HilleVax's stock craters after biotech says it's scrapping a norovirus vaccine for infants after a failed trial

By Ciara Linnane

Stock is down 87% to mark its biggest-ever one-day decline and on track for a record low below $2

HilleVax Inc.'s stock cratered 87% on Monday, after the biotech said it would discontinue the development of a vaccine against norovirus for infants after a trial missed its main goals.

The stock was on track for its biggest ever one-day selloff and was headed toward a record low below $2. Hillevax went public in April of 2022 at an issue price of $17.

The Boston-based company (HLVX) said the Phase 2b trial of HIL-214 for infants about 5 months old at the time of vaccination failed to meet its primary endpoint of efficacy against moderate or severe acute gastroenteritis events due to GI.1 or GII.4 norovirus genotypes.

The trial found vaccine efficacy of just 5% and did not produce any benefit across secondary endpoints, the company said.

"While HIL-214 previously showed clinical benefit in adults, NEST-IN1 was the first efficacy study conducted in infants for a norovirus vaccine candidate," Chief Executive Rob Hershberg said in prepared remarks. "We believe the efficacy in the infant setting may have been impacted by the appearance of multiple emerging GII.4 strains in this trial."

The company will continue to explore the vaccine as a treatment for adults and will also explore its HIL-216 product candidate, a Phase 1-ready vaccine for adults.

Norovirus causes about 700 million cases of moderate or severe acute gastroenteritis globally every year and results in about 200,000 deaths, according to the World Health Organization. That results in more than $4 billion in direct health system costs, HilleVax said. Older adults and young children bear the brunt of the illness.

HilleVax's stock is now down 89% in the year to date, while the S&P 500 SPX has gained 16.7%.

-Ciara Linnane

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07-08-24 1232ET

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