Current major guidelines for treatment of psoriatic arthritis (PsA) shortchange the value of the anti–interleukin-17 biologics for this disease, Kenneth B. Gordon, MD, said at MedscapeLive’s annual Las Vegas Dermatology Seminar, held virtually this year.

Dr. Kenneth B. Gordon, Medical College of Wisconsin

Dr. Kenneth B. Gordon

The 2018 joint American College of Rheumatology/National Psoriasis Association guidelines recommend the anti–tumor necrosis factor agents as first-line biologic therapy for PsA, with the anti–IL-17 biologics held in reserve as second-tier therapy for when the anti-TNFs don’t work. That’s largely because the guidance was developed before the compelling evidence for the anti–IL-17 agents as the biologics of choice was appreciated, according to Dr. Gordon, professor and chair of the department of dermatology at the Medical College of Wisconsin, Milwaukee.

“Many people go by these guidelines,” the dermatologist noted. “I think it’s really critical to look at the data and not just the guidelines because the guidelines don’t give full credit to the anti–IL-17 agents,” he added.

“Emerging psoriatic arthritis data may likely put this class of medications into the forefront of treatment for patients who have both psoriasis and psoriatic arthritis because you generally get higher responses for the skin disease than with anti-TNF therapy, and with similar responses in psoriatic arthritis.”

Two IL-17 inhibitors are approved for both PsA and psoriasis: secukinumab (Cosentyx) and ixekizumab (Taltz). In addition, brodalumab (Siliq), approved for psoriasis, is expected to receive an expanded indication for PsA based upon its strong showing in the AMVISION-1 and -2 trials. Data from those trials, as well as the FUTURE 2 trial for secukinumab and SPIRIT-P1 for ixekizumab, consistently document at least 20% improvement in the ACR criteria for PsA severity – that is, an ACR 20 response – in 50%-60% of patients on one of the three IL-17 inhibitors, as well as ACR 50 response rates of around 30%. Those outcomes are quite consistent with the impact of the anti-TNF biologics on joint disease. But the TNF inhibitors can’t touch the anti–IL-17 biologics when it comes to improvement in Psoriasis Area and Severity Index (PASI) scores: The anti–IL-17 agents have week-52 PASI 75 response rates in the range of 80%, PASI 90 response rates of 70%-75%, and PASI 100 response rates of 40%-55%, with the highest-end results being seen with brodalumab, he continued.

A point worth remembering when prescribing secukinumab is that the approved dose for PsA is 150 mg every 4 weeks, which is just half of the typical dose in psoriasis.

“I spend a lot of time convincing my rheumatology colleagues that if you’re treating both psoriasis and psoriatic arthritis, use the psoriasis dose. There’s some evidence that the higher dose provides some benefit in terms of prevention of permanent joint damage by x-ray,” Dr. Gordon said.

Evidence that TNF inhibitors inhibit permanent joint damage in patients with PsA has been considered a major advantage, establishing this medication class as first-line biologic therapy. But anti–IL-17 therapies appear to have a similar beneficial effect. That was demonstrated in the SPIRIT-P1 trial, where Sharp scores – a radiographic measure of progression of joint damage – were similar at 24 weeks in PsA patients randomized to ixekizumab as compared to adalimumab, with both biologics being superior to placebo. An Assessment of SpondyloArthritis International Society 20% improvement (ASAS 20) response or an ACR 50 response doesn’t capture what’s going on with regard to axial disease. That’s assessed through ASAS 20 and ASAS 40 responses – that is, at least 20% or 40% improvement, compared with baseline, in Assessment in Ankylosing Spondylitis scores. And in the MEASURE 1 and 2 trials, secukinumab achieved robust improvement in axial disease as reflected in favorable ASAS 20 and ASAS 40 responses through 52 weeks in patients with active ankylosing spondylitis.

“The anti–IL-17 agents do actually work in ankylosing spondylitis, which might be a surrogate for the treatment effect in axial psoriatic arthritis,” Dr. Gordon commented.

The phase 3b MAXIMISE trial presented at the 2019 EULAR meeting looked specifically at the impact of secukinumab in patients with psoriatic arthritis with axial involvement. An ASAS 20 response at week 12 was seen in 67% and 65% of patients randomized to secukinumab at 150 or 300 mg, respectively, if they were on concomitant methotrexate, and 64% and 61% if they were not, compared with ASAS 20 rates of 34% and 31% in placebo-treated controls.

“This is the only study of an anti–IL-17 agent that’s been done for axial disease to date in psoriatic arthritis. It’s very, very encouraging,” the dermatologist commented.

Durability of response and safety

“In terms of safety, the anti–IL-17s have been a truly remarkable success story. There are very low rates of things to be concerned about,” Dr. Gordon said.

Oral candidiasis occurs in 2%-4% of treated patients, but he noted, “It’s almost always very mild disease” that’s easily treatable with nystatin or, in the worst case, with some fluconazole.

Inflammatory bowel disease (IBD) as a side effect of anti–IL-17 therapy has been a controversial issue. Dr. Gordon’s interpretation of the evidence is that there probably is a very slight increase in the risk of developing ulcerative colitis, but not Crohn’s disease.

“This rate is extraordinarily low, so while it’s something that I consider, and if a patient has a personal history of IBD I will sometimes hesitate to use an anti–IL-17 agent, in patients who don’t have a personal history I’ll go ahead,” he explained.

There is a signal of a slight increase in risk of depression in patients on brodalumab, which isn’t the case for secukinumab or ixekizumab.

Importantly, large long-term extension studies with years of follow-up show that the initially low adverse event rates associated with the IL-17 inhibitors don’t increase over time; rather, they remain steady over years of use.

Long-term maintenance of response with these biologics is impressive. “It’s not perfect, but it’s still a tremendous advantage for patients, especially if you can get them through that initial period,” Dr. Gordon said.

For example, in the long-term extension of the UNCOVER-1 trial, psoriasis patients who had clear or almost clear skin at week 12 on ixekizumab and continued to take the medication open label for 5 years had PASI 75, 90, and 100 response rates of 94%, 82%, and 47%, respectively, at week 264.

What about IL-12/23 and IL-23 inhibitors in PsA?

In a separate presentation at the MedscapeLive seminar, Bruce E. Strober, MD, PhD, said that, although ustekinumab (Stelara) is approved for both psoriasis and PsA, the IL-12/-23 inhibitor’s efficacy in PsA is inconsistent and lower than other approved biologics. In contrast, the IL-23 inhibitor guselkumab (Tremfya), which also has the dual indications, is a strong performer in both. In the DISCOVER-2 trial, conducted in treatment-naive patients with PsA, guselkumab at the approved dose of 100 mg every 8 weeks achieved ACR 20, 50, and 70 rates of 64%, 31%, and 19%, respectively. It was also significantly better than placebo for resolution of enthesitis.

Dr. Bruce E. Strober

Dr. Bruce E. Strober

An important caveat: While radiographic inhibition of progression of joint disease occurred with guselkumab dosed at 100 mg every 4 weeks in DISCOVER-2, that’s not the approved dose. At 100 mg every 8 weeks – the FDA-approved dosing for both psoriatic arthritis and psoriasis – radiographic inhibition wasn’t better than with placebo, noted Dr. Strober, a dermatologist at Yale University, New Haven, Conn.

Dr. Gordon and Dr. Strober are clinical trialists who reported receiving research support and/or honoraria from more than a dozen pharmaceutical companies, including virtually all of those with biologics for dermatology.

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