A rapid and universal liquid chromatograph-mass spectrometry-based platform, refmAb-Q nSMOL, for monitoring monoclonal antibody therapeutics

Accurate quantitation of antibody is critical for development of monoclonal antibody therapeutics (mAbs). Therapeutic drug monitoring has been applied to measure levels of mAbs in clinics for dose adjustment for autoimmune disease. Trough levels of mAbs can be a biomarker for cancer immunotherapy. Thus, the deployment of a rapid and universal platform for mAb monitoring may benefit processes ranging from drug development to clinical practice for a wide spectrum of diseases. However, mAb monitoring often requires development and conduct of an individual ligand binding assay such as ELISA, which is impractical to scale. We streamlined quantitation of antibody therapeutics by a nano-surface and molecular-orientation limited (nSMOL) proteolysis assay using LC-MS with a universal reference antibody (refmAb-Q), for accurate multiplexed quantitation of unique signature peptides derived from mAbs. This innovative refmAb-Q nSMOL platform may provide a practical solution for quantitating an ever-increasing number of mAbs from developmental to clinical use settings. ### Competing Interest Statement YK: research support from Bristol Myers Squibb (BMS), GlaxoSmithKline, and Shimadzu. ET: advisory boards: PACT Pharma and Genocea Bioscience; research support from Shimadzu. BAF: research support from Shimadzu, The Harder Family, Robert and Elsie Franz, Wes and Nancy Lematta, Lynn and Jack Loacker, the Providence Portland Medical Foundation and the Oral and Maxillofacial Surgery Foundation, The Murdock Trust. BDP: research support from Heat Biologics, Eli Lilly, Illumina, and Shimadzu; advisory boards: Bayer, Takeda, and Optum Labs. WLR: research support from Galectin Therapeutics, BMS, GlaxoSmithKline, MiNA Therapeutics, Inhibrx, Veana Therapeutics, Aeglea Biotherapeutics, Shimadzu, OncoSec, and Calibr; patents/licensing fees: Galectin Therapeutics; advisory boards: Nektar Therapeutics, Vesselon, and Medicenna. AH: research support from Japan Agency for Medical Research and Development, Shimadzu, Daiichi Sankyo, Chugai Pharmaceutical, and AstraZeneca. AY: research support from Shimadzu.