OBJECTIVES: Apremilast, an oral phosphodiesterase 4 inhibitor, regulates 
inflammatory mediators. Psoriatic Arthritis Long-term Assessment of Clinical 
Efficacy 1 (PALACE 1) compared apremilast with placebo in patients with active 
psoriatic arthritis despite prior traditional disease-modifying antirheumatic 
drug (DMARD) and/or biologic therapy.
METHODS: In the 24-week, placebo-controlled phase of PALACE 1, patients (N=504) 
were randomised (1:1:1) to placebo, apremilast 20 mg twice a day (BID) or 
apremilast 30 mg BID. At week 16, patients without ≥20% reduction in swollen and 
tender joint counts were required to be re-randomised equally to either 
apremilast dose if initially randomised to placebo or remained on their initial 
apremilast dose. Patients on background concurrent DMARDs continued stable doses 
(methotrexate, leflunomide and/or sulfasalazine). Primary outcome was the 
proportion of patients achieving 20% improvement in modified American College of 
Rheumatology response criteria (ACR20) at week 16.
RESULTS: At week 16, significantly more apremilast 20 mg BID (31%) and 30 mg BID 
(40%) patients achieved ACR20 versus placebo (19%) (p<0.001). Significant 
improvements in key secondary measures (physical function, psoriasis) were 
evident with both apremilast doses versus placebo. Across outcome measures, the 
30-mg group generally had higher and more consistent response rates, although 
statistical comparison was not conducted. The most common adverse events were 
gastrointestinal and generally occurred early, were self-limiting and 
infrequently led to discontinuation. No imbalance in major adverse cardiac 
events, serious or opportunistic infections, malignancies or laboratory 
abnormalities was observed.
CONCLUSIONS: Apremilast was effective in the treatment of psoriatic arthritis, 
improving signs and symptoms and physical function. Apremilast demonstrated an 
acceptable safety profile and was generally well tolerated.
CLINICAL TRIAL REGISTRATION NUMBER: NCT01172938.