Many Not Receiving Optimal TNF-Alpha Inhibitor Dose in Psoriatic Arthritis

A high number of patients with psoriatic arthritis were not receiving doses of tumor necrosis factor-alpha (TNFα) inhibitor, adalimumab, to obtain optimal clinical benefit, according to data presented at the European League Against Rheumatism Annual Congress (EULAR 2014).

In regards to infliximab, another TNFα inhibitor, about 3/4 of patients were on doses lower than recommended in international guidelines.

The first study revealed that after 28 weeks of treatment, 1/3 of patients (36/103) were found to have adalimumab trough concentrations below the optimal 5mg/mL although the low doses still showed efficacy. Adalimumab concentrations were measured in serum trough samples, using an enzyme linked immunosorbent assay (ELISA). Although 5–8mg/mL appeared necessary to achieve the most clinical benefit, concentrations of approximately 1mg/mL also showed reasonable benefit at Week 28. Moreover, concentrations >8mg/mL appeared to have no additional benefit.

The second study (n=1589) showed that treatment response or therapy adherence was not altered in over 70% Icelandic and Danish patients with psoriatic arthritis that received the low infliximab dosing. Danish patients (n=376) received higher infliximab doses than Icelandic patients (n=86) at baseline (median 3.1mg/kg vs. 2.3mg/kg, P<0.05) and after 12 months (3.3mg/kg vs. 2.9mg/kg, P<0.0001). After 12 months, 58% of Danish and 66% of Icelandic patients maintained treatment. Researchers found that ACR20/50/70 or EULAR-response rates, drug adherence and one-year’s disease were independent of the infliximab baseline dose.

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