Jasper Therapeutics Inc. (NASDAQ:JSPR) on Tuesday released preliminary data from the ETESIAN Phase 1b study of subcutaneous briquilimab in adult participants with allergic asthma.
A single subcutaneous 180mg dose of briquilimab demonstrated substantial reductions in sputum eosinophils at both six and twelve weeks, as well as improvements over baseline in FEV1 (key indicator of lung function) in both Early Asthmatic Response (EAR) and Late Asthmatic Response (LAR).
Significant reductions in serum tryptase were observed, consistent with reductions observed in other briquilimab studies at the 180mg dose level. Briquilimab was well-tolerated in the study, demonstrating a favorable safety profile.
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Treatment with briquilimab also decreased levels of sputum eosinophils before and after allergen challenge. Patients in the briquilimab group had reduced mean sputum eosinophil levels at pre-allergen challenge timepoints of 1.88% at baseline to 0.44% at day 41 and 0.38% at day 83. Briquilimab also reduced mean sputum eosinophil levels 24 hours following allergen challenge.
Briquilimab was well-tolerated in the study, with no dose-limiting toxicities observed. Safety observations potentially related to KIT blockade were infrequent and generally limited to low-grade events, none of which resulted in discontinuations or dose delays, and the majority of which resolved during repeat dosing.
BEACON Cohort 8 & Cohort 9 Internal Investigation
Jasper said it completed its internal investigation into the anomalous lack of clinical response observed in the July 2025 BEACON data for cohort 8 (240mg Q8W) and cohort 9 (240mg/180mg Q8W), where no U.S. patients (n=10) achieved Complete Response or Well Controlled UAS7 by week 12.
Based on the work completed, the additional data from subsequent dosing of the U.S. patients, and input from a panel of chronic spontaneous urticaria (CSU) KOLs, Jasper has concluded that the unexpected efficacy results observed in the U.S. patients were not the result of any issues with the drug product.
Instead, it was likely a result of patient selection issues, as it appears that 9 of the 10 patients in question did not have CSU as their symptoms were not mast cell-driven.
JSPR Price Action: Jasper Therapeutics shares were up 8.72% at $1.87 at the time of publication on Tuesday, according to Benzinga Pro data.
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