Vir's shares crater as influenza mAB flames out in 'disappointing' phase 2 result

Despite interest from GSK and high hopes of leading the next generation of influenza A prophylaxis, Vir Biotechnology’s monoclonal antibody has failed its first phase 2 challenge.

The PENINSULA study encompassed 3,000 adults aged 18 to 64 years without risk factors for serious complications from influenza infection. It marked the first phase 2 outpatient trial to evaluate the role of a monoclonal antibody in the prevention of influenza A illness, Vir noted.

But even participants who received the highest—1,200 mg—dose of the antibody, dubbed VIR-2482, only saw a “non-statistically significant reduction of approximately 16% in influenza A protocol-defined illness,” missing the study’s primary endpoint, Vir revealed in a release Thursday morning. The lower 450-mg dose performed even worse, with a reduction of less than 4%.

One of the trial’s secondary endpoints was a reduction in symptomatic illness as defined by the Centers for Disease Control and Prevention’s criteria, and here the highest dose at least resulted in around a 57% reduction. However, the lower dose performed significantly worse, with a reduction of just 11%.

When defined against the World Health Organization's criteria, the study's other secondary endpoint, these reductions were worse, at 44% and 9.8%, respectively.

“Although these topline data are disappointing, further analysis is necessary to better understand these outcomes, which we plan to present at a major medical congress,” Vir’s chief medical officer Phil Pang, M.D., Ph.D., said in the release. “In the meantime, we are continuing to advance next generation solutions for serious respiratory infections, including VIR-2981, an investigational neuraminidase-targeting monoclonal antibody against both influenza A and B viruses.”

The company had held out high hopes for VIR-2482 due to what it described as “its broad strain coverage and because it does not rely on an individual to create their own protective antibody response.” The theory is that by half-life engineering the antibody, a single dose has the potential to last the entire flu season. During in vitro studies, the hemagglutinin-targeting, intramuscularly administered candidate had been shown to cover all major strains of influenza A, according to Vir.

In what sounded like an attempt to rally wavering investors, Vir CEO Marianne De Backer, Ph.D., used this morning's release to redirect attention to more promising areas of the biotech’s portfolio.

“I’m very excited about the future ahead, with the opportunities that we have, including a robust pipeline, where we expect two data readouts across our hepatitis B and hepatitis D programs in 2023,” De Backer said. “We also have a strong balance sheet with approximately $1.9 billion in cash and investments, as of the end of the second quarter, which will allow us to invest in our ongoing development and future innovation.”

Investors didn’t seem convinced, sending Vir’s stock plunging almost 40% in premarket trading to $13.95 per share from a Wednesday close of $23.05.

Thanks to a 2021 collaboration with Vir, GSK has the exclusive option to co-develop VIR-2482 now that the phase 2 trial has read out. Based on today's results, it's unlikely the Big Pharma will be jumping at the opportunity.