Results of the phase 3b/4 SPIRIT-Head-to-Head (H2H) study in patients with active psoriatic arthritis (PsA), presented as a late-breaking abstract at the European Congress of Rheumatology (EULAR) in Madrid, show that a significantly higher proportion of patients met the primary endpoint at week 24, compared to those using adalimumab.

The assessor-blinded, randomized, controlled trial is the first and only H2H study that utilizes on-label dosing for both Taltz® (ixekizumab) and Humira® (adalimumab) and allows inclusion of concomitant conventional DMARDs. Topline results from the study, which demonstrated Taltz met the primary and all major secondary endpoints, were announced in December 2018. 

The primary endpoint of the study was superiority for Taltz compared to Humira in the proportion of patients who simultaneously achieved a reduction by at least 50 percent in disease activity as defined by the American College of Rheumatology (ACR50) and complete skin clearance as measured by the Psoriasis Area and Severity Index (PASI 100). Key secondary endpoints included non-inferiority in the proportion of patients who achieved ACR50 and superiority in the proportion of patients who achieved PASI 100.

A total of 566 patients with active PsA were enrolled in the SPIRIT-H2H study. Patients were randomized to receive Taltz (n=234) or Humira (n=231) at the approved dose for PsA for a total of 52 weeks, with the primary analysis conducted at 24 weeks. PsA patients who also met the study criteria for moderate- to severe plaque psoriasis received Taltz (n=49) or Humira (n=52) at the approved dose for psoriasis.

At 24 weeks, the proportion of patients achieving both a reduction by at least 50 percent in disease activity as defined by ACR50 as well as complete skin clearance as measured by PASI 100, was significantly higher for Taltz (36 percent) than for Humira (28 percent) (P<.05).

Taltz also met the key secondary endpoints, including non-inferiority compared to Humira for the percentage of patients achieving ACR50 (51% vs. 47%) (95% CI [-4.3% , 12.1%]) (for noninferiority with -12.0% margin) and superiority compared to Humira for the percentage of patients achieving PASI 100 (60% vs. 47%) (P=.001).

In SPIRIT-H2H, the safety profile of Taltz was consistent with previously reported results. The most common adverse reactions were mild to moderate in severity, and included infections (36.0% for Taltz vs. 30.7% for Humira), injection site reactions (9.5% for Taltz vs. 3.2% for Humira), allergic/hypersensitivity reactions (2.5% for Taltz vs. 3.9% for Humira) and cerebrocardiovascular events (1.1% for Taltz vs. 1.8% for Humira). No new safety signals were detected.