First-in-Class TYK Inhibitor Shows Durable Effect for Psoriasis

Ted Bosworth

October 01, 2021

Deucravacitinib, a novel inhibitor of the JAK kinase tyrosine kinase 2 (TYK2), continues to demonstrate strong efficacy and acceptable safety after 52 weeks of follow-up, according to late-breaking data from two pivotal trials presented at the European Academy of Dermatology and Venereology (EADV) Annual Meeting.

From benefit reported on the two co-primary endpoints previously reported at 16 weeks, longer follow-up showed further gains out to 24 weeks and then persistent efficacy out to 52 weeks across these and multiple secondary endpoints, reported Richard Warren, MBChB, PhD, professor of dermatology and therapeutics, University of Manchester, Manchester, UK.

"This could be a unique oral therapy and an important treatment option for moderate to severe psoriasis," Warren contended.

The multinational double-blind trials, called POETYK PSO-1 and PSO-2, enrolled 666 and 1020 patients, respectively. The designs were similar. Patients with moderate to severe plaque psoriasis were randomly assigned in a 2:1:1 ratio to deucravacitinib (6 mg once daily), placebo, or apremilast (Otezla; 30 mg twice daily). At 16 weeks, those on placebo were switched to deucravacitinib.

For the co-primary endpoint of PASI 75 (75% clearance on the Psoriasis and Severity Index), the similar rate of response for deucravacitinib in the two studies (58.7% / 53.6%) at week 16 was superior to the rates observed on both apremilast (35.1% / 40.2%) and placebo (12.7% / 9.4%).

By week 24, the proportion of deucravacitinib patients with a PASI-75 response had reached 69.3% and 58.7% in the POETYK PSO-1 and PSO-2 trials, respectively. The proportion of patients on apremilast with PASI 75 at this timepoint did not increase appreciably in one study and fell modestly in the other.

By week 52, the response rates achieved with deucravacitinib at week 24 were generally unchanged and nearly double those observed on apremilast.

The pattern of relative benefit on the other co-primary endpoint, which was a score of 0 or 1, signifying clear or almost clear skin on the Physicians Global Assessment (sPGA), followed the same pattern. At week 16, 53.6% of patients had achieved sPGA 0/1. This was significantly higher than that observed on either apremilast or placebo, and this level of response was sustained through week 52.

When patients on placebo were switched to deucravacitinib at week 16, the PASI 75 response climbed quickly. There was complete catch-up by 32 weeks. In both groups, a PASI-75 response rate of about 65% or higher was maintained for the remainder of the study.

On a prespecified analysis, prior treatment exposure was not associated with any impact on the degree of response with deucravacitinib. This included a comparison between patients exposed to no prior biologic, one prior biologic, or two or more biologics, Warren reported.    

Unlike patients in POETYK PSO-1, those with a PASI 75 response at 16 weeks in the POETYK PSO-2 trial were re-randomized to remain on deucravacitinib or switch to placebo. Designed to evaluate response durability, this analysis showed a relatively gradual decline in disease control.

"The median time to a loss of response was 12 weeks," Warren said. He was referring in this case to the PASI 75 response, but the slope of decline was similar for sPGA score 0/1. At the end of 52 weeks, 31.3% of patients who had been re-randomized to placebo still maintained a PASI 75 while 80.4% of those who stayed on deucravacitinib still had PASI 75 clearance.

In the 52-week data from these two trials, several secondary endpoints have already been examined, and Warren said more analyses are coming. So far, the pattern of response has been similar for all endpoints.

Reporting on one as an example, Warren said that sPGA 0/1 for scalp psoriasis was achieved at week 16 by 70.3% of those randomly assigned to deucravacitinib vs 17.4% of those in the placebo arm. Among those switched from placebo to deucravacitinib at 16 weeks, the scalp response had caught up to that observed in those initiated on deucravacitinib by week 28. The response was sustained out to 52 weeks in both groups.

In the long-term trials, there have been no new safety concerns, according to Warren. He described this drug as "well tolerated," adding that no significant laboratory abnormalities have been observed on long-term treatment. Although there has been a trend for increased risk of viral infections, such as herpes zoster, relative to apremilast, cases have so far been mild.

The JAK inhibitor tofacitinib (Xeljanz, Xeljanz XR) has been approved for psoriatic arthritis and numerous other JAK inhibitors are now in clinical trials for plaque psoriasis. These agents vary for their relative selectivity for JAK 1, 2, and 3 kinases, but deucravacitinib is the first JAK inhibitor to reach clinical trials that target Tyk2, which inhibits interleukin 23 (IL-23) and other cytokines implicated in the pathogenesis of plaque psoriasis.

"Deucravacitinib is very distinct from the other JAK inhibitors, and I think we are seeing this in the clinical studies," Warren said. As a result of responses in the POETYK PRO trials that rival those achieved with monoclonal antibodies, he expects this drug, if approved, to be an important option for those with moderate to severe disease who prefer oral therapies.

Mark G. Lebwohl, MD, professor of dermatology and dean for clinical therapeutics, Icahn School of Medicine at Mount Sinai, New York City, shares this opinion. In an interview, he emphasized the unique mechanism of deucravacitinib and its clinical potential.

"Unlike other less specific JAK inhibitors, deucravacitinib has a unique binding site on Tyk2, the regulatory domain of the molecule. This makes deucravacitinib more targeted and therefore safer than other JAK inhibitors," said Lebwohl.

"After cyclosporine, which has many side effects, deucravacitinib is the most effective oral therapy we have for psoriasis and one of the safest," he added.

The POETYK PSO-1 and PSO-2 trials received funding from Bristol-Myers Squibb. Warren has financial relationships with AbbVie, Almirall, Boehringer Ingelheim, Celgene, Eli Lilly, Janssen, Leo Pharma, Novartis, Pfizer, Sanofi, UCB, and Xenoport. Lebwohl has financial relationships with more than 20 pharmaceutical companies, including Bristol-Myers Squibb.

European Academy of Dermatology and Venereology: Abstract 2857. Presented September 30, 2021.

Ted Bosworth is a medical journalist based in New York City.

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