Regdanvimab is a recombinant human monoclonal antibody developed as CT-P59 for targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. By binding to the viral RBD, regdanvimab interferes with the interaction required for viral entry into host cells. It was developed by Celltrion and marketed in the European Union under the brand name Regkirona.
Regdanvimab is a biological active pharmaceutical ingredient and therefore requires biologic-specific characterization and quality control. Regulatory assessment has included evaluation of its primary and higher-order structure, post-translational modifications, charge variants, glycosylation and biological activity.
Regdanvimab, also known as CT-P59, is a recombinant human IgG1 monoclonal antibody directed against the SARS-CoV-2 spike-protein RBD. Structural studies identify the antibody as using VH2-70/VL1-51 germline families, with binding to the RBD and high affinity for its target.
The API is a complex protein biologic and should therefore be evaluated through orthogonal analytical methods such as protein identity, peptide mapping, size-based purity, charge-variant analysis, glycan characterization, target-binding assays and biological potency testing.
| Parameter | Value |
|---|---|
| Product Name | Regdanvimab |
| CAS Number | 2444308-95-4 |
| Development Code | CT-P59 |
| Molecular Type | Recombinant monoclonal antibody |
| Antibody Class | Human IgG1 |
| Light Chain | Lambda |
| Target | SARS-CoV-2 spike-protein receptor-binding domain |
| Therapeutic Class | Antiviral monoclonal antibody |
| ATC Code | J06BD06 |
| Biological Target | SARS-CoV-2 spike RBD |
| Pharmaceutical Category | Biological Active Pharmaceutical Ingredient |
The current chemical-reference source lists CAS 2444308-95-4 and describes the research material as an IgG1-LALA antibody. Published structural literature describes regdanvimab as a human IgG1λ antibody.
Regdanvimab was developed for the treatment of COVID-19 in patients at increased risk of progressing to severe disease. EMA authorized Regkirona in November 2021 for adults with COVID-19 who did not require supplemental oxygen and were at increased risk of severe disease.
Regdanvimab acts by binding to the SARS-CoV-2 spike-protein RBD and blocking the interaction involved in viral entry into host cells.
Current regulatory status: the European Commission withdrew the Regkirona marketing authorization on 14 April 2025, following the marketing authorization holder's request to permanently discontinue marketing for commercial reasons.
Regdanvimab requires biologic-specific quality testing. The EMA assessment reports comprehensive characterization of:
EMA also reports that RBD-binding ELISA was considered suitable as a potency assay for release testing.
Regdanvimab API manufacturing requires specialized biologics production and analytical characterization. Appropriate quality systems should control antibody identity, protein concentration, purity, aggregation, charge heterogeneity, glycosylation, biological potency and process-related impurities.
The regulatory assessment confirms that active-substance release specifications included appearance, identity, pH, purity/impurity testing, protein concentration and potency. Methods included SEC-HPLC, non-reduced and reduced CE-SDS, IEC-HPLC and RBD-binding ELISA.
Regdanvimab drug substance was stored under frozen conditions during the regulatory development program. The Swiss regulatory assessment accepted a 12-month drug-substance shelf life under the proposed frozen storage conditions.
The finished Regkirona product was supplied as a sterile liquid in single-use vials and was stored at 2–8°C protected from light.
Typical Regdanvimab biological API documentation may include:
Regdanvimab requires a biologics-focused quality system because its quality cannot be adequately represented by conventional small-molecule API specifications. A comprehensive analytical program should combine structural characterization, purity testing and functional potency assessment.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |