Teri Greiling, MD, PhD, said at the virtual annual meeting of the American Academy of Dermatology.
The interleukin-17A inhibitor induced long-term remission of pityriasis rubra pilaris (PRP) in 4 of the 11 participants in her open-label, single-arm, 24-week clinical trial of ixekizumab (Taltz) at the Food and Drug Administration–approved dosing for psoriasis. Of 11 patients, 7 experienced at least a 50% reduction in signs and symptoms of the disease. Marked quality-of-life improvements occurred as well, reported Dr. Greiling, a dermatologist at Oregon Health & Science University, Portland.
PRP is a rare papulosquamous disorder that’s challenging to diagnosis and often difficult to treat. Indeed, there is no FDA-approved treatment. The disorder is characterized by widespread follicular keratotic plaques with scale and notable islands of sparing, often with an accompanying waxy yellow palmoplantar keratoderma with fissuring. There are adult- and childhood-onset forms of PRP, as well as sporadic and familial subtypes. Some cases are associated with variants in the CARD14 gene, known to also play a role in familial psoriasis.
Patients with PRP say the disorder has a major adverse impact on their quality of life. Itching and pain are often prominent features.
The 11 study participants, drawn from throughout the United States, were adults with a mean 12-year history of symptoms. All were required to have both clinical and biopsy evidence of PRP. Five had classic adult-onset PRP, five had atypical adult-onset PRP, and one had classic juvenile-onset PRP. All had moderate or severe disease as reflected in a Physician’s Global Assessment score of 3 or 4 on the 0-4 scale. Of the 11, 10 had previously received various systemic therapies for their PRP without success.
Since there is as yet no established PRP severity grading tool, Dr. Greiling applied the principles of the Psoriasis Area and Severity Index (PASI). Participants had a mean baseline PASI score of 24.6, a Dermatology Life Quality Index (DLQI) score of 18, and itch and pain scores of 7 and 6, respectively, on a self-rated 10-point scale.
The primary outcome in the study was change in PASI score at week 24, which was 4 weeks after the final dose of ixekizumab. The mean score improved from 24.8 at week 0 to 9.7 at week 24. Five patients achieved at least a 75% decrease in PASI score, or PASI 75 response, and 2 had a PASI 90 response. The DLQI improved from 18 to 3, and both itch and pain scores dropped to a median of 1. There was no association between response to treatment and PRP clinical subtype.
The four top responders – those with a PASI 89 or better response at week 24 – remained clear or almost clear at week 36, fully 16 weeks after their last dose of ixekizumab. Patients with an intermediate week 24 response – that is, a 50%-85% reduction in PASI score – all relapsed before week 36. The patient with the worst PASI score at both baseline and 24 weeks decided to continue on ixekizumab dosed every 2 weeks independent of the study, rather than at the FDA-approved dosing every 4 weeks for psoriasis, with a resultant drop to a PASI score of 8 at week 36.
To look at mechanism of benefit, Dr. Greiling used quantitative polymerase chain reaction to examine key cytokine expression in the epidermis and dermis. Not surprisingly, IL-17A expression was markedly reduced at both sites, suggesting the importance of the Th17 axis in the pathophysiology of PRP. In contrast, there was no significant change in IL-23 expression.
No serious or unexpected adverse events occurred in the 24-week study.
“In terms of ixekizumab, compared to other treatments, I definitely think it is more effective than any conventional therapies, such as topical steroids, methotrexate, or acitretin,” she said in an interview.
Asked about other biologics, Dr. Greiling said she hasn’t found tumor necrosis factor inhibitors very helpful in her patients with PRP. A formal trial of the IL-17A inhibitor secukinumab (Cosentyx) has been done elsewhere, and although the results haven’t yet been published, her understanding is that the efficacy was similar to her ixekizumab trial.
“I’ve had some of my ixekizumab patients switch to secukinumab, for insurance reasons, though, and had it not be quite as effective, although still helpful,” she said.
Dr. Greiling is now enrolling patients with PRP in a trial of the IL-23 inhibitor guselkumab (Tremfya). It’s her early impression that this may prove to be another therapeutic option.
“I have not yet used brodalumab [Siliq], but I wonder if it would also be helpful, since it seems to have a stronger blockade, working on the IL-17 receptor A,” she said.
She cited two pressing needs that would advance PRP research: the lack of standard criteria for disease diagnosis and the absence of PRP-specific disease measurement tools. “We’re trying to remedy that,” the dermatologist said.
Her study was funded by Eli Lilly. She reported receiving research funding from that company and Janssen.