose residues for Gaucher’s disease, with a dose reduction requirement versus remodeled naturally occurring GCR.
• Independent coverage rests on glycan endpoint + lower effective dose. Dependent coverage adds His495, increased fucose, increased N-acetylglucosamine, and Kupffer cell targeting.
• Validity and enforceability risks concentrate on comparator definition (“remodeled naturally occurring”), functional language (“significantly alleviating,” “effective targeting”), and the lack of a numeric threshold for “substantially less.”
• The most viable design-arounds are to avoid terminal mannose exposure, avoid the dependent structural features, or eliminate the asserted dose reduction under the relevant comparator frame.

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FAQs

1. What is the single most important limitation for infringement in US 5,549,892?

The requirement that the effective dosage for the remodeled recombinant GCR is substantially less than the effective dose for remodeled naturally occurring GCR.

2. Does the patent require Kupffer cells to be the target in the broad independent claims?

No. Kupffer cells appear in dependent Claim 9; the independent composition and method claims reference targeting cells in general terms.

3. Are His495, increased fucose, and increased N-acetylglucosamine required for infringement of independent Claim 1/5?

No. Those features appear in dependent claims (Claims 2, 3, 4, 6, 7). Independent claims hinge on terminal mannose exposure and the lower effective dose.

4. What kind of evidence typically decides “exposed terminal mannose residues”?

Glycan structural characterization (e.g., mass spectrometry and glycan profiling) and assays that demonstrate mannose terminal exposure relevant to receptor binding and uptake.

5. What is the most likely strength used in prosecution or enforcement?

The asserted clinical and dosing advantage: “significantly alleviating clinical symptoms” at a “substantially less” dose tied to improved targeting/uptake.

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References

[1] United States Patent 5,549,892. (claims provided in user prompt).

Details for Patent 5,549,892

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Genzyme Corporation	CEREZYME	imiglucerase	For Injection	020367	May 23, 1994	5,549,892	2013-06-21
Genzyme Corporation	CEREZYME	imiglucerase	For Injection	020367	September 22, 1999	5,549,892	2013-06-21

International Patent Family for US Patent 5,549,892

Country	Patent Number	Estimated Expiration
World Intellectual Property Organization (WIPO)	9007573
United States of America	6451600
United States of America	5236838
United States of America	2005026249
United States of America	2005019861