Identification of Friend or Foe: The Laboratory Challenge of Differentiating M-Proteins from Monoclonal Antibody Therapies

Background: Since the first monoclonal antibody (mAb) therapy hit the market in 1996, the number of disorders treated with this class of therapeutics has seen tremendous growth, with over 50 antibody-based therapeutics currently approved for use in the US and Europe. This class of therapeutics recently made profound progress in the treatment of refractory multiple myeloma (MM). Treating MM with the mAbs will challenge the laboratory's ability to differentiate exogenous mAbs being used to treat patients from endogenous mAbs associated with disease. Content: An overview of the therapeutic mAbs (t-mAbs) developed for the treatment of MM is provided. The anticipated impact of these therapies on patient care, laboratory testing, and clinical research is discussed. Efforts underway to develop strategies and technologies to help laboratories address the growing challenge of mAb interferences are reviewed. Summary: Laboratories can implement risk mitigation strategies at the preanalytical and postanalytical phase of testing to reduce the likelihood of reporting false-positive M-protein results in patients receiving t-mAbs. However, at the analytical phase of testing, current laboratory methods are ill-suited to differentiate between residual disease and residual drugs. Mass spectrometry-based methods might be best positioned to aid laboratories with the rapidly evolving landscape of MM treatment.