Association of the clinical components in the distal interphalangeal joint synovio-entheseal complex and subsequent response to ixekizumab or adalimumab in psoriatic arthritis

Objectives: To assess the frequency of simultaneous distal interphalangeal (DIP) joint disease and adjacent nail psoriasis (finger unit) among patients with psoriatic arthritis (PsA) and compare the efficacy of the interleukin (IL)-17A antagonist ixekizumab (IXE) and the tumour necrosis factor (TNF)-alpha inhibitor adalimumab (ADA). Methods: This post hoc analysis evaluated the simultaneous occurrence of DIP joint involvement (tenderness and/or swelling) and adjacent nail psoriasis among patients with PsA from the SPIRIT-H2H (NCT03151551) trial comparing IXE to ADA. Among patients with simultaneous DIP joint involvement and adjacent nail psoriasis in >= 1 digit at baseline, treatment effects were assessed through week 52 for each affected finger unit; 'finger unit' defines the connected DIP joint and adjacent nail of an individual digit. Results: A total of 354 patients had simultaneous DIP joint involvement and adjacent nail psoriasis in >= 1 finger unit at baseline. Among them, 1309 (IXE = 639, ADA = 670) finger units had baseline DIP joint tenderness and/or swelling and adjacent nail psoriasis. Proportions of affected finger units achieving complete resolution were significantly higher with IXE vs ADA as early as week 12 (38.8% vs 28.4%, p< 0.0001) and at all post-baseline assessments through week 52 (64.9% vs 57.5%, p= 0.0055). Conclusions: In this study cohort, patients with DIP joint involvement almost always had adjacent nail psoriasis. Greater resolution of DIP joint tenderness, swelling, and adjacent nail psoriasis was achieved at all timepoints over 52 weeks through targeting IL-17A with IXE than TNF-alpha with ADA, which is noteworthy given prior comparable musculoskeletal outcomes for both drug classes. Graphical Abstract