New Binding Efficacy and Mode of Action Assays for Rituximab

July 26, 2011 - Charles River offers a wide variety of optimized, fully GMP-compliant bioassays. As part of our vast portfolio of products and services, we now offer two new bioassays for Rituximab–an approved chimeric monoclonal antibody for the treatment of cancer.

Binding Assay for Rituximab

This flow cytometry-based binding assay measures the binding efficacy of Rituximab to CD20-expressing Ramos human lymphoma cells. In this test, Rituximab is titrated on these cells and a fluorescently labeled antihuman secondary antibody is used to detect Rituximab’s dose-dependent binding. This Rituximab binding assay was validated according to ICH guideline Q2 (R1).

ADCC Mode of Action Assay for Rituximab

Antibody-Dependent Cell-mediated Cytotoxicity (ADCC) refers to a cell-mediated reaction. Target cells coated with a therapeutic antibody are killed by effector cells. In this mode of action assay, natural killer (NK) cells–derived from periphery blood mononuclear cells (PBMC) of healthy donors–are used as effector cells. NK cells recognize their target cells via the receptors for the Fc fragment of IgG (FcgRIIIA, CD16) that bind to antibody bound to the surface of the target cells. Binding of NK cells to target cells induces lysis of the target cells by direct cell-to-cell contact.

Expertise in Bioassay Development

Charles River has immense experience in the development of cell-based potency and mode of action assays for monoclonal antibodies (e.g., Trastuzumab, Bevacizumab and Infliximab) as well as assays for recombinant proteins (e.g., interferons, erythropoietins and various growth factors). All services are performed in full compliance with cGMP.

Both assays–binding and mode of action for Rituximab–will be presented at BEBPA's 4th Annual Bioassay Conference on September 28-30, 2011, in Nice, France. To learn more about either of these assays, please email us at askcharlesriver@crl.com.