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)"]

Primary EP: [{"id":"aerify1-aer","name":"Annualized moderate-to-severe COPD exacerbation rate at Week 52","type":"PRIMARY","unit":"rate ratio","results":[{"notes":"27% reduction vs placebo — STATISTICALLY SIGNIFI

Efficacy: AERIFY-1 MET primary endpoint: 27% reduction in COPD exacerbations with Q2W (significant), 21% with Q4W (significant). First Phase 3 to show anti-IL-33 reduces COPD exacerbations in former smokers. Effect size (27%) is competitive with Dupixent (30% in eos≥300) but in a NON-eosinophil-selected popul

Safety: AERIFY-1 (n=1127, 52 weeks): Well-tolerated. Overall AEs 67% vs 68% placebo. Serious infections numerically LOWER: 7% vs 10% placebo. Deaths: 1% vs 2% placebo.

Primary EP: [{"id":"aerify2-aer","name":"Annualized moderate-to-severe COPD exacerbation rate at Week 52","type":"PRIMARY","unit":"rate ratio","results":[{"notes":"MISSED primary endpoint at 52 weeks. Benefit see

Efficacy: AERIFY-2 MISSED primary endpoint at 52 weeks. Benefit was observed at earlier timepoints (24 weeks) but did not reach significance at 52 weeks. COVID pandemic reduced overall exacerbation rates across all arms, reducing statistical power. AERIFY-2 was the smaller trial (n=953 vs 1127) and was hit ha

Safety: AERIFY-2 (n=953): AEs 64% (Q2W) vs 64% (placebo). Serious infections 10% (Q2W) vs 7% (placebo). Deaths 3% vs 2%.

Primary EP: [{"id":"itepe-copd-ph2-aer","name":"Annualized moderate-to-severe COPD exacerbation rate","type":"PRIMARY","unit":"rate ratio","results":[{"notes":"FAILED in overall population — not statistically sig

Efficacy: FAILED overall population but SUCCEEDED in former smokers subgroup: 42% exacerbation reduction (RR 0.58, p=0.006) and +90mL FEV1 (p=0.008). Smoking status fundamentally changes how IL-33 is processed — current smokers suppress ST2 on ILC2s, redirecting IL-33 signaling to macrophages/NK cells (non-ty

Safety: Phase 2a (n=437): Well-tolerated. AE rates comparable between arms. No significant safety signals.

Primary EP: [{"id":"itepe-asthma-loac","name":"Loss of asthma control (LOAC) events","type":"PRIMARY","unit":"odds ratio","results":[{"notes":"OR 0.42 (95% CI 0.20-0.88), p=0.02 vs placebo","value":22,"arm_id":"i

Efficacy: Itepekimab monotherapy reduced LOAC by 58% (OR 0.42, p=0.02). Dupilumab monotherapy reduced LOAC by 67% (OR 0.33). KEY FINDING: The itepekimab + dupilumab COMBINATION was NOT superior to either monotherapy (OR 0.52, NS). This implies IL-33 and IL-4/IL-13 operate on the SAME pathway rather than being

Safety: Phase 2 asthma (n=296, 12 weeks): Well-tolerated across all arms. No new safety signals.

Itepekimab - COPD - Ph3 Topline (AERIFY) 2026-2027

IL-33 inhibitor for COPD and CRSsNP (Regeneron/Sanofi). COPD PROGRAM (key investment story): - Phase 2a (NCT03546907): FAILED overall population, but 42% exacerbation reduction in FORMER SMOKERS subgroup (p=0.006). This finding reshaped entire Phase 3 design. - AERIFY-1 (Phase 3, n=1127): MET primary endpoint — 27% exacerbation reduction (Q2W), 21% (Q4W), both significant. - AERIFY-2 (Phase 3, n=953): MISSED primary endpoint — benefit seen at 24 weeks but did not sustain to 52 weeks. COVID-era lower-than-expected exacerbation rates reduced statistical power. - Regulatory path unclear: 1/2 Phase 3 hit. FDA typically wants 2 adequate trials. Totality of data (Ph2a + AERIFY-1 + AERIFY-2 directional) may support filing. COMPETITIVE POSITIONING: - 27% effect in former smokers (NOT eosinophil-selected) vs Dupixent 30% in eos≥300. Potentially broader population. - Anti-IL-33 blocks BOTH ST2 immune pathway AND RAGE/EGFR mucus pathway. Anti-ST2 (astegolimab, Roche) showed only ~15% and failed Phase 3. - Tozorakimab (AZN, also anti-IL-33) in Phase 3 with enriched frequent-exacerbator design. Data ~2026. KEY BIOLOGY: IL-33 blockade captures two disease mechanisms — immune inflammation (via ST2 on ILC2s/macrophages) AND mucus hypersecretion (via RAGE/EGFR on epithelial cells). The RAGE pathway is ST2-independent, which explains why anti-ST2 drugs show only half the effect of anti-IL-33 drugs.