Development of an LC–TOF/MS Method to Quantify Camrelizumab in Human Serum

With the advantages of a high specificity, a long half-life, and a high safety, the use of antibody biologic drugs, including camrelizumab, has been rapidly increasing in clinical practice. Camrelizumab, an immune checkpoint inhibitor and humanized monoclonal antibody, is used to treat several advanced solid cancers. Measuring its concentration supports personalized dosage adjustments, influences treatment decisions for patients, strengthens the control of disease activity through therapeutic drug monitoring, and helps evaluate and prevent drug interactions in combination therapy. Because antibodies are present in complex biological matrices, quantifying monoclonal antibody drugs is challenging, and must rely on precise, selective, and reliable analytical methods. In this study, a quadrupole time-of-flight mass spectrometry TripleTOF 6600+ (AB SCIEX, Framingham, MA, USA) system equipped with a Turbo V ion source was used for the qualitative analysis of monoclonal antibodies using the data-dependent acquisition (IDA) MS/MS mode, followed by quantitative analysis using a targeted MRMHR workflow. This method showed a good linear relationship within the range of 4-160 μg/mL, with a correlation coefficient of R² ≥ 0.996. It demonstrated an acceptable accuracy (88.95-101.18%) and precision (≤15%). Furthermore, the lower limit of quantification was found to be 4 μg/mL, with the lowest detection limit of 0.3217 μg/mL, indicating that this method is rapid, accurate, and reliable for the quantitative analysis of camrelizumab in human serum.