PsA is a systemic inflammatory condition that affects 20-30% of patients with psoriasis. It is characterized by potential involvement of diverse tissues, including peripheral and axial joints, enthesitis, dactylitis and skin and nail disease. The degree of involvement in each domain can vary over time in individual patients and can differ substantially between PsA patients. The clinical heterogeneity along with the varying extent of severity and activity can pose significant challenges to treatment. Although some studies had suggested immunopathophysiological similarities between PsA and RA, more recently important distinctions have been defined. Similarly, although some immunomodulatory therapies have proved effective for both PsA and RA, recent data suggest distinct responses to certain targeted therapies. Herein, current DMARDs and biologic agents as well as the potential role of emerging therapeutics will be reviewed.

ObjectiveTo determine the duration of clinical benefit among patients with psoriatic arthritis (PsA) discontinuing tumour necrosis factor inhibitor (TNFi) therapy while in low disease activity (LDA), and to identify patient characteristics associated with prolonged clinical benefit.MethodsWe performed an observational cohort study assessing patients with PsA from the Consortium of Rheumatology Researchers of North America (CORRONA) registry who had discontinued TNFi after achieving LDA, defined as clinical disease activity index (CDAI) score ≤10 and physician's global assessment (PGA) of skin psoriasis ≤20/100. Kaplan–Meier method was used to estimate the duration of clinical benefit.ResultsOf the 5945 patients with PsA in CORRONA, 302 patients had discontinued TNFi (n=325) while in LDA and had follow-up data available. At time of discontinuation, mean PsA duration was 9.8 years, mean CDAI was 3.9, and mean duration of TNFi use was 1.5 years; 52.6% of patients had discontinued their first TNFi. Median time to loss of benefit was 29.2 months. 179 (55.1%) patients had persistent benefit at their previous clinic visit. An increased risk of losing clinical benefit was seen among patients with higher disease activity at discontinuation (CDAI≥3.2 vs <3.2; HR 1.43 (p=0.32)) and among smokers (HR 1.78 (p=0.027)).ConclusionsPatients with PsA who achieve LDA may maintain clinical benefit after discontinuation of TNFi therapy.

ObjectivesTo compare baseline characteristics between patients with psoriatic arthritis (PsA) who achieved and did not achieve minimal disease activity (MDA) with biologic therapy in the US-based Corrona Psoriatic Arthritis/Spondyloarthritis Registry.MethodsPatients with PsA aged ≥18 years enrolled between March 2013 and March 2016 who were receiving biologics at enrolment (baseline), not in MDA and had ≥2 follow-up visits were included. Patients were classified as those who remained on their index biologic and achieved MDA at the second follow-up visit (MDA achievers (MDA-A)) and those who did not (MDA non-achievers (MDA-NA)). Demographics, clinical characteristics, patient-reported outcomes and medication history were compared between groups.ResultsOf 148 patients with PsA who met the inclusion criteria, 34 (23.0%) and 114 (77.0%) were classified as MDA-A and MDA-NA, respectively. At baseline, most patients (96.6%) were receiving tumour necrosis factor inhibitors, and both groups were similar in age, sex, race, medication history, enthesitis and dactylitis counts, disease duration and comorbidities. Compared with MDA-A, MDA-NA had significantly worse mean tender joint count (7.2 vs 3.4), patient-reported pain (51.2 vs 35.7), patient-reported fatigue (54.1 vs 42.4), physical function (Health Assessment Questionnaire, 1.0 vs 0.6), Bath Ankylosing Disease Activity Index (5.0 vs 3.4) and Bath Ankylosing Spondylitis Functional Index (4.0 vs 2.0) scores (all p<0.05).ConclusionsApproximately one in four patients achieved MDA with their index biologic at the time of the second follow-up visit. Both groups were similar in several baseline demographic and clinical features; however, patients who did not achieve MDA generally had worse tender joint counts and patient-reported outcomes.

Presently, it is agreed upon that use of tumor necrosis factor inhibitors (TNFi) has greatly changed our ability to manage varying aspects of disease in PsA. However, there remain many unanswered questions in which research in PsA is mirroring RA work, these include: i) the need for outcome measures that are more specific to PsA, ii) the concept of early and treat to target, iii) the role of highly sensitive imaging, and iv) efficacy of combination therapy and further targets in those unable to tolerate or fail TNFi.

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