Prior Adalimumab Treatment Affects Etanercept Response in RA

Needle in vile
Needle in vile
Researchers found that testing adalimumab serum concentrations in the last serum sample from patients with rheumatoid arthritis from the Amsterdam Rheumatology and Immunology Center using enzyme-linked immunosorbent assays showed that patients with ≧5.0 μg/mL adalimumab had a lower response rate when switched to etanercept compared with patients who were biologic-naïve. However, researchers believe that a larger study population is required for more detailed results.

Patients with rheumatoid arthritis (RA) with an inadequate response to adalimumab are less likely to benefit from etanercept compared with biologic-naïve patients, according to study results published in the Scandinavian Journal of Rheumatology.

The results indicated that these results only applied to patients with adalimumab concentrations ≥0.5 μg/mL. Patients with <0.5 μg/mL had similar etanercept response compared with biologic-naïve patients.

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The study included participants with RA starting etanercept treatment in the Reade Rheumatology Registry (n=449). In participants previously on adalimumab, the researchers determined serum concentrations before discontinuing treatment. They categorized the participants into 3 subgroups based on serum adalimumab concentration: <0.5 μg/mL, 0.5-5.0 μg/mL, and ≥5.0 μg/mL.

The investigators compared the European League Against Rheumatism (EULAR) good/moderate response rate after 52 weeks of etanercept of the switcher subgroups with biologic-naïve participants.

Of 449 participants, 15% (n=69) switched from adalimumab and 85% (n=380) were biologic-naïve.

Of the biologic-naïve participants, 74% achieved a EULAR good or moderate response. In the switcher subgroups, a EULAR good or moderate response was achieved by 72% of patients in the <0.5 μg/mL group, 50% in the 0.5 to 5.0 μg/mL group, and 52% in the ≥5.0 μg/mL group (P =.15).

The researchers found that participants with an adalimumab concentration ≥0.5 μg/mL were significantly less likely to achieve a EULAR good or moderate response on etanercept compared with biologic-naïve participants. There was no significant difference between participants with an adalimumab concentration <0.5 μg/mL and biologic-naïve participants in the likelihood of achieving a good or moderate EULAR response.

“To our knowledge, this is the first study showing that patients with sufficient drug exposure respond less often to a second [tumor necrosis factor inhibitor],” the researchers wrote.

Reference l’ Ami MJ, Ruwaard J, Krieckaert CLM, et al. Serum drug concentrations to optimize switching from adalimumab to etanercept in rheumatoid arthritis [published online April 23, 2019]. Scand J Rheumatol. doi:10.1080/03009742.2019.1577915