Psoriatic arthritis patients with detectable anti-adalimumab antibodies have significantly lower serum adalimumab concentrations and poorer clinical outcomes at 28 weeks and 52 weeks of treatment, than did patients without antibodies in a prospective cohort study of 103 patients.
Courtesy Wikimedia Commons/James Heilman/Creative Commons LicensePsoriatic arthritis patients had significantly lower serum adalimumab concentrations and poorer clinical outcomes.
At week 52, the 23 patients with detectable anti-adalimumab antibodies had a median adalimumab concentration of 0.9 mg/L, compared with 9.4 mg/L in the 80 patients without detectable antibodies, as well as significantly higher C-reactive protein, Psoriasis Area Severity Index score, and 28-joint Disease Activity Score.
The researchers, led by Erik H. Vogelzang of the Jan van Breemen Research Institute/Reade in Amsterdam, also found that patients on adalimumab monotherapy had significantly lower median adalimumab concentrations at 28 and 52 weeks, compared with patients taking adalimumab and concomitant methotrexate (Ann. Rheum. Dis. 2014 [doi:10.1136/annrheumdis-2014-205554]).
"Further studies regarding measuring drug concentrations would be relevant, since this could give more insight on the cause of inadequate response, especially since treatment options in PsA [psoriatic arthritis] are limited," the investigators wrote.
The study was partly supported by AbbVie and Pfizer. The authors declared a range of consultancies, lecture fees, and research grants from the pharmaceutical industry.