The results of two studies presented at the Annual European Congress of Rheumatology (EULAR) 2017 press conference revealed promising data supporting two new drug classes for the treatment of psoriatic arthritis (PsA).

New agents working on different inflammatory aspects of PsA are needed in the treatment of PsA patients living with this chronic immune–mediated disease, which involves both joint and skin symptoms.

In the first study, in patients with active PsA who had not previously been prescribed an anti–TNF treatment, tofacitinib (an oral Janus kinase inhibitor under investigation for the treatment of PsA), was superior to placebo in ACR20 response rates and change from baseline in the HAQ–DI score at 3 months. Tofacitinib demonstrated superiority to placebo as early as week 2, and this was maintained for 12 months. No new safety risks were identified compared to previous studies in other indications.

In the second study, in patients with active PsA and 3% or more of their body surface area affected by plaque psoriasis despite current or previous treatment with standard–of–care therapies, including anti–TNF treatments, guselkumab demonstrated significant improvement in joint symptoms, physical function, psoriasis, enthesitis, dactylitis and quality of life. Guselkumab, a fully human monoclonal antibody targeting IL–23, in this Phase 2 study for the treatment of PsA, was well tolerated with no unexpected safety findings in this patient population. Guselkumab is now being pursued in a Phase 3 development programme for psoriatic arthritis.

In this Phase 2a study, significantly more guselkumab–treated patients achieved ACR 20/50/70 responses and Psoriasis Area Severity Index (PASI) 75/90/100 responses at week 24. Nearly 40% of patients in the active group, vs. 6.3% in the placebo arm, achieved PASI 100 (completely clear skin) at week 24.

“Guselkumab, which targets IL–23, appears to be a promising new treatment of PsA,” said lead author Professor Atul Deodhar from Oregon Health & Science University, Portland, US. “Although anti–TNF treatments have revolutionised the management of psoriatic arthritis, new next–generation therapies are needed in the treatment of this disease,” he added.

As early as 4 weeks into treatment, 21% in the guselkumab group had a significant treatment effect on ACR20 response, compared to zero in the placebo group (p<0.001). The ACR response in the active arm increased with time, with 58% of subjects reaching a 20% improvement in joint symptoms at week 24, versus 18.4% of those on placebo (p<0.001).

Fourteen percent of patients on guselkumab achieved ACR70, versus 2% on placebo, at week 24 (p=0.023).

Guselkumab was well tolerated; through week 24, the proportion of patients with at least 1 adverse event was comparable between the two groups (guselkumab 36.0% vs. placebo 32.7%). Infections were the most common adverse events (guselkumab 17.0% vs. placebo 20.4%). The researchers reported no serious infections, cancer or death during the 24 weeks of the study.