Jasper Therapeutics (JSPR) Stifel 2024 Healthcare Conference summary

Clinical program updates

• Lead asset briquilimab targets c-Kit and is being tested in mast cell diseases, including chronic spontaneous urticaria, inducible urticaria, and asthma, with the first asthma patient dosing imminent.

• Spotlight study in inducible urticaria showed 93% clinical response and 83% complete response at six weeks, indicating strong efficacy.

• Durability of response observed, with 50% complete response at six weeks post-dose, suggesting mast cell depletion as the mechanism.

• Beacon study in chronic spontaneous urticaria will report top-line data the week of January 6, covering all dose cohorts and including 12-week efficacy and longitudinal safety data.

• A new 360 mg dose cohort was added to explore higher dosing after safely clearing the 240 mg dose.

Mechanism of action and differentiation

• Briquilimab’s shorter half-life (nine days) may allow for drug-free intervals, potentially reducing off-target effects on stem cells and melanocytes compared to longer-acting competitors.

• Efficacy is believed to be driven by achieving a sufficient Cmax to induce mast cell apoptosis, rather than prolonged exposure.

• Dose response observed in healthy volunteer studies, with potential for similar efficacy at lower doses over time.

• Tryptase is a useful biomarker for mast cell burden but is not predictive of clinical response due to complexities in mast cell biology.

Safety and toxicity considerations

• c-Kit inhibition affects other cell types, but stem cells have redundant survival pathways, and transient decreases in blood counts recover within a month.

• Shorter half-life and intermittent dosing may minimize risks such as hypopigmentation and hematologic toxicity.

• Longer-term safety data, especially regarding pigmentation changes, will be important, with seasonal variation potentially influencing observed effects.