Validation of an Analytical Procedure for Evaluating the Biological Activity of a Medicinal Product Based on Tocilizumab and Determination of Acceptance Criteria for Test Results

INTRODUCTION. Bioanalytical techniques are characterised by greater variability and lower stability than physicochemical methods because live test systems are inherently labile. Since regulatory standards do not establish a unified approach, the selection of system suitability criteria and acceptance criteria for test results is based on validation studies.

AIM. This study aimed to validate an analytical procedure for evaluating the biological activity of a medicinal product based on the investigational tocilizumab biosimilar GNR-087 and determine the quantitative limits for system suitability criteria and acceptance criteria for test results.

MATERIALS AND METHODS. The biological activity of the investigational tocilizumab biosimilar was assessed by the inhibition of IL-6-induced secreted embryonic alkaline phosphatase (SEAP) expression by HEK-Blue™ IL-6 cells. Statistical processing of the obtained results was performed using Prism 6.0 software.

RESULTS. The specificity of the analytical procedure was confirmed by the dose-dependent inhibition of IL-6-induced SEAP expression by cells observed with tocilizumab. The analytical procedure was linear, with a coefficient of determination R²≥ 0.99. The precision of the analytical procedure was satisfactory; its repeat ability varied from 2 to 9%, and its intermediate precision was 14%. The recovery coefficients (Rc) for spiked samples simulating activity levels of 60–140%, including blinded samples, ranged from 80 to 120%. The theoretical values of relative potency (RP) were within the confidence intervals of the mean relative potency estimates, which confirmed the accuracy of the analytical procedure. The validation confirmed the robustness of the analytical procedure to controlled variations, including the use of reporter cells at different passages (with a coefficient of variation for relative potency estimates (CV_RP) of 10%), different IL-6 lots (with a CV_RP of 1%), and different SEAP detection reagent lots (with a CV_RP of 3%); the Rc remained in the range of 80–120% of the nominal RP value.

CONCLUSIONS. The analytical procedure for evaluating the biological activity of the investigational tocilizumab biosimilar meets the validation criteria, including accuracy, linearity, precision, specificity, and robustness. The study established system suitability criteria and acceptable limits for biological assay results. This analytical procedure can be used both for routine biological activity control and for demonstrating the biosimilarity of new medicinal products to the original (reference) tocilizumab-based medicinal product.

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