Scope and Claims Analysis for US Patent 9,820,938 (AMG 416 Aqueous Formulation, pH 2.0–5.0)
US Patent 9,820,938 is a US formulation patent concentrated on an aqueous liquid presentation of AMG 416 (amivantamab/related EGFR-MET bispecific antibody “AMG 416” in the Amgen pipeline context) defined by (i) a tight pH envelope, (ii) buffer identity (succinate as a fallback), (iii) drug concentration bands, (iv) optional tonicity control (explicitly NaCl), and (v) stability degradation thresholds. The claim set is layered so that broad coverage (pH 2.0–5.0) is narrowed through dependent claims into narrower pH sub-ranges, buffer specificity, concentration sub-ranges, tonicity modifier identity, and performance (≤10% degradation over defined storage conditions).

What does US Patent 9,820,938 claim for AMG 416 formulations in the US?

Answer: It claims a pharmaceutical formulation that is an aqueous solution of AMG 416 with a specified pH range, optionally stabilized with succinate buffer and tonicity agents (notably sodium chloride), and optionally meeting stability performance criteria.

Claim 1: The independent claim defines the core protected subject matter

Claim 1 (independent):

A pharmaceutical formulation comprising AMG 416 in aqueous solution
pH of 2.0 to 5.0

This is the broadest scope. It is not limited to a specific buffer system, specific tonicity modifier, or specific concentration band (those are introduced in dependent claims). It also does not, in Claim 1, impose any explicit storage stability performance threshold (that appears later as dependent claims 13–14).

Claims 2–4: Narrow pH sub-ranges that can anchor enforceable claim construction

Claim 2: pH 2.5 to 4.5
Claim 3: pH 2.5 to 4.0
Claim 4: pH 3.0 to 3.5

These dependent claims matter because they provide fallback positions if prior art or infringement arguments narrow Claim 1’s interpretation. They also create multiple “infringement targets” a generic or biosimilar developer might try to evade by shifting pH outside the asserted window.

Claim 5–6: Buffer identity and buffering mechanism scope

Claim 5: pH maintained by a pharmaceutically acceptable buffer
Claim 6: buffer is succinate

These claims tighten scope from “buffered” to a specific buffer species. In practice, succinate identity can be a key infringement and freedom-to-operate (FTO) axis because alternative buffers (citrate, acetate, phosphate, histidine, etc.) may be argued not to fall within “succinate buffer” if the competitor selects a different buffering agent and avoids Claim 6.

Claims 7–9: AMG 416 concentration bands create another infringement axis

All are tied to Claim 1’s pH aqueous solution definition:

Claim 7: 0.1 mg/mL to 20 mg/mL
Claim 8: 1 mg/mL to 15 mg/mL
Claim 9: 2.5 mg/mL to 10 mg/mL

From a claim landscape standpoint, the bands let you map infringement risk to actual clinical commercial concentrations. If the accused product uses a concentration within any one dependent range, it increases infringement probability for that dependent claim.

Claims 10–12: Optional tonicity modifier, with sodium chloride called out

Claim 10: formulation further comprises a pharmaceutically acceptable tonicity modifier
Claim 11: tonicity modifier concentration so formulation is approximately isotonic
Claim 12: tonicity modifier is sodium chloride

These claims are not limited to a single pH or concentration beyond Claim 1’s framework, but they create separate infringement possibilities depending on tonicity adjustment strategy. A party that omits tonicity modifier or uses a non-NaCl tonicity agent may aim to avoid Claim 12, while still potentially falling into Claim 10 if a “tonicity modifier” is used and remains “pharmaceutically acceptable.”

Claims 13–14: Stability/performance thresholds for storage

Claim 13: less than 10% degradation when stored at 2–8°C for 2 years
Claim 14: less than 10% degradation when stored at room temperature for 2 years

These are performance claims layered on Claim 1. They can be powerful in litigation because they tie infringement not only to composition and pH but to achieved stability characteristics. They also create practical evidentiary requirements: comparative stability study data, batch history, and storage conditions become central.

Claim 15: A combined “recipe” claim locking key parameters together

Formulation comprising:
- 2 mg/mL to 20 mg/mL AMG 416
- succinate buffer maintaining pH about 3.0 to 3.5
- sodium chloride concentration where formulation is approximately isotonic

Claim 15 functions as a claim-to-actual-product anchor. If the commercial drug product uses those characteristics (pH around 3.0–3.5 with succinate buffer and NaCl isotonicity at 2–20 mg/mL), Claim 15 can dominate infringement analysis.

How broad is the infringement scope of US 9,820,938 across pH, buffer, and concentration?

Answer: Claim 1 is broad on pH (2.0–5.0) and limited only to aqueous AMG 416. The patent narrows through dependent claims to narrower pH bands (2.5–4.5, 2.5–4.0, 3.0–3.5), then to succinate buffer and NaCl isotonicity, then to specific concentration ranges and stability performance.

Claim scope matrix (high-level)

Axis	Claim 1	Claim 2-4	Claim 5-6	Claim 7-9	Claim 10-12	Claim 13-14	Claim 15
pH	2.0–5.0	2.5–4.5; 2.5–4.0; 3.0–3.5	buffer maintains pH	not specified	not specified	not specified	3.0–3.5
Buffer	any pharm. acceptable not required	not required	buffer required	not specified	not specified	not specified	succinate
Concentration	broad range not specified	none beyond pH	none beyond pH	0.1–20; 1–15; 2.5–10	none beyond pH	none beyond pH	2–20 mg/mL
Tonicity	not required	not required	not required	not required	tonicity modifier; isotonic; NaCl	none	NaCl isotonicity
Stability	not required	not required	not required	not required	not required	≤10% degradation in 2-8°C or room temp for 2 years	not required (implicitly by Claim 1 framework)

Practical infringement reading

Products formulated with AMG 416 in aqueous solution at pH 2.0–5.0 can potentially implicate Claim 1, even if buffer, tonicity, and concentration differ from dependent claims.
Products specifically buffered with succinate and/or formulated around pH 3.0–3.5 create stronger dependent claim alignment (Claims 4 and 6 and 15).
Products engineered for clinical dosing that land within 2.5–10 mg/mL or other dependent bands can trigger Claims 9, 8, or 7 depending on the actual concentration.
Products that adjust tonicity with NaCl (isotonic) trigger Claim 12 and likely Claim 15 if the rest aligns.
Stability data meeting the “<10% degradation” benchmarks can be used to support dependent claim satisfaction even when the composition matches but the stability outcome is contested.

What formulations are protected by US 9,820,938 when pH is changed to avoid claims?

Answer: US 9,820,938 creates multiple “pH safe harbor” strategies but only partial. Avoiding Claim 4 (3.0–3.5) does not avoid Claim 1 (2.0–5.0). Avoiding Claim 2 and Claim 3 also does not avoid Claim 1 unless the product is moved to below 2.0 or above 5.0 (not claimed).

pH navigation risks

A formulation at pH 4.6 is outside Claim 2 (2.5–4.5) and outside Claim 3, Claim 4, but still inside Claim 1 (2.0–5.0).
A formulation at pH 2.4 is outside Claim 2 (2.5–4.5) and outside narrower pH claims but still inside Claim 1.
A formulation at pH 3.7 falls within Claim 2 and Claim 3? (3.7 is within 2.5–4.0) but outside Claim 4 (3.0–3.5).
A formulation at pH 5.1 falls outside all listed pH dependent claims and outside Claim 1 only if pH is truly >5.0 as construed.

The patent’s structure suggests Claim 1 is the principal “catch-all” pH range. Dependent claims create additional infringement hooks but are not the only ones.

What buffer systems besides succinate may fall outside or still fall within the patent?

Answer: Non-succinate buffers can potentially avoid Claim 6 and Claim 15’s succinate limitation, but they do not avoid Claim 1 or Claim 2–4, which do not require succinate buffer.

Buffer limitation mapping

Claim 5 only requires a “pharmaceutically acceptable buffer” maintaining pH. If any buffer system is used, Claim 5 can apply.
Claim 6 is the succinate-specific fallback. Avoiding succinate can be used to avoid Claim 6 and Claim 15 if succinate is absent.
Claim 15 is the most restrictive: it requires succinate buffer and NaCl isotonicity, plus pH 3.0–3.5 and AMG concentration 2–20 mg/mL.

How do concentration bands (0.1–20, 1–15, 2.5–10 mg/mL) affect design-around strategies?

Answer: Because these are dependent claims tied to Claim 1, designing a product outside a specific concentration band may avoid that dependent claim but may still infringe Claim 1 if pH stays within 2.0–5.0.

Concentration design logic

If an accused formulation is at 0.05 mg/mL, it avoids Claim 7 but not necessarily Claim 1.
If it is at 25 mg/mL, it avoids Claims 7–9 but may still infringe Claim 1 depending on pH and aqueous solution status.
If it is at 7 mg/mL, it lands within Claim 8 and Claim 9 and likely is covered by those dependent ranges if pH matches.

What role do tonicity modifiers (isotonicity and sodium chloride) play in the patent’s claim coverage?

Answer: The patent adds a second formulation-axis that can be avoided by not using NaCl or not achieving isotonicity with NaCl. But Claim 1 still covers an aqueous AMG 416 solution at pH 2.0–5.0 without requiring tonicity modifiers.

Tonicity-specific interpretation

Claim 10 requires a tonicity modifier.
Claim 11 limits the tonicity modifier concentration to achieve “approximately isotonic.”
Claim 12 specifies NaCl as the tonicity modifier.

For a design-around, a manufacturer could seek to:

omit a tonicity modifier entirely, or
use a tonicity modifier other than sodium chloride, or
use sodium chloride but not to achieve isotonicity as construed.

Even if those attempts avoid Claims 10–12, Claim 1 remains a threat if pH stays within 2.0–5.0.

How strong is the stability-performance portion of US 9,820,938 (claims 13–14)?

Answer: The “<10% degradation” requirements create an additional evidentiary and technical barrier, but they also create multiple proof targets: degradation measurement method, timepoint definitions, and storage condition control.

Storage conditions claimed

2–8°C for 2 years: less than 10% degradation (Claim 13)
Room temperature for 2 years: less than 10% degradation (Claim 14)

In litigation, “degradation” typically depends on assay methodology defined in the specification. The claim language itself frames degradation as a percentage outcome rather than a structural component, meaning the patentee can argue infringement based on measured stability of the accused formulation.

What does Claim 15 practically cover, and why it matters for freedom-to-operate?

Answer: Claim 15 is a “stacked limitations” claim that likely tracks a specific marketed or intended clinical solution: AMG 416 at 2–20 mg/mL, succinate buffer with pH ~3.0–3.5, and NaCl at approximately isotonic conditions.

This type of claim is often the one accused products most closely match because it mirrors practical formulation development goals: acidic pH to manage stability and aggregation, succinate as an acid buffer system, and NaCl to avoid infusion discomfort and align osmolarity.

If the commercial formulation aligns with Claim 15’s recipe, Claim 15 becomes the highest value claim in an infringement case even if Claim 1 is broader.

What is the US patent landscape around AMG 416 formulations and pH-stabilized aqueous antibodies?

Answer: A complete landscape requires the full patent document (specification, claims beyond those provided, priority data, and related family members) and the Orange Book or FDA listing for the associated product. No reliable landscape can be produced from the claim text alone.

What can be stated from the claim set alone (without overreaching)

This patent sits squarely in the “formulation and stability” category: pH windowing, buffer selection, tonicity adjustment, and shelf-life performance.
The claims indicate the patentee selected pH and stability outcomes as the novelty axes, consistent with typical formulation patent strategies for monoclonal antibody solutions where low pH is used to manage charge variants, aggregation, and chemical degradation routes.

When would US 9,820,938 lose exclusivity (expiration timing) for AMG 416 formulations?

Answer: Not determinable from the claim text provided. Expiration depends on priority date, filing date, USPTO maintenance status, patent term adjustments (PTA), and any patent term extensions (PTE). A correct exclusivity timeline requires patent bibliographic data.

What Orange Book status applies to US 9,820,938 for AMG 416?

Answer: Not determinable from the claim text provided. Orange Book listing depends on whether the patent is listed for an approved NDA, whether it is listed as a drug product patent (composition/formulation) or method patent, and whether it covers a listed drug product.

How does US 9,820,938 compare with typical generic entry risks for acidic monoclonal antibody solutions?

Answer: The risk profile is composition-driven: acidic pH and the presence of specific excipients can create infringement. A generic or biosimilar manufacturer trying to launch with a closely related formulation must match the pH range, aqueous nature, and often the excipient system to avoid dependent claims.

Likely infringement stress points based on claim architecture

Matching acidic pH inside 2.0–5.0
Matching succinate buffer use if Claim 6/15 matters
Matching NaCl isotonicity if Claim 12/15 matters
Achieving stability performance below the 10% degradation thresholds if those are asserted

What patent claim drafting patterns indicate about enforceability and litigation posture?

Answer: The set combines broad independent coverage with multiple dependent “fallback” claims and a stacked “recipe” claim. That structure tends to strengthen litigation posture because it provides several alternative infringement theories depending on how the accused product is made.

Enforceability implications of the layered claim set

Broad Claim 1 supports infringement arguments even when excipients differ.
Narrow dependent claims (2–4) and buffer/concentration/tone claims create multiple ways to show infringement.
Stability claims (13–14) provide performance-based validation targets.
Claim 15 can function as a high-confidence infringement claim if the accused product composition aligns closely.

Key Takeaways

US 9,820,938 claims an aqueous AMG 416 formulation defined primarily by pH 2.0–5.0 (Claim 1), with nested dependent claims narrowing pH to 2.5–4.5, 2.5–4.0, and 3.0–3.5.
The patent’s added coverage pillars are succinate buffering (Claim 6), concentration bands (0.1–20, 1–15, 2.5–10 mg/mL), isotonicity with NaCl (Claims 10–12), and stability outcomes (≤10% degradation after 2 years at 2–8°C and at room temperature).
The most restrictive coverage is Claim 15, which stacks AMG 416 2–20 mg/mL, succinate buffer, pH about 3.0–3.5, and NaCl isotonicity.
A design-around based solely on changing buffer or tonicity may not avoid Claim 1 if pH remains within 2.0–5.0.
A full US patent landscape (expiration, Orange Book status, family members, and related litigation) cannot be accurately produced from the claim excerpt alone.

FAQs

If a product has AMG 416 in aqueous solution at pH 4.8, does it avoid US 9,820,938?
No. It may avoid narrower pH dependent claims but still falls within Claim 1’s pH 2.0–5.0 if pH is truly within that range.
Does changing from succinate to another buffer eliminate infringement risk under this patent?
It can avoid succinate-specific dependent claims (e.g., Claim 6 and Claim 15) but does not avoid Claim 1 if pH stays within 2.0–5.0 and the formulation remains an aqueous AMG 416 solution.
Can a generic avoid the sodium chloride limitation by using a different tonicity agent?
It can avoid Claim 12 if sodium chloride is not used as the tonicity modifier, but Claim 1 can still apply without requiring a tonicity modifier.
How are the stability claims (13–14) used in infringement arguments?
They shift the infringement proof toward measured degradation outcomes after the claimed storage periods at 2–8°C and room temperature, tied to the “<10% degradation” threshold.
Which claim is most likely to match an actual marketed acidic monoclonal antibody solution?
Claim 15 is the best candidate because it stacks pH ~3.0–3.5, succinate buffer, NaCl isotonicity, and AMG 416 2–20 mg/mL.

References

United States Patent 9,820,938. (Claims excerpt provided in prompt).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Kai Pharms Inc	PARSABIV	etelcalcetide	SOLUTION;INTRAVENOUS	208325-001	Feb 7, 2017		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Kai Pharms Inc	PARSABIV	etelcalcetide	SOLUTION;INTRAVENOUS	208325-002	Feb 7, 2017		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Kai Pharms Inc	PARSABIV	etelcalcetide	SOLUTION;INTRAVENOUS	208325-003	Feb 7, 2017		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

PCT Information
PCT Filed	June 27, 2014	PCT Application Number:	PCT/US2014/044622
PCT Publication Date:	December 31, 2014	PCT Publication Number:	WO2014/210489

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	096773	⤷ Start Trial
Australia	2014302122	⤷ Start Trial
Brazil	112015032615	⤷ Start Trial
Canada	2916222	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,820,938

Which drugs does patent 9,820,938 protect, and when does it expire?

Summary for Patent: 9,820,938