Glaxo pauses RSV trial in pregnant women after safety review

Bloomberg: GlaxoSmithKline Plc paused a late-stage trial evaluating an experimental vaccine against a respiratory virus called RSV in pregnant women following a safety recommendation from an independent committee.

The move is a setback for Glaxo as the UK drugmaker targets a virus that can be especially serious for infants and older adults and pursues a potential multibillion-dollar market opportunity along with competitors. A vaccine for respiratory syncytial virus has eluded scientists for decades.

The decision doesn’t affect a separate trial for RSV in older adults, the company said in a statement on Friday. That study remains on track with data expected in the first half of 2022. The company said it would provide a further update on the RSV maternal vaccine candidate in due course.

The voluntary pause is a worry given a limited number of advanced blockbuster opportunities in Glaxo’s pipeline and raises questions about its approach of protecting infants via mothers, Bloomberg Intelligence analysts wrote.

“Monitoring safety signals is an integral part of the clinical development process for potential new vaccines,” Glaxo said Friday.

The drugmaker has said that vaccinating mothers could help protect infants too young to be immunized in the first months of life, when they are most vulnerable to RSV infections. If successful, infants would gain protection due to the transfer of antibodies from the vaccinated mother to the unborn child.

Estimates in 2020 showed there were about 33 million cases of RSV annually in children under 5, with about 3 million hospitalized and 120,000 dying each year from complications associated with the infection.