AB0404 VALIDATION OF A THERAPEUTIC DRUG MONITORING TEST TO MEASURE THE ADALIMUMAB BIOSIMILAR SB5 IN COMPARISON WITH THE REFERENCE ADALIMUMAB

Abstract

Background Validation of therapeutic drug monitoring (TDM) tests is an essential requirement for using these tools to help assess reasons for non-response. The arrival of biosimilars has prompted a need to validate that existing TDM tests are suitable to determine drug levels for all versions of a given molecule. The adalimumab (ADL) biosimilar SB5 (Biogen) was authorised by the European Commission in August 2017, and has recently become available for prescription in several European countries. Promonitor-ADL test is routinely used to monitor IBD patients treated with ADL. Objectives In this study we validated the suitability and performance of Promonitor-ADL CE-marked TDM test for quantifying SB5 serum concentrations in comparison to reference adalimumab (Abbvie). Methods The study evaluated imprecision and bias applied to the reference ADL and SB5 biosimilar. The validation study was in line with the design requirements established in the Clinical & Laboratory Standards Institute (CLSI) guideline EP10-A3 for the determination of imprecision and bias. Imprecision was evaluated using three replicates of five human serum sample matrices representative of clinically relevant ADL concentrations and spanning the measurement range of Promonitor-ADL.1 Validations were ran on one instrument with one kit lot by one operator over six non-consecutive operating days and one run per testing day, with an acceptance criterium of CV%=20%. The Lower Limit of Quantification (LLOQ) of Promonitor-ADL was determined according to CLSI guideline EP17-A2. Results The imprecision of Promonitor-ADL was calculated by estimating the components of variance due to within-run and between-day factors meet the accuracy goals proposed at all concentration levels of SB5 vs the reference adalimumab (CV% between 5% and 12%). The assessment of accuracy showed that Promonitor-ADL equally measures the active moiety of the reference adalimumab or the adalimumab biosimilar SB5. The test is able to quantify SB5 in the measurement range of 0.9 to 10.9 mg/mL with a bias estimate of -0.124 (1%) to 0.897 (10%) mg/mL and an overall imprecision of 5% to 11%. The measurement range includes the recommended clinical decision points. LLOQ of the test to determine ADL was determined to be 0.36 mg/mL. Conclusion This study demonstrates that Promonitor-ADL test can measure either the reference ADL drug or the adalimumab biosimilar SB5 with equivalent sensitivity, precision and accuracy.