The first head-to-head comparison of an IL-17 inhibitor and TNF inhibitor in moderate to severe psoriatic arthritis has shown ixekizumab superior to adalimumab for simultaneous improvement of joint and skin disease.

The open-label, blinded assessor study of 566 patients through to 24 weeks of treatment found 36% of patients treated with ixekizumab and 28% of patients treated with adalimumab achieved simultaneous ACR50 and PASI100.

Separately, ixekizumab was superior on skin endpoints and non-inferior to adalimumab on joint endpoints.

The international study, including Australia, found no significant difference between the patient groups for ACR20/50/70 – “suggesting IXE had similar speed and level of response compared to ADA for joint improvement.”

Serious adverse events were higher with adalimumab (8.5%) than ixekizumab (3.5%) and discontinuations due to adverse or serious adverse events were higher in the adalimumab group (4.6% v 2.5%).

Three patients discontinued treatment due to opportunistic infections including legionella pneumonia and lymph node tuberculosis in the adalimumab group and a bacterial arthritis in the ixekizumab group.

Two cases of inflammatory bowel disease were reported in the ixekizumab group compared to none with adalimumab. Three malignancies were observed in adalimumab compared to none with ixekizumab.

Co-investigator on the study Associate Professor Peter Nash from the University of Queensland told the limbic the findings suggest equal efficacy between the TNF and the IL-17 inhibitors from a joint point of view.

“Dactylitis, ethesitis – with all those measures, the IL-17 is the same. Skin is where the real difference lies.”

He said treatment should be individualised for the patient.

“People are currently using the IL-17 if the patients have worse skin or they have failed the TNF inhibitor but both bDMARDs are being used.”

“If the IL-17 stacks up to be safer when it is out of clinical trials in the real world with people who could not get into trials because of comorbidities, then maybe the treatment algorithm should be IL-17 first then TNF next unless there is a TNF specific reason like uveitis or IBD,” he said.

The study, published in Annals of Rheumatic Disease, reported on 24 weeks of treatment. The 52-weeks data will be presented at the ACR/ARP 2019 Annual Meeting in Atlanta next month.

Associate Professor Nash said he believed the results would be similar.

Results of a head-to-head comparison of secukinumab versus TNF inhibitor in psoriatic arthritis are also expected later this year or early next year.