Pfizer Holds Out Hope For C. Diff Vaccine Despite Clinical, Commercial Failures

Pfizer Inc. still believes in the potential for its Clostridioides difficile vaccine candidate PF-06425090 to have a meaningful impact on the lives of older people at high risk of potentially deadly c. difficile infections despite the fact that the vaccine failed to achieve the primary endpoint in the Phase III CLOVER clinical trial. The company said on 1 March that the candidate did not prevent primary c. diff infections but it reduced infections compared with placebo and eliminated hospitalizations for c. diff.

However, predecessors in the c. diff vaccine field have not paved a path to clinical or commercial success. Sanofi discontinued development of its vaccine known as ACAM-CDIFF in 2017 after a Phase III interim analysis, throwing Pfizer’s candidate into the lead, but reinforcing Valneva SE’s decision to hold off on Phase III development of its vaccine candidate until a competitor was successful in a pivotal trial