US Patent 9,572,887: Bendamustine Method-of-Use Claims, Scope and Patent Landscape

US Patent 9,572,887 protects specific methods for administering a stable, non-aqueous bendamustine liquid concentrate after dilution. Its commercial focus is the short-infusion administration of bendamustine for chronic lymphocytic leukemia (CLL) and indolent B-cell non-Hodgkin's lymphoma (NHL), including administration in approximately 50 mL over 10 minutes on defined treatment schedules.

The patent is primarily a method-of-treatment patent. It does not broadly claim every bendamustine formulation or every use of bendamustine. Infringement requires practice of the claimed formulation, stability, dilution, dose, volume, infusion-time, disease, and, for narrower claims, cycle limitations.

What does US Patent 9,572,887 cover?

The patent covers administering bendamustine from a long-term storage-stable, non-aqueous liquid concentrate that is diluted before parenteral administration.

The independent claim requires all of the following:

Limitation	Claim requirement
Disease	CLL or indolent B-cell NHL
Starting formulation	Non-aqueous liquid composition
Bendamustine concentration	Approximately 10-100 mg/mL
Stability	Total impurities below approximately 5% by HPLC at 223 nm after 15 months at 5-25°C
Dilution	Dilution with a parenterally acceptable aqueous diluent
Route	Parenteral administration
Dose	Approximately 25-120 mg/m²
Administration volume	Approximately 100 mL or less
Administration time	15 minutes or less

The claim is directed to the complete treatment process, not merely to the vial or concentrate. A competing product could avoid literal infringement if its use does not meet one required element, although equivalence and induced-infringement theories may remain relevant in litigation.

How are the 29 claims organized?

The claims divide into six technical and clinical groups.

Claims 1-7: Core formulation and solvent limitations

Claim 1 establishes the broadest method. Claims 2-7 narrow the non-aqueous vehicle to specified solvents:

Polyethylene glycol
Propylene glycol
Ethanol
Benzyl alcohol
Glycofurol
Dimethyl sulfoxide
Mixtures of those solvents

Claim 3 narrows the vehicle to polyethylene glycol, propylene glycol, or both. Claims 4-7 each focus on one solvent.

The solvent claims are important because commercial ready-to-dilute bendamustine products commonly rely on non-aqueous excipient systems to avoid the instability associated with aqueous bendamustine solutions. A product using a different non-aqueous solvent could avoid the literal language of claims 2-7, but it would still need to assess claim 1.

Claims 8-13: Patient, diluted concentration and volume

Claim 8 limits the subject to a human. Claims 9-12 establish alternative concentration ranges after dilution:

Claim	Diluted bendamustine concentration
9	Approximately 0.05-12.5 mg/mL
10	Approximately 0.1-6.0 mg/mL
11	Approximately 0.05-3.2 mg/mL
12	Approximately 0.5-5.6 mg/mL

Claim 13 narrows the administration volume to approximately 50 mL in a human.

These concentration ranges overlap substantially. They provide multiple fallback positions if a court limits one range or finds a particular commercial administration outside another range.

Claims 14-15: Antioxidant stabilization

Claim 14 requires a stabilizing amount of an antioxidant. Claim 15 lists:

Thioglycerol or monothioglycerol
Lipoic acid
Propyl gallate
Methionine
Cysteine
Metabisulfites
Sodium formaldehyde sulfoxylate
Certain phenol-containing aromatic and aliphatic compounds
Dihydrolipoic acid

These claims connect chemical stability to the treatment method. They create potential infringement exposure for products using a listed antioxidant, but they do not necessarily cover every stable bendamustine product.

Claims 16-22: CLL treatment regimen

Claims 16-22 focus on CLL. The most commercially significant limitations are:

Intravenous administration
Approximately 50 mL
Approximately 10 minutes or less
Administration on days 1 and 2
A 28-day cycle
Up to six cycles
Dose of approximately 25-100 mg/m²
A preferred dose of approximately 100 mg/m²
Diluted concentration of approximately 1.85-4.84 mg/mL

Claim 17 closely tracks the labeled Bendeka CLL regimen: 100 mg/m² on days 1 and 2 of a 28-day cycle, administered intravenously over 10 minutes after dilution in a small volume [2].

Claims 23-29: Indolent B-cell NHL treatment regimen

Claims 23-29 address indolent B-cell NHL. They require or describe:

Intravenous administration
Approximately 50 mL
Approximately 10 minutes or less
Administration on days 1 and 2
A 21-day cycle
Up to eight cycles
Dose of approximately 60-120 mg/m²
A preferred dose of approximately 120 mg/m²
Diluted concentration of approximately 2.19-5.59 mg/mL

Claim 24 closely corresponds to the labeled bendamustine regimen for indolent B-cell NHL [2].

What are the strongest and weakest parts of the patent claims?

The patent has substantial commercial relevance because its narrower claims track the administration instructions for a ready-to-dilute bendamustine product. Its strength depends on whether a challenger can avoid one or more formulation or administration limitations.

Strengths

The principal strengths are:

Commercial alignment. Claims 17 and 24 correspond closely to FDA-approved CLL and NHL infusion procedures.
Multiple fallback claims. The patent includes broad and narrow concentration, dose, solvent, antioxidant, volume, and treatment-cycle limitations.
Formulation-performance limitation. The impurity threshold after 15 months creates a measurable stability requirement.
Small-volume, short-infusion coverage. The claims distinguish the patented regimen from older bendamustine administration methods using larger infusion volumes and longer administration times.
Method-of-use enforcement. A generic product label that instructs physicians to follow the claimed regimen can create induced-infringement exposure even if the product itself is not claimed in composition form.

Potential vulnerabilities

The main vulnerabilities are:

Stability testing. The claim requires impurities below approximately 5% after a defined storage period, temperature range, and HPLC method. The parties could dispute test conditions, impurity identity, analytical methodology, and whether the limitation is inherent in the commercial product.
“About” ranges. The claims use approximate numerical boundaries. Courts generally construe “about” based on technical context, but boundary disputes can affect infringement and validity.
Treatment-method dependence. The patent does not cover use outside the claimed diseases, doses, schedules, volumes, or administration times.
Prior-art exposure. Bendamustine was an established oncology drug before the patent family. Prior art involving bendamustine stability, solvent systems, dilution, infusion schedules, or reduced administration volumes could affect validity.
Label design-around. A generic applicant may seek approval with labeling that omits or carves out a patented use, although actual prescribing and induced-infringement issues remain separate.
Clinical-practice variation. If the approved or customary administration falls outside a claimed range, the relevant claim may have limited practical reach.

When does US Patent 9,572,887 lose exclusivity?

The patent’s nominal expiration date is February 22, 2033, based on the relevant nonprovisional filing and priority record. The enforceable expiration date must be confirmed against the USPTO patent-term-adjustment calculation and any terminal disclaimer recorded in the official patent file [1].

The patent was issued on February 21, 2017. Patent expiration is separate from FDA regulatory exclusivity. FDA approval of Bendeka occurred on December 7, 2015, and the product’s clinical-investigation exclusivity period was not a substitute for the later-expiring patent rights [2, 3].

Event	Date or status
Bendamustine prior clinical and commercial use	Before the Bendeka approval
Bendeka FDA approval	December 7, 2015
US 9,572,887 issued	February 21, 2017
Nominal patent expiration	February 22, 2033
FDA approval exclusivity	Expired before the patent term
Patent-based generic entry	Potentially before expiry if a challenger prevails, settles, or receives a non-infringing approval

What is the Orange Book status of US 9,572,887?

US 9,572,887 has been associated with the Bendeka bendamustine hydrochloride injection regulatory estate. The FDA Orange Book separates listed patents into product, formulation, method-of-use, and other categories. The specific listing code and current active status should be read from the FDA’s current Orange Book entry for the relevant NDA and patent number [3].

The patent’s importance is greater as an Orange Book-listed method-of-use patent than it would be as an unlisted patent. A listed method patent can require an ANDA applicant to submit a Paragraph IV certification, a section viii statement, or labeling that omits the protected method, depending on the listed use and proposed labeling.

Orange Book listing does not establish validity or infringement. It creates an FDA-related certification and notice framework.

What Paragraph IV challenges and litigation affect Bendeka?

A generic applicant challenging US 9,572,887 would generally select one or more of four positions:

Challenge route	Core theory
Invalidity	The claims are anticipated, obvious, indefinite, or lack adequate written description or enablement
Non-infringement	The proposed product or label does not meet the stability, solvent, concentration, dose, volume, time, or disease limitations
Section viii carve-out	The ANDA omits the patented CLL or NHL method from labeling
Post-expiration entry	The applicant accepts the patent and launches after expiration

For this patent, the most commercially relevant Paragraph IV theories would likely focus on obviousness and non-infringement. A challenger could argue that bendamustine dosing schedules were known, that short infusions and reduced dilution volumes were routine optimization, or that the claimed stability profile was inherent in a known formulation.

Non-infringement would likely focus on:

A different solvent system
A different antioxidant
Impurity levels outside the claimed stability limitation
A diluted concentration outside the relevant claim range
A label that omits the patented regimen
Administration outside the claimed volume or time
A different dosing schedule

The principal litigation question is not whether the generic contains bendamustine. It is whether the proposed product and instructions cause the full claimed method to be practiced.

Public FDA approval data and patent listings should be matched against USPTO Patent Center and PACER records before treating any ANDA certification, notice letter, complaint, settlement, or launch restriction as current [1, 3, 4]. The patent number alone does not establish that a particular manufacturer has filed a Paragraph IV challenge.

Which companies compete in the bendamustine injection market?

The commercial field includes the originator and branded-generic or generic manufacturers of bendamustine hydrochloride injection. Key products include:

Product	Sponsor or commercial association	Formulation profile
Bendeka	Eagle Pharmaceuticals	Ready-to-dilute bendamustine hydrochloride injection
Treanda	Teva/Cephalon legacy product	Earlier bendamustine presentation, including powder and later formulations
Belrapzo	Spectrum Pharmaceuticals legacy product	Bendamustine hydrochloride injection
Generic bendamustine injections	Multiple ANDA sponsors over time	Product-specific formulation, labeling and certification positions

Bendeka’s commercial differentiation is the ready-to-dilute liquid concentrate and short, small-volume infusion. The patent claims are drafted around those characteristics rather than around bendamustine’s chemical identity alone.

How does US 9,572,887 compare with related bendamustine patents?

The bendamustine patent estate generally divides into four categories.

1. Composition and liquid-formulation patents

These patents protect the concentrate, solvent system, antioxidant, bendamustine concentration, impurity profile, or storage stability. They can create direct product exposure because the commercial vial itself may fall within the claims.

2. Administration-method patents

US 9,572,887 is in this category. It protects the relationship between the stable concentrate and the clinical administration protocol.

3. Method-of-use patents

These cover treatment of specific hematologic malignancies, dosing regimens, treatment cycles, or patient populations. They may overlap with the claims in US 9,572,887.

4. Manufacturing and process patents

These can cover preparation of bendamustine, impurity control, sterile filling, container closure systems, or manufacturing conditions. They are particularly relevant to API suppliers and contract manufacturers.

The commercial risk is cumulative. A generic may avoid one method patent yet remain exposed to a composition or manufacturing patent.

What generic launch scenarios exist for Bendeka?

Scenario 1: Launch after patent expiration

This is the lowest-risk route. A manufacturer accepts the patent and launches after the enforceable expiration date, subject to other listed patents and regulatory requirements.

Scenario 2: Paragraph IV challenge

A challenger files an ANDA with a Paragraph IV certification, asserting invalidity or non-infringement. The patent owner may sue within the statutory period, potentially triggering a 30-month FDA approval stay under the Hatch-Waxman framework [5].

Scenario 3: Section viii carve-out

The applicant removes the patented CLL or NHL use from its labeling. This approach reduces induced-infringement risk but may limit the approved label and does not automatically eliminate all method-of-use exposure.

Scenario 4: Design-around formulation

A sponsor uses another solvent, antioxidant, concentration, or stability profile. The sponsor must still evaluate whether the actual label and clinical use meet claim 1.

Scenario 5: Licensed or settled entry

The patent holder and challenger agree on an entry date, license, supply arrangement, or other settlement terms. The commercial entry date may precede patent expiration, but the agreement may preserve restrictions for particular indications, formulations, or customers.

Does US 9,572,887 create biosimilar risk?

No conventional biosimilar pathway applies. Bendamustine is a small-molecule active pharmaceutical ingredient, not a biologic subject to the Biologics Price Competition and Innovation Act.

The relevant competitors use ANDAs or, in some cases, other small-molecule pathways. The principal regulatory risks are Paragraph IV certification, section viii labeling, formulation differences, and product-specific patent listings. Biosimilar interchangeability and the 351(k) pathway are not relevant to this patent.

How strong is the patent estate for Bendeka?

The estate is commercially meaningful but narrower than a composition patent covering every bendamustine injection.

Factor	Assessment
Claim breadth	Moderate; claim 1 is broad in formulation vehicle but narrow in combined clinical and stability limitations
Product alignment	High for ready-to-dilute, short-infusion Bendeka use
Design-around potential	Moderate; solvent, label, infusion, concentration and stability changes may matter
Generic litigation exposure	Material if the ANDA label follows the FDA-approved Bendeka regimen
Biosimilar exposure	Not applicable
Patent term	Nominally through February 22, 2033, subject to official term calculations
Regulatory exclusivity	No longer the principal barrier
Manufacturing barrier	Depends on separate formulation, process and API patents
Geographic reach	US rights only; foreign family members must be assessed separately

What revenue exposure does the patent create?

The most exposed revenue is associated with the ready-to-dilute bendamustine segment used in CLL and indolent B-cell NHL. The claims map directly to the two principal labeled regimens:

CLL: 100 mg/m² on days 1 and 2 of a 28-day cycle
Indolent B-cell NHL: 120 mg/m² on days 1 and 2 of a 21-day cycle

The patent does not cover all bendamustine revenue. Exposure is lower for:

Powder-for-reconstitution products
Products using different administration schedules
Uses outside CLL and indolent B-cell NHL
Doses or concentrations outside the claimed ranges
Products approved with carved-out labeling
Foreign markets where the corresponding national patent has expired or was not granted

A reliable revenue estimate requires product-level sales, indication mix, payer data and generic-entry timing. The patent analysis supports exposure mapping, not a standalone sales forecast.

Key Takeaways

US 9,572,887 is a bendamustine method-of-treatment patent, not a universal bendamustine composition patent.
Its core claim combines a stable non-aqueous concentrate with dilution and rapid, small-volume parenteral administration.
Claims 17 and 24 closely track the labeled Bendeka regimens for CLL and indolent B-cell NHL.
The principal technical limitation is total impurities below approximately 5% after 15 months under specified HPLC and storage conditions.
The nominal patent term runs to February 22, 2033, subject to the official USPTO term calculation.
FDA exclusivity expired before the patent term and is no longer the principal barrier to generic entry.
Generic risk centers on Paragraph IV invalidity and non-infringement claims, section viii carve-outs, formulation design-arounds and settlement-based entry.
No biosimilar pathway applies because bendamustine is a small-molecule drug.
Related formulation, manufacturing and method-of-use patents must be reviewed with US 9,572,887 to determine the full Bendeka exclusivity position.

FAQs About US Patent 9,572,887

Can a generic bendamustine product avoid US 9,572,887 by using a different infusion volume?

Potentially. The generic would need to avoid the applicable volume limitation and evaluate the remaining elements of claim 1 and any narrower claims. A different volume alone does not eliminate exposure if the claim’s approximate range is construed broadly or another claim is met.

Does the patent cover bendamustine tablets or oral administration?

No. The claims require dilution of a non-aqueous liquid composition and parenteral administration. Oral dosage forms fall outside the express route and formulation requirements.

Does using bendamustine hydrochloride instead of free bendamustine avoid the patent?

No. The claims expressly cover bendamustine and pharmaceutically acceptable salts thereof. Bendamustine hydrochloride is within the stated claim scope.

Can a hospital infringe the patent by following the Bendeka label?

A hospital or clinician could practice the claimed method if all limitations are met. Commercial enforcement generally focuses on manufacturers, sponsors, suppliers and parties alleged to induce or contribute to infringement.

Are foreign bendamustine patents covered by US 9,572,887?

No. US 9,572,887 is enforceable only in the United States. Foreign patent family members require separate country-by-country review of grant status, claim scope, term, supplementary protection certificates and litigation.

References

United States Patent and Trademark Office. (2017). US Patent No. 9,572,887, Methods of treating cancer using bendamustine. USPTO Patent Center and Patent Examination Data System. https://patentcenter.uspto.gov/
U.S. Food and Drug Administration. (2023). Bendeka (bendamustine hydrochloride) injection prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
United States Courts. (2024). Public Access to Court Electronic Records. https://pacer.uscourts.gov/
U.S. Food and Drug Administration. (2024). Hatch-Waxman amendments and abbreviated new drug applications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/anda-submissions-guidance-and-resources

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Eagle Pharms	BENDEKA	bendamustine hydrochloride	SOLUTION;INTRAVENOUS	208194-001	Dec 7, 2015		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				FOR THE TREATMENT OF PATIENTS WITH INDOLENT B-CELL NON-HODGKIN LYMPHOMA	⤷ Start Trial
Eagle Pharms	BENDEKA	bendamustine hydrochloride	SOLUTION;INTRAVENOUS	208194-001	Dec 7, 2015		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				FOR THE TREATMENT OF PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA	⤷ 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

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	2867295	⤷ Start Trial
Canada	2867343	⤷ Start Trial
China	104271135	⤷ Start Trial
China	104302291	⤷ Start Trial
China	107157988	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 9,572,887