A phase II clinical trial led by Northwestern Medicine investigators shows that a new psoriasis drug called guselkumab has greater efficacy than the current standard of care for the chronic skin condition.

In the study, published in the New England Journal of Medicine, investigators compared guselkumab to adalimumab, the most common medication currently used to treat psoriasis.

"Research like this study is leading to a series of new medications that promise high levels of response for an increasing number of patients," said first author Kenneth Gordon, MD, professor in Dermatology. "The possibility of getting almost all patients nearly clear and able to live their lives without the burden of this disease impacting them every day is getting close to reality."

Psoriasis is an immune-mediated disease that causes itchy, dry and red skin. It also increases a patient's risk for depression, heart disease and diabetes, among other conditions. The disease affects nearly 3 percent of the world's population, according to the World Psoriasis Day consortium, but about half of all patients with psoriasis do not get any treatment, Dr. Gordon said.

"For patients, the concept that psoriasis is 'just something you live with' is no longer appropriate," he said.

In the multi-center trial, 293 adult patients with moderate-to-severe psoriasis (defined as covering 10 percent or more of the body) were randomly assigned to receive varying doses of one of the two drugs or a placebo over 52 weeks.

At weeks 16 and 40, efficacy of the drugs was measured on a scale of 0 to 5. A significantly higher proportion of patients in the guselkumab group had a score of 0 (cleared psoriasis) or 1 (minimal psoriasis) in both the short and long term periods compared to the adalimumab and placebo groups. At week 40, for example, 81 percent of patients taking a 200-mg dose of guselkumab had a score of 0 or 1, compared to 49 percent of patients taking adalimumab.

The new drug works by blocking a protein specifically implicated in psoriasis, called interluekin 23; older drugs affect the immune process more generally.

"Building on multiple layers of clinical and basic research, we are changing our understanding of how psoriasis works," Dr. Gordon said. "By doing so, we are able to build new treatments that specifically target the immunological processes of psoriasis while leaving even more of the normal immune system intact."

An ongoing phase III trial is continuing to test the safety and efficacy of guselkumab as a psoriasis treatment.