Expert: Human monoclonal antibody neutralizing IL-33, an epithelial-derived alarmin that drives inflammation via two distinct pathways: (1) IL-33red binds membrane-bound ST2 (IL1RL1) on ILC2s, Th2 cells, and macrophages, activating type 2 inflammation (IL-4/5/13); (2) after oxidation, IL-33ox signals through RAGE/EGFR on epithelial cells, driving MUC5AC expression, goblet cell metaplasia, and mucus hypersecretion independently of ST2. Anti-IL-33 antibodies capture IL-33red before oxidation, blocking BOTH pathways. This dual-pathway blockade differentiates anti-IL-33 from anti-ST2 approaches (e.g., astegolimab), which only block the immune/ST2 arm and miss the RAGE/EGFR mucus biology. In COPD, smoking shifts ST2 expression from ILC2s to macrophages, explaining why former smokers show better response to IL-33 blockade (ILC2 recovery post-cessation). sST2 (soluble decoy receptor) is elevated in COPD as a natural brake.
Everyday: Blocks IL-33, an "alarm signal" protein released by damaged lung cells. When lung cells are hurt by smoke, pollution, or infections, they release IL-33 which triggers two problems: (1) it activates immune cells that cause inflammation (like pulling a fire alarm that sends too many fire trucks), and (2) the alarm signal itself changes form and directly causes excess mucus production in the airways. By intercepting the alarm before it reaches anyone, IL-33 blockers aim to prevent both the immune overreaction AND the mucus buildup.
Targets: ["IL-33","IL-33red","IL-33ox (prevented)"]
Anti-IL-33 mAb for COPD (AstraZeneca). Key differentiator: "dual pharmacology" — ultra-fast binding kinetics (KD 30 fM, on-rate 8.5x10^7 M-1 s-1) captures IL-33red before it oxidizes, blocking BOTH:
1. ST2 pathway (immune inflammation — ILC2s, Th2, eosinophils)
2. RAGE/EGFR pathway (mucus hypersecretion, goblet cell metaplasia — epithelial damage)
RAGE BIOMARKER: AZN uses sRAGE (soluble RAGE) as a biomarker for epithelial damage severity. Patients with higher RAGE pathway activity may benefit most from tozorakimab's dual blockade — a differentiation vs itepekimab (which has not explicitly demonstrated RAGE pathway data).
FRONTIER-4 (Phase 2a): Failed ITT but showed HR 0.61 (39% exacerbation reduction) in pre-specified frequent-exacerbator subgroup. Post-BD FEV1 +124mL (p=0.020) in this subgroup.
Phase 3 program (enriched for frequent exacerbators, 2+ moderate or 1+ severe prior year):
- OBERON (NCT05166889) — primary completion est. Jan 2026
- TITANIA (NCT05158387) — ongoing
- MIRANDA (NCT06040086) — ongoing
- PROSPERO extension (NCT05742802)
Competitive context: Both anti-IL-33 drugs (itepekimab, tozorakimab) block upstream of ST2 and RAGE. Astegolimab (Roche, anti-ST2) FAILED in Phase 3 — showing ~15% effect vs anti-IL-33's ~27%, likely because it misses the RAGE/EGFR arm entirely.