THU0026 TARGETING SYNOVIAL FIBROBLASTS IN RHEUMATOID ARTHRITIS BY PEFICITINIB AND FILGOTINIB
Authors: Magnus Diller, Rebecca Hasseli, Iris Aykara, Marie Hülser, Stefan Rehart, Ulf Müller-Ladner, Elena Neumann
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> The Janus kinase inhibitors (JAKi) peficitinib and filgotinib are currently examined in clinical trials for treatment of rheumatoid arthritis. Both inhibitors are well tolerated up to doses causing Cmax values higher than 1 µM [1,2]. This is in contrast to the approved dosages of tofacitinib and baricitinib reaching Cmax values below 0.5 µM [3,4]. However, it is not known if the higher concentrations of peficitinib or filgotinib offer a benefit in treatment of rheumatoid arthritis. <h3>Objectives</h3> The aim of the study compared the effect of different JAKi on inflammatory response and functional behavior of fibroblast-like synoviocytes from patients with RA (RASF). <h3>Methods</h3> Human RASF were isolated and pretreated with JAKi. After stimulation with IL-1β and JAKi with/without soluble IL-6 receptor (sIL-6R) the levels of IL-6 and MMP-3 were measured in supernatants by ELISA. The effect of different JAKi on proliferation of RASF was determined by a BrdU-incorporation assay. The influence of peficitinib on migration of RASF towards a FCS gradient was examined. For short-term adhesion assays, cells were treated with JAKi, detached and seeded in culture plates. The plates were extensively shaken and adherent RASF quantified by counting crystal violet stained cells. Cell viability, cytotoxicity and apoptosis were measured using commercially available assays. <h3>Results</h3> The IL-1β (10 ng/ml) dependant IL-6 release of RASF was decreased by peficitinib (62%, p&lt;0.001) and by filgotinib (30%, p&lt;0.05, n=7) at 5 µM. Peficitinib also decreased the IL-6 release at 1 µM (24%, n=7). In contrast to filgotinib, the JAK-inhibition with peficitinib reduced the MMP-3 levels induced by IL-1β by 88% (n=7, p&lt;0.001) at 5 µM and by 31% at 1 µM (n=7, ns). In direct comparison to tofacitinib and baricitinb the IL-1β (20 ng/ml) induced IL-6 increase was only decreased by peficitinib and filgotinib but not by tofacitinib or baricitinib even at 10 µM. Tofacitinib only blocked the specific IL-6 effect e.g. induced by the combination of the soluble IL-6 receptor (sIL-6R) and low doses of IL-1β (p&lt;0.01). The proliferation of RASF was attenuated by tofacitinib, baricitinib and peficitinib at 5 µM. Peficitinib exerted the strongest decrease of about 70% (p&lt;0.001, n=4) and it was the only inhibitor attenuating the proliferation at 1 µM (23%, p&lt;0.05, n=4). Peficitinib also decreased the migration of RASF by 38% at 1 µM and by 92% at 5 µM. The observed effects were not mediated by apoptosis and even after 48h peficitinib did not act cytotoxic on RASF. In contrast to migration, short-term adhesion onto a plastic surface was not affected by peficitinib. <h3>Conclusion</h3> Peficitinib and filgotinib modulated the IL-1β-induced response of RASF. Peficitinib also inhibited the proliferation and the migration of RASF. Therefore, especially peficitinib could be able to reduce the aggressive pannus formation in RA patients. <h3>References</h3> [1] Cao YJ, et al.: Pharmacokinetics, Pharmacodynamics, and Safety of ASP015K (Peficitinib), a New Janus Kinase Inhibitor, in Healthy Subjects. Clin Pharmacol Drug Dev 2016;5:435-449. [2] Vanhoutte F, et al.: Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Filgotinib, a Selective JAK-1 Inhibitor, After Short-Term Treatment of Rheumatoid Arthritis: Results of Two Randomized Phase IIa Trials. Arthritis Rheumatol 2017;69:1949-1959. [3] Lamba M, et al.: Evaluation of Pharmacokinetics Compared With Immediate-Release Tofacitinib and Impact of Food. J Clin Pharmacol 2016;56:1362-1371. [4] Shi JG, et al.: The pharmacokinetics, pharmacodynamics, and safety of baricitinib, an oral JAK 1/2 inhibitor, in healthy volunteers. J Clin Pharmacol 2014;54:1354-1361. <h3>Disclosure of Interests</h3> Magnus Diller: None declared, Rebecca Hasseli: None declared, Iris Aykara: None declared, Marie Hülser: None declared, Stefan Rehart: None declared, Ulf Müller-Ladner Grant/research support from: Projekt supported by an unrestricted educational grant from Celgene GmbH., Elena Neumann: None declared