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

ABSTRACT

Hageman factor (FXII) is an essential component in the intrinsic coagulation cascade and a therapeutic target for the prophylactic treatment of hereditary angioedema (HAE). CSL312 (garadacimab) is a novel high-affinity human antibody capable of blocking activated FXII activity that is currently undergoing Phase 3 clinical trials in HAE. Structural studies using hydrogen/deuterium exchange coupled to mass spectrometry revealed evidence of interaction between the antibody and regions surrounding the S1 specificity pocket of FXII, including the 99-loop, 140-loop, 180-loop, and neighboring regions. We propose complementarity-determining regions (CDRs) in heavy-chain CDR2 and CDR3 as potential paratopes on garadacimab, and the 99-loop, 140-loop, 180-loop, and 220-loop as binding sites on the beta chain of activated FXII (β-FXIIa).

KEYWORDS:

• HDX-MS
• binding stoichiometry
• epitope mapping
• Hageman factor
• negative stain electron microscopy
• SPR

Abbreviations

2D, Two-dimensional; C1-INH, C1-esterase inhibitor; CDR, Complementarity determining region; EM, Electron microscopy; Fc, fragment crystallizable; FXII, Hageman factor; FXIIa, activated FXII; HAE, Hereditary angioedema; H/D, hydrogen/deuterium; HDX-MS, Hydrogen/deuterium exchange coupled to mass spectrometry; Ig, immunoglobulin; LCMS, liquid chromatography–mass spectrometry; MS, Mass spectrometry; MOA, Mechanism of action; RPLC, Reverse phase liquid chromatography; side-ASA, side-accessibility surface area SPR, Surface plasmon resonance; TCEP, Tris (2-carboxyethyl) phosphine; VADAR, Volume area dihedral angle reporter.

Acknowledgments

The authors thank Robert Ninnis for the conceptualization and initial development of the HDX-MS platform used in this study. The authors also thank Eric Hanssen and Andrew Leis from the Bio21 Ian Holmes Imaging Centre for the support of the negative stain EM experiments.

Disclosure statement

SYO is an associate director for research in CSL Limited. EAK and JS are senior research scientists in CSL Limited. VT and AZ are research scientists in CSL Limited. CP is a senior director for research in CSL Limited. MJW is a vice president for research in CSL Limited. ADN is the chief scientific officer in CSL Limited. MP is a senior director for research in CSL Limited.

SYO, EAK, VT, AZ, and JS participated in the research concept, design, performance of experiments, data analysis, and writing of the article. CP, MJW, ADN, and MP participated in the research concept, design of the experiment, and writing of the article. MJW, JS, and ADN hold patent number EP2548892A1 in the European Patent Application.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19420862.2022.2163459

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This study was supported by CSL Ltd. Parkville, Australia;CSL Limited.