Tumor Necrosis Factor Inhibitors in the Treatment of Pediatric Psoriatic Arthritis

Results from part 1 of the 12-week CLinical Study In Paediatric Patients of Etanercept for Treatment of ERA, PsA, and Extended Oligoarthritis (CLIPPER) published in the May 2013 issue of Annals of Rheumatic Disease, suggest etanercept is a safe and effective treatment in patients with polyarticular course juvenile idiopathic arthritis (JIA), the most common chronic rheumatic disease in children. The study results also indicated that etanercept may also be effective in patients with psoriatic arthritis and other conditions.

The trial enrolled pediatric patients with extended oligoarticular juvenile idiopathic arthritis (eoJIA), enthesitis-related arthritis (ERA), or psoriatic arthritis (PsA). Subjects in each category received a weekly dose of etanercept 0.8 mg/kg, (maximum dose of 50 mg), with an average weekly dose of 35 mg.

A large percentage (93.1%) of the children with psoriatic arthritis (n=29) achieved JIA American College of Rheumatology (ACR) 30 criteria, indicating a 30% improvement in symptoms based on the ACR composite index.

The higher the number, the better the score, said pediatric rheumatologist Nicolino Ruperto, MD, MPH, the study’s senior author. “Improving by 30% is the minimum important clinical improvement but of course improving by 70% or 90% is more desirable,” he said in an e-mail statement.

While those numbers appear favorable, Ruperto indicated the need to better understand the long-term effects of treatment on people in other rheumatic disease categories that are not as well understood.

“The efficacy and safety of etanercept in specific ILAR categories, such as extended oligoarticular JIA (eoJIA), enthesitis-related arthritis (ERA) and psoriatic arthritis (PsA) has not been studied thoroughly,” wrote the study authors.

While Ruperto did not elaborate on specifics, he emphasized the “essential” need for further data since the “chronic” nature of these diseases require ongoing drug treatment—something we know little about. This is especially true since biologic use in juvenile PsA is so new. “This is the first study [using etanercept] that has considered children with PSA,” Ruperto said.

Along similar lines, researchers from the Hospital for Sick Children Research Institute, at the University of Toronto, acknowledged this lack of understanding in a 2013 study published in Pediatric Rheumatology Online.

“There are fewer reports describing the characteristics and long-term outcome of patients with JPsA than other subtypes of JIA,” the authors noted. They also said that this is partially due to a lack of consensus in the medical community, writing “As more than one classification system for JPsA has been used, it can be confusing to compare different studies and, as recently as 2008, no single classification was agreed upon or universally accepted.”

In conclusion, the Canadian researchers theorize that four main groups may make up JPsA, with similar characteristics to non-JPsA JIA in terms of symptoms, disease course, and treatment outcomes.

However, psoriasis itself may offer “little clinical relevance” in terms of treatment outcomes in youngsters with JIA, they added. “Therefore we may consider psoriasis as an extra-articular manifestation seen in JIA, similar to uveitis, rather a feature requiring a distinct classification grouping.”

Returning to the CLIPPER study, to establish an understanding of drug efficacy, researchers compared results using meta-analysis from JIA studies. They reported that compared to placebo, the results suggest that youngsters with PSA are 40.7 times more likely to improve.

“For eoJIA, ERA, and PsA categories, the ORs (95% CI) of ETN versus the historical placebo data were 26.2 (10.6 to 64.2), 15.1 (6.0 to 38.2) and 40.7 (9.4 to 176.9), respectively,” the authors wrote.

To assess drug safety in all three disease categories, researchers looked at common non-infectious side effects reported by subjects. Most commonly reported symptoms were fatigue and pyrexia, headache, and stomach pain. Comparing all three categories, the researchers found “no differences in the rates of non-infectious treatment-emergent adverse effects (TEAEs).”