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United States Patent 5,776,456: Claims, Validity Friction Points, and US Landscape

US Patent 5,776,456 claims combination regimens for B cell lymphoma using a specific chimeric anti-CD20 monoclonal antibody, with dosing windows and optional add-ons including radiolabeled anti-CD20 and chemotherapeutics. The claims are tightly anchored to a single biological source: a “transfectoma comprising anti-CD20 in TCAE 8” deposited at ATCC as deposit number 69119. The landscape pressure around this claim set comes from three directions: (i) prior art chimeric anti-CD20 antibodies and dosing/combination regimens, (ii) enablement and definiteness constraints tied to the deposit-defined antibody, and (iii) obviousness of sequencing and combinations against established anti-CD20 and chemotherapy standards.

What do the claims actually cover?

Core claim scope (claims 1 to 4)

Claim 1: Method of treating B cell lymphoma in a human by administering a therapeutically effective amount of immunologically active chimeric anti-CD20 antibody derived from:
- transfectoma comprising anti-CD20 in TCAE 8
- ATCC deposit 69119
Claim 2: Dose range: 0.001 to 30 mg/kg
Claim 3: Allows a second therapeutically effective dose
Claim 4: Second dose occurs within about 7 days of first administration

This set is a dosing-and-repetition framework over a deposit-defined chimeric anti-CD20.

Expanded combination scope (claims 5 to 6)

Claim 5: Treat B cell lymphoma by: 1) administering the same chimeric anti-CD20 from ATCC 69119 during a first period 2) administering a radiolabeled anti-CD20 antibody during a second period
Claim 6: Radiolabeled anti-CD20 antibody is a monoclonal antibody secreted from a hybridoma:
- ATCC deposit HB 11388

This claim attempts to lock in a specific radiolabeled anti-CD20 component via another deposit.

Multi-dose regimen scope (claims 7 to 10)

Claim 7: A three-dose sequence of the same chimeric anti-CD20 from ATCC 69119 across first, second, and third administration periods.
Claim 8: Each dose is within 0.001 mg/kg to 30 mg/kg
Claim 9: Second administration period is within about 7 days of first
Claim 10: Third administration period is within about 14 days of first

Chemotherapy combination scope (claims 11 to 14)

Claim 11: Adds at least one chemotherapeutic agent
Claim 12: Chemotherapy can be administered after the anti-CD20 dosing
Claim 13: Chemotherapy can be administered before the anti-CD20 dosing
Claim 14: Example chemotherapy agents are selected from:
- cyclophosphamide, doxorubicin, vincristine, prednisone

Net coverage: sequencing flexibility plus broad agent selection limited to a common chemotherapy set.

What makes the claims “deposit-defined” and why it matters

The claims repeatedly anchor the antibody identity to:

TCAE 8 + transfectoma + ATCC deposit 69119 for the chimeric anti-CD20
ATCC deposit HB 11388 for a radiolabeled anti-CD20 hybridoma

Legal and technical implications

Claim construction hinges on biological identity. If an accused product uses a different production cell line, expression construct, or culture condition not within “transfectoma comprising anti-CD20 in TCAE 8,” claim coverage can narrow sharply despite functional similarity.
Enablement and written description can be tested. When a claim is tied to a specific deposit but the specification must support reproducible production and characterization, any gaps can create validity friction. In practice, deposit reference helps, but it does not eliminate scrutiny if functional breadth outstrips disclosure.
Infringement becomes both bio- and process-dependent. Even when a marketed anti-CD20 is “chimeric,” enforcement may require proof that the antibody is derived from the deposit-defined source or is sufficiently identical to satisfy the claim’s anchor.

How do the dosing and timing terms compress freedom-to-operate?

Dose range (claims 2, 8)

0.001 to 30 mg/kg

This is broad enough to cover common antibody dosing approaches in lymphoma at the time such patents matured. Broad numeric windows often reduce selectivity-based design-around options. If prior art dosing overlaps even substantially, obviousness exposure increases.

Timing windows (claims 4, 9, 10)

Second dose within ~7 days (claims 4 and 9)
Third dose within ~14 days (claim 10)

These windows look like “schedule scaffolding” layered on top of known anti-CD20 treatment. A critical question for validity is whether prior art already disclosed repeated dosing at similar intervals. If so, these timing limitations may not be enough to create patentable separation.

What is the strongest novelty angle in the claim set?

The only consistently sharp differentiator is the pairing of:

chimeric anti-CD20 antibody from ATCC 69119, and
the optional combination with radiolabeled anti-CD20 from ATCC HB 11388 (claims 5 to 6), while also layering chemo sequencing options.

If those deposit-defined antibodies are materially different from prior art chimeric anti-CD20 antibodies, then novelty could rest on “what antibody” more than “how” it is administered.

But in many anti-CD20 patent families, most of the functional treatment concepts (CD20 binding, lymphoma targeting, repeat dosing, combination therapy) were already disclosed across multiple approaches. That shifts the novelty battle to identity and characterization rather than to dosing mechanics.

Critical validity friction points (US) for this claim structure

1) Obviousness risk from anti-CD20 treatment and combination norms

These claims use familiar building blocks:

repeat dosing of therapeutic antibodies
use of radiolabeled anti-CD20 in sequence with unlabeled anti-CD20
combination with established chemotherapy regimens

If prior art disclosed any one of:

chimeric anti-CD20 lymphoma treatment in humans,
multi-dose schedules with short inter-dose intervals,
chemo combinations with CD20 antibodies,
radiolabeled anti-CD20 in combination regimens,

then claims 2 to 4, 7 to 10, and 11 to 14 may be seen as routine optimization or obvious scheduling. The deposit-defined antibody identity can reduce this risk, but only if the deposit-defined antibody is demonstrably different in a non-trivial way from prior art CD20 chimerics.

2) Claim breadth could outstrip antibody-specific disclosure

The antibody is deposit-defined, but the method is broad:

wide dosing range up to 30 mg/kg
timing ranges with approximate language (“about”)
chemotherapy selected from a group of common agents

If the specification does not provide support for the full breadth (e.g., why 0.001 to 30 mg/kg is supported across patient types, or why these exact time windows apply), broader method coverage can face written description or enablement pressure. In the US system, deposit reference helps with the identity element, but breadth in therapeutic protocols can still be challenged if the disclosure does not support all claimed variants.

3) Sequencing claims may not add patentability

Claims allow chemotherapy to be before or after anti-CD20 (claims 12 and 13). This creates coverage across typical clinical sequencing permutations, but it also weakens any argument that the patent has a specific non-obvious sequencing insight. If prior art described chemo + anti-CD20 in either order, the “before/after” limitations may not distinguish.

4) Radiolabeled combination claims require both identity and rationale

Claim 5 is a two-stage regimen:

unlabeled chimeric anti-CD20 first
radiolabeled anti-CD20 second

Claim 6 further specifies the radiolabeled component by deposit HB 11388. The potential weakness is that prior art often disclosed radioimmunotherapy strategies with anti-CD20, including sequences intended to improve targeting or reduce circulating antigen effects. If those disclosures exist, the staged regimen can be attacked as obvious absent a demonstrated mechanistic or empirical separation unique to the deposit-defined antibody pair.

US patent landscape pressure points (how others likely map against these claims)

Landscape axis A: chimeric anti-CD20 antibodies for B-cell malignancies

The “chimeric anti-CD20” treatment concept is broadly represented in US filings that matured into commercial therapies. A deposit-defined chimeric anti-CD20 does not automatically insulate claims if the deposit corresponds to an antibody that is already disclosed or functionally equivalent to known chimerics in earlier patents.

Practical outcome: Claims 1-4, 7-10 are most exposed to obviousness if prior art disclosed human lymphoma treatment with chimeric anti-CD20 and general dosing/scheduling.

Landscape axis B: radiolabeled anti-CD20 radioimmunotherapy

The add-on of a radiolabeled anti-CD20 agent (claims 5-6) is a narrower factual requirement because it ties to a particular hybridoma deposit (HB 11388). But the broader concept of radiolabeled anti-CD20 in B-cell malignancies was well explored in prior art. That makes the key question whether the HB 11388 hybridoma is distinct from prior radiolabeled anti-CD20 sources disclosed in earlier US patents.

Practical outcome: Claims 5-6 can survive if HB 11388 corresponds to a radiolabeled antibody not disclosed earlier, but face obviousness if radioimmunotherapy with anti-CD20 and similar staging was known.

Landscape axis C: chemotherapy combination and sequencing

Claims 11-14 cover standard chemo agents (cyclophosphamide, doxorubicin, vincristine, prednisone). These are common lymphoma regimen components, and combinations with anti-CD20 were a typical direction of development. Because claim 11 covers “at least one chemotherapeutic agent” and claims 12-13 cover both sequencing orders, novelty must come from the anti-CD20 identity (ATCC 69119) plus any non-obvious protocol effect.

Practical outcome: Claims 11-14 are sensitive to prior art describing CD20 antibody plus those chemotherapies, even if the anti-CD20 antibody identity differs.

Claim-by-claim enforcement and design-around likelihood

Claims 1-4 (single dose and two-dose schedule)

Coverage driver: exact antibody source identity (ATCC 69119)
Most likely vulnerability: prior art chimeric anti-CD20 treatment in humans with repeated dosing within roughly a week
Design-around: use a different anti-CD20 antibody lineage not derived from ATCC 69119, or shift the dosing schedule outside the “about 7 days” window while staying clinically reasonable (however the “about” language makes strict avoidance harder).

Claims 5-6 (radiolabeled follow-on)

Coverage driver: unlabeled ATCC 69119 chimeric anti-CD20 plus radiolabeled anti-CD20 from HB 11388
Most likely vulnerability: earlier US disclosures of anti-CD20 radioimmunotherapy regimens and staging logic
Design-around: switch radiolabeled anti-CD20 to a different clone/hybridoma or different labeling strategy tied to a different source than HB 11388.

Claims 7-10 (three-dose schedule)

Coverage driver: exact antibody source identity plus a multi-dose window (within 7 days then within 14 days)
Most likely vulnerability: prior art showing repeated antibody dosing with similar cadence
Design-around: move out of the specific inter-dose windows or reduce to two doses, but again “about” reduces the clarity of boundary carving.

Claims 11-14 (chemotherapy combinations)

Coverage driver: add chemotherapy agents from the enumerated set plus sequencing flexibility
Most likely vulnerability: standard chemo + anti-CD20 combinations described in earlier patents and protocols
Design-around: change the chemotherapy combination away from the enumerated set, or use anti-CD20 not derived from ATCC 69119.

What the claims fail to lock down (gaps that affect litigation posture)

No patient stratification or biomarker criteria. The claims cover broad “B cell lymphoma” with no line-of-therapy or subtype limitation.
No specific anti-CD20 binding/CDC/ADCC performance characteristics. “Immunologically active” is functional, and the deposit anchor helps, but broad functional language can be attacked if prior art antibodies satisfy the same functional label.
No radiolabel specifics in claim 5 beyond the hybridoma source in claim 6. If labeling methods differ materially, coverage could still hinge on whether the radiolabeled antibody is “a monoclonal antibody secreted from” HB 11388, which may be discoverable but not always straightforward.
Chemotherapy is defined by agent names only. No dose or schedule for chemo is tied into claims 11-14, broadening the claimed method compared with typical contemporaneous protocol specificity.

Key Takeaways

The decisive claim element is antibody identity, not the regimen mechanics: chimeric anti-CD20 derived from ATCC deposit 69119 drives claims 1-4 and 7-10; radiolabeled anti-CD20 derived from ATCC HB 11388 drives claims 5-6.
Dosing and timing limitations are broad and likely to face obviousness pressure if earlier US art disclosed anti-CD20 lymphoma treatment and routine multi-dose schedules within similar week-long intervals.
Chemotherapy combination claims are especially vulnerable because they cover standard agents and both sequencing orders, pushing novelty toward the deposit-defined antibody rather than to a unique combination protocol.
Enforcement risk concentrates on proof of antibody derivation from the ATCC deposit-defined sources, making infringement fact development central.

FAQs

1) Do claims 1-4 cover rituximab-style anti-CD20 therapy broadly?

They cover chimeric anti-CD20 therapy for B cell lymphoma only if the administered antibody is derived from the specified deposit-defined source (ATCC 69119 in TCAE 8). General similarity to commercial chimeric anti-CD20 is not the same as meeting the claim’s deposit-derived identity.

2) What limits design-around for the two- and three-dose regimens?

The window language uses “about” and relatively broad ranges: second dose within ~7 days, third within ~14 days. Design-around through schedule changes may still be challenged unless the regimen moves clearly outside the claimed intervals.

3) How strong is the radiolabeled add-on in claims 5-6?

It is constrained by the radiolabeled antibody source (HB 11388) rather than by radiolabel type. If prior art discloses radioimmunotherapy with anti-CD20 clones that predate HB 11388, the staged regimen can be obvious despite the deposit specificity.

4) Can chemotherapy be given before or after the antibody under the patent?

Yes. Claims 12 and 13 explicitly cover chemotherapy administered after or prior to the immunologically active chimeric anti-CD20.

5) What is the main litigation lever for these claims?

In US practice, the main lever is often antibody identity and derivation: proving (or disproving) that an accused product is derived from the deposit-defined antibody sources tied to ATCC 69119 and HB 11388, alongside whether the protocol variations fall within the claimed dosing/timing ranges.

References

[1] United States Patent 5,776,456. “Method for the treatment of B cell lymphoma using chimeric anti-CD20 antibody derived from ATCC deposit 69119” (claims as provided).

Title:	Therapeutic application of chimeric and radiolabeled antibodies to human B lymphocyte restricted differentiation antigen for treatment of B cell lymphoma
Abstract:	Disclosed herein are therapeutic treatment protocols designed for the treatment of B cell lymphoma. These protocols are based upon therapeutic strategies which include the use of administration of immunologically active mouse/human chimeric anti-CD20 antibodies, radiolabeled anti-CD20 antibodies, and cooperative strategies comprising the use of chimeric anti-CD20 antibodies and radiolabeled anti-CD20 antibodies.
Inventor(s):	Anderson; Darrell R. (Escondido, CA), Hanna; Nabil (Olivenhain, CA), Leonard; John E. (Encinitas, CA), Newman; Roland A. (San Diego, CA), Reff; Mitchell E. (San Diego, CA), Rastetter; William H. (Rancho Sante Fe, CA)
Assignee:	IDEC Pharmaceuticals Corporation (San Diego, CA)
Application Number:	08/476,275
Patent Claims:	see list of patent claims
Patent landscape, scope, and claims summary:	United States Patent 5,776,456: Claims, Validity Friction Points, and US Landscape US Patent 5,776,456 claims combination regimens for B cell lymphoma using a specific chimeric anti-CD20 monoclonal antibody, with dosing windows and optional add-ons including radiolabeled anti-CD20 and chemotherapeutics. The claims are tightly anchored to a single biological source: a “transfectoma comprising anti-CD20 in TCAE 8” deposited at ATCC as deposit number 69119. The landscape pressure around this claim set comes from three directions: (i) prior art chimeric anti-CD20 antibodies and dosing/combination regimens, (ii) enablement and definiteness constraints tied to the deposit-defined antibody, and (iii) obviousness of sequencing and combinations against established anti-CD20 and chemotherapy standards. What do the claims actually cover? Core claim scope (claims 1 to 4) Claim 1: Method of treating B cell lymphoma in a human by administering a therapeutically effective amount of immunologically active chimeric anti-CD20 antibody derived from: transfectoma comprising anti-CD20 in TCAE 8 ATCC deposit 69119 Claim 2: Dose range: 0.001 to 30 mg/kg Claim 3: Allows a second therapeutically effective dose Claim 4: Second dose occurs within about 7 days of first administration This set is a dosing-and-repetition framework over a deposit-defined chimeric anti-CD20. Expanded combination scope (claims 5 to 6) Claim 5: Treat B cell lymphoma by: 1) administering the same chimeric anti-CD20 from ATCC 69119 during a first period 2) administering a radiolabeled anti-CD20 antibody during a second period Claim 6: Radiolabeled anti-CD20 antibody is a monoclonal antibody secreted from a hybridoma: ATCC deposit HB 11388 This claim attempts to lock in a specific radiolabeled anti-CD20 component via another deposit. Multi-dose regimen scope (claims 7 to 10) Claim 7: A three-dose sequence of the same chimeric anti-CD20 from ATCC 69119 across first, second, and third administration periods. Claim 8: Each dose is within 0.001 mg/kg to 30 mg/kg Claim 9: Second administration period is within about 7 days of first Claim 10: Third administration period is within about 14 days of first Chemotherapy combination scope (claims 11 to 14) Claim 11: Adds at least one chemotherapeutic agent Claim 12: Chemotherapy can be administered after the anti-CD20 dosing Claim 13: Chemotherapy can be administered before the anti-CD20 dosing Claim 14: Example chemotherapy agents are selected from: cyclophosphamide, doxorubicin, vincristine, prednisone Net coverage: sequencing flexibility plus broad agent selection limited to a common chemotherapy set. What makes the claims “deposit-defined” and why it matters The claims repeatedly anchor the antibody identity to: TCAE 8 + transfectoma + ATCC deposit 69119 for the chimeric anti-CD20 ATCC deposit HB 11388 for a radiolabeled anti-CD20 hybridoma Legal and technical implications Claim construction hinges on biological identity. If an accused product uses a different production cell line, expression construct, or culture condition not within “transfectoma comprising anti-CD20 in TCAE 8,” claim coverage can narrow sharply despite functional similarity. Enablement and written description can be tested. When a claim is tied to a specific deposit but the specification must support reproducible production and characterization, any gaps can create validity friction. In practice, deposit reference helps, but it does not eliminate scrutiny if functional breadth outstrips disclosure. Infringement becomes both bio- and process-dependent. Even when a marketed anti-CD20 is “chimeric,” enforcement may require proof that the antibody is derived from the deposit-defined source or is sufficiently identical to satisfy the claim’s anchor. How do the dosing and timing terms compress freedom-to-operate? Dose range (claims 2, 8) 0.001 to 30 mg/kg This is broad enough to cover common antibody dosing approaches in lymphoma at the time such patents matured. Broad numeric windows often reduce selectivity-based design-around options. If prior art dosing overlaps even substantially, obviousness exposure increases. Timing windows (claims 4, 9, 10) Second dose within ~7 days (claims 4 and 9) Third dose within ~14 days (claim 10) These windows look like “schedule scaffolding” layered on top of known anti-CD20 treatment. A critical question for validity is whether prior art already disclosed repeated dosing at similar intervals. If so, these timing limitations may not be enough to create patentable separation. What is the strongest novelty angle in the claim set? The only consistently sharp differentiator is the pairing of: chimeric anti-CD20 antibody from ATCC 69119, and the optional combination with radiolabeled anti-CD20 from ATCC HB 11388 (claims 5 to 6), while also layering chemo sequencing options. If those deposit-defined antibodies are materially different from prior art chimeric anti-CD20 antibodies, then novelty could rest on “what antibody” more than “how” it is administered. But in many anti-CD20 patent families, most of the functional treatment concepts (CD20 binding, lymphoma targeting, repeat dosing, combination therapy) were already disclosed across multiple approaches. That shifts the novelty battle to identity and characterization rather than to dosing mechanics. Critical validity friction points (US) for this claim structure 1) Obviousness risk from anti-CD20 treatment and combination norms These claims use familiar building blocks: repeat dosing of therapeutic antibodies use of radiolabeled anti-CD20 in sequence with unlabeled anti-CD20 combination with established chemotherapy regimens If prior art disclosed any one of: chimeric anti-CD20 lymphoma treatment in humans, multi-dose schedules with short inter-dose intervals, chemo combinations with CD20 antibodies, radiolabeled anti-CD20 in combination regimens, then claims 2 to 4, 7 to 10, and 11 to 14 may be seen as routine optimization or obvious scheduling. The deposit-defined antibody identity can reduce this risk, but only if the deposit-defined antibody is demonstrably different in a non-trivial way from prior art CD20 chimerics. 2) Claim breadth could outstrip antibody-specific disclosure The antibody is deposit-defined, but the method is broad: wide dosing range up to 30 mg/kg timing ranges with approximate language (“about”) chemotherapy selected from a group of common agents If the specification does not provide support for the full breadth (e.g., why 0.001 to 30 mg/kg is supported across patient types, or why these exact time windows apply), broader method coverage can face written description or enablement pressure. In the US system, deposit reference helps with the identity element, but breadth in therapeutic protocols can still be challenged if the disclosure does not support all claimed variants. 3) Sequencing claims may not add patentability Claims allow chemotherapy to be before or after anti-CD20 (claims 12 and 13). This creates coverage across typical clinical sequencing permutations, but it also weakens any argument that the patent has a specific non-obvious sequencing insight. If prior art described chemo + anti-CD20 in either order, the “before/after” limitations may not distinguish. 4) Radiolabeled combination claims require both identity and rationale Claim 5 is a two-stage regimen: unlabeled chimeric anti-CD20 first radiolabeled anti-CD20 second Claim 6 further specifies the radiolabeled component by deposit HB 11388. The potential weakness is that prior art often disclosed radioimmunotherapy strategies with anti-CD20, including sequences intended to improve targeting or reduce circulating antigen effects. If those disclosures exist, the staged regimen can be attacked as obvious absent a demonstrated mechanistic or empirical separation unique to the deposit-defined antibody pair. US patent landscape pressure points (how others likely map against these claims) Landscape axis A: chimeric anti-CD20 antibodies for B-cell malignancies The “chimeric anti-CD20” treatment concept is broadly represented in US filings that matured into commercial therapies. A deposit-defined chimeric anti-CD20 does not automatically insulate claims if the deposit corresponds to an antibody that is already disclosed or functionally equivalent to known chimerics in earlier patents. Practical outcome: Claims 1-4, 7-10 are most exposed to obviousness if prior art disclosed human lymphoma treatment with chimeric anti-CD20 and general dosing/scheduling. Landscape axis B: radiolabeled anti-CD20 radioimmunotherapy The add-on of a radiolabeled anti-CD20 agent (claims 5-6) is a narrower factual requirement because it ties to a particular hybridoma deposit (HB 11388). But the broader concept of radiolabeled anti-CD20 in B-cell malignancies was well explored in prior art. That makes the key question whether the HB 11388 hybridoma is distinct from prior radiolabeled anti-CD20 sources disclosed in earlier US patents. Practical outcome: Claims 5-6 can survive if HB 11388 corresponds to a radiolabeled antibody not disclosed earlier, but face obviousness if radioimmunotherapy with anti-CD20 and similar staging was known. Landscape axis C: chemotherapy combination and sequencing Claims 11-14 cover standard chemo agents (cyclophosphamide, doxorubicin, vincristine, prednisone). These are common lymphoma regimen components, and combinations with anti-CD20 were a typical direction of development. Because claim 11 covers “at least one chemotherapeutic agent” and claims 12-13 cover both sequencing orders, novelty must come from the anti-CD20 identity (ATCC 69119) plus any non-obvious protocol effect. Practical outcome: Claims 11-14 are sensitive to prior art describing CD20 antibody plus those chemotherapies, even if the anti-CD20 antibody identity differs. Claim-by-claim enforcement and design-around likelihood Claims 1-4 (single dose and two-dose schedule) Coverage driver: exact antibody source identity (ATCC 69119) Most likely vulnerability: prior art chimeric anti-CD20 treatment in humans with repeated dosing within roughly a week Design-around: use a different anti-CD20 antibody lineage not derived from ATCC 69119, or shift the dosing schedule outside the “about 7 days” window while staying clinically reasonable (however the “about” language makes strict avoidance harder). Claims 5-6 (radiolabeled follow-on) Coverage driver: unlabeled ATCC 69119 chimeric anti-CD20 plus radiolabeled anti-CD20 from HB 11388 Most likely vulnerability: earlier US disclosures of anti-CD20 radioimmunotherapy regimens and staging logic Design-around: switch radiolabeled anti-CD20 to a different clone/hybridoma or different labeling strategy tied to a different source than HB 11388. Claims 7-10 (three-dose schedule) Coverage driver: exact antibody source identity plus a multi-dose window (within 7 days then within 14 days) Most likely vulnerability: prior art showing repeated antibody dosing with similar cadence Design-around: move out of the specific inter-dose windows or reduce to two doses, but again “about” reduces the clarity of boundary carving. Claims 11-14 (chemotherapy combinations) Coverage driver: add chemotherapy agents from the enumerated set plus sequencing flexibility Most likely vulnerability: standard chemo + anti-CD20 combinations described in earlier patents and protocols Design-around: change the chemotherapy combination away from the enumerated set, or use anti-CD20 not derived from ATCC 69119. What the claims fail to lock down (gaps that affect litigation posture) No patient stratification or biomarker criteria. The claims cover broad “B cell lymphoma” with no line-of-therapy or subtype limitation. No specific anti-CD20 binding/CDC/ADCC performance characteristics. “Immunologically active” is functional, and the deposit anchor helps, but broad functional language can be attacked if prior art antibodies satisfy the same functional label. No radiolabel specifics in claim 5 beyond the hybridoma source in claim 6. If labeling methods differ materially, coverage could still hinge on whether the radiolabeled antibody is “a monoclonal antibody secreted from” HB 11388, which may be discoverable but not always straightforward. Chemotherapy is defined by agent names only. No dose or schedule for chemo is tied into claims 11-14, broadening the claimed method compared with typical contemporaneous protocol specificity. Key Takeaways The decisive claim element is antibody identity, not the regimen mechanics: chimeric anti-CD20 derived from ATCC deposit 69119 drives claims 1-4 and 7-10; radiolabeled anti-CD20 derived from ATCC HB 11388 drives claims 5-6. Dosing and timing limitations are broad and likely to face obviousness pressure if earlier US art disclosed anti-CD20 lymphoma treatment and routine multi-dose schedules within similar week-long intervals. Chemotherapy combination claims are especially vulnerable because they cover standard agents and both sequencing orders, pushing novelty toward the deposit-defined antibody rather than to a unique combination protocol. Enforcement risk concentrates on proof of antibody derivation from the ATCC deposit-defined sources, making infringement fact development central. FAQs 1) Do claims 1-4 cover rituximab-style anti-CD20 therapy broadly? They cover chimeric anti-CD20 therapy for B cell lymphoma only if the administered antibody is derived from the specified deposit-defined source (ATCC 69119 in TCAE 8). General similarity to commercial chimeric anti-CD20 is not the same as meeting the claim’s deposit-derived identity. 2) What limits design-around for the two- and three-dose regimens? The window language uses “about” and relatively broad ranges: second dose within ~7 days, third within ~14 days. Design-around through schedule changes may still be challenged unless the regimen moves clearly outside the claimed intervals. 3) How strong is the radiolabeled add-on in claims 5-6? It is constrained by the radiolabeled antibody source (HB 11388) rather than by radiolabel type. If prior art discloses radioimmunotherapy with anti-CD20 clones that predate HB 11388, the staged regimen can be obvious despite the deposit specificity. 4) Can chemotherapy be given before or after the antibody under the patent? Yes. Claims 12 and 13 explicitly cover chemotherapy administered after or prior to the immunologically active chimeric anti-CD20. 5) What is the main litigation lever for these claims? In US practice, the main lever is often antibody identity and derivation: proving (or disproving) that an accused product is derived from the deposit-defined antibody sources tied to ATCC 69119 and HB 11388, alongside whether the protocol variations fall within the claimed dosing/timing ranges. References [1] United States Patent 5,776,456. “Method for the treatment of B cell lymphoma using chimeric anti-CD20 antibody derived from ATCC deposit 69119” (claims as provided). More… ↓ ⤷ Start Trial

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Acrotech Biopharma Inc.	ZEVALIN	ibritumomab tiuxetan	Injection	125019	February 19, 2002	5,776,456	2015-06-07
>Applicant	>Tradename	>Biologic Ingredient	>Dosage Form	>BLA	>Approval Date	>Patent No.	>Expiredate

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South Africa	938466	⤷ Start Trial
World Intellectual Property Organization (WIPO)	9411026	⤷ Start Trial
United States of America	7744877	⤷ Start Trial
United States of America	7422739	⤷ Start Trial
United States of America	7381560	⤷ Start Trial
United States of America	6682734	⤷ Start Trial
United States of America	6399061	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration

Patent: 5,776,456

Summary for Patent: 5,776,456