HDX-MS study on garadacimab binding to activated FXII reveals potential binding interfaces through differential...

Area of Science:

• Biochemistry
• Immunology
• Pharmacology

Background:

• Hageman factor (FXII) is central to the intrinsic coagulation cascade.
• FXII is a therapeutic target for hereditary angioedema (HAE) prophylaxis.
• Garadacimab (CSL312) is a novel antibody inhibiting activated FXII activity.

Purpose of the Study:

• To elucidate the structural basis of garadacimab's interaction with activated FXII.
• To identify potential binding sites (paratopes) on garadacimab and binding regions on FXII.

Main Methods:

• Hydrogen/deuterium exchange mass spectrometry (HDX-MS) was employed for structural studies.
• Analysis focused on the interaction between garadacimab and activated FXII (β-FXIIa).

Main Results:

• HDX-MS revealed garadacimab interacts with regions around the FXII S1 specificity pocket.
• Key interacting regions on FXII include the 99-loop, 140-loop, and 180-loop.
• Potential antibody paratopes are suggested to be heavy-chain CDR2 and CDR3.

Conclusions:

• Garadacimab binds to specific loops (99, 140, 180, 220) on the beta chain of activated FXII.
• This interaction, involving garadacimab's CDRs, underlies its FXII inhibitory function.
• Understanding these structural interactions is vital for HAE therapeutic development.