|
Vaxcyte Inc, a clinical-stage vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases, has announced the initiation of the phase 2 study of VAX-31 in healthy infants and that the first study participants have been dosed.
This study is to evaluate the safety, tolerability and immunogenicity of VAX-31, a 31-valent pneumococcal conjugate vaccine (PCV) candidate designed to prevent invasive pneumococcal disease (IPD).
The company expects to share topline data from the primary three-dose immunization series of the study in mid-2026, followed by topline data from the booster dose approximately nine months later.
“The initiation of the VAX-31 phase 2 infant study marks a significant milestone as we continue advancing our PCV clinical programmes, which also include the fully enrolled, ongoing VAX-24 phase 2 infant study,” said Grant Pickering, CEO and co-founder of Vaxcyte. “PCVs are vital to combating Streptococcus pneumoniae, a serious public health threat exacerbated by increasing antimicrobial resistance. As the broadest-spectrum PCV candidate in the clinic today, VAX-31 has the potential to expand coverage and provide protection against both currently circulating and historically prevalent serotypes. We look forward to sharing topline data for safety, tolerability and immunogenicity from the VAX-31 phase 2 infant study’s primary immunization series in mid-2026, and from the booster dose approximately nine months later.”
“Despite the effectiveness of current vaccines, Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths globally in children under five and IPD, including meningitis and bacteremia, remains persistent in the first years of life,” said Jim Wassil, executive vice president and COO of Vaxcyte. “It has been clearly signaled by the public health community that a pneumococcal vaccine with a broader spectrum of coverage is needed to provide greater protection against this disease. VAX-31 is designed to cover approximately 94% of IPD and approximately 93% of acute otitis media in US. Children under five, with the potential to offer much greater coverage relative to the standard-of-care PCVs.”
The VAX-31 phase 2 infant study is a randomized, double-blind, active controlled, dose-finding, two-stage clinical study evaluating the safety, tolerability and immunogenicity of VAX-31 compared to Prevnar 20 (PCV20) in healthy infants.
Stage 1 of the study is evaluating the safety and tolerability of VAX-31 at three dose levels (low, middle and high) and compared to PCV20 in approximately 48 infants in a dose-escalation approach. In the low, middle and high doses, all serotypes were dosed at 1.1mcg, 2.2mcg and 3.3mcg, respectively, except serotypes 1, 5 and 22F, which were dosed at 1.65mcg, 3.3mcg, and 4.4mcg, respectively. Participants who receive VAX-31 in Stage 1 will continue the standard dosing regimen as part of Stage 2 and will be included in the safety, tolerability and immunogenicity analysis of the study.
Stage 2 of the study will evaluate the safety, tolerability and immunogenicity of VAX-31 at the same three dose levels and compared to PCV20 in approximately 750 infants.
In line with recommendations from the Advisory Committee on Immunization Practices, the study design includes a primary immunization series consisting of three doses given at two months, four months and six months of age, followed by a subsequent booster dose at 12-15 months of age.
The key prespecified immunogenicity study endpoints include an assessment of immune responses for each of the VAX-31 dose levels in comparison with PCV20 for the 20 common and 11 unique serotypes in VAX-31. Post-primary series (post-dose 3 or PD3) immune responses will be assessed based on serotype-specific immunoglobulin G (IgG) seroresponse rates (proportion of participants achieving the accepted IgG threshold value of =0.35mcg/mL) at 30 days PD3. IgG geometric mean titers will be assessed at 30 days PD3 and post-dose 4 (PD4), along with other key immunogenicity endpoints.
All participants in the study will be evaluated for safety through six months following the booster dose.
The study is being conducted at approximately 50 sites in the United States.
Pneumococcal disease (PD) is an infection caused by Streptococcus pneumoniae bacteria. It can result in invasive pneumococcal disease (IPD), including meningitis and bacteremia, and non-invasive PD, including pneumonia, otitis media and sinusitis. In the United States, pneumococcal pneumonia is estimated to result in approximately 150,000 hospitalizations each year. Streptococcus pneumoniae is among the World Health Organization’s top antibiotic-resistant pathogens to be urgently addressed, and the US CDC lists drug-resistant Streptococcus pneumoniae as a “serious threat.” In children under five, Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths globally. Pneumococci also cause over 50% of all cases of bacterial meningitis in the United States. Antibiotics are used to treat PD, but some strains of the bacteria have developed resistance to treatments. The morbidity and mortality due to PD are significant, particularly for young children and older adults, underscoring the need for a broader-spectrum vaccine.
In November 2024, Vaxcyte announced that the FDA granted Breakthrough Therapy designation to VAX-31 for the prevention of IPD in adults. The Breakthrough Therapy designation process is designed to expedite the development and review of drugs that are intended to treat a serious or life-threatening condition.
|