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Vaxcyte PCVX is a clinical-stage biotech focused on developing vaccines to prevent or treat bacterial infectious diseases.
In the past month, PCVX's shares have nosedived 56%. This downside came after Vaxcyte reported mixed results from a phase II study on its investigational pneumococcal conjugate vaccine (PCV) in healthy infants.
Adding to this headwind, the broader biotech/drug sector is feeling the pressure from the resignation of a senior FDA official instrumental in driving biotech innovation, which has raised alarms around the agency’s ability to maintain momentum on innovation and regulatory clarity.
PCVX Stock’s Performance
Vaxcyte’s shares have plummeted more than 62% year to date compared with the industry’s 8% decline, as seen in the chart below. During this timeframe, the stock has also underperformed the broader Medical sector and the S&P 500 Index. The company’s shares are also trading below its 50 and 200-day moving averages.
PCVX Stock Underperforms Industry, Sector & S&P 500
Image Source: Zacks Investment Research
More on PCVX’s Pneumococcal Vaccine Study Results
Last week, Vaxcyte reported top-line results from the mid-stage study that evaluated its 24-valent PCV VAX-24 against Pfizer’s PFE Prevnar 20. The Pfizer vaccine is approved for preventing invasive pneumococcal disease (IPD) caused by 20 serotypes, all of which are included in the Vaxcyte vaccine, along with four additional ones.
Data from this dose-finding study showed that the mid-dose of VAX-24 met the non-inferiority criteria for seroconversion and showed robust immune responses across all serotypes, particularly for the highest circulating ones. However, the vaccine did not meet the non-inferiority criteria for four of the 24 serotypes compared with Pfizer’s Prevnar 20. This mixed result was a major reason behind the decline in PCVX's share price.
Additionally, VAX-24 was well-tolerated and demonstrated a safety and tolerability profile similar to Pfizer’s Prevnar 20. The mid-dose of VAX-24 also met the target IgG Geometric Mean Ratio and generated strong opsonophagocytic assay responses, which are considered key markers for protection against IPD.
Based on these results, Vaxcyte has selected the mid-dose formulation of VAX-24 for potential advancement into late-stage development. Depending on the top-line results from the ongoing mid-stage study on its investigational 31-valent PCV vaccine VAX-31 in infants, expected in mid-2026, the company plans to start a phase III study in infants with either VAX-24 or VAX-31.
Vaxcyte intends to report full post-dose 4 booster data for VAX-24 by the end of this year.