After 8 weeks on low-dose ixekizumab, the proportion of patients reporting any skin disease-related sexual difficulties within the past week fell from a baseline of 30% to 16%. After 8 weeks of high-dose ixekizumab, the figure was just 7%. Those rates remained unchanged at 16 weeks. In contrast, the placebo group remained unchanged over time, with 32% of patients still reporting sexual difficulties caused by their skin disease at week 8.
The degree to which a patient’s psoriasis improved in response to therapy with the humanized monoclonal antibody was closely related to the reduction in skin-related sexual problems. Among the 76 ixekizumab-treated patients who achieved a PASI 75 response at week 16, the rate of self-reported sexual difficulties within the previous week was 7%. For those with less than a PASI 75 response, the rate was 24%.
An impressively high 38% percent of patients on high-dose ixekizumab achieved a PASI 100 response. Only 5% of them reported any skin-related sexual difficulties at week 8, as did 9% at week 16.
Dr. Guenther also looked at the data restricting the analysis to patients with more severe baseline sexual impairment as defined by a response of 2 or 3 on item 9 of the DLQI. Among patients on high-dose izekizumab, the rate dropped from 10.5% at baseline to 1.8% at week 8 to zero at week 16. For patients on low-dose izekizumab, the progression was 13.8% to 8.8% to 3.5% at week 16. Rates remained unchanged over time in the control group.
Although this phase 2 study was limited in size, Dr. Guenther found much the same thing earlier in the much larger phase 3 PHOENIX 1 and 2 trials of ustekinumab (Stelara), which together featured 1,334 psoriasis patients randomized to the human anti-interkelukin-12/23 monoclonal antibody. In that analysis, the proportion of ustekinumab-treated patients with impaired sexual function as assessed by DLQI item 9 plunged from 22.4% at baseline to 2.7% at week 12, compared with no change in placebo-treated controls. The bigger the PASI improvement, the greater the reduction in psoriasis-related sexual dysfunction (J. Eur. Acad. Dermatol. Venereol. 2011;25:851-7).
The phase 2 ixekizumab study was funded by Eli Lilly. Dr. Guenther is a consultant to the company. Positive primary outcomes in three pivotal phase 3 clinical trials of ixekizumab totalling nearly 3,900 randomized psoriasis patients have since been reported. The company plans to apply for marketing approval of the biologic in the first half of 2015.