Details for Patent: 5,403,833

United States Patent 5,403,833 Landscape: Scope, Claim Construction, and Competitive Patent-Protection Map for Rapamycin + Corticosteroid Transplant Rejection Inhibition

Executive summary

US Patent 5,403,833 covers a treatment method for inhibiting organ or tissue transplant rejection in mammals using a combination regimen of rapamycin plus a corticosteroid, with additional claim-dependent limits on rapamycin dose range, route (oral or parenteral), treatment duration (including indefinite dosing and 1 to 180 days). The claim set is structured around (i) combination therapy as the core inventive concept, and (ii) practical regimen parameters that can be targeted in claim design-arounds (single-agent therapy, steroid elimination, different drug pairing, and different dosing/period boundaries).

What is US Patent 5,403,833 protecting: rapamycin plus corticosteroid transplant rejection methods?

Core protection. Independent claim 1 defines the invention as a method of inhibiting transplant rejection by administering rapamycin in combination with a corticosteroid in an amount effective to inhibit rejection.

Key legal framing. The claim is a classic method claim with a functional endpoint (“inhibiting transplant rejection”) and a defined therapeutic regimen (rapamycin + corticosteroid). That combination structure creates two infringement axes:

1. whether the accused regimen includes rapamycin (not merely mTOR inhibition generally), and
2. whether it is administered with a corticosteroid as part of the effective regimen for transplant rejection inhibition.

Claim 1: functional combination regimen elements

Claim 1 elements

• Patient: “a mammal in need thereof” (no further limitation).
• Condition: “organ or tissue transplant rejection.”
• Act: “administering… in combination rapamycin and a corticosteroid.”
• Amount: “an amount effective to inhibit transplant rejection.”
• Included: “effective amount of rapamycin and corticosteroid.”

Claim 1 risk points for design-arounds

• Omitting the corticosteroid. If the regimen does not include a corticosteroid, literal infringement is weakened because “in combination rapamycin and a corticosteroid” is explicit.
• Substituting a non-steroidal immunosuppressant for the corticosteroid. The claim is corticosteroid-specific.
• Arguing that the regimen does not “inhibit transplant rejection” may be fact-dependent and tied to clinical outcome evidence or standard-of-care inference.

Scope of “in combination”

The claim uses “in combination,” not “simultaneously,” and does not define spacing between administrations. For infringement, “combination” often invites arguments over whether co-administration within a therapeutic course is required. The dependent duration claims (claims 7 and 10) reinforce that the regimen is part of an ongoing transplant management strategy, not a one-off co-dosing experiment.

How do the dependent claims narrow scope: dose, route, and duration limits?

The dependent claims operationalize claim 1 by adding measurable boundaries that can be used both to strengthen enforcement (pin down the regimen) and to support design-arounds (step outside ranges, change route, or change treatment timeline).

Dose limits for rapamycin (mg/kg/day)

The claims recite multiple overlapping dose windows:

• Claim 2: about 0.5 to 50 mg/kg/day
• Claim 3: about 1 to 5 mg/kg/day
• Claim 4: about 0.5 to 5 mg/kg/day
• Claim 8: about 0.25 to 5 mg/kg/day (tied to indefinite period in claim 7)
• Claim 9: about 0.25 to 50 mg/kg/day

What this means for claim scope

• The narrowest explicit window is about 1 to 5 mg/kg/day (claim 3).
• Multiple broader claims cover down to about 0.25 mg/kg/day and up to about 50 mg/kg/day.
• Overlap is heavy: a regimen at “about 0.5 to 5 mg/kg/day” lands in claims 2/4 and also effectively within the “indefinite period” dependent framing if combined with claim 7.

Infringement leverage

• If an accused regimen uses rapamycin doses within any of the recited windows and includes corticosteroid co-administration, the patentee can select the dependent claim that best matches the facts.

Design-around leverage

• Literal “dose” avoidance requires pushing outside all covered ranges. Because several claims extend up to 50 mg/kg/day and down to 0.25 mg/kg/day, the practical space for a fully non-infringing dose is smaller than it would appear if only one dose claim existed.
• “About” introduces flexibility. Courts often interpret “about” through the lens of specification guidance and prosecution history, so dose-edge tactics can still create infringement risk.

Route limits

• Claim 5: rapamycin administered orally
• Claim 6: rapamycin administered parenterally

Implication

• The independent claim (1) does not restrict route, but dependent claims specify oral and parenteral embodiments. In practice, this means route is unlikely to be a clean design-around because claim 1 already does not demand a particular route.

Treatment duration limits

• Claim 7: rapamycin administered for an indefinite period of time to maintain inhibition of rejection.
• Claim 10: combination administered for between about 1 to about 180 days.

Implication

• There are at least two time-based protected regimen archetypes:
  • “Indefinite” maintenance dosing (claim 7 + claim 8 dose window).
  • A shorter course “1 to 180 days” (claim 10) for the combination.
• If an accused regimen is explicitly in a post-transplant maintenance strategy that is “indefinite” or long-term, claim 7 becomes a strong fit.
• If it is a defined course within 1 to 180 days, claim 10 becomes relevant.

How strong is the patent estate from the claim structure: what aspects are hardest to design around?

Hard-to-design-around components

1. Regimen core: rapamycin plus a corticosteroid for rejection inhibition (claim 1).
2. Functional endpoint: “inhibit transplant rejection” ties the claim to the therapeutic purpose.
3. Indefinite maintenance strategy: claim 7 aligns with chronic immunosuppression practice patterns.
4. Broad dose coverage: multiple overlapping dose ranges reduce “dose escape” opportunities.

Potentially easier to design around components

1. Corticosteroid substitution: removing corticosteroid is the most direct escape route because corticosteroid is expressly required.
2. Different drug pairing: replacing rapamycin with a different mTOR inhibitor (or different compound) could avoid “rapamycin” literally, but depends on whether the accused drug is chemically and legally “rapamycin” versus a distinct analogue (e.g., a different branded entity or derivative).
3. Duration framing: if the accused protocol is clearly outside 1 to 180 days and not “indefinite” maintenance, claim 10 and claim 7 may be avoided. However, claim 1 has no explicit duration limitation, so time-only avoidance does not eliminate claim 1 exposure; it only reduces dependent-claim match precision.

What patents are likely adjacent: how this claim maps onto typical rapamycin transplant IP clusters?

This patent is a method-of-use claim tied to combination immunosuppression. In many transplant IP landscapes, protection typically clusters into:

• Core mTOR inhibitor treatment (rapamycin as immunosuppressant).
• Combination regimens (rapamycin + steroid; rapamycin + calcineurin inhibitor; rapamycin + antiproliferative).
• Dose and schedule (mg/kg/day windows and chronic administration).
• Formulation and delivery (oral formulations, parenteral forms).
• Indications and endpoints (rejection inhibition, graft survival markers).

US 5,403,833 sits most directly in the combination regimen and treatment method parameterization zone. In licensing or litigation, that typically means enforcement can focus on real-world protocols that mirror the claimed regimen elements.

What would an infringement analysis look like: step-by-step mapping of an accused regimen to claim elements?

Claim 1 checklist

• Is the accused therapy using rapamycin?
• Is it administered in combination with a corticosteroid?
• Is the patient a mammal needing therapy for organ/tissue transplant rejection?
• Is the administration “effective to inhibit transplant rejection”?

If the regimen matches all four, claim 1 is implicated. Dependent claims then add specificity:

• Does the rapamycin dose match one of the mg/kg/day windows?
• Is rapamycin oral or parenteral?
• Is the regimen indefinite maintenance or within 1 to 180 days?

When does US 5,403,833 lose exclusivity: patent-term and practical enforcement window?

No term/expiration data is included in the provided material, so the exclusivity calendar cannot be computed here. Patent exclusivity timelines in the US are governed by:

• utility patent term (filing date dependent),
• potential adjustments,
• any exclusivity extension under Hatch-Waxman is usually not applicable to method claims of this type in the absence of a listing context.

Because only the claim text is provided, exclusivity timing cannot be stated accurately.

What generic entry risks exist for transplant therapy: how this method patent affects competition?

Even without Orange Book listing facts, the competitive mechanism is clear: method patents can create risk for generic manufacturers and biosimilar-like competitors if they market or induce use for the patented method.

Key points

• If generic rapamycin is available, a generic can still be vulnerable if it is used (and especially if it is promoted/encouraged) for the rapamycin + corticosteroid transplant rejection inhibition regimen.
• Labeling and promotional language can drive induced infringement exposure. A protocol that is standard-of-care and includes corticosteroid co-therapy increases the chance the regimen falls within claim 1.

How does US 5,403,833 compare with later rapamycin transplant patents: what claim design differences usually appear?

Common later-generation differences include:

• more granular corticosteroid selection,
• specific transplant types (kidney, liver, lung),
• combination with specific co-therapies,
• more precise schedule timing (induction vs maintenance),
• formulation-specific claims (e.g., oral solution/tablets versus parenteral),
• biomarker endpoint claims.

US 5,403,833 is broad on transplant type (“organ or tissue”) and broad on route via claim 1 (with dependent clarifications). That breadth can make it a stronger barrier for many transplant protocols, even if later patents carve out narrower settings.

What does the claim language imply about corticosteroid scope?

The claims do not specify which corticosteroid (e.g., prednisone, prednisolone, methylprednisolone). That increases the practical scope:

• Any corticosteroid that meets the category likely falls within “corticosteroid.”
• A design-around that avoids the corticosteroid category entirely would be required for clean avoidance.

What formulations are protected by the patent: does it cover delivery systems or only dosing?

US 5,403,833 is framed as a method of inhibiting rejection via administration. It does not, from the claim text provided, appear limited to a particular formulation or excipient. The only formulation-like limitation is route via dependent claims 5 and 6.

Thus:

• Protection is primarily about the therapeutic regimen rather than drug product composition.

What US regulatory status affects enforceability: is this an FDA-labeling-driven patent?

With only claim text available, regulatory linkage (Orange Book listing, listed patents, or method-of-use listing) cannot be determined. Practically, enforcement leverage often correlates with whether the patent is tied to labeling and whether FDA-listed patents exist for the relevant NDA/ANDA. Those facts are not provided.

Key claim-to-business mapping: where infringement or licensing focus would be highest

1. Transplant centers using chronic rapamycin plus steroid maintenance
   • highest fit with claim 1 + claim 7.
2. Protocols with explicit dosing in mg/kg/day and defined maintenance windows
   • highest fit with claims 2–4 and claim 10.
3. Regimens that use a steroid co-therapy as a standard immunosuppressant component
   • highest fit with claim 1 due to the corticosteroid requirement.

Key Takeaways

• US 5,403,833 is a method-of-use patent centered on rapamycin + corticosteroid co-administration to inhibit organ or tissue transplant rejection in mammals.
• Claim 1 is broad: it requires rapamycin, a corticosteroid, and an effective regimen outcome for rejection inhibition; it is not limited by route or duration.
• Dependent claims narrow the protected embodiments through rapamycin dose ranges, oral vs parenteral administration, and treatment duration (including indefinite maintenance and 1 to 180 days combination administration).
• Competitive risk concentrates on any therapeutic protocols that keep corticosteroid co-therapy and rapamycin within or near the claimed dosing and scheduling constructs.

FAQs

1) Does US 5,403,833 require simultaneous dosing of rapamycin and the corticosteroid?
The claim requires “in combination,” with no explicit simultaneity requirement in the provided claim text.

2) Can a company avoid infringement by using rapamycin without a corticosteroid?
Removing corticosteroid use is the most direct path to avoiding the explicit “rapamycin and a corticosteroid” combination requirement in claim 1.

3) What rapamycin dosing ranges are explicitly covered?
The dependent claims cover multiple overlapping windows including about 0.5 to 50 mg/kg/day, about 1 to 5 mg/kg/day, about 0.5 to 5 mg/kg/day, about 0.25 to 5 mg/kg/day (indefinite dosing), and about 0.25 to 50 mg/kg/day.

4) Does the patent cover both oral and parenteral administration of rapamycin?
Dependent claims expressly cover both oral and parenteral routes, and claim 1 is not limited by route.

5) How much does duration matter given claim 1 lacks an express time limit?
Duration tightly matches the dependent claims (indefinite; 1 to 180 days), but claim 1 can still be implicated regardless of timing if the regimen otherwise meets the combination and functional inhibition elements.

References

1. United States Patent No. 5,403,833 (claims provided in prompt).