The development, optimization and validation of an ELISA bioanalytical method for the determination of Cetuximab in human serum

Liquid Chromatography Tandem Mass Spectrometric Method for Quantification of Margetuximab in Rat Plasma and Application to a Pharmacokinetic Study

Margetuximab was approved for the treatment of advanced HER2+ breast cancer. A feasible analytical technique that can measure this drug was obligatory. In light of this, a novel and thoroughly validated liquid chromatographic (LC)-tandem mass spectrometric (MS/MS) approach was developed for the quantification of margetuximab in rat plasma. The liquid-liquid extraction method was used to extract the analyte from rat plasma. The analyte was separated using acetonitrile and formic acid buffer (30:70) as a mobile phase on Waters, alliance e-2695 model HPLC having Symmetry C18 column, 150 mm × 4.6 mm, 3.5-µm column. The overall runtime was 6 min at a flow rate of 1.0 ml/min. The method showed significant sensitivity and acceptable linearity over the concentration range of 6-120 ng/ml. Accuracy was within 98.51-99.92%. The intraday precision ranged between 0.41 and 8.98% CV. Also, the findings of pharmacokinetic parameters such as Cmax, tmax, AUC0-∞, AUC0-t, and half-life results of margetuximab showed that the technique was helpful for accurately measuring drug concentrations in rat plasma. The method that was developed was useful and effective for quantifying margetuximab.

Automated flow fluorescent noncompetitive immunoassay for measurement of human plasma levels of monoclonal antibodies used for immunotherapy of cancers with KinExA™ 3200 biosensor

This study describes, for the first time, the development of an automated sensitive flow fluorescent noncompetitive immunoassay based on kinetic-exclusion analysis (KinExA) for the quantitative determination of human plasma levels of monoclonal antibodies (mAbs) used for cancer immunotherapy. The assay was adapted on KinExA™ 3200 biosensor and optimized and validated for bevacizumab (BEV) and cetuximab (CET), as representative examples of the mAbs, using their specific antigens. These antigens were the human vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) for BEV and CET, respectively. The limits of detection were 1.28 and 52.64 ng mL^-1 for BEV and CET, respectively. The accuracy of the assay was demonstrated with analytical recovery of analytes from spiked plasma at 96.2-104.3 and 96.8-105.3% for BEV and CET, respectively. The precision of the assay was satisfactory as shown by relative standard deviation (RSD) at 2.2-5.7 and 2.5-6.1% for assay of BEV and CET, respectively. The high sensitivity of the assay allowed the use of very small volumes (~ 1 µL) of plasma sample for analysis. Automated analysis by the proposed KinExA-based assay facilitates the processing of large numbers of mAbs-containing specimens in studies of pharmacokinetics (PK), pharmacodynamics (PD), and therapeutic drug monitoring (TDM) of therapeutic mAbs. The proposed assay can be used to overcome the problems encountered in the existing conventional immunoassays for mAbs.

Development and use of specific ELISA methods for quantifying the biological activity of bevacizumab, cetuximab and trastuzumab in stability studies

Bevacizumab (BVZ), cetuximab (CTX) and trastuzumab (TTZ) are monoclonal antibodies (mAbs) used worldwide for the treatment of several widespread kinds of cancer. They are marketed as medicines under their respective tradenames: Avastin(®), Erbitux(®) and Herceptin(®). The aim of this research was to develop in-house specific enzyme-linked immunosorbent assays (ELISA) to assess the long-term stability of these three mabs. These assays assess the biological functionality of the mAbs by quantifying their biological activity. For this purpose, we developed an indirect ELISA procedure whereby the specific antigens against which the mAbs are directed are used as specific "capturing" antibodies on the ELISA plates. We therefore used vascular endothelial growth factor (VEGF) in the ELISA for BVZ; human epidermal growth factor receptor (hEGFR) in the ELISA for CTX and human receptor HER2 (hHER2) in the ELISA for TTZ. After the mAbs had attached to their antigen, we used an anti-human IgG (whole molecule) peroxidase-conjugate and o-phenylenediaminedihydrochloride substrate. The reaction was stopped using sulphuric acid and absorbance was recorded at a wavelength of 450nm. The three ELISA methods were validated in terms of calibration models, range of the assay, limits of detection and quantitation, intra and interday precision and accuracy, and specificity by cross reactions. Forced degradation studies were also conducted on the medicines, providing useful information. Finally, the proposed ELISA were successfully used in a long-term stability study to quantify the remaining biological activity in medicines that had been opened and then stored under two different storage conditions, i.e. refrigerated at 4°C and frozen at -20°C. Results indicated that BVZ (Avastin(®)) is the most stable of the three in terms of its biological functionality.

Versatile immunoassays based on isomagnetophoresis

We report an isomagnetophoretic immunoassay capable of detecting an attomolar level of proteins and adjusting the dynamic range of target analytes. Here, the magnetic nanoparticles are used as labels on microbeads in sandwich-type immunoassay, detecting the amount of bound analytes by isomagnetophoretic focusing the solid-support microbeads under the magnetic susceptibility gradient and magnetic field in a microchannel. For the practical purpose, this platform was applied to detect three types of breast cancer biomarkers.