Enbrel Effective in Juvenile Psoriatic Arthritis

A 96-week-long trial of etanercept (Enbrel) indicates durable therapeutic benefits and no serious adverse events in pediatric patients with psoriatic arthritis and other types of juvenile idiopathic arthritis.

A new paper published in The Journal of Rheumatology includes data on 127 arthritis patients with a least 2 affected joints, no prior experience with biologic agents and, in most cases, an inadequate response to traditional disease-modifying antirheumatic drugs (DMARDs) such as methotrexate, hydroxychloroquine, cholorquine, sulfasalazine, or non-steroidal anti-inflammatory drugs (NSAIDs).

Nearly half of the patients (60) had extended oligoarthritis, while 38 had enthesitis-related arthritis and 29 had psoriatic arthritis. All but 5 of them received at least 12 weeks of treatment, and 109 of them entered the second part of the study and received the full 96 weeks of treatment.

At week 96, 84.3% of patients (95% confidence interval [CI], 76.7% to 90.1%) had achieved an American College of Rheumatology 30 (ACR30) response, which indicates a 30 % reduction in overall disease symptoms. Some 83.5% of patients (95% CI, 75.8% to 89.5%) had achieved an ACR50 response, while 78.7% (95% CI, 70.6% to 85.5%) had achieved an ACR70 response, 55.1% (95% CI, 46.0% to 63.9%) had achieved an ACR90 response and 45.7% (95% CI, 36.8% to 54.7%) had achieved an ACR100 response. Fully 27.6% (95% CI, 20.0% to 36.2%) were classified as having inactive disease.

The most common adverse events (as measured by both total events and the number of events per 100 patient years) were headache (23, 10.7), pyrexia (12, 5.6), and diarrhea (10, 4.6). The most common infections were upper respiratory tract infection (83, 38.6), pharyngitis (50, 23.2), gastroenteritis (22, 10.2), bronchitis (19, 8.8), and rhinitis (17, 7.9). No patients developed any malignancy, active tuberculosis, demyelinating disorders during the trial, nor did any patients die.

“Over 96 weeks of therapy, etanercept demonstrated sustained efficacy at treating the clinical symptoms of all 3 juvenile idiopathic arthritis categories, with no major safety issues,” the investigators wrote.

The new data is not the first to emerge from what has been dubbed the CLIPPER trial. The investigators who ran the open-label multi-center study reported 12-week results in 2012: 88.6% of all patients (95% CI, 81.6% to 93.6%) achieved an ACR30 response, while 81.1% achieved an ACR50 response, 61.5% achieved an ACR70 response, 29.8% achieved an ACR90 response and 12.1% were judged to have inactive disease.

Patients with psoriatic arthritis responded particularly well in that initial study period. Some 93.1% of all psoriatic arthritis patients (95% CI, (77.2% to 99.2%) achieved ACR30 compared to 89.7% of extended oligoarticular arthritis patients (95% CI, 78.8% to 96.1%) and 83.3% of enthesitis-related arthritis patients (95% CI, 67.2% to 93.6%).

The odds ratio of response on etanercept versus standard placebo results was 40.7 for psoriatic arthritis patients, compared to 26.2 for extended oligoarticular arthritis patients and 15.1 for enthesitis-related arthritis patients.

Etanercept is already indicated for the treatment of juvenile idiopathic arthritis in patients aged 2 years and older, but the investigators who undertook the new study believe their work adds valuable new information about the medication’s long-term efficacy. The trial was originally sponsored by Wyeth, which was acquired by Pfizer in 2009.