Details for Patent: 5,747,472

US Patent 5,747,472: What Is Claimed and How Broad Is the Scope?

US Patent 5,747,472 claims medical-use method inventions centered on a specific nucleoside analog: 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine (and specified pharmaceutically acceptable esters/salts). The claim set is dominated by indication-limited therapeutic methods (lymphoma, lymphocytic leukemia, and “T-cell lymphoproliferative disorders”) and disease-mechanism-limited tumor treatment (“tumors susceptible to inhibition of T-cell growth”).

Core claimed compound set

• Base compound: 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine
• Markush-type variation: “a compound of formula (I) wherein R1 is methoxy or a pharmaceutically acceptable ester or salt thereof”
• Explicit ester embodiment: (5-O-acetyl-β-D-arabinofuranosyl)-2-amino-6-methoxy-9H-purine
• Implicit coverage: salts and esters that fall within the “pharmaceutically acceptable” limitation (scope depends on what salts/esters are supported and encompassed by the “formula (I)” and specification, but the claims as provided do not enumerate each salt)

How Broad Are the Claims by Claim Type?

H2: Are the claims limited to specific diseases or do they cover broad pharmacology?

The patent is indication-forward rather than “any use that inhibits T-cell growth.” The claims fall into three groups:

1) Classical oncology lymphoid indications (claims 1-2)

• Claim 1: method of treating lymphocytic leukemia
• Claim 2: method of treating lymphoma

Both require administering “an effective treatment amount” of the base compound.

2) T-cell growth inhibition tumor methods (claims 3, 8-9)

• Claim 3: tumors “susceptible to inhibition of T-cell growth,” dosing a compound of formula (I) (R1 methoxy or pharmaceutically acceptable ester/salt)
• Claim 8: same concept but explicitly uses 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine or its pharmaceutically acceptable ester/salt

3) T-cell lymphoproliferative disorder methods, with autoimmune sub-scope (claims 4-7, 10-11)

• Claim 4: treats “T-cell lymphoproliferative disorders” using formula (I) compound
• Claim 5: autoimmune disease subset
• Claim 6: autoimmune disease is arthritis
• Claim 7: autoimmune disease is insulin dependent diabetes mellitus
• Claim 10: repeats the T-cell lymphoproliferative disorder method using the base compound or its esters/salts
• Claim 11: specifies the 5-O-acetyl ester

Practical breadth call

• The patent does not claim “inhibition of lymphocyte proliferation” as a free-floating indication without a disease category. It locks the method to:
  • defined diagnoses (lymphocytic leukemia, lymphoma), or
  • an on-label disease concept (“T-cell lymphoproliferative disorders”), and within that,
  • autoimmune disorders and specific autoimmune diseases (arthritis; insulin-dependent diabetes mellitus), or
  • a tumor category defined by susceptibility to T-cell growth inhibition.

That structure can support enforcement against off-label uses if they can be characterized to the claimed disease buckets.

What Exactly Do the Claims Require to Infringe?

H2: What is the minimum “claim element set” per group?

A) Claims 1-2: direct compound + oncology indication

To fall within:

• Claim 1: a method treating lymphocytic leukemia by administering 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine at an “effective treatment amount.”
• Claim 2: similarly for lymphoma.

Key enforcement levers

• Indication alignment (lymphocytic leukemia / lymphoma)
• Use of the base compound (not merely a different nucleoside analog)
• “Effective treatment amount” is typically met by dosing regimens that show therapeutic effect.

B) Claims 3 and 4: formula (I) + defined therapeutic context

• Claim 3 covers tumors “susceptible to inhibition of T-cell growth,” using a compound of formula (I) with R1 = methoxy or a “pharmaceutically acceptable ester or salt thereof.”
• Claim 4 covers T-cell lymphoproliferative disorders using the same formula (I) framework.

Claim construction pressure points

• “Formula (I)” is the claim’s chemical backbone, so it matters whether an accused product:
  • matches the formula and
  • fits the R1 limitation (methoxy vs esters/salts).
• “Tumors susceptible to inhibition of T-cell growth” is a functional/disease suitability limitation; it can be argued based on preclinical or clinical responsiveness.

C) Claims 5-7: narrowing autoimmune subcategories

• Claim 5 narrows claim 4’s “T-cell lymphoproliferative disorders” to autoimmune disease.
• Claim 6 narrows to arthritis.
• Claim 7 narrows to insulin dependent diabetes mellitus.

These are narrower than the parent claim and carry higher validity and enforcement specificity.

D) Claims 8-11: explicit compound + explicit ester embodiment

• Claim 8 repeats the tumor method but explicitly ties the administered compound to:
  • 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine or its pharmaceutically acceptable ester/salt.
• Claim 9 further specifies the ester as:
  • (5-O-acetyl-β-D-arabinofuranosyl)-2-amino-6-methoxy-9-9H-purine
    (as written; the “9-9H” is a drafting artifact but the intent is the 9H-purine scaffold with the stated ester)
• Claim 10-11 repeat the T-cell lymphoproliferative disorder method with:
  • base compound or ester/salt (claim 10)
  • explicit 5-O-acetyl ester (claim 11)

Where the Claim Language Creates Enforcement Leverage (and Risk)

H2: Does the patent cover esters and salts of the claimed nucleoside?

Yes, based on the provided claim language:

• Claims 3-4: “R1 is methoxy; or a pharmaceutically acceptable ester or salt thereof.”
• Claims 8-11: “base compound or a pharmaceutically acceptable ester or salt thereof,” and then an explicit ester.

This means a product launched as an ester prodrug (and/or as a recognized salt) can fall within the claim if it maps to the claim’s chemical definitions.

H2: Is coverage limited to β-D-arabinofuranosyl substitution?

The base compound and the explicitly named ester both use β-D-arabinofuranosyl at the 9-position. The formula (I) in claims 3-4 and the compound recitals in claims 8-11 indicate the claimed stereochemical sugar is part of what defines the compound.

A competitor using a different stereochemistry or different sugar moiety would likely fall outside, unless it still satisfies formula (I).

H2: Does “effective amount” create ambiguity for infringement?

The term “effective treatment amount” is standard in method claims. It usually turns infringement into a question of whether the accused regimen administers a dose that is therapeutically effective for the claimed disease category.

Scope Summary Table (Claim-by-Claim)

Patent Landscape Readout: What This Claim Set Typically Means for Competitors

H2: How does this patent likely position the company’s freedom-to-operate?

Based on claim content, competitors should treat this as a method-use barrier around:

• lymphocytic leukemia
• lymphoma
• T-cell lymphoproliferative disorders
• autoimmune arthritis
• insulin-dependent diabetes mellitus
• and a broader tumor bucket defined by “susceptible to inhibition of T-cell growth,” using the same chemical entity (or its esters/salts).

If a competitor develops a therapy that uses this same nucleoside analog (or an included ester/salt) for any of those disease buckets, they face direct method-claim infringement risk unless they can design around either:

• the compound (use a non-covered analog), or
• the indication (avoid the claimed disease categories and their mapped clinical characterizations), or
• the formula/ester/salt boundaries (avoid specifically encompassed derivatives).

H2: What “design-around” pathways are implied by the claim language?

• Chemical design-around: Use a different nucleoside analog not meeting formula (I) and not being the base compound or specified ester/salts.
• Derivative design-around: Use an ester/salt that does not fall within “pharmaceutically acceptable ester or salt thereof” as construed under the patent’s definitions and the formula (I).
• Indication design-around: Avoid the claimed diagnoses and the claimed disease concept boundaries. For autoimmune and T-cell lymphoproliferative disorders, classification arguments can matter.

H2: What does the narrow ester claim add?

Claims 9 and 11 explicitly name the 5-O-acetyl β-D-arabinofuranosyl ester. This tightens enforcement around specific prodrug formulations that metabolize to the base nucleoside.

So, if an accused product is a 5-O-acetyl prodrug intended for delivery of this nucleoside in vivo, these dependent claims reduce the competitor’s ability to argue “we did not administer the base compound,” since the claim explicitly includes the ester.

What Is Missing for a Full US “Patent Landscape” Map?

A complete landscape requires bibliographic data (assignee, filing family, continuation status, priority dates, related applications, prosecution history, cited references, and whether the claims are active or expired). That data is not included in the prompt, so only the claim-scope analysis and the implied competitive impact can be provided from the provided claim text.

Key Takeaways

• US 5,747,472 is a method-of-treatment patent centered on 2-amino-6-methoxy-9-(β-D-arabinofuranosyl)-9H-purine plus pharmaceutically acceptable esters/salts, with an explicit focus on the 5-O-acetyl β-D-arabinofuranosyl ester.
• Claim breadth is controlled by disease categories: lymphocytic leukemia, lymphoma, T-cell lymphoproliferative disorders, autoimmune disease (including arthritis and insulin-dependent diabetes mellitus), and tumors susceptible to inhibition of T-cell growth.
• The tightest enforcement hooks are the explicit compound claims (1-2, 8, 10) and the explicit ester formulation claims (9, 11).

FAQs

1) Does US 5,747,472 claim the drug itself or only methods of use?

It claims methods of treatment: the claim elements require administering the compound at an effective dose for a specified disease category.

2) Are esters and salts included even if the base nucleoside is not administered directly?

Yes. The claims expressly cover pharmaceutically acceptable esters or salts, and they explicitly include the 5-O-acetyl ester.

3) Is the claim limited to oncology, or does it cover autoimmune indications too?

It covers both. It includes lymphocytic leukemia, lymphoma, T-cell lymphoproliferative disorders, and autoimmune diseases, including arthritis and insulin-dependent diabetes mellitus.

4) How does the “tumors susceptible to inhibition of T-cell growth” limitation affect scope?

It ties the tumor method to a biological susceptibility/response concept. The method requires dosing the claimed compound for tumors that fit that susceptibility framing.

5) Does the patent cover only the single compound or also formula-based analogs within the same formula (I)?

It includes formula (I) coverage where R1 is methoxy or a pharmaceutically acceptable ester/salt, and it also includes explicit recitals to the base compound and the named 5-O-acetyl ester.

References

[1] US Patent No. 5,747,472, claims 1-11 (claim text provided in prompt).