OC 04.3 - N-glycan-mediated shielding of ADAMTS13 effectively prevents binding of pathogenic autoantibodies in high-titer patients with immune-mediated Thrombotic Thrombocytopenic Purpura

Saturday, July 9, 2022

1:30 PM – 1:45 PM

Location: ICC Capital Suite Room 14-16

Presentation Format: In-Person

Presenting Author(s)

Tim Postmus

PhD Student
Sanquin Research, Amsterdam, The Netherlands
Duivendrecht, Noord-Holland, Netherlands

Co-Author(s)

NG

Nuno Graca

PhD Student
Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
Amsterdam, Noord-Holland, Netherlands
BE

Bogac Ercig

PhD Student
Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
Amsterdam, Noord-Holland, Netherlands
BL

Brenda Luken

Program Manager
Sanquinnovate
Amsterdam, Noord-Holland, Netherlands
PC

Paul Coppo

PhD and MD
Service d’Hématologie, Hôpital Saint-Antoine, APHP.6-SU, INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France.
Paris, Ile-de-France, France
AV

Agnes Veyradier

Professor
Université Paris Diderot UFR Médecine
Paris, Ile-de-France, France
Karen Vanhoorelbeke, PhD

Prof., Dr.
Laboratory for Thrombosis Research, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
Kortrijk, West-Vlaanderen, Belgium
JV

Jan Voorberg

Professor, Principal investigator
Department of Molecular Hematology, Sanquin Research and Landsteiner Laboratory
Amsterdam, Noord-Holland, Netherlands

Background: Thrombotic Thrombocytopenic Purpura (TTP) is a rare thrombotic disorder, with 1.5 to 6.0 new cases per million per year. The majority of TTP patients develop inhibitory antibodies targeting predominantly the spacer domain of ADAMTS13. ADAMTS13 is responsible for cleaving VWF multimers, thereby regulating platelet adhesion at sites of vascular perturbation. Inhibition of ADAMTS13 by pathogenic autoantibodies results in accumulation of VWF multimers which promote the formation of platelet-rich microthrombi. We have previously shown that introduction of an N-glycan in the spacer domain of ADAMTS13 prevents the binding of pathogenic autoantibodies that develop in patients with immune TTP.

Aims: Evaluate whether N-glycan mediated shielding of ADAMTS13 effectively prevents binding of pathogenic autoantibodies and restores ADAMTS13 activity in high-titer patients with immune-mediated TTP.

Methods: We screened the N-Glycan mutants against immune TTP (iTTP) patient antibody binding and for their activity in the presence and absence of samples derived from 28 patients with iTTP. In parallel we introduced additional modifications in the spacer domain and characterized the potential of these variants to escape the binding of pathogenic antibodies present in plasma of patients with iTTP.

Results: Newly tested patient samples reinforced our previous findings that N-glycans can shield ADAMTS13 from antibody binding. The N-glycan was both protective against inhibitory anti-ADAMTS13 antibodies binding as well as able to restore ADAMTS13 activity especially in samples of patients with high titer inhibitors. Dose-response experiments revealed that the N-glycan modified ADAMTS13 was up to ten-fold more effective when compared to wild type ADAMTS13 upon addition of patient plasma containing high titer inhibitors. Preliminary findings indicated that introduction of an additional N-glycan in the spacer domain further prevented patient antibodies to bind and inhibit ADAMTS13.

Conclusion(s): Collectively our findings show that N-glycan mediated shielding of ADAMTS13 effectively prevents the binding of pathogenic autoantibodies in high titer patients with immune TTP.