Jasper Therapeutics (JSPR) Study Result summary

Investigation into BEACON trial anomalies and findings

• Internal review found unexpected lack of efficacy in U.S. BEACON trial cohorts 8 and 9, with none of 10 U.S. patients achieving clinical response, while EU patients using a different drug lot showed better outcomes.

• Comprehensive investigation included manufacturing, drug handling, site training, patient screening, and independent lab testing, finding no issues with drug lots or clinical operations.

• PK/PD data and tryptase reduction were consistent across drug lots, indicating drug potency and activity were intact.

• Expert panel concluded most non-responding U.S. patients likely did not have mast cell-driven CSU, suggesting misdiagnosis as the primary cause of poor efficacy.

• Recommendations include stricter patient selection, specialist involvement, and expanded patient history review to improve diagnostic accuracy in future trials.

BEACON trial efficacy, redosing, and safety outcomes

• Briquilimab demonstrated rapid onset and deep clinical response in earlier BEACON cohorts and OLE, with high rates of complete and well-controlled disease.

• Redosing U.S. patients with a new drug lot showed no change in PK/PD or efficacy, supporting the conclusion that drug quality was not the issue.

• Robust and sustained tryptase reduction confirmed effective mast cell depletion with both drug lots.

• Safety profile remained favorable with low rates of adverse events and consistent tolerability across dosing regimens; most adverse events were low grade and resolved during repeat dosing.

• Most common adverse events included nasopharyngitis, neutrophil count decrease, taste disorder, fatigue, and hair color change.

ETESIAN study results in allergic asthma

• Single 180mg dose of briquilimab in allergic asthma patients led to significant and sustained reductions in serum tryptase and sputum eosinophils, and reduced airway hyperresponsiveness at 6 and 12 weeks post-dose.

• Improvements in FEV1 were observed in both early and late asthmatic responses, with LAR % Max FEV1 improving by 10.4% at 6 weeks and 8.7% at 12 weeks compared to baseline.

• Methacholine challenge showed increased resistance to methacholine in briquilimab-treated patients, indicating reduced airway sensitivity.

• Safety profile was favorable, with no serious treatment-related adverse events and only low-grade, transient c-Kit-related effects.

• Results provide proof of concept for briquilimab in asthma, supporting further development in broader asthma populations.