In psoriatic arthritis patients, ixekizumab has superior efficacy compared to adalimumab in terms of joint pain improvement.

An open-label, phase 3b/4, multicentre, randomized, blinded-assessor, 52-week study (SPIRIT head-to-head [SPIRIT-H2H]) was carried out to compare the safety and efficacy of ixekizumab and adalimumab in bionaive individuals suffering from psoriatic arthritis.

This study included the outcomes of the prespecified subgroup analyses on the basis of the presence/absence of moderate to severe psoriasis and concomitant conventional synthetic disease-modifying anti-rheumatic drugs (csDMARD) utilization. 

The study cohort included 566 psoriatic arthritis subjects with an unsatisfactory response to conventional synthetic DMARDs and no prior exposure to biologic DMARDs. Subjects were randomly allocated (1:1) to adalimumab (n=283) or ixekizumab (n=283).

The primary endpoint was the superiority of ixekizumab to adalimumab based on Psoriasis Area and Severity Index (PASI) 100 and American College of Rheumatology (ACR) 50 responses after 24 weeks. The prespecified endpoints after 52 weeks were psoriasis, quality of life, safety, and musculoskeletal outcomes.

Of the total cohort, 246 (87%) subjects who were administered ixekizumab and 237 (84%) subjects who were administered adalimumab completed the 52-week trial visit. A considerably greater percentage of patients treated with ixekizumab compared to adalimumab simultaneously achieved  both ACR50 i.e. a 50% improvement in arthritis symptoms and PASI100, clinical responses at week 52, as shown in the following table:

The efficacy of ixekizumab and adalimumab was similar at week 52 for ACR50 (49.8% vs 49.8%), treat-to-target outcomes, enthesitis, and dactylitis resolution. Irrespective of concomitant csDMARD use, the responses to ixekizumab were found to be consistent.

When used as monotherapy for 52 weeks in a subgroup analysis, ixekizumab was found to be better than adalimumab for simultaneous attainment of both ACR50 and PASI100, and PASI100 responses, as shown in the following table:

No novel safety findings for ixekizumab or adalimumab was noted. In bionaive patients having psoriatic arthritis, ixekizumab offered considerably better simultaneous joint and skin improvement compared to adalimumab through week 52. Ixekizumab displayed higher efficacy on psoriasis and its performance was comparable to adalimumab on musculoskeletal manifestations.

Treatment with ixekizumab was better than adalimumab regarding attaining ACR 50 and PASI 100 responses. Concomitant usage of conventional synthetic DMARD had a response-modifying impact in the adalimumab arm, but not the ixekizumab arm.

Ixekizumab efficacy depicted consistency irrespective of concomitant synthetic DMARD usage. The responses to ixekizumab displayed consistency in monotherapy as well as in combo with conventional synthetic DMARDs. 

Compared to adalimumab,  ixekizumab appears to be better to treat patients having psoriatic arthritis.