Alnylam, Vir to Advance Experimental RNAi Therapeutic VIR-2703 as Potential COVID-19 Treatment

Alnylam Pharmaceuticals and Vir Biotechnology announced that they plan to develop VIR-2703, an investigational RNAi therapeutic targeting the SARS-CoV-2 genome as an inhalational formulation for the potential treatment or prevention of COVID-19.

“To our knowledge, this is one of the most potent direct-acting antivirals targeting SARS-CoV-2 reported to date,” commented John Maraganore, chief executive at Alnylam, with the companies indicating that they intend to initiate clinical testing of VIR-2703, also referred to as ALN-COV, “at or around year-end.”

VIR-2703 is the first development candidate selected in Vir’s expanded collaboration with Alnylam announced in March for up to four RNAi potential therapeutics for COVID-19.

According to the companies, Alnylam synthesised hundreds of small interfering RNAs targeting highly conserved regions of the SARS-CoV-2 genome, with several demonstrating a 3-log reduction of viral replication in an in vitro SARS-CoV-2 live virus model. “In dose-response assays, VIR-2703 was shown to have an effective concentration for 50% inhibition (EC50) of less than 100 picomolar and an EC95 of less than 1 nanomolar in the SARS-CoV-2 live virus model measuring inhibition of infectious virion production,” they explained. Alnylam and Vir also said VIR-2703 has predicted reactivity against virtually all of the more than 4300 SARS-CoV-2 genomes currently available for analysis in public databases.

Last month, GlaxoSmithKline acquired a $250-million stake in Vir as the companies entered into a collaboration to develop antiviral antibodies for coronaviruses, including SARS-CoV-2, with an initial focus on VIR-7831 and VIR-7832.