Background: Filgotinib (FIL) is an oral, selective Janus kinase 1 inhibitor that, compared with placebo (PBO), significantly improved patient-reported outcomes in active psoriatic arthritis (PsA) in the phase 2 EQUATOR randomized controlled trial (RCT; NCT03101670) [1]. PsA Impact of Disease (PsAID) is a validated, EULAR-developed, PsA-specific questionnaire for measurement of health–related quality of life (HRQoL) [2]. PsAID is less complex than generic HRQoL tools, such as the 36–Item Short Form Survey (SF–36). To our knowledge, this is the first RCT reporting efficacy results using PsAID9.

Objectives: To determine the effect of FIL vs PBO on PsAID9 in participants of EQUATOR.

Methods: EQUATOR was a multicenter, double-blind study in which patients were randomized 1:1 to FIL 200 mg or PBO once daily for 16 weeks [1]. HRQoL was assessed at weeks 4 and 16 with PsAID9 (total and individual domain scores [each scored 0–10]) and, for comparison, with the Physical Component Summary (PCS) and Mental Component Summary (MCS) of SF-36. Higher PsAID scores correspond to greater impact of PsA [2]. Analysis of covariance was used to compare outcomes between groups.

Results: There were 131 participants in EQUATOR (FIL: n=65; PBO: n=66). Mean (standard deviation [SD]) age was 49 (12.2) and 50 (10.9) years and mean (SD) baseline PsAID9 scores were 5.8 (1.6) and 5.7 (2.0) for FIL and PBO, respectively. Effects of FIL on PsAID9 and SF-36 scores were observed as early as week 4. FIL significantly improved PsAID9 total scores vs PBO; at week 16, PsAID9 total scores were 3.5 (2.0) for FIL and 4.9 (2.2) for PBO. Mean change (SD) from baseline at week 16 was –2.3 (1.8) vs

–0.8 (2.2), respectively (Figure 1a); least-squares (LS) mean of group difference (95% confidence interval) was –1.48 (–2.12, –0.84), p<0.0001. At week 16, significant improvements were observed in all nine individual PsAID9 domains for FIL vs PBO, including pain (p<0.0001; Figure 1b). A significant improvement in SF–36 PCS, but not in MCS, with FIL vs PBO was observed. The mean change (SD) from baseline in PCS at week 16 was 7.4 (6.6) vs 2.4 (6.6) for FIL vs PBO, respectively (LS mean of group difference 4.67 [2.58, 6.76], p<0.0001).

Conclusion: Compared with PBO, FIL significantly improved disease impact in patients with active PsA, as measured by the PsA-specific PsAID9 total score and individual domain scores. Significant improvement in SF-36 PCS score was also seen with FIL.

Reference [1] Mease P, et al. Lancet 2018;392:2367–77. 2. Orbai AM, et al. J Rheumatol2018;doi: 10.3899/jrheum.181077.

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Acknowledgement: This study was funded by Galapagos NV (Mechelen, Belgium). Medical writing support was provided by Alice Wareham PhD, CMPP (Aspire Scientific Ltd, Bollington, UK) and funded by Galapagos NV.

Disclosure of Interests: Ana-Maria Orbai Grant/research support from: AbbVie, Celgene, Horizon Pharma, Janssen, Lilly, and Novartis, Consultant for: Lilly, Janssen, Novartis, Pfizer, and UCB, Alexis Ogdie Grant/research support from: (To my university) Novartis, Pfizer, Grant/research support from: Novartis, Pfizer, Grant/research support from: Novartis, Pfizer, Grant/research support from: Novartis, Pfizer, Consultant for: AbbVie, Bristol-Myers Squibb, Celgene, Corrona, Eli Lilly and Company, Novartis, Pfizer, and Takeda, Consultant for: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Corrona, Eli Lilly, Novartis, Pfizer Inc, Takeda, Consultant for: Abbvie, Amgen, BMS, Celgene, Corrona, Lilly, Novartis, Pfizer, Takeda, Consultant for: Abbvie, Amgen, BMS, Celgene, Corrona, Lilly, Novartis, Pfizer, Takeda, Laure Gossec Grant/research support from: AbbVie, BMS, Celgene, Janssen, Lilly, MSD, Novartis-Sandoz, Pfizer, Sanofi, and UCB, Consultant for: AbbVie, Biogen, BMS, Celgene, Janssen, Lilly, MSD, Nordic Pharma, Novartis-Sandoz, Pfizer, Roche, Sanofi, and UCB, Consultant for: L Gossec has received honoraria from Celgene as investigator for this study, William Tillett Grant/research support from: AbbVie, Celgene, and Lilly, Consultant for: AbbVie, Celgene, Lilly, Novartis, and Pfizer, Speakers bureau: Abbvie, Celgene, Lilly, Janssen, Novartis, UCB, and Pfizer, Ying Ying Leung Grant/research support from: Abbvie, Novartis, Speakers bureau: Abbvie and Novartis, Speakers bureau: Novartis, Jingjing Gao Shareholder of: AbbVie and Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., Mona Trivedi Shareholder of: Amgen and Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., Chantal Tasset Shareholder of: Warrants from Galapagos, Employee of: Galapagos, Luc Meuleners Shareholder of: Warrants from Galapagos, Employee of: Galapagos, Robin Besuyen Shareholder of: Warrants from Galapagos, Employee of: Galapagos, Thijs Hendrikx Shareholder of: Warrants from Galapagos, Employee of: Galapagos, Laura C Coates Grant/research support from: AbbVie, Celgene, Lilly, Novartis and Pfizer, Consultant for: AbbVie, Amgen, BMS, Celgene, Galapagos, Gilead Sciences Inc., Janssen, Lilly, Novartis, Pfizer, Prothena Corp and UCB