Obinutuzumab is a recombinant, humanized and glycoengineered IgG1κ monoclonal antibody that specifically targets the CD20 antigen expressed on pre-B and mature B lymphocytes. It is classified as a type II anti-CD20 monoclonal antibody.
Obinutuzumab is glycoengineered to contain increased levels of bisected, non-fucosylated Fc glycans, which enhance its interaction with FcγRIII receptors and contribute to increased antibody-dependent cellular cytotoxicity (ADCC).
EMA reports an approximately 146 kDa molecular mass for deglycosylated, non-reduced obinutuzumab.
Obinutuzumab is composed of two heavy chains and two kappa light chains. Its Fc region is glycoengineered with reduced fucose content, contributing to enhanced FcγRIII receptor binding and immune-effector activity.
The primary structure has been confirmed through tryptic peptide mapping, while disulfide-linked peptides, oxidation, deamidation, glycation and molecular mass have been characterized using LC-MS-based analytical techniques.
Obinutuzumab binds to CD20 on B lymphocytes and promotes B-cell depletion through several mechanisms, including:
Its reduced-fucose Fc glycosylation contributes to enhanced ADCC activity compared with conventional non-glycoengineered antibodies.
Obinutuzumab is used as a CD20-directed biological therapeutic. Current U.S. labeling includes applications in chronic lymphocytic leukemia (CLL), follicular lymphoma and active lupus nephritis.
Because obinutuzumab is a monoclonal antibody, its quality assessment uses biologic-specific analytical methods rather than conventional small-molecule API tests.
EMA describes characterization using:
Product-related variants include size-related, charge-related, acidic and glycosylation variants, while process-related/adventitious impurities include endotoxins, bacteria, fungi, mycoplasma and adventitious viruses.
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |