List of Excipients in Branded Drug ONTRUZANT

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ONTRUZANT Excipient Strategy and Commercial Opportunities

Last updated: October 19, 2026

ONTRUZANT is Samsung Bioepis’ trastuzumab biosimilar, marketed in the United States by Organon. Its commercial value is driven by biosimilar interchangeability potential, lower treatment cost, hospital contracting, and manufacturing scale rather than by a novel excipient profile. The product uses a conventional lyophilized monoclonal-antibody formulation containing histidine buffers, polysorbate 20, and trehalose. This composition supports protein stability while limiting regulatory and comparability risk.

ONTRUZANT is approved for HER2-positive breast cancer and HER2-positive metastatic gastric or gastroesophageal junction adenocarcinoma. It is regulated as a biologic under the FDA biosimilar pathway, not as a conventional small-molecule generic. The product does not have an Orange Book listing because biologic products are tracked principally through the FDA Purple Book.

What is ONTRUZANT and who commercializes it?

ONTRUZANT is the U.S. brand name for SB3, a biosimilar to Genentech’s HERCEPTIN, or trastuzumab. Samsung Bioepis developed the product. Organon commercializes ONTRUZANT in the United States under its collaboration with Samsung Bioepis.

Attribute	ONTRUZANT
Active ingredient	Trastuzumab
Reference product	HERCEPTIN
Developer	Samsung Bioepis
U.S. commercial partner	Organon
FDA approval	January 2019
U.S. dosage forms	Intravenous lyophilized powder for reconstitution
Common vial strengths	150 mg and 420 mg
Therapeutic class	HER2-targeted monoclonal antibody
Regulatory pathway	FDA 351(k) biosimilar pathway
Orange Book status	Not applicable
Purple Book status	Listed as a biosimilar to trastuzumab
Interchangeability	The original U.S. approval was not an interchangeable biosimilar designation

The FDA approved ONTRUZANT for HER2-overexpressing breast cancer and metastatic gastric or gastroesophageal junction cancer consistent with the approved uses of HERCEPTIN.[1]

What excipients are used in ONTRUZANT?

ONTRUZANT’s U.S. prescribing information identifies the following inactive ingredients:

Excipient	Formulation role
L-histidine	Primary buffering agent
L-histidine hydrochloride monohydrate	Buffer capacity and pH control
Polysorbate 20	Surfactant that reduces interfacial and agitation-related aggregation
Trehalose dihydrate	Stabilizing sugar and bulking agent for lyophilization

The product is supplied as a sterile, preservative-free, single-dose lyophilized powder. It is reconstituted before intravenous infusion.[1]

Why does ONTRUZANT use a lyophilized formulation?

Lyophilization can improve the storage stability of a monoclonal antibody by reducing molecular mobility and limiting degradation reactions during storage. The approach also supports a conventional cold-chain presentation for hospital use.

For a trastuzumab biosimilar, the formulation objective is not simply maximum stability. The manufacturer must demonstrate that the finished product remains highly similar to the reference product in physicochemical properties, biological activity, purity, aggregates, charge variants, and clinically relevant quality attributes. A familiar excipient system reduces the number of formulation variables that can complicate comparability.

How strong is the ONTRUZANT excipient strategy?

The excipient strategy is commercially practical but unlikely to create a strong standalone exclusivity position. Histidine, polysorbate 20, and trehalose are widely used in biologic formulations. Their value lies in enabling a stable, manufacturable product rather than creating a differentiated composition-of-matter barrier.

Formulation advantages

The formulation provides several commercial benefits:

1. It uses established excipients with substantial pharmaceutical precedent.
2. It avoids preservatives in a single-dose injectable product.
3. It supports lyophilized storage and conventional hospital reconstitution.
4. It limits the risk of unexpected excipient-related immunogenicity or tolerability findings.
5. It is compatible with standard monoclonal-antibody fill-finish infrastructure.

Formulation limitations

The same conventional composition limits differentiation. ONTRUZANT does not appear to compete through a novel delivery system, subcutaneous presentation, extended shelf life, ready-to-use liquid format, or device combination. These areas provide greater opportunity for future competitors.

Polysorbate 20 can undergo hydrolysis and oxidation, generating degradation products that may affect protein stability or create particulate risk. Trehalose and histidine support stabilization but do not eliminate the need for tight control of container closure, headspace, light exposure, temperature excursions, reconstitution, and infusion handling.

What commercial opportunities exist for ONTRUZANT?

ONTRUZANT’s principal opportunity is institutional cost reduction in trastuzumab therapy. The product can compete in oncology hospitals, integrated delivery networks, specialty pharmacies, and public-sector purchasing programs.

Hospital contracting

Trastuzumab treatment can involve repeated intravenous dosing over many months. Small unit-price differences can produce material budget effects across a hospital system. Buyers evaluate:

• Acquisition price per vial
• Expected wastage from vial size and dose rounding
• Stability after reconstitution and dilution
• Availability during supply disruptions
• Payer coverage and reimbursement
• Switching policies
• Pharmacovigilance and traceability requirements

The 150 mg and 420 mg vial configuration supports different dosing patterns, but vial wastage remains a key economic variable. A product with a lower nominal price can lose part of its advantage if dose rounding creates more discarded drug.

Breast cancer and gastric cancer markets

The largest commercial opportunity is HER2-positive breast cancer, including early-stage and metastatic disease. Gastric and gastroesophageal junction cancer represent a smaller but clinically important indication.

ONTRUZANT can compete against:

• HERCEPTIN
• Other trastuzumab biosimilars
• Subcutaneous trastuzumab products
• Fixed-dose combination products
• Regimens using alternative HER2-targeted agents

The product’s intravenous presentation may be less attractive than subcutaneous or fixed-dose alternatives where infusion-center time is a major cost driver. Its advantage is likely strongest where hospital formularies prioritize vial economics and existing intravenous workflows.

What is the FDA regulatory status of ONTRUZANT?

ONTRUZANT was approved through the FDA’s 351(k) biosimilar pathway. Approval required analytical, functional, pharmacokinetic, immunogenicity, and clinical evidence supporting biosimilarity to HERCEPTIN.[1]

The product’s U.S. approval covers:

• HER2-positive breast cancer as part of specified treatment regimens
• HER2-positive metastatic breast cancer
• HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma

The original approval was not an interchangeable designation. Under the Biologics Price Competition and Innovation Act, interchangeability requires additional statutory criteria and may affect pharmacy-level substitution depending on state law and payer policy.[2]

What patents protect ONTRUZANT and trastuzumab products?

ONTRUZANT is a biologic biosimilar, so its competitive position is shaped by reference-product patent litigation, regulatory exclusivity, manufacturing know-how, and commercial agreements rather than by a conventional Orange Book patent list.

HERCEPTIN’s U.S. biologic exclusivity period expired before ONTRUZANT approval. The principal barriers involved patent disputes and settlement arrangements covering trastuzumab-related composition, treatment, formulation, and manufacturing claims. Samsung Bioepis obtained approval after resolving or managing the relevant reference-product patent and launch restrictions.

The key patent categories are:

Patent category	Relevance to ONTRUZANT
Antibody composition patents	Can cover the antibody sequence or structurally defined variants
Method-of-use patents	Can cover HER2-positive cancer treatment regimens
Formulation patents	Can cover concentration, buffers, stabilizers, or liquid presentations
Manufacturing patents	Can cover cell culture, purification, viral clearance, or process controls
Device and delivery patents	Can affect subcutaneous or ready-to-administer presentations

Patent exposure should be analyzed by jurisdiction and claim scope. A U.S. biosimilar approval does not establish freedom to launch in every market. European, Canadian, Japanese, Korean, and other national patent positions can differ.

What is the Orange Book and Purple Book status of ONTRUZANT?

ONTRUZANT is not expected to have an Orange Book patent listing because the Orange Book primarily covers approved drug products, while trastuzumab is a biologic. The FDA Purple Book identifies biological products, reference products, biosimilars, and interchangeable biosimilars.[3]

The relevant regulatory questions are:

• Whether ONTRUZANT is listed as biosimilar to HERCEPTIN
• Whether it has an interchangeable designation
• Whether supplemental approvals expand its label
• Whether manufacturing-site changes affect supply continuity
• Whether a competing biosimilar receives interchangeability before ONTRUZANT

A lack of Orange Book listing does not eliminate patent risk. Biologic patent disputes can proceed under the BPCIA framework and through conventional patent litigation.

Which companies challenge ONTRUZANT commercially?

ONTRUZANT competes in a crowded trastuzumab market. Major biosimilar competitors include products developed or commercialized by companies such as Amgen, Pfizer, Celltrion, Biocon Biologics, and Fresenius Kabi, depending on the market and launch timing.

Competing products may differentiate through:

• Interchangeability status
• Lower acquisition cost
• Subcutaneous delivery
• Ready-to-use liquid formulation
• Larger or smaller vial presentations
• Distribution scale
• Payer contracting
• Local manufacturing
• Supply reliability

The most significant competitive threat is a biosimilar with both a lower net price and a lower administration burden. Subcutaneous trastuzumab products can compete on chair-time savings even when the drug acquisition price is similar.

What manufacturing and IP barriers affect ONTRUZANT?

The primary manufacturing barrier is the reproducible production of a highly similar monoclonal antibody at commercial scale. Critical capabilities include:

• Stable mammalian-cell expression
• Control of glycosylation and charge variants
• Aggregate reduction
• Viral clearance
• High-yield purification
• Aseptic lyophilization and fill-finish
• Container-closure integrity
• Cold-chain distribution
• Batch-to-batch comparability after process changes

The excipients themselves are generally available from multiple suppliers. The stronger barrier is process knowledge. Small changes in cell culture, purification, filtration, freeze-drying, or reconstitution can affect quality attributes and regulatory comparability.

This creates an opportunity for contract manufacturers with validated biologics capacity, especially those able to provide dual sourcing, regional fill-finish, and flexible vial production.

How does ONTRUZANT compare with competing trastuzumab formulations?

Product strategy	ONTRUZANT position	Commercial implication
Lyophilized IV vial	Yes	Compatible with established oncology workflows
Ready-to-use liquid	No conventional marketed differentiation identified	Competitors may reduce pharmacy preparation
Subcutaneous delivery	No	Competes poorly on administration time
Novel excipient system	No clear differentiation	Limited formulation exclusivity
Interchangeability	Original approval was not interchangeable	May reduce automatic substitution potential
Vial-size flexibility	150 mg and 420 mg presentations	Supports dosing but does not eliminate wastage
Hospital contracting	Strong potential	Price and supply reliability are central

ONTRUZANT is best positioned as a cost-effective intravenous trastuzumab option. It is less differentiated against products that combine biosimilar pricing with subcutaneous delivery, interchangeability, or ready-to-use packaging.

What generic and biosimilar launch risks exist?

Traditional generic launch analysis does not apply directly. The relevant risks are biosimilar substitution, contracting, patent litigation, regulatory exclusivity, and manufacturing continuity.

Key risks include:

• A competitor receiving interchangeable status
• Aggressive net-price discounting
• Hospital preference for subcutaneous administration
• Supply interruption or manufacturing deviations
• Low utilization in indications with competing HER2 therapies
• Vial wastage reducing the apparent price advantage
• Payer policies that favor another biosimilar
• Patent claims affecting a specific formulation or delivery format

ONTRUZANT’s conventional excipient profile reduces formulation complexity but provides limited protection against these market forces.

What licensing deals support ONTRUZANT?

Samsung Bioepis and Organon have a commercialization relationship covering ONTRUZANT in the United States. Samsung Bioepis provides development and manufacturing capabilities, while Organon contributes U.S. commercial infrastructure, market access, and distribution.[4]

This structure can improve launch efficiency and reduce the need for Samsung Bioepis to build a standalone U.S. oncology commercial organization. The tradeoff is shared economics and dependence on the commercial partner’s contracting performance.

What is the revenue exposure for ONTRUZANT?

Revenue exposure is tied to trastuzumab market share rather than to excipient licensing. The main value drivers are:

• U.S. and European net price
• Share captured from HERCEPTIN
• Share captured from other biosimilars
• Oncology hospital contracts
• Utilization in early-stage breast cancer
• Adoption in metastatic breast and gastric cancer
• Persistence of intravenous administration
• Manufacturing cost per vial
• Supply reliability

Excipient suppliers may benefit indirectly through recurring demand for pharmaceutical-grade histidine, polysorbate 20, and trehalose. The larger commercial opportunity is in biologics manufacturing services, formulation development, analytical comparability, and fill-finish capacity.

Key Takeaways

• ONTRUZANT is a trastuzumab biosimilar developed by Samsung Bioepis and commercialized in the United States by Organon.
• Its formulation uses L-histidine, L-histidine hydrochloride monohydrate, polysorbate 20, and trehalose dihydrate.
• The formulation is conventional and commercially practical, but it is unlikely to provide strong standalone patent differentiation.
• The main commercial opportunity is hospital and payer cost reduction in intravenous trastuzumab treatment.
• Subcutaneous, ready-to-use, and interchangeable trastuzumab products present the strongest competitive threats.
• ONTRUZANT is tracked through the FDA Purple Book, not the Orange Book.
• Manufacturing know-how, quality control, supply reliability, and contracting are more important barriers than excipient availability.
• Excipient-related opportunities are strongest in biologics formulation support, analytical testing, fill-finish, and supply-chain services.

Frequently Asked Questions

Does ONTRUZANT contain polysorbate 20?

Yes. Polysorbate 20 is used as a surfactant to reduce protein adsorption and aggregation during manufacturing, storage, reconstitution, and handling.[1]

Is ONTRUZANT interchangeable with HERCEPTIN?

The original FDA approval was as a biosimilar, not as an interchangeable biosimilar. Pharmacy-level substitution therefore depends on later regulatory status and applicable state law.

Is ONTRUZANT a generic drug?

No. ONTRUZANT is a biologic biosimilar approved under the FDA 351(k) pathway. It is not an Abbreviated New Drug Application product.

Can ONTRUZANT’s excipient composition be patented?

A specific excipient combination can be claimed in a formulation patent if it meets patentability requirements. Common excipients alone generally provide limited differentiation, and any claim must survive novelty, obviousness, enablement, and infringement analysis.

What is the largest commercial weakness of ONTRUZANT?

Its largest weakness is limited delivery differentiation. An intravenous lyophilized vial can lose share to products offering interchangeability, subcutaneous administration, ready-to-use liquid dosing, lower total administration cost, or stronger hospital contracting.

References

1. U.S. Food and Drug Administration. (2019). ONTRUZANT (trastuzumab-dttb) prescribing information.
2. U.S. Food and Drug Administration. (2024). Biosimilar and interchangeable biosimilar biological products.
3. U.S. Food and Drug Administration. (2024). Purple Book: Database of licensed biological products.
4. Organon. (2021). Organon and Samsung Bioepis expand commercialization agreement for biosimilar medicines.