Longer intervals between injections of anti-TNF drugs in patients with psoriatic arthritis is "safe, effective, cost-effective, and facilitates patient compliance," according to researchers.
New research suggests that lengthening the intervals between doses of anti-tumor necrosis factor (anti-TNF) alpha therapies does not reduce their effectiveness in many patients with psoriatic arthritis.
Italian researchers studied the effects of varying the length of time between doses of etanercept (Embrel) and adalimumab (Humira) over a 4-year period in 141 psoriatic arthritis outpatients who received treatment at the Rheumatology Clinic of the University of Padova.
Patients received normal doses of either medication, spaced at normal intervals, until diagnostic tests revealed minimal disease activity. Researchers then progressively lengthened the intervals between injections until each patient showed signs of increased disease activity.
At baseline, the mean patient age was 51.22 years (± 12.34 years) and the mean period of disease duration was 12.1 years (±8.42 years). Some 47.5% of the patients were treated with etanercept throughout the study period while the remaining 52.5% were treated with adalimumab.
By the end of the study period, the researchers found that medication intervals could be extended in 46.1% of all patients without inducing any signs of relapse as measured by clinical, biochemical, and disease activity indexes. Among all the patients who used etanercept, which is normally administered twice a week, 58% were able to go longer between doses. Among all the patients who used adalimumab, which is normally given every 2 weeks, 35% were able to go longer between doses.
“The mean therapy interval at the end of the study period was 3.12 weeks for adalimumab 40 mg (with respect to 2 weeks) and 2.75 weeks for etanercept 25 mg (with respect to 0.5 weeks),” the study authors wrote in the International Journal of Immunopathology and Pharmacology. “The new therapy timetable also led to cost savings. In conclusion, lengthening the time intervals between injections of anti-TNF agents in psoriatic arthritis patients who reach minimal disease activity is safe, effective, cost-effective, and facilitates patient compliance.”
The results of the new trial echo those of a smaller trial, which were presented last year at the Congress of the European League Against Rheumatism. A total of 67 patients, 42 with rheumatoid arthritis and 25 with psoriatic arthritis, took part in that 30-month trial, which explored the safety of lengthening the intervals between injections of etanercept (23 patients), adalimumab (39 patients) and golimumab (5 patients).
Starting with normal dosing intervals, researchers lengthened those intervals every 6 months until patients showed signs of increased disease activity or reached target doses: 50 mg of etanercept every 15 days, 40 mg of adalimumab every 21 days or 50 mg of golimumab every 35 days. Each patient’s disease was monitored at 6, 12, 18, 24 and 30 months using the Disease Activity Score 28 (DAS28) calculator and by measuring serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).
“According to the data obtained, DAS28 in rheumatoid arthritis cases slightly increased with lengthening of the dosing interval but does not reach values exceeding low disease activity,” the study authors wrote in their abstract. “Although no statistically significant results were obtained due to the small number of patients, in all cases the disease control was achieved. Furthermore, better control was achieved with the combined use of biological therapy and methotrexate, as well as with adalimumab. However, a larger number of cases and longer follow-up period is needed in order to confirm that prolonging the anti-TNF dosing interval is useful for disease control.”