Clostridioides Difficile Vaccine Candidate Indicates Strong Potential Effect

New York-based Pfizer Inc. announced results from the CLOVER pivotal Phase 3 study evaluating its Clostridioides difficile (C. difficile) vaccine candidate (PF-06425090) in the prevention of C. difficile infection (CDI).

Initial analyses of two protocol-defined secondary endpoints indicated a highly favorable benefit in reducing CDI severity and 100% vaccine efficacy in preventing medically attended CDI.

However, the trial did not meet its pre-specified primary endpoint of prevention of primary CDI.

"We are encouraged by the promising potential benefit observed against more severe C. difficile infection, as a large portion of cases leads to extended diarrhea episodes that can require hospitalization," said Kathrin U. Jansen, Ph.D., SVP and Head of Vaccine Research & Development, Pfizer, in a press release issued on March 1, 2022.

"We will evaluate the next steps for our program in coordination with regulatory agencies."

Currently, there is no vaccine to prevent initial or recurrent CDI.

Clostridioides difficile infection is a serious infection associated with diarrhea that may progress to severe and debilitating illnesses with potentially fatal outcomes.

The U.S. CDC has classified CDI as an urgent public health threat.

Close to 10% of patients aged 65 or older with a healthcare-associated C. difficile infection are at risk of death within 30 days of diagnosis and constitute 90 percent of those with risk for fatal outcome.

Pfizer plans to present the Phase 3 CLOVER trial results, including all secondary endpoints, at a future medical congress and for publication in a peer-reviewed scientific journal.