Mechanism of action of therapeutic monoclonal antibodies: Promises and pitfalls of in vitro and in vivo assays

► The major known mechanisms of action of therapeutic mAbs are summarized. ► The methods and problems with cell death and proliferation assays are reviewed. ► The assays and pitfalls of immune mediated activities of antibodies are reviewed. ► Whether in vitro and in vivo assays of antibodies predict clinical efficacy is discussed.