Janssen Pharmaceutical has reported positive data from the Phase III Discover-1 and Discover-2 clinical trials of Tremfya (guselkumab) in patients with active psoriatic arthritis (PsA).

According to the 24-week data, the drug met the primary endpoint of superior ACR20 responses, demonstrating at least a 20% improvement in signs and symptoms in a significantly greater proportion of patients compared to placebo.

Tremfya is a human monoclonal antibody targeting the p19 subunit of IL-23, which is involved in the pathogenesis of inflammatory diseases, including psoriatic arthritis.

The Discover-1 and Discover-2 trials assessed the safety and efficacy of a subcutaneous formulation of the drug in 381 and 739 adults with active PsA, respectively.

Discover-1 involved patients with an inadequate response to standard therapies, including those who previously received anti-tumour necrosis factor (TNF) alpha biologics.

Meanwhile, Discover-2 enrolled biologic-naive patients with an inadequate response to standard treatments.

In the Discover-1 study, the drug led to ACR20 response in 59% of participants treated every four weeks (q4w) and 52% of those treated at weeks zero and four followed by every eight weeks thereafter (q8w).

The response was observed in 22% of patients in the placebo group.

The trial also analysed the effect of the drug in patients with a >3% body surface area (BSA) affected with psoriasis and an >2 Investigator Global Assessment (IGA) score at baseline.

Data showed 75% of patients on Tremfya q4w and 57% on q8w experienced an IGA score of zero or one and a >2 grade decrease versus 15% with placebo.

In Discover-2, 64% of subjects treated with q4w or q8w dosing regimen had an ACR20 response, compared to 33% receiving placebo.

Compared to 19% of patients in the placebo arm, the IGA score was zero or one in 69% receiving q4w and 71% receiving q8w dosing.

During the trials, adverse events relating to the drug were generally consistent with prior studies.

Janssen Research & Development vice-president Alyssa Johnsen said: “These results from the discover programme represent a major step in the development of Tremfya as a treatment for psoriatic arthritis.”

The drug holds approval in multiple markets, including the US and EU, for the treatment of adults with moderate to severe plaque psoriasis.