HilleVax Releases Phase 2b Study Results for HIL-214 in Infants

HilleVax, Inc., a clinical-stage biopharmaceutical company specialized in vaccine development, has recently unveiled the topline data results from its NEST-IN1 clinical study. This Phase 2b trial was designed to evaluate the efficacy, safety, and immunogenicity of HIL-214, a vaccine candidate intended to prevent moderate-to-severe acute gastroenteritis (AGE) caused by norovirus, in infants around five months old. The study was conducted across various sites in the United States and Latin America.

The NEST-IN1 study, which was randomized, double-blind, and placebo-controlled, did not achieve its primary or secondary efficacy endpoints. The primary endpoint focused on the vaccine's efficacy against moderate or severe AGE events caused by GI.1 or GII.4 norovirus genotypes. The data revealed 51 primary endpoint events, with 25 occurring in the vaccine group (n=1,425) and 26 in the placebo group (n=1,399), resulting in a vaccine efficacy of just 5% (95% confidence interval; -64%, 45%). No clinical benefits were observed in any of the secondary endpoints either.

Despite this setback, the safety and immunogenicity profile of HIL-214 was consistent with earlier studies, including the prespecified analysis of the initial 200 subjects in the NEST-IN1 trial and previously reported data.

Expressing his disappointment, Rob Hershberg, MD, PhD, Chairman and CEO of HilleVax, acknowledged that while HIL-214 had shown clinical benefits in adult studies, NEST-IN1 was the first trial to evaluate its efficacy in infants. Dr. Hershberg suggested that the presence of multiple emerging GII.4 strains during the trial might have impacted the results.

Dr. Hershberg extended his gratitude to the trial investigators, clinical sites, and the HilleVax team for their rigorous efforts, as well as to the infants and families who participated in the study.

Following these results, HilleVax has decided to halt further development of HIL-214 for infants. However, the company is exploring the potential for continued development of HIL-214 and another vaccine candidate, HIL-216, which is ready for Phase 1 trials, in adults. This decision comes after a previous Phase 2b study in adults, NOR-211, demonstrated statistically significant efficacy against moderate or severe AGE due to norovirus.

HilleVax's initial program, HIL-214, focuses on preventing moderate-to-severe AGE caused by norovirus infection, a significant global health issue. Norovirus is estimated to cause approximately 700 million cases of AGE and 200,000 deaths annually worldwide, leading to over $4 billion in direct healthcare costs and $60 billion in societal costs each year. The burden of norovirus predominantly affects young children and older adults.

In summary, while the NEST-IN1 study did not achieve its desired outcomes, HilleVax remains committed to advancing its vaccine candidates, HIL-214 and HIL-216, for adult populations, aiming to address the significant global health challenge posed by norovirus.