Patients with juvenile idiopathic arthritis (JIA) receiving treatment with adalimumab (sold as Humira and other brand names) exhibit high levels of antibodies against the therapy, a factor that seems to be related to an increased number of relapses, a new study shows.

The study supporting that finding, “Anti-adalimumab antibodies in a cohort of patients with juvenile idiopathic arthritis: incidence and clinical correlations,” was published in the journal Clinical Rheumatology.

JIA is a common rheumatic disease in children and an important cause of short- and long-term disability. The disease is characterized by high levels of inflammation that are caused, at least in part, by a response based on a molecule called TNF-alpha. Adalimumab is a TNF-alpha blocker.

The development of anti-drug antibodies (ADA) has been reported in patients with several different inflammatory conditions. These antibodies can have a significant clinical impact regarding hypersensitivity reactions and reduce effectiveness of the treatment.

There is limited information available on the presence of anti-adalimumab antibodies (AAA) in JIA patients. One of the major reasons is there is no reliable test to determine the presence of AAA.

So, researchers used a validated test — Biacore T100 — to determine the presence of AAA in samples from patients with JIA who were treated with adalimumab.

In total, researchers analyzed 27 children with JIA who had received adalimumab for at least three months. Disease activity was measured using the Juvenile Arthritis Disease Activity Score with 10 joint count (JADAS-10).

Results showed that 37% of patients (10 out of 27), had at least one AAA-positive sample. Patients were found to develop AAA between three and 38 months after starting treatment with adalimumab.

Further analysis showed that 70% of the children who were AAA positive (7 out of 10) experienced at least one relapse. Conversely, only 23.5% of AAA-negative children (4 our of 17) experienced at least one relapse. These results indicate that the presence of AAA antibodies may contribute to an increased relapse rate.

JADAS-10 conducted at the last follow-up visit did not show a statistically significant difference among children who were AAA positive and those who were AAA negative. However, there was an increasing trend in JADAS-10 score (meaning worse disease activity) for children who were AAA positive.

“In conclusion, using an innovative and accurate assay method, we found a high incidence of anti-drug antibodies in a cohort of adalimumab-treated JIA patients observed over a mean period of 40 weeks; the presence of anti-adalimumab antibodies seemed to be related to the number of relapses,” the researchers concluded.