TNF Inhibitor Side Effects Occur at Similar Rates in Rheumatic Diseases

Researchers analyzed data from 729 people treated with either etanercept or adalimumab

Marisa Wexler MS avatar

by Marisa Wexler MS |

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Side effects to anti-TNF therapies are as common and similar among people with ankylosing spondylitis as they are among other rheumatic diseases, a new study indicates.

The study, “Disease-specific ADRs of TNF-[alpha] inhibitors as reported by patients with inflammatory rheumatic diseases: a registry-based prospective multicenter cohort study,” was published in Expert Opinion on Drug Safety.

Anti-TNF therapies are a class of medications approved for ankylosing spondylitis and some other inflammatory conditions, such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA). They work by blocking the activity of the pro-inflammatory signaling molecule TNF (tumor necrosis factor).

Some previous studies have suggested that side effects related to these therapies are more common in people with certain conditions, but the comparative safety profile in different indications has not been thoroughly studied.

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Scientists in The Netherlands analyzed data from the Dutch Biologic Monitor, a system that allows patients to report adverse reactions to therapies for managing rheumatic diseases.

The team identified data for 729 people (average age 57.4, 59.7% female) with inflammatory rheumatic diseases who were treated with one of two anti-TNF medications: Enbrel (etanercept) or adalimumab (sold as Humira and Cyltezo). Among the patients, 442 had RA, 172 had PsA, and 115 had ankylosing spondylitis or axial spondyloarthritis.

Just under half — 354, or 48.6% — reported any adverse reaction to the therapy. There was no difference in the rate of reported side effects between the three different diseases, statistical analyses showed.

“Although previous studies concluded that the underlying disease may play a crucial role in the incidence rates of [adverse events] and safety profile of TNF-[alpha] inhibitors in patients with different [inflammatory diseases], we could not draw the same conclusion,” the researchers said.

One explanation for this difference is that the study relied on patient-reported reactions, rather than reactions documented by a healthcare professional, they said. The researchers noted this approach “is required to obtain an unbiased impression of patients’ perspective,” but acknowledged that having only patient-reported data runs a risk of some events being misattributed as reactions to therapy.

“To enrich the safety profile of drugs, perspectives of both patient and HCP [healthcare professional] reports should ideally be combined,” they wrote.

Additional analyses based on the reaction type indicated patients with rheumatoid arthritis or ankylosing spondylitis were more likely than those with PsA to report side effects affecting the chest and lungs, classified as “respiratory, thoracic and mediastinal disorders.” These reactions were significantly more common in patients treated with adalimumab compared to Enbrel.

Ankylosing spondylitis patients also were more likely than those with PsA to report reactions classified as “other” in the system.

The researchers emphasized the difficulty of drawing conclusions about cause and effect from these findings, especially given the limitations of relying only on patient-reported reactions.