title: Effect of the Anti-C1s Humanized Antibody TNT009 and Its Parental Mouse Variant TNT003 on HLA Antibody-Induced Complement Activation-A Preclinical In Vitro Study.
abstract: The classic pathway (CP) of complement is believed to significantly contribute to alloantibody-mediated transplant injury, and targeted complement inhibition is currently considered to be a promising approach for preventing rejection. Here, we investigated the mode of action and efficacy of the humanized anti-C1s monoclonal antibody TNT009 and its parental mouse variant, TNT003, in preclinical in vitro models of HLA antibody-triggered CP activation. In flow cytometric assays, we measured the attachment of C1 subcomponents and C4/C3 split products (C4b/d, C3b/d) to HLA antigen-coated flow beads or HLA-mismatched aortic endothelial cells and splenic lymphocytes. Anti-C1s antibodies profoundly inhibited C3 activation at concentrations >20 μg/mL, in both solid phase and cellular assays. While C4 activation was also prevented, this was not the case for C1 subcomponent attachment. Analysis of serum samples obtained from 68 sensitized transplant candidates revealed that the potency of inhibition was related to the extent of baseline CP activation. This study demonstrates that anti-C1s antibodies TNT009 and TNT003 are highly effective in blocking HLA antibody-triggered complement activation downstream of C1. Our results provide the foundation for clinical studies designed to investigate the potential of TNT009 in the treatment or prevention of complement-mediated tissue injury in sensitized transplant recipients.
authors.affiliation: Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Wahrmann
authors.affiliation: Department of Surgery, Medical University Vienna, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Mühlbacher
authors.affiliation: Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: L
authors.initials: L
authors.lastname: Marinova
authors.affiliation: Clinical Institute of Pathology, Medical University Vienna, Vienna, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Regele
authors.affiliation: Clinical Institute of Pathology, Medical University Vienna, Vienna, Austria.
authors.forename: N
authors.initials: N
authors.lastname: Huttary
authors.affiliation: Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Eskandary
authors.affiliation: Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Cohen
authors.affiliation: Department of Blood Group Serology and Transfusion Medicine, Medical University Vienna, Vienna, Austria.
authors.forename: G F
authors.initials: GF
authors.lastname: Fischer
authors.affiliation: True North Therapeutics, Inc., South San Francisco, CA.
authors.forename: G C
authors.initials: GC
authors.lastname: Parry
authors.affiliation: True North Therapeutics, Inc., South San Francisco, CA.
authors.forename: J C
authors.initials: JC
authors.lastname: Gilbert
authors.affiliation: True North Therapeutics, Inc., South San Francisco, CA.
authors.forename: S
authors.initials: S
authors.lastname: Panicker
authors.affiliation: Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: G A
authors.initials: GA
authors.lastname: Böhmig
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D003167:Complement Activation / Q000276:immunology*; D003173:Complement C1s / Q000276:immunology*; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006084:Graft Rejection / Q000188:drug therapy* / Q000209:etiology; D006085:Graft Survival; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007518:Isoantibodies / Q000009:adverse effects*; D007676:Kidney Failure, Chronic / Q000276:immunology / Q000601:surgery; D007677:Kidney Function Tests; D016030:Kidney Transplantation / Q000009:adverse effects*; D051379:Mice; D011379:Prognosis
chemical_list: D000911:Antibodies, Monoclonal; D006680:HLA Antigens; D007518:Isoantibodies; C000608635:TNT003; D003173:Complement C1s
keywords: basic (laboratory) research/science; complement biology; flow cytometry; fusion proteins and monoclonal antibodies; histocompatibility; immunosuppressant; immunosuppression/immune modulation; major histocompatibility complex (MHC); rejection: antibody-mediated (ABMR); translational research/science