Vaxcyte shares plummeted 50% in early afternoon trading after the biopharmaceutical company released topline results from its Phase 2 dose-finding study of VAX-24, its 24-valent pneumococcal conjugate vaccine candidate. Despite the sharp market reaction, analysts at Evercore ISI suggest the setbacks may be less concerning than investors initially feared.
The clinical trial evaluated VAX-24's safety, tolerability, and immunogenicity compared to Pfizer's Prevnar 20 in healthy infants. According to Evercore ISI, Vaxcyte's candidate missed four serotypes versus Prevnar20 in what analysts described as the "all-important" infant data.
"An imperfect vaccine press release on the heels of Peter Marks resignation is just tough timing," noted Evercore ISI in their analysis, referring to the recent departure of the FDA's key vaccine official. However, the firm maintained its optimistic outlook on the company's prospects.
Clinical Trial Details and Results
VAX-24 is designed to prevent invasive pneumococcal disease by targeting 24 different serotypes of Streptococcus pneumoniae. The Phase 2 dose-finding study specifically focused on establishing the vaccine's profile in the pediatric population, a critical demographic for pneumococcal vaccines.
While specific data points were not disclosed in detail, Evercore ISI's analysis suggests that three of the four serotype misses in the Phase 2 results were "narrow" and would "quite likely be ok" when tested in a larger Phase 3 trial with more statistical power.
The exact nature of these misses—whether they failed to meet non-inferiority thresholds for antibody responses or other immunological parameters—was not specified in the initial release. However, the overall safety and tolerability profile appears to have been acceptable, as analysts maintained their positive outlook on the program's future.
Market Reaction and Analyst Perspective
Vaxcyte shares dropped dramatically following the announcement, falling $34.89 to $34.57, representing approximately a 50% decline in value. This sharp reaction highlights the high expectations investors had placed on the VAX-24 program and the competitive landscape for pneumococcal vaccines.
Despite this setback, Evercore ISI maintained its "Outperform" rating on Vaxcyte shares, suggesting confidence in the company's ability to address these issues in future trials. The firm's analysis indicates that the serotype misses, while disappointing, do not fundamentally undermine the vaccine's potential.
Pneumococcal Disease Landscape
Pneumococcal disease remains a significant global health concern, particularly for vulnerable populations such as infants and the elderly. Invasive pneumococcal disease can lead to serious conditions including pneumonia, meningitis, and bacteremia.
The current standard of care includes Pfizer's Prevnar 20, which protects against 20 serotypes of pneumococcus. Vaxcyte's VAX-24 aims to expand coverage to 24 serotypes, potentially offering broader protection against this pathogen.
Path Forward
The company is expected to proceed with its development program, likely incorporating learnings from the Phase 2 results into the design of its pivotal Phase 3 trials. The larger sample size in Phase 3 studies may help resolve the statistical issues that led to the serotype misses in the current data set.
Industry observers will be watching closely to see how Vaxcyte addresses these challenges and whether the company can demonstrate non-inferiority or superiority to Prevnar 20 across all targeted serotypes in future trials.
The timing of the announcement, coinciding with the resignation of Peter Marks from the FDA, adds an additional layer of uncertainty to the regulatory landscape for vaccine approvals, according to Evercore ISI's commentary.
