Results from a study of ENBREL® (etanercept), the only fully human TNF receptor, were presented demonstrating significant inhibition in the progression of structural damage in patients with psoriatic arthritis. These radiographic results were presented as part of an oral presentation at the 66th American College of Rheumatology Annual Scientific Meeting in New Orleans.
“ENBREL is the first therapy to reduce signs and symptoms, and inhibit the progression of bone erosions and joint space narrowing associated with psoriatic arthritis, a disease which has unique and distinct radiographic features not seen in rheumatoid arthritis,” said Dr. Peter Ory, department of radiology, University of Washington, and lead investigator of the study. “Patients with psoriatic arthritis often exhibit the painful bone and joint destruction and eventual deformities to fingers, hands and wrists which are associated with disability in this disease.”
ENBREL is approved to reduce the signs and symptoms of active arthritis in patients with psoriatic arthritis.
A phase 3 study evaluated 205 patients with active psoriatic arthritis who also had stable psoriasis. Patients first completed a 6-month placebo-controlled blinded portion, then were eligible to enter a 48 week open-label study with ENBREL (25-mg twice-weekly subcutaneous injections). A primary endpoint of the study was determination of radiographic progression in patients treated with ENBREL versus placebo. X-rays of patients’ hands and wrists were obtained at baseline, 6 months, upon rollover to active drug and at 12 months.
At one year, there was inhibition of radiographic progression in the ENBREL group (n=101) compared with the placebo group (n=104). The mean change from baseline in total Sharp score (TSS) was a reduction in progression of –0.03 units in the ENBREL group versus an increase in progression of +1.00 units in the placebo group (p=0.0001). The Sharp method uses a 4-point scale to rate joints according to the severity of erosions and degree of joint space narrowing. The erosion and joint space-narrowing subscores are then added to obtain a total radiographic score.
Progression of structural damage was inhibited when measured not only by the TSS, but also by joint erosion scores and joint space narrowing scores. Mean changes from baseline in erosion scores over a year were -0.09 units in patients treated with ENBREL versus +0.66 units in the patients treated with placebo (p=0.0001). Additionally, mean changes in joint space narrowing from baseline over a year were +0.05 units in patients treated with ENBREL, versus +0.34 units in patients treated with placebo (p=0.04).
Adverse events were similar to those reported in previous clinical trials of ENBREL in patients with rheumatoid arthritis. There was no increase in the number of serious adverse events occurring in patients treated with ENBREL compared to those receiving placebo. Only the rate of injection site reactions (ISRs) in patients receiving ENBREL was statistically different compared to placebo (9% with placebo versus 36% with ENBREL in the placebo controlled segment).