FRI0645 EVALUATION OF MARKETED KITS FOR MEASUREMENT OF ABP 501, THE FIRST APPROVED ADALIMUMAB BIOSIMILAR, DRUG CONCENTRATION AND ANTI-DRUG ANTIBODY LEVELS IN PATIENT SERUM
Authors: Dan Mytych, Marta Starcevic Manning, Alexander Colbert, Sarah Hoofring, Jill Miller, Melissa Gessner, Vincent Chow, Gary Fanjiang
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Adalimumab and its biosimilars are anti-tumour necrosis factor (TNF)- monoclonal antibodies that are approved in Europe as treatment for various autoimmune-related indications, including Crohn's disease and ulcerative colitis. Despite the clinical success of adalimumab, some patients show a diminished response after prolonged treatment. It is known that serum adalimumab trough levels are correlated with clinical response and the development of anti-adalimumab antibodies (AAA) may negatively impact trough levels. Currently, therapeutic drug monitoring (TDM) is used to measure adalimumab concentration and/or AAA allowing individualized optimization of treatment regimens. This then facilitates better clinical outcomes by avoiding delay in treatment decisions. Therefore, having a single assay that provides reliable TDM for both adalimumab and adalimumab biosimilars is important for physicians and patients. ABP 501, the first adalimumab biosimilar, is approved for the same indications as adalimumab (except those protected by regulatory exclusivity). <h3>Objectives</h3> The aim of this study was to evaluate the Promonitor® TDM kits for measurement of drug levels and AAA in serum samples from a selected representative subset of subjects, treated with ABP 501 or adalimumab reference product (RP) in the phase 3 study (NCT01970475). <h3>Methods</h3> A total of 30 subjects (15 ADA-positive; 15 ADA-negative) served as a representative subset in this evaluation. AAA positive control antibody and serum samples from subjects treated with either ABP 501 or adalimumab RP in the Phase 3 study were used to assess the suitability of the TDM (Promonitor®) kits for AAA (Promonitor® ANTI-ADL) and quantitative drug detection (Promonitor® ADL). <h3>Results</h3> The Promonitor®-ANTI-ADL TDM kit was able to detect a low level (10 ng/ml) of AAA positive control antibodies for ABP 501. In subjects whose serum was evaluated (18 treated with ABP 501 adalimumab biosimilar and 10 treated with adalimumab RP), the TDM kit produced 100% concordant positive or negative AAA results when compared to the assay that had been used in the phase 3 study. The quantitative drug assessment in subjects whose serum was evaluated (11 treated with ABP 501 and 9 treated with adalimumab RP) using the Promonitor® ADL TDM kit displayed a high degree of correlation (average Pearson's r = 0.987) compared with results obtained in the phase 3 study. <h3>Conclusion</h3> This evaluation indicates that the Promonitor® kits are suitable for use in routine detection of AAA and in quantitating serum levels of the ABP 501 adalimumab biosimilar in patients. <h3>Acknowledgement</h3> Monica Ramchandani <h3>Disclosure of Interests</h3> Dan Mytych Shareholder of: Amgen, Employee of: Amgen, Marta Starcevic Manning Shareholder of: Amgen, Employee of: Amgen, Alexander Colbert Shareholder of: Amgen, Employee of: Amgen, Sarah Hoofring Shareholder of: Amgen, Employee of: Amgen, Jill Miller Shareholder of: Amgen, Employee of: Amgen, Melissa Gessner Shareholder of: Amgen, Employee of: Amgen, Vincent Chow Shareholder of: Amgen, Employee of: Amgen, Gary Fanjiang Shareholder of: Amgen, Employee of: Amgen