Omalizumab biosimilars

Humanised IgG1 kappa monoclonal antibody of about 149 kDa, produced in Chinese hamster ovary cells, that binds free immunoglobulin E at the site IgE uses to bind its high-affinity receptor.

Binds circulating free IgE and prevents it from attaching to Fc epsilon RI receptors on mast cells and basophils, lowering free IgE by more than 95% and downregulating receptor expression, so allergen exposure no longer triggers mediator release. It does not bind IgE already on cells and so does not cause degranulation.

Subcutaneous bioavailability about 62%, peak concentrations at seven to eight days and a half-life of about 26 days. Dose and interval are set from baseline IgE and body weight, which is why comparative programmes fix both in the study population.

75 mg to 600 mg every two or four weeks by subcutaneous injection according to pre-treatment IgE and weight for asthma; 300 mg every four weeks for chronic urticaria. Supplied as 75 mg/0.5 mL and 150 mg/mL pre-filled syringes and pens, and 150 mg lyophilised vials in some markets.

• Moderate to severe persistent allergic asthma inadequately controlled by inhaled corticosteroids
• Chronic spontaneous urticaria
• Chronic rhinosinusitis with nasal polyps
• IgE-mediated food allergy (United States, 2024)

Anti-omalizumab antibodies are rare and anaphylaxis, though uncommon, is the principal safety concern with the reference product. Comparative programmes use analytical similarity, a pharmacokinetic and pharmacodynamic study in healthy volunteers with free IgE suppression as the marker, and a comparative efficacy study in chronic spontaneous urticaria with change in weekly itch severity score at week 12, an endpoint regulators have accepted as sensitive.

Xolair was licensed by FDA on 20 June 2003 (BLA 103976) and authorised in the EU on 25 October 2005 (EMEA/H/C/000606), first for allergic asthma, with urticaria, nasal polyps and, in the US, food allergy added later. Celltrion's Omlyclo was authorised in the EU in May 2024 and approved by FDA in March 2025 as the first omalizumab biosimilar and the first interchangeable one, on the day of licensure. Reliance Life Sciences received an Indian manufacturing permission in February 2020.

Sources: Purple Book (S016), EMA medicines data (S017), CDSCO lists (S011, S013).

Omalizumab is the immunology molecule with the most white space in this register: one biosimilar in the West, one domestic product in India, none registered in the UAE. The urticaria endpoint gives a compact comparative study, and the pharmacodynamic marker, free IgE, is unusually direct. The complication for developers is the weight-and-IgE dosing table and the anaphylaxis history, which shape the risk management plan more than the clinical package.