For US healthcare professionals only

Frequently Asked Questions

What is a biosimilar, and what does interchangeability mean?

A biosimilar is a biologic medication that is highly similar to its reference product, with no clinically meaningful differences in safety, purity, or potency. An interchangeable biosimilar must first meet the FDA standard for biosimilarity and then satisfy additional requirements to confirm no greater risk in safety or reduced effectiveness than continued use of the reference product alone. Subject to state pharmacy laws, a biosimilar may be substituted for the reference product without first consulting the prescriber.1,2

What is extrapolation and how does the FDA evaluate biosimilars across indications?

The FDA may approve a biosimilar across multiple reference-product indications through scientific extrapolation. When a biosimilar is approved for one disease, the FDA may allow it to be used for other indications approved for the reference product, without requiring separate clinical trials for each. However, the biosimilars manufacturer must provide justification for those indications. This is called extrapolation. OMLYCLO has been established as a biosimilar across all approved Xolair® indications, including labeled pediatric populations.1,3

What is OMLYCLO, and for which patients is it indicated?

OMLYCLO—the first and only biosimilar interchangeable with Xolair®—offers an FDA-approved alternative to treat3,4:

  • Moderate to severe persistent asthma in adults and pediatric patients ≥6 years of age with a positive skin test or in vitro reactivity to a perennial aeroallergen and symptoms that are inadequately controlled with inhaled corticosteroids
  • Chronic rhinosinusitis with nasal polyps (CRSwNP) in adult patients ≥18 years of age with inadequate response to nasal corticosteroids, as add-on maintenance treatment
  • IgE-mediated food allergy in adult and pediatric patients ≥1 year of age for the reduction of allergic reactions (Type I), including anaphylaxis, that may occur with accidental exposure to one or more foods. To be used in conjunction with food allergen avoidance
  • Chronic spontaneous urticaria (CSU) in adults and adolescents ≥12 years of age and older who remain symptomatic despite H1 antihistamine treatment

Limitations of Use: Not indicated for acute bronchospasm or status asthmaticus; emergency treatment of allergic reactions, including anaphylaxis; and other forms of urticaria.

What clinical evidence supports OMLYCLO?

OMLYCLO was compared with Xolair® in a double-blind, randomized, active-controlled phase 3 study of adult and pediatric patients aged 12 years and older with chronic spontaneous urticaria. OMLYCLO demonstrated therapeutic equivalence to Xolair for the primary efficacy endpoint and showed comparable clinical response, pharmacokinetics, immunogenicity, and safety.5

What evidence supports switching patients from Xolair® to OMLYCLO?

In a randomized phase 3 study in patients with chronic spontaneous urticaria, patients who switched from Xolair to OMLYCLO maintained clinical response, with similar or numerically higher UAS7 response rates compared with continued treatment at week 24. Improvements in disease activity were also maintained through week 40.5

The transition also showed no meaningful impact on pharmacokinetics or immunogenicity, and safety findings were similar across patients who continued OMLYCLO, continued Xolair, or transitioned to OMLYCLO.5

As an interchangeable biosimilar to Xolair, OMLYCLO can be expected to produce the same clinical result in any given patient and presents no greater risk in safety or reduced effectiveness when transitioning between products for any indication.3

UAS7, weekly urticaria activity score.

What evidence supports the use of OMLYCLO in pediatric patients?

Through the totality of evidence supporting biosimilarity, OMLYCLO is expected to provide the same safety and efficacy as Xolair® across its approved indications, including labeled pediatric populations.3,4

How is OMLYCLO dosed and administered?

The dosing of OMLYCLO is identical to Xolair®1,2. OMLYCLO is available in prefilled syringes for ease of use and precision dosing.3

Dosing and administration for OMLYCLO is based on the primary indication for which it is prescribed. Refer to the dosing calculator and dosing tables to identify the appropriate regimen for an individual patient.3

What patient access and support services are available with OMLYCLO?

  • Celltrion CONNECT® provides help in verifying patients' insurance coverage for OMLYCLO, identifying plan-specific requirements, and clarifying available benefits for your OMLYCLO-prescribed patients
  • Eligible patients may pay as little as $0 per dose through the Celltrion CARES® Co-pay Assistance Program*
  • Celltrion INFORM provides additional reimbursement solutions for patients and practices. Contact your Field Reimbursement Manager at 1-877-812-6662, Monday – Friday, between 8 AM – 8 PM ET, for more information
  • Celltrion Nurse Connector™ helps patients start and continue OMLYCLO through expert nurse-supported injection training, storage and handling guidance, dosing education, and more†

*All patients enrolled in the Celltrion CONNECT® Patient Support Program are automatically screened for financial assistance. Program calendar maximums apply. Please see full Terms and Conditions .

†Participation in the Nurse Connector program is voluntary. Patients can opt out of this service at any time. Nurse Connectors will not offer medical advice and will always refer the patient back to the prescriber for any questions.

When switching a patient from Xolair to Omlyclo for self-administration, is it necessary for the patient to repeat the three initial in-clinic doses?

Patients who are already stable on self-administered Xolair can generally continue self-administration after switching to Omlyclo, provided they receive appropriate training on any device-specific differences. New patients, or those requiring re-establishment of therapy, would follow the standard supervised initiation process.

References: 1. US Food and Drug Administration. Biosimilar product regulatory review and approval. Accessed March 17, 2026. https://www.fda.gov/files/drugs/published/Biosimilar-Product-Regulatory-Review-and-Approval.pdf 2. US Food and Drug Administration. Biosimilars Info Sheet Level 1. Accessed May 5, 2026. https://www.fda.gov/media/154911/download 3. OMLYCLO Prescribing Information. Celltrion USA, Inc; 2025. 4. US Food and Drug Administration. BLA approval letter 761399 for OMLYCLO. Published March 7, 2025. 5. Saini SS, Maurer M, Dytyatkovska Y, et al. CT-P39 compared with reference omalizumab in chronic spontaneous urticaria: results from a double-blind, randomized, active-controlled, phase 3 study. Allergy. 2025;80(7):2167-2177. doi:10.1111/all.16446

IMPORTANT SAFETY INFORMATION

WARNING: ANAPHYLAXIS

Anaphylaxis presenting as bronchospasm, hypotension, syncope, urticaria, and/or angioedema of the throat or tongue has been reported to occur after administration of omalizumab products. Anaphylaxis has occurred as early as after the first dose of omalizumab products, but also has occurred beyond 1 year after beginning regularly administered treatment. Because of the risk of anaphylaxis, initiate OMLYCLO therapy in a healthcare setting and closely observe patients for an appropriate period of time after OMLYCLO administration. Healthcare providers administering OMLYCLO should be prepared to manage anaphylaxis, which can be life-threatening. Inform patients of the signs and symptoms of anaphylaxis and instruct them to seek immediate medical care should symptoms occur. Selection of patients for self-administration of OMLYCLO should be based on criteria to mitigate risk from anaphylaxis.

Contraindications:

Severe hypersensitivity reaction to omalizumab products or any ingredient of OMLYCLO.

Anaphylaxis. Life-threatening anaphylaxis has occurred after omalizumab products, with signs/symptoms including bronchospasm, hypotension, syncope, urticaria, and/or angioedema of the throat or tongue; it can occur as early as the first dose, beyond 1 year after starting, and has been reported up to 4 days after administration. Initiate OMLYCLO in a healthcare setting equipped to manage anaphylaxis and observe patients for an appropriate period after dosing; educate patients on signs/symptoms and the need for immediate medical care. Risk is increased in patients with a history of anaphylaxis to foods, medications, or other causes. After therapy is safely established, self-administration OMLYCLO prefilled syringe may be appropriate for selected patients/caregivers based on risk mitigation (including no prior history of anaphylaxis, at least 3 supervised doses without hypersensitivity, ability to recognize and appropriately treat anaphylaxis, and ability to perform SC injections correctly). Discontinue OMLYCLO in patients who experience a severe hypersensitivity reaction.

Malignancy. Malignant neoplasms have been observed in clinical studies; the impact of longer exposure and use in patients at higher baseline risk is not known, and limitations of longer-term observational data preclude definitively ruling out a malignancy risk with omalizumab products.

Acute Asthma Symptoms and Deteriorating Disease. Omalizumab products have not been shown to relieve acute asthma exacerbations; do not use OMLYCLO to treat acute bronchospasm or status asthmaticus. Advise patients to seek medical care if asthma remains uncontrolled or worsens after starting OMLYCLO.

Corticosteroid Reduction. Do not abruptly discontinue systemic or inhaled corticosteroids when starting OMLYCLO for asthma or CRSwNP; taper gradually under physician supervision. In CSU patients, use of omalizumab products in combination with corticosteroids has not been evaluated.

Eosinophilic Conditions. In rare cases, patients with asthma on omalizumab products have developed serious systemic eosinophilia, sometimes with vasculitis consistent with Churg-Strauss syndrome, often in the setting of oral corticosteroid reduction. Be alert for eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, and/or neuropathy; a causal association has not been established.

Fever, Arthralgia, and Rash. In post-approval use, a serum sickness-like constellation (arthritis/arthralgia, rash, fever, lymphadenopathy) has occurred 1 to 5 days after injections and may recur with additional doses; stop OMLYCLO if this constellation develops.

Parasitic (Helminth) Infection. Monitor patients at high risk of geohelminth infection during OMLYCLO therapy; available data are insufficient to define the duration of monitoring needed after stopping treatment. A clinical trial in a high-risk setting observed more infections with omalizumab than placebo; response to appropriate anti-geohelminth treatment was not different between groups.

Laboratory Tests. Total serum IgE increases after dosing and may remain elevated for up to 1 year after discontinuation due to drug-IgE complexes; do not use total IgE levels obtained less than 1 year after discontinuation to reassess dosing regimen for asthma, CRSwNP, or IgE-mediated food allergy because these levels may not reflect steady-state free IgE levels.

Potential Medication Error Related to Emergency Treatment of Anaphylaxis. OMLYCLO should not be used for the emergency treatment of allergic reactions, including anaphylaxis. Instruct patients that OMLYCLO is for maintenance use to reduce allergic reactions, including anaphylaxis, while avoiding food allergens.

Most Common Adverse Reactions:

  • Asthma: In patients ≥12 years, reported in ≥1%: arthralgia, general pain, leg pain, fatigue, dizziness, fracture, arm pain, pruritus, dermatitis, and earache. In pediatric patients (6 to <12 years), reported in ≥3%: nasopharyngitis, headache, pyrexia, upper abdominal pain, streptococcal pharyngitis, otitis media, viral gastroenteritis, arthropod bites, and epistaxis.
  • CRSwNP: In ≥3% of adults: headache, injection site reactions, arthralgia, upper abdominal pain, and dizziness.
  • IgE-Mediated Food Allergy: In ≥3% of patients: injection site reactions and pyrexia.
  • CSU: In ≥2% of patients: nausea, nasopharyngitis, sinusitis, upper respiratory tract infections (viral and non-viral), arthralgia, headache, and cough.

INDICATIONS

OMLYCLO® (omalizumab-igec) injection is an anti-IgE antibody indicated for:

  • Moderate to severe persistent asthma in adults and pediatric patients ≥6 years of age with a positive skin test or in vitro reactivity to a perennial aeroallergen and symptoms that are inadequately controlled with inhaled corticosteroids.
  • Chronic rhinosinusitis with nasal polyps (CRSwNP) in adult patients ≥18 years of age with inadequate response to nasal corticosteroids, as add-on maintenance treatment.
  • IgE-mediated food allergy in adult and pediatric patients ≥1 year of age for the reduction of allergic reactions (Type I), including anaphylaxis, that may occur with accidental exposure to one or more foods. To be used in conjunction with food allergen avoidance.
  • Chronic spontaneous urticaria (CSU) in adults and adolescents ≥12 years of age who remain symptomatic despite H1 antihistamine treatment.

Limitations of Use: Not indicated for acute bronchospasm or status asthmaticus; emergency treatment of allergic reactions, including anaphylaxis; and other forms of urticaria.

Please see the full Prescribing Information for complete details. To report suspected adverse reactions, contact CELLTRION USA, INC. at 1‑800‑560‑9414 or FDA at 1‑800‑FDA‑1088 or www.fda.gov/medwatch.

IMPORTANT SAFETY INFORMATION

WARNING: ANAPHYLAXIS

Anaphylaxis presenting as bronchospasm, hypotension, syncope, urticaria, and/or angioedema of the throat or tongue has been reported to occur after administration of omalizumab products. Anaphylaxis has occurred as early as after the first dose of omalizumab products, but also has occurred beyond 1 year after beginning regularly administered treatment. Because of the risk of anaphylaxis, initiate OMLYCLO therapy in a healthcare setting and closely observe patients for an appropriate period of time after OMLYCLO administration. Healthcare providers administering OMLYCLO should be prepared to manage anaphylaxis, which can be life-threatening. Inform patients of the signs and symptoms of anaphylaxis and instruct them to seek immediate medical care should symptoms occur. Selection of patients for self-administration of OMLYCLO should be based on criteria to mitigate risk from anaphylaxis.

Contraindications:

Severe hypersensitivity reaction to omalizumab products or any ingredient of OMLYCLO.

Anaphylaxis. Life-threatening anaphylaxis has occurred after omalizumab products, with signs/symptoms including bronchospasm, hypotension, syncope, urticaria, and/or angioedema of the throat or tongue; it can occur as early as the first dose, beyond 1 year after starting, and has been reported up to 4 days after administration. Initiate OMLYCLO in a healthcare setting equipped to manage anaphylaxis and observe patients for an appropriate period after dosing; educate patients on signs/symptoms and the need for immediate medical care. Risk is increased in patients with a history of anaphylaxis to foods, medications, or other causes. After therapy is safely established, self-administration OMLYCLO prefilled syringe may be appropriate for selected patients/caregivers based on risk mitigation (including no prior history of anaphylaxis, at least 3 supervised doses without hypersensitivity, ability to recognize and appropriately treat anaphylaxis, and ability to perform SC injections correctly). Discontinue OMLYCLO in patients who experience a severe hypersensitivity reaction.

Malignancy. Malignant neoplasms have been observed in clinical studies; the impact of longer exposure and use in patients at higher baseline risk is not known, and limitations of longer-term observational data preclude definitively ruling out a malignancy risk with omalizumab products.

Acute Asthma Symptoms and Deteriorating Disease. Omalizumab products have not been shown to relieve acute asthma exacerbations; do not use OMLYCLO to treat acute bronchospasm or status asthmaticus. Advise patients to seek medical care if asthma remains uncontrolled or worsens after starting OMLYCLO.

Corticosteroid Reduction. Do not abruptly discontinue systemic or inhaled corticosteroids when starting OMLYCLO for asthma or CRSwNP; taper gradually under physician supervision. In CSU patients, use of omalizumab products in combination with corticosteroids has not been evaluated.

Eosinophilic Conditions. In rare cases, patients with asthma on omalizumab products have developed serious systemic eosinophilia, sometimes with vasculitis consistent with Churg-Strauss syndrome, often in the setting of oral corticosteroid reduction. Be alert for eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, and/or neuropathy; a causal association has not been established.

Fever, Arthralgia, and Rash. In post-approval use, a serum sickness-like constellation (arthritis/arthralgia, rash, fever, lymphadenopathy) has occurred 1 to 5 days after injections and may recur with additional doses; stop OMLYCLO if this constellation develops.

Parasitic (Helminth) Infection. Monitor patients at high risk of geohelminth infection during OMLYCLO therapy; available data are insufficient to define the duration of monitoring needed after stopping treatment. A clinical trial in a high-risk setting observed more infections with omalizumab than placebo; response to appropriate anti-geohelminth treatment was not different between groups.

Laboratory Tests. Total serum IgE increases after dosing and may remain elevated for up to 1 year after discontinuation due to drug-IgE complexes; do not use total IgE levels obtained less than 1 year after discontinuation to reassess dosing regimen for asthma, CRSwNP, or IgE-mediated food allergy because these levels may not reflect steady-state free IgE levels.

Potential Medication Error Related to Emergency Treatment of Anaphylaxis. OMLYCLO should not be used for the emergency treatment of allergic reactions, including anaphylaxis. Instruct patients that OMLYCLO is for maintenance use to reduce allergic reactions, including anaphylaxis, while avoiding food allergens.

Most Common Adverse Reactions:

  • Asthma: In patients ≥12 years, reported in ≥1%: arthralgia, general pain, leg pain, fatigue, dizziness, fracture, arm pain, pruritus, dermatitis, and earache. In pediatric patients (6 to <12 years), reported in ≥3%: nasopharyngitis, headache, pyrexia, upper abdominal pain, streptococcal pharyngitis, otitis media, viral gastroenteritis, arthropod bites, and epistaxis.
  • CRSwNP: In ≥3% of adults: headache, injection site reactions, arthralgia, upper abdominal pain, and dizziness.
  • IgE-Mediated Food Allergy: In ≥3% of patients: injection site reactions and pyrexia.
  • CSU: In ≥2% of patients: nausea, nasopharyngitis, sinusitis, upper respiratory tract infections (viral and non-viral), arthralgia, headache, and cough.

INDICATIONS

OMLYCLO® (omalizumab-igec) injection is an anti-IgE antibody indicated for:

  • Moderate to severe persistent asthma in adults and pediatric patients ≥6 years of age with a positive skin test or in vitro reactivity to a perennial aeroallergen and symptoms that are inadequately controlled with inhaled corticosteroids.
  • Chronic rhinosinusitis with nasal polyps (CRSwNP) in adult patients ≥18 years of age with inadequate response to nasal corticosteroids, as add-on maintenance treatment.
  • IgE-mediated food allergy in adult and pediatric patients ≥1 year of age for the reduction of allergic reactions (Type I), including anaphylaxis, that may occur with accidental exposure to one or more foods. To be used in conjunction with food allergen avoidance.
  • Chronic spontaneous urticaria (CSU) in adults and adolescents ≥12 years of age who remain symptomatic despite H1 antihistamine treatment.

Limitations of Use: Not indicated for acute bronchospasm or status asthmaticus; emergency treatment of allergic reactions, including anaphylaxis; and other forms of urticaria.

Please see the full Prescribing Information for complete details. To report suspected adverse reactions, contact CELLTRION USA, INC. at 1‑800‑560‑9414 or FDA at 1‑800‑FDA‑1088 or www.fda.gov/medwatch.