#2267 IL-33 Inhibition with tozorakimab for diabetic kidney disease: a randomized, placebo-controlled phase 2b study
Authors: Heerspink Hiddo Lambers , Hofherr Alexis , Mäki-Petäjä Kaisa , Selvarajah Viknesh , Grice Daniel , Bartesaghi Stefano , Jimenez Eulalia , Kaila Nitin , Pecoits-Filho Roberto 
Published: May 2024

Abstract

Background and Aims
In patients with type 2 diabetes (T2D) and chronic kidney disease (CKD), persistent, low-grade inflammation is a significant risk factor for adverse kidney outcomes. Previously, we identified interleukin-33 (IL-33) as an over-expressed inflammatory cytokine in kidney biopsies from patients with CKD and showed a significant benefit of inhibiting IL-33 signaling in a rodent model of diabetic kidney disease (DKD). Here, we investigate the therapeutic potential of tozorakimab, a high-affinity IL-33-neutralizing immunoglobulin G1 monoclonal antibody, in patients with DKD.

Method
FRONTIER-1 (NCT04170543) was a phase 2b, randomized, double-blind, placebo-controlled, multicenter study to evaluate the efficacy, safety, pharmacokinetics (PK), and immunogenicity of tozorakimab in patients with DKD; defined as T2D with an estimated glomerular filtration rate (eGFR) of 25-75 mL/min/1.73 m2, a urinary albumin-to-creatinine ratio (UACR) of 100-3,000 mg/g, and on angiotensin-converting-enzyme inhibitor (ACEi) or angiotensin-receptor blocker (ARB) for &gt; 6 weeks before the treatment period. Participants were randomly assigned to four different doses of tozorakimab or volume-matched placebo, administered subcutaneously every 28 days for 24 weeks. The randomization process was stratified based on region and the use of SGLT2 inhibitors (SGLT2i). All participants received 10 mg of dapagliflozin Days 85–168, discontinuing existing SGLT2i if applicable. The primary objective of the study was to evaluate the effect of tozorakimab on UACR. A sample size of 565 patients provided at least 80% power to detect a 30% reduction in the change from baseline to week 24 in UACR between each tozorakimab treatment group and placebo. Efficacy endpoints were evaluated in the Per Protocol Population (PPP; initiated dapagliflozin treatment), whereas safety and tolerability were assessed for all dosed participants.

Results
Between 11 December 2019 and 16 May 2023, we assessed 1,575 patients for eligibility in Argentina, Canada, Chile, Peru, South Korea, Japan, and the United States. 599 (38%) participants were assigned to tozorakimab or placebo. Owing to the COVID-19 pandemic, the study was temporarily halted between March and June 2020. This precautionary measure resulted in the discontinuation of 26 participants. Upon resuming, the study incorporated significant modifications to adapt to the pandemic environment. 573 participants (Full Analysis Population) were randomized after the study was restarted: 29.7% were female; their mean age (±SD) was 67 years (±10); mean eGFR was 48 mL/min/1.73 m2 (±15); and the geometric mean UACR was 460 mg/g (coefficient of variation = 151%). Most participants were taking an ACEi (30%) or ARB (65%), and 28% an SGLT2i. 139 participants received placebo, while 96, 91, 95, and 152 participants received 30, 60, 120, and 300 mg tozorakimab, respectively. The baseline characteristics were balanced across treatment groups, and significant target engagement was observed in all dose arms. Tozorakimab was generally well tolerated and the incidences of adverse events (Aes), serious Aes, discontinuations, and death were similar to placebo. Initial evaluation identified 476 participants in the PPP with 109, 81, 80, 72, and 134 on placebo, 30, 60, 120, and 300 mg tozorakimab, respectively. The primary efficacy analysis demonstrated an inhibition of IL-33 signaling but failed to establish a statistically significant difference in UACR reduction between placebo and treatment groups. The median %-change from baseline was –22% (–46%, 24%) in the placebo group and ranged from –23% to –25% in the tozorakimab groups at week 24. Similarly, no significant effect on eGFR was observed. Following study completion, Good Clinical Practice concerns arose at one clinical trial site with 15 participants. The investigation of these issues is ongoing, but significant alterations to the study results are not anticipated.

Conclusion
This study did not demonstrate a clinically meaningful reduction in UACR with tozorakimab treatment in patients with T2D and CKD. Further investigation is warranted to clarify the role of IL-33 in DKD.