Pfizer's Progress on C. diff Vaccine and Pneumococcal Shot Wins Analyst Conviction

Pfizer hosted a discussion with sell-side analysts to provide an update on one of the vaccine pipeline items – a second-generation Clostridioides difficile (C. diff) vaccine effort in Phase 2.

Goldman Sachs analyst Chris Shibutani maintained a Buy rating on Pfizer, Inc PFE with a price target of $33.

Shibutani recalled that Pfizer had reported negative results from a Phase 3 study for a first-generation asset in March 2022, where the primary endpoint was unmet.

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Still, results did include signals from secondary endpoints that suggested reduced disease severity.

Pfizer has since been exploring updated formulations (reducing the 3-dose regimen to 2 doses), including a version in Phase 2. Immunogenicity data are anticipated in 2025, with potential for advancement into Phase 3 by the end of 2025.

For a potential Phase 3 study, Shibutani noted the objective would be to discern the potential to reduce the severity of a C. diff infection (CDI) instead of aiming to reduce the risk and prevention of disease.

Pfizer estimates ~500k infections annually in the U.S., and no vaccine options currently available. Acknowledging that there is an unmet need The analyst acknowledged that there is an unmet need and said the data thus far suggests a potential basis for a path forward for the program in the context of comments from R&D leadership during the discussion Shibutani hosted with investors.

The emphasis on the forward will be on programs with the most significant potential for economic returns. The analyst expects that investor enthusiasm will likely remain relatively subdued, especially in the context of uncertainties deriving from health policy dynamics relating to vaccines, that are an overhang to sentiment.

Shibutani does not currently include revenue estimates for a C. diff vaccine in his model and looks to monitor data updates and decisions regarding plans for this program to guide his forecasts in the future.

Separately, the analyst flagged Pfizer management’s mention of the fourth generation 25-valent pneumococcal vaccine (PCV), which management affirms continues to progress in Phase 2.

Shibutani recalled that Pfizer had previously commented that the immunogenicity data from Phase 1 were encouraging, as highlighted by the improved immunogenicity observed for serotype 3.

Pfizer is currently in a Phase 2 proof-of-concept study for its second-generation Clostridioides difficile (C. diff) vaccine, PF-07831694. This vaccine targets C. diff toxins A and B, which cause Clostridioides difficile infection (CDI).  

Their goal for the second generation is to build off the 1st generation’s efficacy and duration by developing a more potent, more durable formulation, allowing for a 2-dose regiment (instead of 3-dose), resulting in higher and faster series completion.

After evaluating adjuvants in formulation for their next-generation candidates, Pfizer noted they can increase the strength or magnitude of the immune response, potentially resulting in lower doses.

Pfizer advanced 1 of the three updated 2nd-generation candidates to Phase 2 based on Phase 1/2 safety and immunogenicity data.

The Phase 2 trial endpoints will evaluate the immunogenicity and safety of the 2-dose regimen. Trial data is expected in 2025, with a potential Phase 3 start in late 2025, pending positive results.

Pfizer in Phase 2 is the furthest along of the C. diff vaccine assets. Idorsia Pharmaceuticals initiated Phase 1 for their competing C. diff asset in July. Vaxxilon and Matrivax Research & Development Corporation both have preclinical assets. GSK Plc’s GSK CDI vaccine completed a Phase 1 trial in 2022 but is no longer listed as a pipeline asset.  

Pfizer stock has dropped over 11.5% year-to-date. Investors can gain exposure to the stock through SPDR S&P 500 SPY and Vanguard S&P 500 ETF VOO.

Price Action: PFE stock is up 0.82% at $26.58 at the last check on Monday.

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