Blueprint Medicines (BPMC) TD Cowen Chronic Urticaria Summit summary

Scientific and clinical insights

• Mast cells play a central role in urticaria and other inflammatory diseases, with activity in skin, lung, and GI tract compartments.

• KIT is a master regulator of mast cells, and targeting it can impact diseases across multiple tissues.

• Chronic urticaria often requires escalating therapy, with wild-type KIT inhibition positioned for patients unresponsive to antihistamines.

• BLU-808, a selective wild-type KIT inhibitor, is designed for tunable dosing to address varying patient needs.

• Preclinical models show dose-dependent mast cell inhibition and apoptosis, supporting flexible dosing strategies.

Clinical development and trial design

• BLU-808 is in a phase I healthy volunteer study, with plans to escalate dosing to achieve up to IC90 inhibition.

• Dose selection for patient studies will be based on safety, pharmacokinetics, and biomarker responses.

• Initial data from the healthy volunteer study is expected to be shared early next year.

• The healthy volunteer study is viewed as a significant de-risking event for the program.

• Multiple dosing paradigms, including loading and maintenance doses, are being explored for optimal efficacy.

Biomarker and selectivity considerations

• Tryptase reduction is a benchmark for mast cell depletion, but its quantitative relationship to activity at submaximal inhibition is unclear.

• Additional undisclosed biomarkers are being evaluated to guide dosing in submaximal inhibition settings.

• BLU-808 demonstrates high selectivity over kinases such as PDGFRα, FLT3, and CSF1R, with a low kinome S-score.

• High-dose pharmacology is associated with on-target adverse events, but off-target effects are minimized by design.