Experimental TYK2/JAK1 inhibitor shows promise against plaque psoriasis

PF-06700841, a TYK2/JAK1* inhibitor under investigation, shows good efficacy against moderate-to-severe plaque psoriasis and carries a well-tolerable safety profile, according to new results of a phase IIa trial.

The study included 212 patients who were randomly assigned to receive the test drug at a 30-mg or 60-mg dose once-daily for the initial 4-week induction phase, followed by 8 weeks of 10 mg or 30 mg once daily, or 100 mg once weekly. Some patients were also randomized to take placebo for the entire duration of the study.

The primary study outcome was the 12-week change in the Psoriasis Area and Severity Index (PASI) score. Score reductions were apparent in all patients who had received the active treatment, and by week 12, all improvements were significantly different than in the placebo arm. A total of 164 patients were able to complete the study and were included in these outcome analyses.

Patients who received the 30-mg once-daily dose during the 4-week induction and 8-week maintenance phases showed the greatest mean 12-week change in PASI scores (least squares mean change, –17.3, 95 percent confidence interval [CI], –20.0 to –14.6).

The proportion of patients achieving 75-percent (PASI 75) and 90-percent (PASI 90) reduction in PASI scores relative to baseline were set as secondary outcomes. Both measures were higher across all active treatment groups relative to placebo. As with the primary outcome, patients taking the 30-mg once-daily dose throughout the 12-week period saw the best PASI75 and PASI 90.

In terms of safety, treatment-emergent adverse events (TEAEs) were reported in 136 patients across the seven active treatment groups, as opposed to only 13 in the placebo group. Forty-four episodes of TEAEs were deemed related to treatment, and nine patients had to discontinue treatment due to it; most of the treatment-related side effects were mild to moderate in severity and were resolved after discontinuation.

*Tyrosine kinase 2/Janus kinase 1