oral ulcers the hallmark of behçet s syndrome can be resistant to conventional treatment therefore alternative agents are needed apremilast is an oral phosphodiesterase 4 inhibitor that modulates several inflammatory pathways we conducted a phase 2 multicenter placebo controlled study in which 111 patients with behçet s syndrome who had two or more oral ulcers were randomly assigned to receive 30 mg of apremilast twice daily or placebo for 12 weeks this regimen was followed by a 12 week extension phase in which the placebo group was switched to apremilast and a 28 day post treatment observational follow up phase the patients and clinicians were unaware of the study assignments throughout the trial the primary end point was the number of oral ulcers at week 12 secondary outcomes included pain from these ulcers measured on a 100 mm visual analogue scale with higher scores indicating worse pain the number of genital ulcers overall disease activity and quality of life the mean sd number of oral ulcers per patient at week 12 was significantly lower in the apremilast group than in the placebo group 0 5 1 0 vs 2 1 2 6 p 0 001 the mean decline in pain from oral ulcers from baseline to week 12 was greater with apremilast than with placebo 44 7 24 3 mm vs 16 0 32 5 mm p 0 001 nausea vomiting and diarrhea were more common in the apremilast group with 22 9 and 12 incidents respectively among 55 patients than in the placebo group with 10 1 and 2 incidents respectively among 56 patients findings that were similar to those in previous studies of apremilast there were two serious adverse events in patients receiving apremilast apremilast was effective in treating oral ulcers which are the cardinal manifestation of behçet s syndrome this preliminary study was neither large enough nor long enough to assess long term efficacy the effect on other manifestations of behçet s syndrome or the risk of uncommon serious adverse events funded by celgene clinicaltrials gov number nct00866359.