151 The selectivity index (SI) for astodrimer sodium against SARS-CoV-2 ranged from 793 to 2197 152 for the initial assays where compound was added 1 hour prior to infection and 1 hour after 153 infection, respectively, and was >70 to >80 in the repeat assays, in which cytotoxicity was not 154 observed up to the highest concentration tested (0.86 mg/mL). 155 The positive control, remdesivir, was also active in the CPE inhibition assay, with a SI of >33.
156 3.2 Virucidal assay
157 A second study was performed to determine if astodrimer sodium was able to reduce viral 158 infectivity by binding to SARS-CoV-2 directly prior to infection of Vero E6 cells. Astodrimer 159 sodium treatment demonstrated a similar level of antiviral efficacy to the CPE studies (Table 1; 160 Figure 1C) with an EC50 of 1.83 µM (0.030 mg/mL) and SI of 130; n=1.
These studies are all in Vero E6 cells, which don't predict as well as human lung cells.