Development and Validation of a Simoa Assay for Determination of Recombinant Batroxobin in Human Serum

Recombinant batroxobin (S3101) is a thrombin-like serine protease that binds to fibrinogen or is taken up by the reticuloendothelial system. A literature survey showed no adequate method that could determine sufficient concentrations to evaluate pharmacokinetic parameters for phase I clinical studies. Therefore, a sensitive method is urgently needed to support the clinical pharmacokinetic evaluation of S3101. In this study, a sensitive bioanalytical method was developed and validated, using a Quanterix single molecular array (Simoa) assay. Moreover, to thoroughly assess the platform, enzyme-linked immunosorbent assay and electrochemiluminescence assay were also developed, and their performance was compared with that of this novel technology platform. The assay was validated in compliance with the current guidelines. Measurements with the Simoa assay were precise and accurate, presenting a valid assay range from 6.55 to 4000 pg/mL. The intra- and inter-run accuracy and precision were within -19.3% to 15.3% and 5.5% to 17.0%, respectively. S3101 was stable in human serum for 280 days at -20°C and -70°C, for 2 h prior to pre-treatment and 24 h post pre-treatment at room temperature (22°C-28°C), respectively, and after five and two freeze-thaw cycles at -70°C and -20°C, respectively. The Simoa assay also demonstrated sufficient dilution linearity, assay sensitivity, and parallelism for quantifying S3101 in human serum. The Simoa assay is a sensitive and adequate method for evaluating the pharmacokinetic parameters of S3101 in human serum.