Patent: 9,206,251

Summary for Patent: 9,206,251

Title:	Nucleic acids encoding anti-C5 antibodies having improved pharmacokinetics
Abstract:	The disclosure provides antibodies that are useful for, among other things, inhibiting terminal complement (e.g., the assembly and/or activity of the C5b-9 TCC) and C5a anaphylatoxin-mediated inflammation and, thus, treating complement-associated disorders. The antibodies have a number of improved properties relative to eculizumab, including, e.g., increased serum half-life in a human.
Inventor(s):	Andrien, Jr.; Bruce A. (Guilford, CT), Sheridan; Douglas L. (Branford, CT), Tamburini; Paul P. (Kensington, CT)
Assignee:	Alexion Pharmaceuticals, Inc. (Cheshire, CT)
Application Number:	14/789,329
Patent Claims:	see list of patent claims

United States Patent 9,206,251: Claims, Validity Risks, and US Patent Landscape

US Patent 9,206,251 is directed to nucleic acids and expression systems encoding antibody CDRs or variable regions that bind human complement component C5. The claims are framed as sequence-defined binding compositions anchored to specific C5-targeting amino acid sequences listed as SEQ ID NOs, with dependent claim coverage spanning vectors, expression vectors, host cells, and production methods.

What is claimed in US 9,206,251?

Claim scope summary (method-to-composition chain)

The independent claim set is sequence-anchored to C5-binding heavy chain CDRs, progressing through heavy/light variable region configurations, and then expanding to heavy chain full polypeptides and combined heavy/light polypeptides.

Core binding-recognition scope

• Heavy chain CDR nucleic acids binding C5
  • Claim 1: nucleic acid encoding heavy chain variable region CDRs binding human C5 with amino acid sequence SEQ ID NO:12.
• Heavy + light chain variable region CDR nucleic acids binding C5
  • Claim 2: nucleic acid encoding heavy CDRs (SEQ ID NO:12) and light CDRs (SEQ ID NO:8).
• Heavy chain variable region nucleic acids binding C5
  • Claim 3: nucleic acid encoding heavy variable region binding C5 with SEQ ID NO:12.
• Heavy + light chain variable region nucleic acids binding C5
  • Claim 4: heavy variable region (SEQ ID NO:12) and light variable region (SEQ ID NO:8) bind C5.
• Heavy chain polypeptide nucleic acids binding C5
  • Claim 5: nucleic acid encoding heavy chain polypeptide binding C5 with SEQ ID NO:14.
• Heavy + light chain polypeptide nucleic acids binding C5
  • Claim 6: heavy chain polypeptide (SEQ ID NO:14) + light chain polypeptide (SEQ ID NO:11) bind C5.

Downstream embodiments (standard patenting lattice)

• Vectors / expression vectors / host cells
  • Claims 7 to 9 (anchored to Claim 1)
  • Claims 12 to 14 (anchored to Claim 2)
  • Claims 17 to 19 (anchored to Claim 3)
  • Claims 22 to 24 (anchored to Claim 4)
  • Claims 27 to 29 (anchored to Claim 5)
  • Claims 32 to 34 (anchored to Claim 6)
• Production methods
  • Claims 10 to 11, 15 to 16, 20 to 21, 25 to 26, 30 to 31, 35 to 36 for culturing and optionally isolating the encoded C5-binding antibody or fragment.

What the claims do not cover (critical reading)

1. No explicit functional breadth beyond binding C5
   The claims track C5 binding, but they do not recite MoA details (e.g., C5 cleavage inhibition, MAC formation inhibition) in the claim language provided. That limits enforcement arguments if prior art antibodies bind C5 by distinct epitopes but do not match the claimed sequences.

2. No explicit immunoglobulin class or engineering motifs
   There is no express coverage of Fc engineering, effector modulation, half-life extension, or specific fragment formats beyond “antibody, or antigen-binding fragment thereof.” Absent explicit claim language, engineered variants could be argued outside scope unless they still fall under the claimed sequence definitions.

3. Reliance on SEQ ID NO-defined sequences
   Enforceability and novelty hinge on whether accused products literally infringe or can be mapped under equivalence to the sequence-defined CDRs/variable regions/polypeptides.

How strong are the claim elements for novelty and non-obviousness?

1) Sequence-defined binding regions reduce obviousness pathways

Claims 1-6 are not “anti-C5 antibodies” in the abstract; they are nucleic acids encoding specific CDRs/variable regions/polypeptides tied to specific SEQ ID NO sequences. That narrows the set of possible disclosures that anticipate the claims.

From a validity perspective, sequence specificity typically:

• increases the chance of distinguishing from generic anti-C5 libraries,
• forces the examiner/patentee to rely on the actual disclosed sequences, not just binding performance.

2) But sequence specificity raises obviousness risk via substitutions

If the specification or prosecution history reflects that these CDRs/regions were derived from known frameworks with routine changes, challengers can argue the CDR changes were the predictable result of well-known affinity maturation or substitution strategies.

For CDR-heavy antibody patents, common obviousness theories are:

• known C5 epitopes and known anti-C5 frameworks,
• routine shuffling of CDRs into preferred human antibody frameworks,
• selection by binding screen that yields “obvious to try” candidates.

The strength of the defense is sequence-level unpredictability, not just antibody existence.

3) Dependent claims add predictable patent lattice, not patentably distinct invention

Claims 7-9, 12-14, 17-19, 22-24, 27-29, 32-34 and the production methods 10-11, 15-16, 20-21, 25-26, 30-31, 35-36 are structurally standard:

• vector containing the claimed nucleic acid,
• expression vector containing it,
• cell comprising it,
• method of producing via culturing and optionally isolating.

These downstream claim sets often have less independent novelty value and face higher invalidation leverage if the top sequence claims are weakened.

Where is the patent landscape concentrated for C5 antibodies in the US?

Landscape structure: key licensing and competitor activity

The US C5 antibody space is dominated by (i) complement inhibitors targeting C5, (ii) antibodies and variants disclosed through patent families covering sequences, and (iii) platform patents on antibody engineering and production.

In practice, enforceable boundaries tend to track:

• exact CDR/variable region sequence coverage,
• binding epitope and cross-reactivity claims (when included),
• and whether a competitor’s antibodies are sequence-close.

Common overlap zones

Even without the full text of US 9,206,251, the claim architecture indicates overlap will likely be tested against:

1. Earlier sequence patents disclosing the same or highly similar CDRs/variable regions against human C5.
2. Humanization and maturation families where only minor substitutions separate candidates.
3. Broad functional anti-C5 antibody families that may anticipate if the disclosed embodiments match the claimed SEQ IDs.
4. Antibody fragment and expression system families that cover the same nucleic acid composition in vector/cell form.

Enforcement reality check (critical)

For a SEQ ID anchored claim set, infringement hinges on whether the accused sequences map to the claimed sequences:

• If a competitor uses different CDRs or variable region sequences, the claim may be avoided even if binding to C5 is strong.
• If a competitor uses an engineered variant with different CDR residues, literal infringement can fail while doctrine of equivalents becomes fact-intensive.

What claim-to-claim risks exist inside US 9,206,251?

Risk concentration: Claims 1-4 and 5-6 likely share the same sequence core

Claims 1-4 focus on CDRs and variable regions; Claims 5-6 focus on heavy (and heavy+light) polypeptides with specified SEQ IDs. Invalidation of the underlying sequence novelty can cascade across the dependent chain.

Claim construction pressure points

Patentability and claim scope will likely turn on:

• what constitutes “CDRs” boundaries (structural definition, not just amino acid positions),
• whether the “variable region” includes additional framework residues not explicitly stated in the claim elements you provided,
• whether “antibody, or antigen-binding fragment thereof” is limited to formats whose sequences are still captured by SEQ IDs.

In disputes, this becomes critical: competitors sometimes design around by switching frameworks while keeping binding residues.

What should an investor or R&D team assume about freedom-to-operate (FTO)?

FTO baseline: high sensitivity to sequence-level design

Because the claims are sequence-defined, FTO for a competitor antibody cannot be answered by target identification alone. It depends on:

• exact CDR and variable region sequences,
• whether the commercial candidate uses the same heavy/light pairs (as implied by SEQ ID pairs),
• whether production uses nucleic acids that encode the claimed sequences in the claimed forms.

Practical FTO mapping approach implied by the claim set

To evaluate whether US 9,206,251 blocks a program, an FTO analysis must map:

• the program’s antibody CDRs and variable regions to the sequences represented by SEQ ID NO:12, 8, 14, and 11,
• the specific heavy-light pairing,
• the nucleic acid sequences used for expression (not just the protein sequences).

If the program uses a different heavy-light pairing, it may avoid Claims 2/4/6 depending on pairing requirements.

How could the patent be challenged?

1) Anticipation by earlier C5 antibodies with matching SEQ ID sequences

If earlier US publications or patents disclose the same antibody variable regions/regions:

• Claim 1 (heavy CDR nucleic acid) can be anticipated by matching heavy CDR sequence disclosure.
• Claim 2 (heavy+light CDR pairing) can be anticipated only if both heavy CDR sequence and light CDR sequence match the specific SEQ ID pair.
• Claims 5-6 can be anticipated if the exact heavy polypeptide and heavy/light polypeptides match SEQ IDs.

2) Obviousness from known C5 epitope + routine maturation

Even if no single reference discloses the exact SEQ IDs, obviousness can arise from:

• known C5-binding antibodies,
• predictable CDR substitution patterns,
• standard humanization frameworks,
• selection by binding assay.

Downstream claims on vectors/cells/methods generally fall with the primary antibody sequence claims.

3) Written description and enablement pressure for nucleic acids encoding CDRs

Sequence-coding claims must be supported with sufficient disclosure that enables making the claimed constructs without undue experimentation:

• if only one expression construct is shown but claims cover broad nucleic acid embodiments,
• if CDR boundaries are ambiguous,
• or if multiple fragments are implied without sequences.

In practice, antibody patents often withstand enablement challenges if the sequences and recombinant expression are disclosed cleanly.

How to interpret the claim set as a competitive moat

The patent moat is narrow and strong:

• Narrow because it is anchored to specific SEQ ID sequences.
• Strong because the claim chain covers not only the antibodies but also nucleic acids, vectors, host cells, and production methods.

For a competitor, designing around is possible by selecting a different CDR/variable region sequence set. For a production partner or CDMO, the risk depends on whether their expression constructs encode the claimed sequences and whether they operate on the claimed cells/vectors.

Key Takeaways

• US 9,206,251 is a sequence-anchored anti-human C5 antibody patent with claims focused on nucleic acids encoding specific heavy/light CDRs and variable regions (Claims 1-4) and specific heavy and heavy/light polypeptides (Claims 5-6), all referenced to SEQ ID NO:12, 8, 14, and 11.
• The downstream claims (vectors, expression vectors, cells, production methods) are structurally broad but dependent on the sequence claims. Their validity and scope likely track the top sequence elements.
• Freedom-to-operate is determined by sequence mapping, not only by C5 binding. A competitor can often design around by changing CDR/variable region sequences or heavy-light pairing.
• The main validity risk is whether earlier US patent publications disclose the same SEQ ID sequences or render them obvious from known anti-C5 antibodies plus routine maturation.
• The enforcement boundary is likely tight because the claims are framed around specific sequences and CDR/variable region definitions.

FAQs

1) Do these claims cover any anti-C5 antibody, or only specific sequences?

Only specific sequences. The claims require nucleic acids encoding CDRs/variable regions/polypeptides that bind human C5 and match the specified SEQ ID amino acid sequences.

2) Are CDR-only claims broader than full variable region or polypeptide claims?

They can be, but in practice the independent claim set is split between CDR/variable region formats (Claims 1-4) and polypeptide formats (Claims 5-6). Scope depends on how the claimed sequences align with the SEQ ID definitions and the protein constructs used.

3) Does the patent protect production methods for any cell that expresses the antibody?

The method claims protect culturing a cell comprising the claimed expression construct (vector/expression vector/cell chain). If a cell expresses a non-matching sequence, the claim alignment can break.

4) What is the key pairing constraint in the patent?

Where claimed (Claims 2 and 4 for CDR pairing; Claim 6 for heavy/light polypeptide pairing), both heavy and light chain sequences must match the specific SEQ ID assignments for the pair.

5) Which claim set should be prioritized in an FTO review?

Claims 1-6 first, because vector/cell/method claims (Claims 7-36) are downstream and generally stand or fall with the sequence-defining binding compositions.

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References

[1] United States Patent 9,206,251.

Details for Patent 9,206,251

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Alexion Pharmaceuticals, Inc.	ULTOMIRIS	ravulizumab-cwvz	Injection	761108	December 21, 2018	9,206,251	2035-07-01
Alexion Pharmaceuticals, Inc.	ULTOMIRIS	ravulizumab-cwvz	Injection	761108	October 09, 2020	9,206,251	2035-07-01
Alexion Pharmaceuticals, Inc.	ULTOMIRIS	ravulizumab-cwvz	Injection	761108	June 22, 2022	9,206,251	2035-07-01

International Patent Family for US Patent 9,206,251

Country	Patent Number	Estimated Expiration
World Intellectual Property Organization (WIPO)	2015134894
United States of America	9803007
United States of America	9663574
United States of America	9371377
United States of America	9107861
United States of America	9079949