A randomized phase 1 study of the anti‐interleukin‐33 antibody tozorakimab in healthy adults and patients with chronic obstructive pulmonary disease

Tozorakimab is a human monoclonal antibody that neutralizes interleukin (IL)‐33. IL‐33 is a broad‐acting epithelial “alarmin” cytokine upregulated in lung tissue of patients with chronic obstructive pulmonary disease (COPD). This first‐in‐human, phase I, randomized, double‐blind, placebo‐controlled study (NCT03096795) evaluated the safety, tolerability, pharmacokinetics (PKs), immunogenicity, target engagement, and pharmacodynamics (PDs) of tozorakimab. This was a 3‐part study. In part 1, 56 healthy participants with a history of mild atopy received single escalating doses of either intravenous or subcutaneous tozorakimab or placebo. In part 2, 24 patients with mild COPD received multiple ascending doses of subcutaneous tozorakimab or placebo. In part 3, 8 healthy Japanese participants received a single intravenous dose of tozorakimab or placebo. The safety data collected included treatment‐emergent adverse events (TEAEs), vital signs, and clinical laboratory parameters. Biological samples for PKs, immunogenicity, target engagement, and PD biomarker analyses were collected. No meaningful differences in the frequencies of TEAEs were observed between the tozorakimab and placebo arms. Three tozorakimab‐treated participants with COPD experienced treatment‐emergent serious adverse events. Subcutaneous or intravenous tozorakimab demonstrated linear, time‐independent PKs with a mean half‐life of 11.7–17.3 days. Treatment‐emergent anti‐drug antibody frequency was low. Engagement of tozorakimab with endogenous IL‐33 in serum and nasal airways was demonstrated. Tozorakimab significantly reduced serum IL‐5 and IL‐13 levels in patients with COPD compared with placebo. Overall, tozorakimab was well tolerated, with a linear, time‐independent serum PK profile. Additionally, biomarker studies demonstrated proof of mechanism. Overall, these data support the further clinical development of tozorakimab in COPD and other inflammatory diseases.