Oral apremilast in the treatment of active psoriatic arthritis: results of a multicenter, randomized, double-blind, placebo-controlled study

Objective: To evaluate the efficacy and safety of apremilast, a novel, orally available small molecule that specifically targets phosphodiesterase 4, in the treatment of active psoriatic arthritis (PsA).

Methods: This phase II, multicenter, randomized, double-blind, placebo-controlled study included the following: a 12-week treatment phase, with patients receiving placebo, apremilast 20 mg twice per day, or apremilast 40 mg once per day; a 12-week treatment-extension phase, with patients in the placebo group re-randomized to receive apremilast; and a 4-week observational phase after treatment cessation. The primary end point was the proportion of patients achieving the American College of Rheumatology criteria for 20% improvement (ACR20) at week 12. Safety assessments included adverse events (AEs), physical examinations, vital signs, laboratory parameters, and electrocardiograms.

Results: Of the 204 patients with PsA who were randomized to a treatment group, 165 completed the treatment phase. At the end of the treatment phase (week 12), 43.5% of patients receiving apremilast 20 mg twice per day (P < 0.001) and 35.8% of those receiving 40 mg once per day (P = 0.002) achieved an ACR20 response, compared with 11.8% of those receiving placebo. At the end of the treatment-extension phase (week 24), >40% of patients in each group (patients receiving apremilast 20 mg twice per day, patients receiving apremilast 40 mg once per day, and patients in the placebo group re-randomized to receive apremilast) achieved the ACR20 level of improvement. Most patients in the treatment phase (84.3%) and treatment-extension phase (68.3%) reported ≥ 1 AE. Diarrhea, headache, nausea, fatigue, and nasopharyngitis were reported most frequently; most events were mild or moderate. No clinically relevant laboratory or electrocardiographic abnormalities were reported.

Conclusion: Treatment with apremilast at a dosage of 20 mg twice per day or 40 mg once per day demonstrated efficacy in comparison with placebo and was generally well tolerated in patients with active PsA. The balance of efficacy, tolerability, and safety supports further study of apremilast in PsA.