 Approximately 165 subjects 55 subjects per arm will be randomized in a 1:1:1 ratio to receive oral apremilast 30 mg BID or 40 mg BID, or identically appearing placebo BID for up to 12 weeks Double-blind Placebo-controlled Phase, followed by 40 weeks of blinded active treatment with apremilast, either 30 mg BID or 40 mg BID Blinded Active-treatment Phase. 