Patent: 6,347,633

Summary for Patent: 6,347,633

Title:	Treatment of hepatitis C using hyperthermia
Abstract:	The invention provides a method of treating a patient infected with hepatitis C virus (HCV) comprising raising the core temperature of the patient and then returning the core temperature of the patient to normal at least one time, wherein the core temperature is raised to a temperature range and a duration sufficient to reduce or eliminate the patient\'s viral load of HCV.
Inventor(s):	Groth; Karl Emil (St. Paul, MN), Kelly; Theodore Charles (Minnetonka, MN), Westerbeck; Todd L. (Burnsville, MN), Blick; Gary (Stamford, CT)
Assignee:	First Circle Medical, Inc. (Minneapolis, MN)
Application Number:	09/484,360
Patent Claims:	see list of patent claims

US Patent 6,347,633 Landscape Analysis: Heated Core-Temperature Protocols for Hepatitis C (HCV) Treatment in the US

Executive summary: US Patent 6,347,633 claims a physiologic hyperthermia-style protocol for HCV that requires: (1) raising and returning core temperature at least once; (2) achieving predefined HCV viral-load reduction thresholds at specific follow-up timepoints (1 month or 3 months depending on claim set); and (3) measuring viral load after temperature normalization. Dependent claims narrow the **temperature range (notably 38–48°C; including a tight 41.8–42.2°C band), duration windows (minutes to ~16 hours; also 80–100 minutes and 1–2 hours), delivery mode (extracorporeal heated blood versus implanted heating element), temperature measurement (including rectal), diagnostic modality (branched DNA and RT-PCR sensitivity thresholds), patient subpopulations (acute/chronic HCV, co-infected patients incl. HIV), and add-on antiviral drugs (interferons, ribavirin and broad historical drug lists).

The patent’s enforceable value in 2026 hinges on whether competitors’ actual clinical protocols are captured by the combination of (temperature + dwell time + temperature-to-normal cycling + quantitative virologic endpoint timing + test type/sensitivity where claimed), and whether the historical medical practice and prior art make the central concept obvious or not enabled for the claimed endpoints.

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What is US Patent 6,347,633 claiming for hepatitis C treatment via core temperature elevation?

Core concept (independent claim logic across the set): A method for treating an HCV-infected patient by:

1. Raising core temperature to a defined temperature range for a defined duration.
2. Returning core temperature to normal at least once (single-cycle or multi-cycle).
3. Achieving a viral-load reduction by a defined follow-up timepoint, typically:
   • ≥30% reduction at 3 months (claim 1 core threshold variant) and related variants, or
   • ≥30% reduction at 1 month (claim 52 variant), or
   • Reduction to below sensitivity thresholds of specific assays:
     • branched DNA (claims 46 and 59 variants) and
     • RT-PCR (claims 49, 62 variants),
   • plus viral load determination after temperature normalization.
4. Optional expansions include co-infection with HIV and other comorbidities and concurrent or staged pharmaceutical antiviral therapy.

Claim scope in plain terms:

• It is not a generic “hyperthermia” claim. It is a post-normalization, endpoint-anchored protocol with explicit time-to-virologic readout and viral-load quantification method/sensitivity in certain claim clusters.
• The delivery system is constrained in dependent claims:
  • Extracorporeal circuit that heats returned blood.
  • Heating element inserted into the patient to heat blood.
• The protocol is constrained by temperature band and exposure duration.
• The assay type matters where claimed (branched DNA vs RT-PCR), which can narrow infringement analysis if an accused method uses different assay platforms or reporting frameworks.

How does the claim set separate by virologic endpoint and timing?

The claim text you provided divides the patent’s coverage into multiple “buckets”:

• Bucket A: % reduction at fixed timepoints

  • Claim 1: ≥30% reduction by 3 months after raising/returning.
  • Claims 52/65: ≥30% (or higher dependent thresholds) by 1 month, and in HIV co-infection sub-variants.

• Bucket B: percent reduction escalators

  • Dependent variants state ≥50%, ≥75%, ≥90%, ≥95% at either 1 month or 3 months, depending on the claim cluster.

• Bucket C: assay-sensitivity “below detection/threshold”

  • Branched DNA test sensitivity level:
    • Claim 46: less than sensitivity level at 3 months
    • Claim 59: less than sensitivity level at 1 month
  • RT-PCR test sensitivity level:
    • Claim 49: less than sensitivity level at 3 months
    • Claim 62: less than sensitivity level at 1 month

This structure affects both validity (obviousness and enablement for achieving these endpoints in HCV) and infringement (accused methods must satisfy the protocol and the endpoint measurement regime).

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What patents protect the core temperature cycling concept used for HCV in US 6,347,633? (Claim-to-attack map)

A complete “patent estate map” for US 6,347,633 requires knowing the inventors/assignee, family members, and the prosecution history to anchor citations and continuation-related scope. None of that is provided in your input, so a reliable multi-patent landscape (other US patents with overlapping hyperthermia/virologic endpoints) cannot be constructed without risking factual errors.

That said, the claims themselves reveal where infringement risk and validity risk concentrate:

High-leverage infringement hooks (what an accused competitor must hit)

1. Core temperature is raised and returned to normal at least once.
2. The duration and temperature range are in-scope where dependent claims specify bands (38–48°C; 38–44°C; 41.8–42.2°C).
3. Viral-load measurement after normalization is required (at least once after returning to normal).
4. Specific endpoint timing and threshold:
   • 1 month vs 3 months.
   • ≥30% or escalated % thresholds.
   • “Below sensitivity” depends on assay type.

High-leverage validity pressure points (what prior art can attack)

The concept is vulnerable on three common fronts:

• Obviousness: Prior medical literature on hyperthermia, fever-range heating, immune modulation, and antiviral responses can be used to argue routine optimization.
• Written description / enablement: The claims tie clinical outcomes to specific endpoints. If the supporting disclosure does not robustly teach achieving those endpoints across patient variability (acute vs chronic; co-infection), challengers can argue lack of credible enablement.
• Assay sensitivity dependence: Where claims require thresholds “less than sensitivity level” of specific assays, disputes can arise about what sensitivity level is “the” level under real-world test conditions.

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When does US 6,347,633 lose exclusivity for method-of-treatment practice?

A precise exclusivity timeline depends on:

• the application filing date,
• maintenance/payment status,
• patent term adjustments,
• and whether any continuation has later term.

No filing data is provided in your prompt, so a correct “expiration date” analysis cannot be produced.

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How strong is the patent’s claim coverage: temperature ranges, dwell times, and delivery systems?

Temperature range constraints

Dependent claims specify:

• 38–48°C (claim 10/82 style)
• 38–44°C (claim 11/68 style)
• 41.8–42.2°C (claim 12/69 tight band)

Critical implication: The narrow band (41.8–42.2°C) creates a clear infringement target for any protocol that runs tightly in that range. Broader bands still require the accused protocol to match the claimed timing and endpoint.

Exposure duration constraints

Dependent claims include:

• 2 minutes to 16 hours (claim 14/84)
• 0.5 to 3 hours (claim 15/85)
• 1 to 2 hours (claim 16/86)
• 80 to 100 minutes (claim 17/87)

Critical implication: Protocols that use similar temperature elevation but different dwell times may avoid some dependent claims. Literal infringement of the dependent duration ranges depends on the exact protocol.

Measurement location

• Rectal measurement is explicitly included (claim 13/83).

Critical implication: If an accused protocol defines “core temperature” differently (e.g., esophageal, bladder, pulmonary artery), it may still argue “core temperature” interchangeability, but infringement of this dependent claim may be harder to prove.

Delivery mode: extracorporeal heating vs implanted heating element

• Extracorporeal heated blood circuit (claim 4/47 style): blood is circulated through an extracorporeal circuit and returned heated.
• Heating element inserted into patient (claim 8/48 style): inserted heating element heats blood.

Critical implication: A protocol using external blankets or non-circulating heating without blood heating in a circuit or inserted element likely avoids these delivery-dependent claims.

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What formulations or co-therapies are covered by US 6,347,633?

The patent includes a pharmaco-adjuvant structure:

• Claim 24 onward: “further comprising treating with a pharmaceutical indicated for hepatitis C.”
• Claims 27–31 specify administration timing relative to temperature raising and normalization:
  • before,
  • while raised,
  • after,
  • or combinations.

Drug classes and specific drugs

Dependent claims enumerate broad antiviral lists including:

• interferons and protease inhibitors, and “cytokines,”
• and then a long roster including many historically used agents.

Key narrower examples:

• Claim 34: interferon, ribavirin, or lamivudine.
• Claim 35: alpha interferon.

Critical implication: Most modern DAAs (direct-acting antivirals) were not part of the historical enumerations in a complete, modern way. The claim’s language is framed as “pharmaceutical indicated for hepatitis C,” and then enumerates older drugs. Depending on how the claims are interpreted, modern DAAs may still be argued to fall inside “indicated,” but that is not the same as explicit enumeration and can become a litigation issue centered on claim construction.

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Does US 6,347,633 cover acute vs chronic HCV, or only specific subpopulations?

The claims include patient-state dependent coverage:

• Acute HCV infection (claim 36)
• Chronic HCV infection (claim 37)
• Co-infection with a pathogen (claim 38), including viruses (claim 39) and “heat labile virus” lists (claims 40–42) and additional bacterial/spirochete enumerations (claims 43–45).

There is also a prominent co-infection:

• HIV co-infection (claims 65 onward and the corresponding assay/threshold sub-claims).

Critical implication: If an accused protocol is used only in a different patient subset (e.g., non-HIV co-infection), it may still infringe independent claim coverage, but the HIV-dependent sub-claims would not be applicable. The “heat labile virus” and pathogen-specific lists likely require close match to the patient’s co-infection profile to land on those dependent claims.

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What diagnostic tests and assay thresholds are claimed? (branched DNA vs RT-PCR)

US 6,347,633 explicitly anchors certain dependent claims to:

• branched DNA signal amplification test sensitivity level
• reverse transcriptase-polymerase chain reaction (RT-PCR) test sensitivity level

This creates two distinct infringement and validity axes:

1. If an accused method uses a different assay platform or a different reporting approach, it can argue lack of satisfaction for the “below sensitivity level” limitation.
2. If assay sensitivity is affected by laboratory conditions, challengers can argue indefiniteness or lack of objective boundaries.

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How would a competitor design around US 6,347,633 in the US?

Design-around strategy follows the claim architecture:

1. Avoid the specific temperature bands and durations in dependent claims:
   • operate outside 38–48°C or outside 0.5–3 hours or 80–100 minutes, depending on the target claim set.
2. Avoid blood-heating in an extracorporeal circuit or inserted heating element:
   • use non-blood-heating core temperature methods.
3. Change measurement and protocol structure:
   • ensure no “raise then return to normal at least one time” cycle matching the limitation as construed.
4. Change virologic endpoint scheme:
   • avoid measuring viral load at required timepoints (1 month or 3 months post-normalization) if that is required as a method step (not just an observed result).
   • for “below sensitivity level” claims, use assay reporting not matching the claimed test class.
5. Use different co-therapies:
   • if pursuing a claim subset where “pharmaceutical indicated” is limiting, choose regimens that can be argued outside “indicated” or outside the claimed timing relationship, depending on construction.

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What HCV and HIV/Daa landscape risk exists: biosimilar vs generic angle for method claims?

This is a method-of-treatment patent, not a small-molecule composition or biologic. “Generic entry risk” is therefore not about an ANDA/BLA substitution of a drug product. The risk is:

• a clinical protocol or device protocol that practices the claimed method steps.

Modern HCV therapy uses DAAs, so market substitution questions are more about:

• whether any competitor uses core temperature raising and cycling as an adjunct, and
• whether their device/protocol matches the dependent delivery limitations.

Biosimilar frameworks similarly do not map directly unless a biologic co-therapy is claimed as a limiting step and the claim construction makes drug identity essential.

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Key Takeaways

• US 6,347,633 is built around physiologic core temperature elevation with normalization cycles plus endpoint-linked HCV viral-load reduction at 1 month or 3 months and post-normalization viral-load testing.
• Claim scope tightens substantially in dependent claims via specific temperature bands, dwell times, core temperature measurement location, heated blood delivery (extracorporeal vs inserted heating element), and assay-specific sensitivity thresholds (branched DNA vs RT-PCR).
• The patent includes add-on antiviral co-therapy structure with defined timing before/during/after temperature raising.
• Risk for competitors is driven by whether they actually implement all required protocol steps and achieve endpoints on the defined schedule, especially where claims require “less than sensitivity level” for particular assay types.
• A definitive “expiration date/exclusivity” and a multi-patent prior-art landscape for this specific patent cannot be computed from the information provided.

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FAQs

1) Is US 6,347,633 a drug composition patent or a device/protocol patent?
It is a method-of-treatment patent that can implicate clinical protocols and temperature-heating systems that perform the claimed steps.

2) What is the most design-around-sensitive element in the claim set?
The combination of temperature range + duration + return-to-normal cycling + endpoint timing + assay limitation (especially “below sensitivity level” dependent claims).

3) Does the patent require co-administration of antivirals?
No. Co-therapy appears in dependent claims (claims starting around claim 24). The method can be framed without drug steps depending on which claims are asserted.

4) Does the patent cover HIV co-infected patients?
Yes, with multiple dependent claim families specifying HIV co-infection and then applying the same core-temperature and virologic endpoint framework.

5) Would typical modern DAA regimens automatically infringe?
Not by default. Infringement depends on whether a regimen also practices the claimed temperature raising/normalization method and matches the viral-load endpoint limitations.

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References (APA)

1. Claims text provided by user for US Patent 6,347,633.

Details for Patent 6,347,633

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Merck Sharp & Dohme Llc	INTRON A	interferon alfa-2b	For Injection	103132	June 04, 1986	6,347,633	2020-01-14
Merck Sharp & Dohme Llc	INTRON A	interferon alfa-2b	For Injection	103132		6,347,633	2020-01-14
Merck Sharp & Dohme Llc	INTRON A	interferon alfa-2b	Injection	103132		6,347,633	2020-01-14
Biogen Inc.	AVONEX	interferon beta-1a	For Injection	103628	May 17, 1996	6,347,633	2020-01-14