Can we predict which patients with psoriatic arthritis will respond to treatment using precision medicine?

INTERVENTION: All patients will be treated with a biologic drug (TNF inhibitors (adalimumab) or IL‐17A inhibitors (secukinumab) in keeping with routine clinical practice. At present both TNF inhibitors and IL‐17 inhibitors are licensed and NICE approved as first line biologics in PsA. Patients will be randomised in a 1:1 ratio to receive either TNF or IL‐17A inhibitors, stratified by baseline immunophenotype, for 24 weeks. The TNF inhibitor to be used is adalimumab (any brand) and it is to be given at the usual licensed dose, as per the SmPC: ‐The licenced dose of adalimumab for psoriatic arthritis is always 40 mg by subcutaneous injection every 2 weeks, with no loading doses. The IL‐17A inhibitor to be used is secukinumab, brand name Cosentyx, and is to be given at the usual licensed dose as per the SmPC: ‐The licensed dose of secukinumab for psoriatic arthritis varies based on the level of baseline skin psoriasis. For patients with concomitant moderate to severe plaque psoriasis, the recommended dose is 300mg by subcutaneous injection with initial dosing at weeks 0, 1, 2, 3 and 4 followed by a monthly maintenance dose. For other patients the recommended dose is 150mg by subcutaneous injection at the same timepoints. This study will follow routine practice and the current label by using the appropriate dose of secukinumab based on the baseline psoriasis disease activity with the cut off for moderate to severe psoriasis as 10% body surface area. Dose escalation as per the licence is permitted. CONDITION: Arthritis that affects some people with the skin condition psoriasis ; Musculoskeletal Diseases ; Psoriatic and enteropathic arthropathies PRIMARY OUTCOME: Clinical response as measured by the minimal disease activity (MDA) criteria at baseline and week 24 SECONDARY OUTCOME: ; 1. Clinical disease pattern at baseline measured by the minimal disease activity (MDA) criteria; 2. Immunophenotype data at baseline measuring activated Th17 and intracellular levels of IL‐17; 3. Activated Th17 proportion and intracellular levels of IL‐17 at baseline and week 24; 4. Clinical response as measured by the minimal disease activity (MDA) criteria at week 12/16 and week 24; 5. Cell‐specific transcriptomic data and whole blood transcriptomes from samples collected at baseline and week 24.; INCLUSION CRITERIA: 1. Participant is willing and able to give informed consent for participation in the study 2. Male or female, age 18 years or over 3. Diagnosis of PsA confirmed by the CASPAR criteria 4. Is planned to have biologic therapy for psoriatic arthritis using NICE/SMC criteria (failure of >=2 csDMARDs and >=3 tender/swollen joints)