Effectiveness and Safety of Upadacitinib in Treating Oligoarticular and Polyarticular Psoriatic Arthritis: Primary Analysis from the UPJOINT-Study.

INTRODUCTION: This study aimed to investigate the effectiveness and safety of upadacitinib in patients with either oligo- or polyarticular active psoriatic arthritis (oPsA/pPsA) in routine clinical practice. METHODS: UPJOINT is a post-marketing, multicenter observational study in patients with active psoriatic arthritis (PsA), treated with upadacitinib according to local label over a period of 48 weeks. The decision for treatment initiation with upadacitinib was independent of the study participation. The study's denominated primary endpoint was the proportion of patients achieving minimal disease activity (MDA) at week 24 under continuous treatment with upadacitinib. Furthermore, maintenance of MDA response at week 48 among those who achieved response at week 24 was evaluated. Also, very low disease activity (VLDA), and improvement of the Disease Activity Index for Psoriatic Arthritis (DAPSA) in oPsA/pPsA were further composite outcomes of interest evaluated at baseline and weeks 4, 12, 24, 36, and 48 after treatment initiation. Safety data were collected in a separate dataset using standardized operating procedures regarding the documentation of adverse events, followed by MedDRA hierarchy categorization using system organ classes. RESULTS: A total of 364 patients were included in the effectiveness dataset for an as-observed analysis. The proportion of patients achieving MDA increased from 3.6% (overall) at baseline, 7.1% (oPsA), and 1.3% (pPsA) to 41.5% (overall), 55.8% (oPsA), and 32.0% (pPsA) at week 24, respectively. At week 48, 47.5% of the patients with oPsA and 35.1% of the patients with pPsA achieved MDA. The proportion of MDA responders increased noticeably as early as week 4 in both subgroups (oPsA 38.4%, pPsA 16.3%). The proportion of patients achieving VLDA and DAPSA remission increased from 0% for both outcomes at baseline in patients with oPsA and pPsA to 22.2% and 14.3% and 24.2% and 14.9%, respectively, at week 48. Altogether 127 (33.3%) patients experienced 213 adverse events (AEs) with a reasonable possibility of being related to the study drug. Forty-one serious AEs were reported in 26 patients (6.8%). From the categorized AEs of particular interest, infections were most common. However, in line with previous clinical studies, no new safety signals were identified. CONCLUSION: Our data confirm that the effectiveness of upadacitinib in routine clinical practice is consistent with previous phase 3 trials for the treatment of active PsA, independent of the disease phenotype. Fast treatment effects reflected MDA achievement after 4 weeks of treatment in both PsA subgroups, similar to what is known from clinical studies. TRIAL REGISTRATION: NCT04758117 (ClinicalTrials.gov).