title: Measuring humanized antibodies in plasma of patients treated with antibody-based therapy using bead-based flow cytometry: the story of alemtuzumab.
abstract: Alemtuzumab (Campath), the humanized rat monoclonal antibody that targets the CD52 surface antigen, is currently used for treatment of patients with resistant chronic lymphocytic leukemia. Monitoring levels of the antibody in plasma/serum could provide insight into the optimal dosing and scheduling of therapy. Current methods of detecting alemtuzumab in serum or plasma are complicated and difficult to adapt to high-throughput testing. We describe a novel bead-based assay that measures circulating alemtuzumab by taking advantage of remnant rat sequence in the antibody. Levels of total alemtuzumab complexed with CD52, and free alemtuzumab are quantitated in the serum or plasma by flow cytometry. This approach is applicable to the measurement of other humanized antibodies that contain an appropriate remnant animal sequence.
authors.affiliation: Department of Hematopathology, Quest Diagnostics Nichols Institute, San Juan Capistrano, CA, USA.
authors.forename: Huai En Huang
authors.initials: HE
authors.lastname: Chan
authors.forename: Iman
authors.initials: I
authors.lastname: Jilani
authors.forename: Richard
authors.initials: R
authors.lastname: Chang
authors.forename: Maher
authors.initials: M
authors.lastname: Albitar
mesh_terms: D000074323:Alemtuzumab; D000818:Animals; D000911:Antibodies, Monoclonal / Q000097:blood / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm / Q000097:blood* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000097:blood / Q000627:therapeutic use*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D009369:Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm; D000970:Antineoplastic Agents; D007074:Immunoglobulin G; D000074323:Alemtuzumab