By week 24 in the study, a significantly higher proportion of patients receiving tildrakizumab (at any dose) achieved a 90% reduction in Psoriasis Area and Severity Index (PASI 90), and a 50% reduction in American College of Rheumatology response criteria (ACR 50) versus placebo. There were four active treatment groups in which patients received 20mg, 100mg or 200mg tildrakizumab every 12 weeks, or 200mg every four weeks.
The response rates improved with increasing dose however the shortening of dosing interval of 200mg from 12 to four weeks did not result in a measurable increase in skin or joint response scores. In patients receiving 200mg tildrakizumab every 12 weeks, 79.6% and 50% achieved PASI 75 and PASI 90 respectively versus 16.7% and 7.1% in the placebo group (p<0.0001).
"Our results demonstrate a clear separation between tildrakizumab and placebo as early as eight weeks," said Philip Mease, MD, MACR, Swedish Medical Center/Providence St. Joseph Health and the University of Washington, Seattle, Washington, USA. "A promising role is suggested for tildrakizumab in the treatment of patients suffering with psoriatic arthritis."
Psoriatic arthritis is a chronic inflammatory disease that affects the joints, causing pain and disability. Tildrakizumab is a high-affinity, humanised, monoclonal antibody targeting interleukin (IL) 23p19 and is currently approved to treat moderate-to-severe plaque psoriasis.
Current recommendations state that, in psoriatic arthritis patients with peripheral arthritis (one or more tender and swollen joints), biological disease-modifying anti-rheumatic drugs (DMARDs) targeting IL 12/23 or IL-17 pathways may be considered in patients who have had an inadequate response to conventional synthetic DMARDs and for whom tumour necrosis factor inhibitors are not appropriate.
"We welcome these promising results for tildrakizumab in patients with psoriatic arthritis," said Professor Hans Bijlsma, President, EULAR. "Extending research into different patient groups may bring benefits that address current unmet needs."
The 24-week, randomised, double-blind, placebo-controlled, multiple-dose, phase 2B study included 391 adults with psoriatic arthritis who had three or more tender and three or more swollen joints. Patients were randomised (1:1:1:1:1) to receive tildrakizumab 200mg every four weeks, 200mg, 100mg or 20mg every 12 weeks, or placebo every four weeks. Stable concomitant methotrexate or leflunomide use was permitted but not mandated.
Serious adverse events (AEs) occurred in 2.2% of tildrakizumab-treated patents and 2.5% of placebo-treated patients. Treatment-related serious AEs occurred in 0.3% of tildrakizumab-treated patients (as judged by the investigator). The most frequent AEs included nasopharyngitis and diarrhoea with no reports of candidiasis, inflammatory bowel disease, major adverse cardiac events, or malignancy. No patients discontinued treatment due to AEs and no deaths were reported.