Jasper Therapeutics (JSPR) Study Update summary

Study design and patient population

• BEACON is a randomized, double-blind, placebo-controlled, multi-ascending dose Phase 1b/2a trial in adults with moderate to severe CSU refractory to omalizumab or antihistamines, conducted across 30 sites in the US and EU.

• Dosing regimens ranged from 10 mg to 360 mg, with both single and repeat dosing schedules, including new cohorts at 240 mg Q8W and 240 mg induction/180 mg Q8W.

• Participants were well-balanced in demographics and represented a high unmet need, difficult-to-treat population.

Efficacy results

• Briquilimab produced rapid, deep, and durable reductions in UAS7 scores, with mean decreases over 25 points at doses ≥120 mg.

• 100% complete response was achieved in the 240 mg single-dose cohort by week 2, durable through 8 weeks.

• Dose-dependent increases in complete and well-controlled responses were observed at doses ≥80 mg, with over 50% achieving well-controlled disease in multiple regimens.

• Rapid onset of effect was seen as early as week 1 across all dose levels, with sustained responses up to 26 weeks in repeat dosing.

• Substantial reductions in serum tryptase, often below quantification limits, correlated with clinical response.

Safety and tolerability

• Briquilimab was well tolerated up to 240 mg, with no dose-limiting toxicities, no anaphylaxis, and no significant increase in adverse events compared to placebo.

• Most common adverse events were nasopharyngitis, fatigue, hair color change, and taste changes, mostly mild, infrequent, and resolving between doses.

• Predictable, reversible decreases in neutrophil counts were observed, with one grade 3 neutropenia unrelated to treatment and no associated infections or dose delays.

• No discontinuations or dose delays due to on-target effects; one grade 2 hypersensitivity event led to discontinuation.