Real-world use of apremilast for patients with psoriasis in Japan.

Apremilast is a novel oral phosphodiesterase 4 inhibitor effective for psoriasis. It regulates the production of pro-inflammatory mediators. Apremilast was approved in December 2016 in Japan; however, its efficacy and safety in a real-world setting among Japanese patients have not been reported. We report on 44 patients treated with apremilast between March and October 2017. The median treatment duration was 25 weeks (range, 2-33). Thirty-five patients (79.5%) continued the drug for at least 23 weeks, and five (11.4%) achieved a Psoriasis Area and Severity Index 100 response within 12 weeks. Nine patients discontinued the drug within 24 weeks mainly due to insufficient efficacy (n = 3) and adverse events (n = 4). Seven patients continued their previous systemic therapies such as cyclosporin (n = 1), methotrexate (n = 1), etretinate + methotrexate (n = 1) and biologics (n = 4) combined with apremilast. Of these patients, 55.9% had at least one adverse event although no severe adverse events. The most common adverse event was diarrhea (31.8%), followed by nausea (25.0%), headache (13.6%), abdominal discomfort (6.8%) and vomiting (6.8%). The proportion of diarrhea in our patients was higher than those of previous clinical trials. Among 10 patients with psoriatic arthritis, apremilast did not improve joint pain in nine (90%). To investigate the relationship between treatment efficacy and plaque size, we defined a small plaque as an individual rash diameter of 1 inch or less. The efficacy of apremilast was greater in patients with small plaques than in patients with large plaques.