Scope and Claims Analysis for US Patent 6,727,253: Bisdioxopiperazine (Dexrazoxane/ICRF-187) Methods to Treat Topoisomerase II Poison Extravasation

US 6,727,253 is a US method patent that claims treating or preventing local tissue damage caused by accidental extravasation of a topoisomerase II (Topo II) cytotoxic poison using a Topo II catalytic inhibitor that is a bisdioxopiperazine, with dexrazoxane (ICRF-187, dexrazoxane/dexrazoxane hydrochloride depending on formulation) as the exemplified sub-class. The claim set is drafted to capture both systemic and local administration routes, multiple timing windows relative to extravasation recognition and relative to drug administration, multiple dosing repetition regimes, and a wide selection of Topo II poisons including etoposide/teniposide and multiple anthracyclines.

A practical takeaway for freedom-to-operate (FTO), licensing, and Paragraph IV risk mapping is that the patent’s enforceable scope is centered on: (i) the extravasation use case, (ii) administration of a bisdioxopiperazine Topo II catalytic inhibitor, and (iii) a defined timing and repeat-dose framework that can be satisfied by many clinical dexrazoxane “rescue” protocols.

The remainder of this analysis is limited to what can be derived from the claim language you provided.

US Patent 6,727,253: What methods and actives does it claim for Topo II poison extravasation?

Claim 1 is the independent claim. It covers a method for preventing or treating local tissue damage due to accidental extravasation of a Topo II poison in a patient who is receiving treatment with the Topo II poison, by administering a Topo II catalytic inhibitor that is a bisdioxopiperazine.

What is the claimed “trigger” event?

“Accidental extravasation” of a cytotoxic Topo II poison.
The patient is receiving treatment with the Topo II poison at the time of extravasation (“in a patient receiving treatment with the topoisomerase II poison”).

What is the claimed “injury” target?

“Local tissue damage due to accidental extravasation.”

What is the required therapeutic intervention class?

“Topo II catalytic inhibitor” that is “a bisdioxopiperazine.”
Dependent claim 2 explicitly anchors the bisdioxopiperazine to ICRF-187 (dexrazoxane).

What Topo II poisons are encompassed?

Claim 5 lists specific Topo II poisons:

etoposide
etoposide phosphate
teniposide
mitoxantrone
m-AMSA

Claim 22-27 further require the poison to be an anthracycline in those dependent claims and specify:

daunorubicin
doxorubicin
idarubicin
epirubicin

What dosing/administration modes are covered?

The patent includes both route variants:

Claim 3: local administration to affected tissue
Claim 4: systemic administration to tissue affected by extravasation

What timing concepts are built into the claims?

The claims create multiple overlapping timing gates:

After treatment (general): claim 6
After treatment while tissue contains poison or active metabolites: claim 7
After occurrence of extravasation: claim 8
After first pain/erythema/swelling: claim 9
After fixed time thresholds relative to Topo II poison administration:
- more than 24 hours: claim 10
- within 18 hours: claim 13 (but note the claim reads “within 3 weeks” for claim 13 and “within 18 hours” for claim 14, so both windows exist)
- within 12 hours of recognition/suspicion: claim 20
- within 12 hours of administration of the Topo II poison: claim 21
- within 6 hours: claim 29
- within 4 hours: claim 30
- within 2 hours: claim 31

The timing structure is drafted to catch both “early rescue” and “delayed rescue” regimens.

Claim-by-claim mapping: where is the scope broad vs. narrow?

Below is a scope map based strictly on the provided claims.

Independent claim scope (Claim 1)

Broadest coverage hinges on three elements:

Accidental extravasation of a Topo II poison.
Administration of a Topo II catalytic inhibitor that is a bisdioxopiperazine.
Goal: prevent or treat local tissue damage.

Because Claim 1 does not require a specific Topo II poison subclass beyond “Topoisomerase II poison” nor a specific dosing schedule, it functions as the primary infringement hook.

Sub-class specificity (Claim 2)

Limits bisdioxopiperazine to ICRF-187 (dexrazoxane).
This claim is narrower than Claim 1 but can be used when the defendant’s product or method clearly uses dexrazoxane.

Route specificity (Claims 3 and 4)

Local vs systemic route are separately claimed.
This matters for designing “around” approaches such as switching route or carrier system. The patent anticipates both.

Poison selection (Claims 5, 22-27)

Claim 5 covers a mixed list of Topo II poisons, including both podophyllotoxins (etoposide/teniposide) and other Topo II poisons (mitoxantrone, m-AMSA).
Claim 22-27 covers anthracyclines.

If a therapeutic setting involves dexrazoxane rescue after extravasation of a non-anthracycline Topo II poison, the Claim 5 path is the relevant one. If it involves anthracyclines, Claim 22-27 provide stronger narrowing hooks.

Timing and “recognition” windows (Claims 6-21, 29-31)

The claims create a broad intersection of:

Post-administration rescue (claims 6-7, 10, 13-14)
Recognition-based rescue (claims 9, 20)
Administration-time-relative windows (claims 21, 29-31, and also claim 10 “more than 24 hours”)

This is a typical strategy to reduce “timing design-around” risk: even if a defendant argues a later or earlier administration, multiple dependent claims cover different cutoffs.

Dosing repetition mechanics (Claims 15-19)

The claims require repeated dosing in specific dependent claims:

at least 2 repeated dosages with interval 1 to 3 days (claim 16)
at most 24 hours interval (claim 17)
at least 3 repeated dosages (claim 18)
at least 4 repeated dosages (claim 19)

These repetition claims are narrow relative to Claim 1 but can be potent if clinical protocols use multi-dose dexrazoxane.

Dose amount sufficiency (Claim 28)

Dexrazoxane must be administered in an amount sufficient “to be present in the tissue to be prevented from or treated.”
This is a tissue exposure concept that could be argued about with pharmacokinetic and formulation differences, but it also supports infringement if the method includes a route and dose known to achieve tissue presence at the site.

What is the likely claim construction focus for “catalytic inhibitor” and “bisdioxopiperazine”?

This patent’s enforceability will likely hinge on how courts interpret:

“Topo II catalytic inhibitor”
“bisdioxopiperazine”
dexrazoxane as “ICRF-187”

Given that dependent claim 2 explicitly ties bisdioxopiperazine to ICRF-187 (dexrazoxane), a dexrazoxane-based method is structurally positioned to satisfy the chemical class limitation.

For “Topo II catalytic inhibitor,” the claims do not require specifying inhibition mechanism beyond the catalytic inhibition designation. That increases the chance that an accused method is deemed to satisfy the functional class if the bisdioxopiperazine pharmacology aligns.

How broad is the patent across therapeutic agents: anthracyclines vs podophyllotoxins vs other Topo II poisons?

Breadth is two-tiered:

Claim 1 is agent-agnostic within the Topo II poison category.
Claims 5 and 22-27 add enumerated agent lists.

If the extravasant is an anthracycline

Dependent claims 22-27 provide explicit coverage. That is especially relevant for common clinical extravasation scenarios:

doxorubicin
epirubicin
daunorubicin
idarubicin

If the extravasant is etoposide/teniposide

Claim 5 includes:

etoposide
etoposide phosphate
teniposide

If the extravasant is mitoxantrone or m-AMSA

Also covered under claim 5.

Implication for competitors: any Topo II poison extravasation rescue that uses dexrazoxane or another bisdioxopiperazine is likely to fall within Claim 1 regardless of which listed Topo II poison is involved, with additional dependent claim hooks if the accused poison matches a list entry.

Where do timing windows concentrate infringement risk?

The timing claims are a dense cluster. The most infringement-relevant windows are those that mirror real-world “rescue” practice: rescue initiated soon after recognition and sometimes after several hours or more.

Timing relative to recognition/suspicion

Within 12 hours of recognition or suspicion: claim 20

Timing relative to administration of the Topo II poison

Within 12 hours of administration: claim 21
Within 6 hours: claim 29
Within 4 hours: claim 30
Within 2 hours: claim 31
More than 24 hours: claim 10

Timing relative to extravasation event

After occurrence of accidental extravasation: claim 8
After first pain/erythema/swelling: claim 9
After treatment while tissue contains poison/metabolites: claim 7

Extended post-dosing windows

Claim 13 reads as “within 3 weeks after administration of the Topo II poison.”
Claim 14 reads “within 18 hours after administration of the Topo II poison.”

Implication: even if a protocol deviates from “early rescue,” the presence of both early and delayed-dependent claims reduces the ability to design around by shifting timing.

How is dosing repetition drafted: what does it require and what does it avoid?

The repetition claims target multi-dose protocols, which align with how dexrazoxane is often administered for anthracycline extravasation rescue.

Minimum repetition coverage

At least 2 repeated dosages: claim 15
At least 3: claim 18
At least 4: claim 19

Interval options

1 to 3 day intervals for at least 2 dosages: claim 16
At most 24 hours interval for at least 2 dosages: claim 17

What repetition does not require

The claims do not specify an absolute dose amount in mg/kg at the claim level (except claim 28’s tissue presence sufficiency). So an accused method that meets repetition, route, class, and timing elements can still fall within scope even with different exact dosing amounts.

What “around” strategies might be blocked by this claim set (based on claim language only)?

Switching route is not a clean workaround

Because both:

local (claim 3) and
systemic (claim 4) are claimed, switching route alone does not remove coverage for methods that otherwise meet Claim 1.

Switching to a non-bisdioxopiperazine Topo II catalytic inhibitor could avoid Claim 1

Claim 1 limits the inhibitor to “a bisdioxopiperazine.” If an alternative catalytic inhibitor is not a bisdioxopiperazine, Claim 1 is not satisfied by definition.

Timing shifts have limited value

Given the number of timing-dependent claims (2 hours, 4 hours, 6 hours, 12 hours, more than 24 hours, and extended within-3-weeks), shifting administration timing is unlikely to avoid all dependent claim paths if the defendant’s protocol overlaps any of those windows.

Reducing dosing frequency might help only if it avoids all repetition-dependent claims

If the accused method uses a single administration and avoids the “at least 2 repeated dosages” dependent claims, it could avoid those specific repetitions, but Claim 1 still covers a method regardless of repetition.

So, an actual workaround would likely require:

not using a bisdioxopiperazine Topo II catalytic inhibitor, or
not treating/preventing local tissue damage caused by extravasation, or
not performing the required method steps as claimed.

US patent estate context: how to think about related dexrazoxane extravasation IP (without external dossier data)

The claim language itself indicates this patent is anchored on a known agent and use case: dexrazoxane (ICRF-187) for Topo II poison extravasation injury. That typically sits in a dense landscape that includes:

method-of-use patents for extravasation rescue,
formulation/composition patents,
and sometimes additional patents covering administration regimens.

However, without the patent family list, continuation history, or the full text specifications and claims beyond those you provided, a complete landscape (other US patents by same assignee, global equivalents, or specific Orange Book and litigation status) cannot be generated accurately.

Accordingly, this analysis focuses on scope and claim mechanics of US 6,727,253 itself.

Key claim elements summary table (infringement checklist)

Element	Where in claims	What must be present for coverage
Accidental extravasation	Claim 1	Extravasation of Topo II cytotoxic poison
Local tissue damage prevention/treatment	Claim 1	Treatment intent and effect on local tissue damage
Patient receiving Topo II poison	Claim 1	Context tied to ongoing chemotherapy with Topo II poison
Topo II catalytic inhibitor	Claim 1	Therapeutic agent must be a Topo II catalytic inhibitor
Inhibitor is bisdioxopiperazine	Claim 1	Chemical class limitation
Dexrazoxane specifically	Claim 2	If accused method uses ICRF-187/dexrazoxane
Local administration route	Claim 3	Local delivery to affected tissue
Systemic administration route	Claim 4	Systemic dosing where tissue is affected
Specific Topo II poisons	Claim 5	etoposide/etoposide phosphate/teniposide/mitoxantrone/m-AMSA
Anthracyclines covered	Claim 22-27	daunorubicin/doxorubicin/idarubicin/epirubicin
Timing after treatment / after extravasation	Claims 6-9	Post-event rescue concepts
Timing windows	Claims 10, 13, 14, 20-21, 29-31	Multiple thresholds allow early or delayed rescue coverage
Repeat dosing regimes	Claims 15-19	Multi-dose intervals and minimum dose counts
Tissue presence sufficiency	Claim 28	Dose must be sufficient to be present in tissue

Key Takeaways

US 6,727,253 is a method patent focused on dexrazoxane-class bisdioxopiperazine Topo II catalytic inhibition as extravasation rescue.
Claim 1 is broad on the event (accidental extravasation), purpose (prevent/treat local tissue damage), and therapeutic class (Topo II catalytic inhibitor that is a bisdioxopiperazine).
Dependent claims add significant narrowing hooks for:
- dexrazoxane (ICRF-187),
- both local and systemic administration,
- multiple Topo II poison enumerations (etoposide family, mitoxantrone, m-AMSA, and anthracyclines),
- multiple early and delayed timing windows (2 hours through more than 24 hours and extended within-3-weeks),
- and repeat-dose regimens (at least 2 to at least 4 doses with specific interval concepts).
Design-around value is constrained by class limitation (bisdioxopiperazine) and timing density.

FAQs

1. Does US 6,727,253 require dexrazoxane specifically, or does it cover other bisdioxopiperazines?
Claim 1 covers any bisdioxopiperazine Topo II catalytic inhibitor. Claim 2 specifically recites ICRF-187 (dexrazoxane).

2. Are both local and systemic dosing of the Topo II catalytic inhibitor covered?
Yes. Claim 3 covers local administration to the affected tissue and claim 4 covers systemic administration to tissue affected by extravasation.

3. How early after recognition of extravasation does the patent claim cover?
It includes a dependent claim for administration within 12 hours of recognition or suspicion (claim 20).

4. Does the patent cover delayed rescue beyond a day?
Yes. Claim 10 recites administration more than 24 hours after administration of the Topo II poison, and other dependent timing claims extend into multiple windows.

5. Is repeat dosing required?
Not for the independent claim. Repeat dosing is required in specific dependent claims (claims 15-19). Claim 1 does not impose a repetition requirement.

References

No external sources were cited because only the claim language provided in the prompt was used.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Denmark	1999 00355	Mar 12, 1999

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	265215	⤷ Start Trial
Australia	3272600	⤷ Start Trial
Australia	769533	⤷ Start Trial
Brazil	0009473	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 6,727,253