Improvement of scalp and nail lesions with ixekizumab in a phase 2 trial in patients with chronic plaque psoriasis

Background Scalp and nail psoriasis have a major impact on quality of life and are traditionally resistant to therapy. Ixekizumab is a monoclonal antibody that targets IL-17A, a key cytokine in psoriasis pathogenesis. Objective Changes in nail and scalp psoriasis associated with ixekizumab treatment were evaluated in a post hoc analysis of a phase 2 study comprising a 20-week randomized, placebo-controlled (RCT) period and 48 weeks of an open-label extension (OLE) period. Methods There were 142 patients with moderate-to-severe plaque psoriasis at baseline of the RCT. Patients were randomized to receive placebo, 10, 25, 75 or 150 mg of ixekizumab injected subcutaneously at weeks 0, 2, 4, 8, 12 and 16. In the OLE, all patients received 120 mg ixekizumab every 4 weeks. Nail Psoriasis Severity Index (NAPSI) and Psoriasis Scalp Severity Index (PSSI) were used to evaluate nail and scalp psoriasis respectively. Fifty-eight (41.0%) patients had nail psoriasis (NAPSI > 0) and 105 (74.0%) had scalp psoriasis (PSSI > 0) at baseline; these cases were evaluated for the present analyses. Results At RCT week 20, patients with scalp psoriasis in the 25-, 75- and 150-mg groups had significant mean change and percent improvement from baseline PSSI of -16.3 (75.3%; P = 0.001), -11.6 (83.7%; P = 0.001) and -18.2 (82.2%; P < 0.001) respectively compared to -6.0 (18.8%) in placebo. Patients with nail psoriasis in the 75- and 150-mg groups had significant improvements from baseline NAPSI of -26.3 (63.8%; P = 0.003) and -23.1 (52.6%; P = 0.009) respectively compared to 0.4 (-1.7%) in placebo. By OLE week 48, 78.0% of patients with scalp psoriasis and 51.0% of patients with nail psoriasis experienced complete resolution of lesions (PSSI = 0 or NAPSI = 0). Conclusions Ixekizumab monotherapy improved scalp psoriasis quickly with maintenance of clinical response and complete resolution of plaques in the majority of patients. Additionally, over 50.0% of patients with nail psoriasis experienced complete resolution of nail lesions by OLE week 48.