Vir Biotechnology, Inc. announced initial topline data from its ongoing trial of VIR-3434 in patients with chronic hepatitis B virus (HBV) infection. Data from the first blinded cohort of eight patients, two of whom received placebo and six of whom received a single dose of 6 mg of VIR-3434, showed that six of eight patients achieved a mean reduction of 1.3 log10 IU/mL in serum hepatitis B virus surface antigen (HBsAg) by day eight, the day when nadir was achieved in most patients. VIR-3434 is an HBV-neutralizing monoclonal antibody designed to block entry of all 10 genotypes of HBV into hepatocytes and reduce the level of virions and subviral particles in the blood. It has also been Fc engineered to include the XX2 “vaccinal mutation,” allowing it to potentially function as a T cell vaccine, in this case, against HBV. The XX2 vaccinal mutation, which has the potential to transform standard antibodies into T cell vaccines, has also been incorporated into one of Vir’s investigational COVID-19 monoclonal antibodies, VIR-7832, which is currently planned to enter a Phase 1b/2a trial this quarter. Vir has licensed exclusive rights to the XX2 mutation for use in infectious diseases. The Phase 1 clinical trial of VIR-3434 is a randomized, placebo-controlled trial designed to assess the safety, tolerability, pharmacokinetics, antiviral and immunomodulatory activity of VIR-3434 in healthy volunteers and patients with chronic HBV infection with HBsAg levels less than 1,000 IU/ml. The trial is designed to progress from healthy volunteers to chronic HBV patients in a staggered, parallel fashion with the goal of rapidly generating early proof-of-concept data in patients. Additional data will be submitted for presentation at an upcoming medical conference. A Phase 2 trial combining VIR-3434 with Vir’s HBV-targeting siRNA, VIR-2218, is expected to commence in the second half of this year.