Narsoplimab (anti-MASP-2) is a human immunoglobulin gamma 4 (IgG4) monoclonal antibody against mannose-binding protein-associated serine protease 2 (MASP-2) achieved by high affinity (zymogen form: KD=0.062nM, IC50~3.4nM; enzymatically active form: KD=0.089nM) to block lectin pathway[1]. Narsoplimab selectively inhibits human C5b-9, IC50~1nM; its potency in cynomolgus monkey serum was IC50~33nM. The efficiency of Narsoplimab is EC50=6.1μg/mL ex vivo and IC50=33nM in vitro [1]. Narsoplimab shows positive potential results in hematopoietic stem-cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) in a clinical trial[2].
In vitro experiments show that Narsoplimab act as a positive control to evaluate inhibitory efficiency among the N proteins of SARS-CoV, MERS-CoV and SARS-CoV-2(purified human MASP-2; 2.4μg/ml at 37°C; 3h)[3]. Moreover, MASP2 inhibition by Narsoplimab suppresses endotheliopathies characteristic of transplant-associated thrombotic microangiopathy (primary human neonatal microvascular endothelial cell; 10µg/ml; 5h)[4].
References:
[1] Dudler, Thomas et al. “Development and characterization of narsoplimab, a selective MASP-2 inhibitor, for the treatment of lectin-pathway-mediated disorders.” *Frontiers in immunology* vol. 14 1297352. 8 Nov. 2023, doi:10.3389/fimmu.2023.1297352
[2] Khaled, Samer K et al. “Narsoplimab, a Mannan-Binding Lectin-Associated Serine Protease-2 Inhibitor, for the Treatment of Adult Hematopoietic Stem-Cell Transplantation-Associated Thrombotic Microangiopathy.” *Journal of clinical oncology : official journal of the American Society of Clinical Oncology* vol. 40,22 (2022): 2447-2457. doi:10.1200/JCO.21.02389
[3] Gao, Ting et al. “Highly pathogenic coronavirus N protein aggravates inflammation by MASP-2-mediated lectin complement pathway overactivation.” *Signal transduction and targeted therapy*vol. 7,1 318. 14 Sep. 2022, doi:10.1038/s41392-022-01133-5
[4]Elhadad, Sonia et al. “MASP2 inhibition by narsoplimab suppresses endotheliopathies characteristic of transplant-associated thrombotic microangiopathy: in vitro and ex vivo evidence.” Clinical and experimental immunology vol. 213,2 (2023): 252-264. doi:10.1093/cei/uxad055