Vir’s GSK-allied flu prevention antibody fails PhII, sinking shares and late-stage hope

Vir Biotechnology’s influenza antibody has failed a critical Phase II clinical trial, which could spell bad news for its partner GSK, who has the option to take over development of VIR-2482.

A flop on the mid-stage PENINSULA trial, funded in part by a $55 million boost from the federal government, throws a wrench in the San Francisco biotech’s speedy influenza R&D. The monoclonal antibody flunked at preventing influenza A illness on a variety of definitions of flu — the protocol’s, the CDC’s and the World Health Organization’s — in healthy adults who had not received a flu vaccine. The company said the antibody was “generally well tolerated and no safety signals were identified.”

Vir’s shares $VIR cratered nearly 40% before Thursday’s opening bell.

It’s the first big clinical readout for new CEO Marianne De Backer, a former Bayer executive who accepted the baton from industry vet George Scangos in early April. In the Thursday morning press release, she emphasized Vir had $1.9 billion in cash and investments at the end of the second quarter and still has other critical readouts this year in hepatitis B and D. The company said it will share more during its quarterly update on Aug. 3.

A Vir spokesperson also confirmed to Endpoints News that the biotech plans to disclose data on another trial of VIR-2482, a Phase Ib in elderly patients who have received a flu vaccine, in the third quarter.

Next steps on the GSK collaboration “have yet to be determined” as the partners are in “ongoing discussions,” the spokesperson said. GSK and Vir sped to an emergency use authorization for their Covid-19 treatment, but pandemic variants upended sotrovimab’s use, and FDA peeled back the green light in April 2022. It’s authorized in other countries, and the duo is still testing it for other tools in the Covid-19 fight. The two are also working together on antibodies against respiratory syncytial virus.

In the approximately 3,000-person PENINSULA trial, participants were evenly split among three groups: placebo, 450 mg of VIR-2482 and 1,200 mg of the intramuscularly-delivered mAb. On the primary endpoint — influenza-like-illness as defined by PCR-confirmed flu infection and one or more respiratory symptoms — trial investigators observed a 3.78% and 15.85% relative risk reduction in the low- and high-dose groups, respectively. The p-values were 0.89 and 0.56, respectively.

It’s well below what management had wanted. In a May 4 note, TD Cowen analyst Phil Nadeau said Vir leadership “views at 50% reduction in illness as meaningful.” The analysts believed VIR-2482 “could address a $B+ market if sufficiently potent and well tolerated.”

Speaking at the Goldman Sachs global healthcare conference last month, De Backer said Vir believed they “have really all the elements to have a shot at this,” touting VIR-2482 as a broadly neutralizing, half-life extended antibody.

Phil Pang

She also said Vir thought they had a “much better chance of success” than antibodies that have been tested for treatment, rather than prophylaxis. Vir called it the first mid-stage outpatient trial to test a mAb for preventing influenza A illness.

The relative risk reductions were greater when viewed under the CDC’s definition of influenza-like-illness, which constitutes a fever and cough and/or sore throat. Those figures were 11.45% and 57.23%.

“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,” Phil Pang, Vir’s medical chief and interim head of research, said in a statement. He said work continues on another investigational mAb, VIR-2981, for both influenza A and B.

Last October, Vir disclosed a $55 million contract with the federal government for the US-only Phase II. As part of the multi-year contract with BARDA, Vir could receive $1 billion to help fund as many as 10 candidates for emerging infectious disease or Chemical, Biological, Radiological, and Nuclear (CBRN) medical countermeasures.

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