Conference Coverage

SPIRIT-H2H results confirm superiority of ixekizumab over adalimumab for PsA



– Ixekizumab (Taltz) provided significantly greater improvement in joint and skin symptoms, compared with adalimumab (Humira), in biologic-naive patients with active psoriatic arthritis (PsA), according to final 52-week safety and efficacy results from the randomized SPIRIT-H2H study.

Dr. Josef Smolen of the Medical University of Vienna

Dr. Josef Smolen

The high-affinity monoclonal antibody against interleukin-17A also performed at least as well as the tumor necrosis factor (TNF)–inhibitor adalimumab across multiple PsA domains and regardless of methotrexate use, Josef Smolen, MD, reported during a late-breaking abstract session at the annual meeting of the American College of Rheumatology.

Multiple biologic disease-modifying antirheumatic drugs (bDMARDs) are available for the treatment of PsA, but few studies have directly compared their efficacy and safety, said Dr. Smolen of the Medical University of Vienna. He noted that the SPIRIT-H2H study aimed to compare ixekizumab and adalimumab and also to address “one of the most clinically relevant questions for clinicians,” which relates to the efficacy of bDMARDs with and without concomitant methotrexate.

Ixekizumab is approved for adults with active PsA and moderate to severe plaque psoriasis, but TNF inhibitors like adalimumab have long been considered the gold standard for PsA treatment, he explained.

Of 283 patients with PsA randomized to receive ixekizumab and 283 randomized to receive adalimumab, 87% and 84%, respectively, completed week 52 of the head-to-head, open-label study comparing the bDMARDs. Treatment with ixekizumab achieved the primary endpoint of simultaneous improvement of 50% on ACR response criteria (ACR50) and 100% on the Psoriasis Area and Severity Index (PASI100) in 39% of patients, which was significantly higher than the rate of 26% with adalimumab, Dr. Smolen said.

Ixekizumab also performed at least as well as adalimumab for the secondary outcome measures of ACR50 response (50% in both groups) and PASI100 response (64% vs. 41%), as well as for all other outcomes measures, including multiple musculoskeletal PsA domains, he said.

“Remarkably ... at 1 year, more than one-third of the patients achieved an ACR70 in both groups, and half of the patients achieved an ACR50,” he added, noting that the ACR100 responses were in line with previous investigations.

Stratification by methotrexate use showed that the simultaneous ACR50 and PASI100 response rates were improved with ixekizumab versus adalimumab both in users and nonusers of methotrexate (39% vs. 30% and 40% vs. 20%, respectively). This finding highlights the ongoing debate about whether TNF inhibitors should or should not be used with methotrexate for PsA.

“This study was not adequately powered to say that, but there is some indication, and I think that this is food for thought for future further analysis because the data in the literature are discrepant in this respect,” Dr. Smolen said.

In non-methotrexate users in SPIRIT-H2H, the ACR20 responses were 53% with ixekinumab vs. 40% with adalimumab, ACR50 responses were 72% vs. 60%, and ACR70 responses were 41% vs. 27%, respectively, he said noting that the difference for ACR70 was statistically significant, and that the ACR70 response with ixekinumab was about the same as the ACR50 for adalimumab.

As for ACR20, ACR50, and ACR70 responses in methotrexate users, “the lines criss-crossed” early on, he said, but all were “slightly superior” with adalimumab than with ixekizumab at 52 weeks (75% vs. 68%, 56% vs. 48%, and 39% vs. 32%, respectively).

Study participants had a mean age of 48 years and had active PsA with at least 3/66 tender joints, at least 3/68 swollen joints, at least 3% psoriasis body surface area involvement, no prior treatment with bDMARDs, and prior inadequate response to one or more conventional synthetic DMARDs. Treatment was dosed according to drug labeling through 52 weeks.

The safety profiles of both agents were consistent with previous reports; treatment-emergent adverse events occurred in 73.9% of ixekizumab and 68.6% of adalimumab patients, and serious adverse events occurred in 4.2% and 12.4%, respectively.

“On the other hand, ixekizumab had more injection site reactions: 11% vs. close to 4%,” he said, noting that 4.2% of the ixekizumab patients and 7.4% of the adalimumab patients discontinued treatment because of adverse events. No deaths occurred in either group.

As reported previously in Annals of the Rheumatic Diseases, ixekizumab was superior to adalimumab for simultaneous achievement of ACR50 and PASI100 at 24 weeks, and these final 52-week results confirm those results, he said.

The study was funded by Eli Lilly, which markets ixekizumab. Dr. Smolen reported research grants and/or honoraria from Eli Lilly and AbbVie, which markets adalimumab, as well as many other pharmaceutical companies.

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SOURCE: Smolen J et al. Arthritis Rheumatol. 2019;71(suppl 10), Abstract L20.

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