SPIRIT-P1 (N=417) and -P2 (N=363) were phase 3, randomized, double-blind, placebo-controlled trials to evaluate the efficacy and safety of Taltz compared with placebo in patients with active psoriatic arthritis. Patients in SPIRIT-P1 were biologic-naive. Patients in SPIRIT-P2 were tumor necrosis factor inhibitor (TNFi)-experienced, having had an inadequate response and/or intolerance to 1 or 2 prior TNFis. In both trials, the primary efficacy endpoint was the proportion of patients achieving ACR20 response at week 24. All patients were ≥18 years of age and had ≥3 swollen and ≥3 tender joints. Patients were randomized to placebo or Taltz 80 mg every 2 or 4 weeks following a 160 mg starting dose. In SPIRIT-P1, an active reference arm of Humira® (adalimumab) 40 mg every 2 weeks was included. Patients in all study arms were allowed to continue taking stable background medications during the trial. Inadequate responders (as defined by blinded criteria of <20% improvement in tender and in swollen joint counts) at week 16 received rescue therapy and were analyzed as nonresponders after week 16 until the primary endpoint. After receiving rescue therapy, inadequate responders in the placebo and Humira arms were re-randomized to Taltz 80 mg every 2 or 4 weeks. Nonresponder imputation (NRI) methods were used for categorical efficacy analyses during the double-blind treatment period.
Reference: 1. Taltz [package insert]. Indianapolis, IN: Eli Lilly and Company; 2020. 2. Mease PJ, van der Heijde D, Ritchlin CT, et al; on behalf of SPIRIT-P1 Study Group. Ixekizumab, an interleukin-17A specific monoclonal antibody, for the treatment of biologic-naive patients with active psoriatic arthritis: results from the 24-week randomised, double-blind, placebo-controlled and active (adalimumab)-controlled period of the phase 3 trial SPIRIT-P1. Ann Rheum Dis. 2017;76(suppl):1-30. 3. Nash P, Kirkham B, Okada M, et al; on behalf of SPIRIT-P2 Study Group. Ixekizumab for the treatment of patients with active psoriatic arthritis and an inadequate response to tumour necrosis factor inhibitors: results from the 24-week randomised, double-blind, placebo-controlled period of the SPIRIT-P2 phase 3 trial. Lancet. 2017;389:2317-2327. 4. Nash P, Kirkham B, Okada M, et al; on behalf of SPIRIT-P2 Study Group. Ixekizumab for the treatment of patients with active psoriatic arthritis and an inadequate response to tumour necrosis factor inhibitors: results from the 24-week randomised, double-blind, placebo-controlled period of the SPIRIT-P2 phase 3 trial. Lancet. 2017;389:2317-2327. Supplementary appendix.
ACR20=American College of Rheumatology 20% response.