Lesofavumab (MHAB5553A) is a human IgG1κ anti-influenza B virus antibody.
Lesofavumab (MHAB5553A) binds to a conserved epitope in the vestigial esterase domain of hemagglutinin (HA), a major immunodominant surface glycoprotein on influenza B viruses, and blocks HA-mediated membrane fusion in the endosome[1].Lesofavumab (46B8) is able to neutralize all eleven IBV strains tested that were associated with human infections spanning >70 years, with IC50 values ranging from 0.58 to 0.95 nM[2].Lesofavumab (46B8; 0-100 ng/mL) blocks membrane fusion and induces antibody-dependent cellular cytotoxicity (ADCC) in vitro[2].
Lesofavumab (46B8; 15 mg/kg; i.v.; single dose) is able to protect mice against lethal challenge of the mutant influenza B virus[2].
References:
[1]. Rao GK, et al. In Vivo Assessment of Antibody-Dependent Enhancement of Influenza B Infection. Toxicol Sci. 2019 Jun 1;169(2):409-421.
[2]. Chai N, et al. A broadly protective therapeutic antibody against influenza B virus with two mechanisms of action. Nat Commun. 2017 Jan 19;8:14234.