Shares in Vir Biotechnology rose 74% on the strength of data from a blinded, eight-subject cohort in its phase 1 hepatitis B trial. The analysis suggests the neutralizing monoclonal antibody may be more potent than expected and provides a boost to Vir’s prospects of delivering a functional cure.
Investigators enrolled eight patients with chronic hepatitis B virus infection in the 6-mg cohort of Vir’s phase 1 trial. Six of the participants received VIR-3434, an antibody designed to stop the virus from entering hepatocytes. The other two subjects received placebo. The cohort remains blinded, but Vir pooled data from six subjects who had reductions in serum hepatitis B virus surface antigen.
Those six patients experienced a 1.3 log10 IU/mL mean reduction in surface antigen by the eighth day. Levels of the antigen fell to their lowest point in most patients by day eight.
Optimism about those findings is, in part, a result of the dose tested. Based on preclinical data, Vir Chief Medical Officer Phillip Pang, M.D., Ph.D., expected a dose much higher than 6 mg may be needed to trigger a response. Vir safely administered doses of up to 3,000 mg to healthy volunteers. Vir may be able to dial up the efficacy further still by increasing the dose above 6 mg.
Vir is yet to generate or share many important pieces of information. The cohort remains blinded, so, in theory, the six responders could include patients who received placebo. Safety, durability and a host of other issues that could trip Vir up remain largely unknown.
Investors seized on the results though, adding billions to Vir’s value in a trading session that saw its share price rise 74%. The surge was potentially underpinned by a combination of the implications of the data for Vir’s prospects in hepatitis B, a major indication, and its broader platform and pipeline. Other Vir candidates, including its COVID-19 antibodies, share similarities to VIR-3434.
In a note to investors, analysts at BofA Securities said the suggestion of “robust efficacy” in the phase 1 raises Vir’s prospects of a functional cure and provides “positive read-throughs” for the biotech’s platform. Notably, the XX2 alteration to the Fc region, which Vir makes to trigger T-cell immunity, is found in other candidates including anti-SARS-CoV-2 antibody VIR-7832.
Vir plans to build on the signs of efficacy in the eight-subject cohort by moving VIR-3434 into phase 2 in the second half of the year. The midphase clinical trial will evaluate VIR-3434 in combination with Vir’s siRNA asset VIR-2218.