GENEVA The interleukin-17A inhibitor ixekizumab provided rapid clearance of genital psoriasis in a phase 3b clinical trial, with significant improvement seen as early as week 1, Caitriona Ryan,
The highly targeted monoclonal antibody also improved the intense itching that’s a particularly prominent feature of genital psoriasis.
“Most importantly, in my view, ixekizumab minimized how often genital psoriasis limited the frequency of sexual activity. This is a disease that can have a very significant impact on quality of life and sexual health,” observed Dr. Ryan of St. Vincent’s Hospital, Dublin.
“Genital psoriasis is a hidden part of psoriasis. Unfortunately, as dermatologists we do a bad job of evaluating our patients for it. They are ashamed and embarrassed to bring up the topic with their dermatologists. Hopefully, this study will create some awareness around the topic,” she said.
This was the first-ever randomized trial to evaluate the effect of a biologic agent specifically on genital psoriasis. It was also the first study of a biologic in psoriasis patients with less than 10% body surface area involved.
“That’s a very important thing,” according to the dermatologist. “There are lots of patients with genital psoriasis who have less than 10% body surface area involved and therefore don’t qualify for biologic therapy, even though their genital psoriasis can be incredibly debilitating.”
The 12-week, multicenter, double-blind trial included 149 patients with a baseline static Physician’s Global Assessment of Genitalia (sPGA-G) score of at least 3 on a 0-5 scale. All participants had failed to respond to at least one topical therapy for their genital psoriasis, such as a corticosteroid, a calcineurin inhibitor, or a vitamin D analog. The subjects averaged a 16-year history of psoriasis and a 9-year history of genital psoriasis. Thirty-eight percent of participants had an involved body surface area of at least 1% but less than 10%.
Patients were randomized to ixekizumab (Taltz) given in the usual way – a subcutaneous loading dose of 160 mg, followed by repeat 80-mg injections every 2 weeks – or placebo.
The primary study endpoint was achievement of an sPGA-G score of 0 or 1, meaning clear or almost clear, as assessed by blinded investigators. At the 12-week mark, the rate was 73% in the ixekizumab group and 8% in controls. The sPGA-G score already differed significantly between the two study arms at the first assessment, after 1 week. The treatment success rate was closely similar in patients with or without at least 10% total body surface area involved.
A key secondary endpoint concerned sexual health. Among patients who at baseline indicated that in the past week, their genital psoriasis “sometimes,” “often,” or “always” limited the frequency of their sexual activity, at week 12, 78% of those in the ixekizumab group answered the same question on the Sexual Frequency Questionnaire “never” or “rarely,” compared with 21% of controls.
“This is huge. It’s such an important part of our patients’ lives, and there was a big difference by week 1,” Dr. Ryan noted.
On another secondary endpoint, 60% of the ixekizumab group reported at least a 3-point improvement in the 0-10 Genital Itch Numeric Rating Scale at week 12, compared with 8% of controls, with a statistically significant difference apparent at week 2.
“Itch is the most frequently reported symptom in our patients with genital psoriasis, and it seems to be much more impactful than itch from psoriasis elsewhere,” Dr. Ryan commented.
The side effect profile of ixekizumab was the same as has been seen in larger, longer-term studies. There were no serious ixekizumab-related adverse events, and no cases of candidiasis.
The study was sponsored by Eli Lilly. Dr. Ryan reported serving as an advisory board member to and/or receiving honoraria from that company and more than half a dozen other pharmaceutical companies.