This Summary of Research provides an overview of the results of a phase 3 study that assessed the efficacy and safety of apremilast in Japanese patients with moderate to severe palmoplantar pustulosis (PPP) who had not responded to topical treatment (NCT05174065). Patients were randomized to apremilast or placebo for 16 weeks, after which patients randomized to placebo transitioned to apremilast through 52 weeks. This study showed that apremilast significantly improved PPP clinical severity, symptoms, and patient-reported quality of life compared with placebo after 16 weeks of treatment. The benefits of apremilast were maintained or further improved over 52 weeks of treatment. The most common side effects (experienced by > 10% of patients) included diarrhea, nasopharyngitis, nausea, soft stool, and headache, and were consistent with previous studies of apremilast. Side effects were mainly mild to moderate. The results from this phase 3 study support apremilast as a systemic oral treatment option for patients with PPP with inadequate response to topical treatment, for whom treatment options are limited.