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 chronic spontaneous urticaria (CSU) refractory or intolerant to omalizumab or antihistamines, conducted across 30 sites in the US and Europe.

• Dosing regimens ranged from 10 mg to 360 mg, including single and repeat dosing schedules, with ongoing cohorts for 240 mg Q8 weeks, 240 mg induction/180 mg Q8 weeks, and 360 mg single dose.

• Participants had demographics typical for CSU and represented a high unmet need population.

• Primary endpoints were safety and tolerability; secondary endpoints included efficacy (UAS7, UCT) and PK/PD.

Efficacy results

• Briquilimab produced rapid, deep, and durable reductions in UAS7 scores, with mean decreases over 25 points at doses ≥120 mg and >-26.6 at 8 weeks for 240 mg single dose.

• Complete responses (UAS7=0) were achieved at all doses ≥80 mg, with 100% CR at 240 mg single dose by week 2, durable through 8 weeks.

• Well-controlled disease (UAS7≤6) was seen in all doses ≥80 mg, with over 50% of patients achieving this in multiple regimens and 100% at 240 mg single dose at week 8.

• Efficacy was observed as early as week 1, with durability through 12 weeks and up to 26 weeks in higher dose and repeat dosing cohorts.

• Combined therapeutic doses (120, 180, 240 mg) showed 52% CR and 64% well-controlled disease at 4 weeks post-dose.

Safety and tolerability

• Briquilimab was well tolerated up to 240 mg, with no dose-limiting toxicities, no anaphylaxis, and adverse event rates similar to placebo.

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

• Adverse events related to c-Kit blockade (hair color/taste changes, neutropenia) were infrequent, low grade, and resolved during treatment.

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

• No hair color changes were observed in the 240 mg cohort.