The phase II trial, which involved almost 300 people with psoriasis, compared guselkumab to Humira (adalimumab) and a placebo. About a third of trial patients taking Humira had completely clear skin after four months, according to the results.
Guselkumab, which is being developed by Janssen, is an injectable medication that targets interleukin 23 (IL-23), which is a kind of protein known as a cytokine that is involved in inflammation in psoriatic disease. Humira, as well as other biologics such as Enbrel (etanercept) and Remicade (infliximab), target a different cytokine, known as tumor necrosis factor-alpha.
Study participants were randomly assigned Humira, a placebo or one of several doses of guselkumab. After four months, all placebo patients were switched to guselkumab, researchers reported.
Patients on guselkumab, no matter the dose, experienced more improvement than those taking the placebo, according to the results. Patients on the highest three doses of guselkumab, ranging from 50 milligrams (mg) to 200 mg, also experienced significantly more improvement than patients on Humira.
Patients on guselkumab experienced improvement in as little as a month, the researchers noted.
After four months, up to 86 percent of patients on guselkumab had clear or almost clear skin, while up to 45 percent had completely clear skin, according to the findings.
In the same amount of time, researchers reported, 58 percent of Humira patients had clear or almost clear skin, while 30 percent had completely clear skin.
The number of patients who experienced a side effect within the first four months was similar among all the trial patients, according to the data, with about half on each treatment experiencing at least one side effect.
By the end of the year, almost 61 percent of Humira patients experienced a side effect, while about 49 percent of guselkumab patients did.
When looking specifically at how many patients in the trial came down with infections, which were the most common side effect, the rates were highest for those taking guselkumab. In the first four months of the trial, 20 percent of guselkumab patients experienced an infection, while 12 percent on Humira and 14 percent on placebo did, researchers reported.
Over the entire year, about 1 percent of guselkumab patients experienced a serious side effect, while about 2 percent of patients on Humira did, according to the data.
Guselkumab is not yet available by prescription, and is currently being tested in phase III trials. Another drug targeting the same cytokine, IL-23, is being developed by Boehringer Ingelheim.
Stelara (ustekinumab), a biologic that is frequently used to treat psoriatic disease, targets both IL-23 and another cytokine called IL-12.