P329 Adalimumab therapeutic drug monitoring test validated for measuring ABP 501 biosimilar

Abstract Background Promonitor®-ADL test is routinely used to monitor IBD patients treated with adalimumab (ADL). ABP 501 [adalimumab biosimilar; EU: AMGEVITA® (adalimumab); US: AMJEVITAT (adalimumab-atto), Amgen] was authorised throughout the European Union in March 2017 and has been recently launched in several countries. Therapeutic drug monitoring (TDM) is broadly used as an aid for patient management. However, all TDM tests available should be properly validated against each new approved biosimilar to ensure safe application for patient monitoring as these may guide dose adjustments. Here we validate the suitability and performance of Promonitor-ADL CE-marked test for quantification of AMGEVITA in comparison to the reference HUMIRA®. Methods The validation study was in accordance with the design requirements established in the Clinical and Laboratory Standards Institute (CLSI) guideline EP17-A2 (Lower Limit of Quantification, LLOQ) and EP10-A3 (imprecision and bias). CLSI guidelines set a standard for the diagnostic industry accepted by all regulatory agencies. LLOQ was determined with four independent human serum sample matrices per each of three low level ADL concentrations, replicated three times per two lots of Promonitor-ADL (Progenika, Spain) kits for each drug HUMIRA and AMGEVITA over 3 days by one operator. 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, run 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 criteria of CV%≤20%. Results The LLOQ of Promonitor-ADL for AMGEVITA and HUMIRA were 0.34 μg/ml and 0.36 μg/ml, respectively. LLOQ values met accuracy goal proposed based on total error ≤25% and precision. The imprecision of Promonitor-ADL 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 AMGEVITA vs. HUMIRA (CV% between 5% and 10%). The bias study showed that Promonitor-ADL can equally measure the active moiety ADL either in the reference biologic ADL or in the biosimilar AMGEVITA. The test is able to quantify AMGEVITA in the measurement range of 0.9 to 10.9 μg/ml with a bias estimate of −0.089 to 0.306 μg/ml and an overall imprecision of 6% to 9%. The measurement range includes the recommended clinic