ATI of RMC-treated, CT-P13-treated or RMC to CT-P13 switched patients show full cross-reactivity with CT-P13 and SB2. Findings suggest that immunodominant epitopes in the reference and CT-P13 drugs are equally present in SB2. Data support full interchangeability between biosimilars in regard to immunogenicity.

Anti-IFX antibodies of Remicade-treated patients cross-react with either Inflectra or Remsima. Although additional epitopes may be present in the biosimilar, results suggest that epitopes influencing the immune response to IFX are also present in the biosimilar. Antibody-positive patients treated with Remicade should not be switched to the biosimilar, since antibodies will interact with the new drug and potentially lead to loss of response. This finding supports the utility for therapeutic drug monitoring before a switching strategy is considered.

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BackgroundPromonitor-ADL test is routinely used to monitor IBD patients treated with adalimumab (ADL). ABP 501 (adalimumab biosimilar; 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 in order to ensure safe application for patient monitoring as these may guide dose adjustments.ObjectivesHere we validate the suitability and performance of Promonitor-ADL CE-marked test for quantification of the adalimumab biosimilar ABP 501 in comparison to the reference adalimumab drug (Abbvie).MethodsThe validation study was in accordance with the design requirements established in the Clinical & 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, the reference drug and the adalimumab biosimilar ABP 501, over three 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%.ResultsThe LLOQ of Promonitor-ADL for the adalimumab biosimilar ABP 501 and reference adalimumab were 0.34 mg/mL and 0.36 mg/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 ABP 501 vs the reference adalimumab (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 ABP 501. The test is able to quantify the adalimumab biosimilar ABP 501 in the measurement range of 0.9 to 10.9 mg/mL with a bias estimate of -0.089 to 0.306 mg/mL and an overall imprecision of 6% to 9%. The measurement range includes the recommended clinical decision points.ConclusionPromonitor-ADL test can equivalently measure either the reference ADL or the approved adalimumab biosimilar ABP 501 with the same sensitivity, precision and accuracy.Disclosure of InterestsM. Begoña Ruiz-Argüello Employee of: Progenika Biopharma - Grifols employee, Ainara Maguregui Employee of: Progenika Biopharma - Grifols employee, Antonio Martínez Employee of: Progenika Biopharma - Grifols employee, Daniel Nagore Employee of: Pro...

BackgroundValidation 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.ObjectivesIn 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).MethodsThe 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.ResultsThe 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.ConclusionThis study demonstrates that Promonitor-ADL test can measure either the reference ADL drug or the adalimumab biosimilar SB5 with equivalent sensitivity, precision and accuracy.References[1] Feuerstein, et al 2017. Gastroenterology 153: 827–834 AGA Institute Guideline on Therapeutic Drug Monitoring in IBD.Disclosure of InterestsM. Begoña Ruiz-Argüello Employee of: Progenika Biopharma - Grifols employee, Ainara Maguregui Employee of: Progenika Biopharma - Grifols employee, Antonio Martínez Employee of: Progenika Biopharma - Grifols employee, Daniel Nagore Employee of: Progenika Biopharma - Grifols employee