List of Excipients in Branded Drug CLOLAR

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Sanofi-Aventis US LLC	CLOLAR	clofarabine	0024-5860	SODIUM CHLORIDE
Sanofi-Aventis US LLC	CLOLAR	clofarabine	0024-5860	WATER

CLOLAR Excipient Strategy and Commercial Opportunities

Last updated: August 3, 2026

CLOLAR is clofarabine, a small-molecule purine nucleoside analog approved by the FDA for pediatric patients aged 1 to 21 years with relapsed or refractory acute lymphoblastic leukemia after at least two prior regimens. Its commercial formulation is unusually simple: a sterile, preservative-free aqueous solution containing clofarabine, sodium chloride, and water for injection, with pH adjustment. The main commercial opportunities are improved pediatric dose flexibility, ready-to-administer presentations, stability-enhanced packaging, pharmacy workflow products, and regional supply agreements rather than conventional excipient substitution.

What is CLOLAR and how is it formulated?

CLOLAR is an intravenous clofarabine product supplied at 1 mg/mL. The labeled presentation is a single-use 20 mL vial containing 20 mg of clofarabine. The solution is administered by intravenous infusion over approximately two hours, generally at a dose of 52 mg/m² once daily for five consecutive days in a treatment cycle.[1]

Attribute	CLOLAR profile
Active ingredient	Clofarabine
Drug class	Purine nucleoside analog
Dosage form	Sterile intravenous solution
Strength	1 mg/mL
Vial	20 mg in 20 mL
Route	Intravenous infusion
Population	Pediatric patients aged 1 to 21 years
Indication	Relapsed or refractory acute lymphoblastic leukemia
Key excipients	Sodium chloride and water for injection
Preservatives	None identified in the FDA label
Labeled pH	Approximately 4.5
Administration	Diluted before infusion and administered over two hours

The product is not a lyophilized powder, lipid formulation, depot injection, oral dosage form, or biologic. Its formulation strategy prioritizes rapid preparation and chemical simplicity.

What excipients are used in CLOLAR?

The FDA prescribing information identifies sodium chloride and water for injection as inactive ingredients. Sodium hydroxide and hydrochloric acid may be used for pH adjustment during manufacture, although these materials are not generally treated as functional excipients in the same way as buffers, surfactants, or tonicity agents.[1]

The formulation has several commercial advantages:

1. Sodium chloride provides a familiar tonicity component.
2. Water for injection supports a simple aqueous system.
3. The absence of preservatives reduces pediatric exposure to antimicrobial agents.
4. The absence of surfactants and complex buffering systems simplifies manufacturing and extractables assessment.
5. The 1 mg/mL concentration permits dose calculation based on body-surface area.

The same simplicity limits conventional reformulation differentiation. A company cannot easily create a strong product distinction merely by replacing one buffer or tonicity agent. The more defensible opportunities involve stability, container closure, infusion compatibility, administration logistics, and dose presentation.

How strong is the CLOLAR formulation patent estate?

CLOLAR’s commercial differentiation is likely weaker at the basic-composition level than that of products protected by complex delivery systems or proprietary excipient matrices. A formulation containing clofarabine, sodium chloride, and water for injection is technically straightforward and may face substantial obviousness and enablement scrutiny if claimed broadly.

A more durable formulation patent strategy would focus on narrowly defined technical results, such as:

• Improved chemical stability at a specified concentration and pH.
• Reduced impurity formation during long-term storage.
• Compatibility with a defined infusion bag or administration set.
• Reduced adsorption to polymeric containers or tubing.
• A particular oxygen-control or headspace configuration.
• A ready-to-use formulation with a defined shelf life.
• A pediatric dose-concentration system that minimizes compounding errors.
• A stable premix that remains suitable for administration after refrigerated storage.
• A container closure system that limits leachables and particulate formation.

Patent claim categories with the greatest commercial value

Claim category	Commercial value	Main vulnerability
Broad clofarabine aqueous solution	Low to moderate	Obviousness and prior-art overlap
Specific pH and concentration range	Moderate	Routine optimization challenge
Long-term stability profile	Moderate to high	Requires strong comparative data
Ready-to-use infusion bag	High	Design-around and hospital adoption
Container closure and low-adsorption system	Moderate	May be difficult to enforce
Pediatric dosing kit	Moderate	Combination-product and obviousness issues
Manufacturing impurity-control process	Moderate to high	Trade-secret alternative
Novel oral or depot delivery	Potentially high	Clinical and regulatory burden

The strongest patents would tie the excipient or packaging choice to measurable performance. A claim limited to “clofarabine in water with sodium chloride” would generally be less defensible than a claim requiring a defined impurity threshold after a specified storage period.

What formulation patents could protect a CLOLAR lifecycle product?

A lifecycle product could use several patent families, each directed to a different commercial problem.

Ready-to-use infusion formulations

CLOLAR requires dilution before administration. A premixed infusion bag could reduce pharmacy preparation time and exposure to cytotoxic or hazardous drug handling procedures. Patent claims could cover:

• A specific clofarabine concentration in a final infusion vehicle.
• A sterile bag filled at a defined volume.
• Stability after dilution.
• Storage at refrigerated or controlled room temperature.
• Compatibility with common polyolefin, multilayer, or ethylene-vinyl acetate bags.
• A defined allowable hold time after preparation.

A ready-to-use product would compete on workflow, not only drug price. Hospitals could value reduced preparation steps, lower compounding labor, fewer calculation errors, and less drug waste.

Pediatric dose-flexible presentations

The current 20 mL vial may create wastage when patient doses do not align with vial size. Alternative presentations could include:

• Smaller single-dose vials.
• Multi-strength vial configurations.
• Unit-dose syringes.
• Pharmacy-ready dose bands.
• Concentrated formulations designed for dilution into a standard final volume.

A dose-flexible system has commercial relevance in pediatric oncology because dosing is based on body-surface area and patient weights vary substantially. Patent protection would be stronger if linked to a defined dosing method, stability period, or device configuration rather than a vial size alone.

Stability-enhanced solutions

A stability program could test pH, ionic strength, oxygen exposure, light exposure, container composition, and storage temperature. Possible technical targets include lower formation of degradation products, lower particulate levels, or longer post-dilution use periods.

The commercial objective is to extend the product from an immediately prepared hospital formulation to a pharmacy stock product. That change can support centralized compounding, specialty-distributor inventory, and smaller hospital accounts that lack high-volume oncology pharmacies.

Packaging and administration systems

Packaging can support both patent and trade-secret protection. Relevant opportunities include:

• Low-sorption polymer containers.
• Light-protective secondary packaging.
• Low-extractables closures.
• Integrated transfer devices.
• Closed-system drug-transfer compatibility.
• Prefilled infusion containers.
• Barcoded unit-dose packaging.

Packaging claims are more likely to create a differentiated product when the company has data showing a meaningful reduction in potency loss, contamination, particulate formation, or occupational exposure.

When does CLOLAR lose exclusivity?

CLOLAR’s regulatory exclusivity is materially different from its patent position. The product received orphan-drug designation for pediatric relapsed or refractory acute lymphoblastic leukemia. Orphan exclusivity generally lasts seven years from approval for the designated indication under the U.S. Orphan Drug Act.[2]

The FDA approved CLOLAR in December 2006.[3] The seven-year orphan period would therefore have extended into December 2013, subject to the scope of the designated indication and statutory limitations.

Milestone	Date or status
FDA approval	December 2006
Orphan exclusivity framework	Seven years from approval
Approximate orphan exclusivity endpoint	December 2013
Core small-molecule exclusivity today	Primarily patent and regulatory-listing dependent
Biosimilar exclusivity	Not applicable

CLOLAR is a small molecule, so biosimilar competition is not the relevant risk. A competing clofarabine product would generally proceed through an abbreviated new drug application if it met applicable requirements for pharmaceutical equivalence, bioequivalence, labeling, and manufacturing quality.

What is the Orange Book status of CLOLAR?

The FDA Orange Book is the controlling source for approved drug products, listed patents, and certain exclusivity information. CLOLAR was approved under NDA 021673, according to FDA product materials.[1,3]

Orange Book analysis should separate three questions:

1. Is the NDA product listed as active or discontinued?
2. Are any patents listed for the NDA?
3. Are any listed patents associated with a use code, formulation, or other limitation?

For generic-entry analysis, the relevant pathway would be an ANDA with a Paragraph IV certification against any listed patent. A Paragraph IV certification could trigger patent litigation if the NDA holder filed suit within the statutory period after receiving notice. A generic applicant could also use a Paragraph III certification, wait for patent expiration, or submit a section viii statement carving out patented methods of use.

The FDA label alone does not establish the current patent-listing position. Commercial diligence must rely on the current Orange Book patent table and the latest FDA listing data.

What Paragraph IV challenges and generic launch risks exist?

CLOLAR has several characteristics that could support generic entry:

• It is a small molecule.
• It is an aqueous injectable solution.
• The inactive-ingredient profile is simple.
• The product has a defined concentration and vial strength.
• No biologic comparability pathway is required.
• The clinical use is concentrated in a narrow oncology population.

Injectable generic development still presents meaningful barriers. An ANDA applicant must establish sterility assurance, container-closure integrity, particulate control, extractables and leachables, manufacturing consistency, and compatibility with the labeled dilution and infusion conditions.

Generic launch scenarios

Scenario	Market effect
No approved generic	Brand retains most institutional demand but faces tender and discount pressure
One generic entrant	Price erosion is possible, but supply reliability may preserve brand share
Multiple generic entrants	Greater price compression and hospital formulary substitution
Generic with a different vial size	Competition centers on waste reduction and net treatment cost
Generic premix or ready-to-use product	Workflow differentiation may offset simple unit-price competition
Supply disruption	Brand or authorized distributor may regain share temporarily

The highest-value defensive strategy is not necessarily another broad composition patent. A company may obtain stronger commercial protection from a reliable ready-to-use presentation, a low-waste vial architecture, or a validated stability profile that competitors do not replicate easily.

What is the FDA regulatory status of CLOLAR?

FDA approved CLOLAR for pediatric patients with relapsed or refractory acute lymphoblastic leukemia after at least two prior regimens. The approval was based on response data in a heavily pretreated population, with complete response and complete response without total platelet recovery serving as central efficacy measures.[1,3]

The product carries significant safety warnings, including risks associated with tumor lysis syndrome, systemic inflammatory response, capillary leak, hepatotoxicity, renal toxicity, and infection. Any reformulation must preserve the approved dosing and administration profile unless the sponsor pursues a supplemental application with supporting data.

A new excipient or delivery system could create a regulatory burden if it changes:

• Exposure or infusion rate.
• Dilution requirements.
• Product stability.
• Container materials.
• Administration duration.
• Pediatric dose measurement.
• Compatibility with standard oncology infusion systems.

A formulation that remains pharmaceutically equivalent and uses well-characterized excipients may support a comparatively efficient regulatory strategy. A novel route, sustained-release system, or oral formulation would require substantially more clinical development.

Which commercial opportunities are most attractive for CLOLAR?

Hospital-ready premix

This is the clearest formulation opportunity. A premixed bag can reduce pharmacy labor and improve handling consistency. The commercial case is strongest in pediatric cancer centers, centralized compounding networks, and hospitals with high hazardous-drug compliance costs.

Smaller vial sizes

Smaller vials can reduce unused drug. The opportunity is strongest where patient doses are substantially below 20 mg or where the calculated dose produces high residual volume. A 5 mg or 10 mg presentation could carry a premium if the total cost of treatment falls after waste is included.

Contract manufacturing and regional supply

Clofarabine is a niche oncology product. Reliable supply may be more valuable than broad promotional activity. Opportunities include:

• Regional licensing.
• Secondary manufacturing.
• Hospital-system supply contracts.
• Authorized generic arrangements.
• Dual-source API procurement.
• Public-sector and pediatric oncology tenders.

Global access products

The narrow indication and orphan history may leave underserved markets with limited access. A lower-cost vial configuration, local packaging, or regional distribution agreement could expand use in countries where pediatric oncology infrastructure exists but specialty products are expensive.

Combination development

Clofarabine has been studied in combination regimens, including combinations involving cytarabine and other antileukemic agents. Combination products create clinical and patent opportunities but also increase regulatory complexity. A sponsor would need to establish that the formulation or regimen provides a meaningful clinical or operational advantage over separately administered products.

How does CLOLAR compare with competing leukemia products?

CLOLAR competes in a relapsed or refractory pediatric leukemia market rather than a broad primary-treatment market. Relevant alternatives can include intensive salvage chemotherapy, targeted agents, antibody-based therapies, cellular therapies, and clinical trials.

Product category	Competition with CLOLAR	Formulation opportunity
Conventional salvage chemotherapy	Direct clinical alternative	Lower-cost and easier administration
Blinatumomab	Different mechanism and infusion model	Ready-to-use infusion convenience
Inotuzumab ozogamicin	Different target and toxicity profile	Less relevant excipient comparison
CAR-T therapies	Potentially competing salvage strategy	CLOLAR has simpler logistics
Generic cytarabine-based regimens	Cost-sensitive alternative	CLOLAR can compete on response or workflow
Clinical trials	Major alternative in relapsed disease	Supply reliability and protocol compatibility

CLOLAR’s commercial advantage is operational simplicity compared with cell therapy and some complex biologics. Its disadvantage is a narrow patient population and substantial competition from newer targeted and cellular therapies.

What patent litigation and settlement risks affect CLOLAR?

The principal litigation risk is an ANDA Paragraph IV challenge involving composition, formulation, manufacturing, or method-of-use claims. A sponsor should monitor:

• Orange Book patent listings for NDA 021673.
• Paragraph IV notice activity.
• District court filings under the Hatch-Waxman framework.
• Patent-term-adjustment calculations.
• Pediatric exclusivity additions.
• Authorized-generic or settlement arrangements.
• FDA approval dates for competing clofarabine products.

Method-of-use patents may have limited practical value if the label already covers a narrow salvage population and a generic applicant can use a section viii carve-out. Formulation patents are more commercially useful when they cover a product presentation that hospitals actively prefer, such as a stable premix or low-waste package.

Key Takeaways

• CLOLAR is a simple aqueous clofarabine injection containing sodium chloride and water for injection.
• The basic excipient composition offers limited room for broad, high-strength formulation patents.
• The strongest opportunities involve premixed infusion bags, smaller vial sizes, post-dilution stability, container compatibility, and pharmacy workflow.
• Orphan exclusivity from the 2006 FDA approval would have expired around December 2013.
• Biosimilar competition does not apply because clofarabine is a small molecule.
• Generic risk depends on current Orange Book listings, ANDA filings, Paragraph IV certifications, and injectable manufacturing capability.
• Commercial value is concentrated in pediatric oncology centers, specialty distribution, hospital tenders, and supply reliability.
• A lifecycle product should pair any formulation patent with stability, packaging, manufacturing, or operational data.

FAQs

Is CLOLAR a biologic or a small-molecule drug?

CLOLAR is a small-molecule drug. It contains clofarabine, a purine nucleoside analog, and would face generic rather than biosimilar competition.

Can CLOLAR be reformulated for oral administration?

An oral clofarabine product would require new pharmaceutical development and likely clinical evaluation. It would not be a simple excipient change to the approved intravenous product.

What is the most valuable CLOLAR lifecycle product?

A validated ready-to-use premixed infusion with a meaningful refrigerated or room-temperature shelf life is likely the most commercially attractive lifecycle product.

Why are smaller CLOLAR vials commercially important?

CLOLAR dosing is based on body-surface area. Smaller vials could reduce residual drug waste and improve the total treatment economics for pediatric patients.

Does CLOLAR have biosimilar exclusivity?

No. Biosimilar exclusivity applies to biologics, while CLOLAR is a conventional small-molecule injectable.

References

1. U.S. Food and Drug Administration. (2016). CLOLAR (clofarabine) injection, prescribing information. FDA.
2. U.S. Food and Drug Administration. (n.d.). Orphan drug designation and exclusivity. FDA.
3. U.S. Food and Drug Administration. (2006). FDA approves Clolar for relapsed or refractory acute lymphoblastic leukemia. FDA.