Reslizumab is a humanized anti-human interleukin-5 (IL-5) monoclonal antibody of the IgG4κ class. It is a recombinant biological API developed for the treatment of severe eosinophilic asthma. Reslizumab binds human IL-5 and inhibits IL-5-mediated eosinophil proliferation, activation and survival. FDA records identify reslizumab as a recombinant monoclonal antibody produced using a murine myeloma non-secreting 0 (NS0) cell line.
The FDA substance record identifies CAS 241473-69-8 and UNII 35A26E427H for Reslizumab.
FDA's chemistry review reports a theoretical molecular mass of 146,776 Da, while the approved product labeling describes the antibody as approximately 147 kDa.
Unlike conventional small-molecule APIs, Reslizumab is a complex recombinant glycoprotein. It consists of two identical heavy chains and two identical light chains characteristic of an IgG antibody. The FDA chemistry review identifies Reslizumab as a human IgG4κ protein and reports N-glycosylation at Asn293 and 16 disulfide bonds.
Because Reslizumab is a biological macromolecule, conventional small-molecule parameters such as molecular formula, melting point, logP and exact mass are not appropriate primary CMS release specifications.
Reslizumab is an anti-IL-5 biologic used for the management of severe eosinophilic asthma. The biological rationale is based on reducing IL-5-driven eosinophil production, recruitment, activation and survival.
The FDA-approved Cinqair product was supplied as a 100 mg/10 mL (10 mg/mL) single-dose intravenous formulation. The FDA Purple Book identifies the product as a 351(a) biological product with BLA 761033.
Historically, reslizumab has also been investigated for eosinophil-driven disorders including hypereosinophilic syndrome and eosinophilic esophagitis, but these should not be represented as FDA-approved indications based solely on those clinical development programs.
Reslizumab specifically binds to human IL-5. IL-5 is an important cytokine involved in the growth, differentiation, recruitment, activation and survival of eosinophils.
Reslizumab blocks IL-5 from binding to the IL-5 receptor complex on eosinophils, thereby inhibiting IL-5 signaling and reducing eosinophil production and survival. The FDA label reports an IL-5 binding dissociation constant (Kd) of approximately 81 pM.
FDA development documentation further describes an IL-5 epitope involving residues 89–92 and identifies additional residues involved in antibody recognition.
As a monoclonal antibody API, Reslizumab requires biologic-specific characterization and quality testing, including:
The FDA chemistry review specifically identifies biological activity testing based on inhibition of cell proliferation and relative potency assessment.
Reslizumab is produced using recombinant DNA technology in murine myeloma NS0 cells and purified from the culture supernatant.
Manufacturing of Reslizumab API requires controlled upstream cell culture, harvest, purification and viral-safety processes followed by extensive analytical characterization. Critical quality attributes include protein identity, molecular mass, glycosylation, aggregation, charge heterogeneity, potency and process-related impurities.
Because the molecule is a recombinant monoclonal antibody, manufacturing controls should follow applicable biologics and GMP requirements rather than conventional small-molecule API processing specifications.
The molecular mass and structural characteristics are supported by the FDA chemistry review, while concentration and pH refer specifically to the approved finished formulation and should not be confused with a universal bulk drug-substance specification.
The approved Reslizumab injection is supplied as a 100 mg/10 mL (10 mg/mL) sterile, preservative-free solution in a single-use vial. The formulation is clear to slightly hazy/opalescent and colorless to slightly yellow.
The FDA-approved product is stored under refrigeration at 2–8°C, should not be frozen or shaken, and should be protected from light in the original package.
For bulk Reslizumab drug substance, storage and packaging conditions should follow validated manufacturer stability data and the applicable approved specification rather than automatically applying finished-product conditions.
Typical documentation for Reslizumab API or biological drug substance may include:
A qualified Reslizumab API manufacturer in India should have appropriate capabilities for recombinant monoclonal antibody production and characterization. Particular attention should be given to control of cell-culture processes, purification, viral safety, protein aggregation, glycosylation, charge variants, potency and process-related impurities.
For Reslizumab, biologic-specific analytical capabilities are essential because conventional small-molecule API testing alone cannot adequately establish identity, purity, structural integrity and biological activity.
| 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% |
| pH (1% Solution) | 5.5 |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |