Bavarian Nordic Takes on Pfizer-BioNTech with COVID-19 Booster Candidate

Denmark-based biotech company Bavarian Nordic announced Thursday that the upcoming Phase III trial for ABNCoV2, its COVID-19 booster candidate, has been redesigned to compete against Pfizer-BioNTech's mRNA-based vaccine.

The company is trying its luck in the highly competitive COVID-19 space, where it will face off with some of the industry’s heaviest hitters. Set to enroll around 4,000 patients, the Phase III trial will now also include Pfizer and BioNTech’s Comirnaty, which was authorized for emergency use as a booster in September last year, as a comparator.

The revisions in the trial’s design will allow Bavarian Nordic to conduct a double-blind and controlled comparison of both shots. The company aims to prove that ABNCoV2 can elicit an antibody response that is non-inferior to levels induced by the licensed vaccine.

The trial will consist of two groups running in parallel. The first will enroll 1,000 participants, randomly allocated to receive a single dose of either ABNCoV2 or Comirnaty, to compare their efficacies. Meanwhile, the second group will test ABNCoV2’s safety and tolerability on the remaining 3,000 participants, who will all be given a single dose of Bavarian Nordic’s candidate. Only fully vaccinated adults, including those who have already received one booster dose, are eligible for enrolment.

Bavarian Nordic said the redesign was made possible with the help of vaccine manufacturers and regulatory authorities. Despite delays in enrollment, the company believes that the overall development timeline for ABNCoV2 remains unchanged and expects initial results to come in later this year.  

“We are pleased to be able to run the Phase III trial of ABNCoV2 as a double-blind, controlled study, which provides us with a more robust foundation for the regulatory process towards approval,” Paul Chaplin, president and CEO of Bavarian Nordic, said in a statement. “With its differentiated approach, we believe that ABNCoV2 could provide several advantages over the current licensed COVID-19 vaccines and look forward to initiating the study and presenting the first Phase III data for this universal booster vaccine candidate later this year.”

Indeed, unlike Pfizer-BioNTech’s mRNA-based Comirnaty, ABNCoV2 is a capsid virus-like particle, initially developed by fellow Danish company AdaptVac. ABNCoV2 has shown a consistently impressive immunogenic profile from preclinical to Phase II studies, according to data released in February. In May, the company also announced its candidate could significantly boost antibody activity against the Omicron variant.

Bavarian Nordic recently attracted attention after inking high-profile deals with countries seeking to secure doses of its smallpox vaccines for use against monkeypox.

Aside from Pfizer and BioNTech’s Comirnaty, Moderna’s Spikevax, also mRNA-based, is currently dominating the market. Recently, an advisory committee for the U.S. Food and Drug Administration voted to recommend the use of both vaccines in young children.

Right on their heels, however, is the promising partnership between Sanofi and GlaxoSmithKline, whose next-generation booster candidate, designed using the virus’ Beta variant, outperformed Pfizer-BioNTech’s vaccine, leading to a much stronger immune response. A separate Phase III study also showed that the Sanofi-GSK candidate could impart protection against the original Omicron variant and its BA.2 subvariant.