Takeda spinout HilleVax’s stock $HLVX sunk over 85% on Monday morning after the company announced its norovirus vaccine candidate failed a mid-stage trial in infants.
While the vaccine, dubbed HIL-214, previously showed benefit in adults, it failed in the Phase 2b NEST-IN1 trial which was the first efficacy study conducted in infants for a norovirus vaccine candidate.
Robert HershbergIn the study’s primary endpoint, based on more than 2,800 participants, there were 25 moderate or severe acute gastroenteritis events in the vaccine arm and 26 with placebo, which calculates to a vaccine efficacy of 5%. The company was investigating how effective the vaccine was in protecting infants against such an event due to GI.1 or GII.4 norovirus genotypes.
HilleVax CEO Rob Hershberg said in a statement that the company believes “the efficacy in the infant setting may have been impacted by the appearance of multiple emerging GII.4 strains in this trial.” The study recruited in the US and Latin America.
While HilleVax is discontinuing the candidate in infants, it is “exploring the potential” to continue to develop it in adults, as well as move forward with HIL-216, HilleVax’s Phase 1 ready norovirus vaccine that it purchased from Chengdu Kanghua in January.
“We believe there is still value in the company, particularly with HIL-216’s potential for broader coverage,” Leerink analysts wrote in a Monday note. There are currently no vaccines for norovirus.
The analysts added that HIL-214 previously showed evidence of efficacy in adults in a Phase 2b trial, “so we think it’s reasonable that pursuit of an adult trial might not replicate the results seen in infants.”
HilleVax’s stock also dipped last year when it delayed topline data from the NEST-IN1 trial due to logistical issues.