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Pfizer unveils positive results from phase 2 study of Clostridium difficile vaccine

PBR Staff Writer Published 27 January 2017

A phase 2 study evaluating Pfizer's investigational vaccine candidate for the prevention of Clostridium difficile (C. difficile) has yielded positive results.

PF-06425090, following the findings from the pre-planned interim analysis, will now progress towards a phase 3 trial, slated to be initiated in the first half of this year.

Its randomized phase 2 trial dubbed NCT02561195 evaluated the safety, tolerability, and immunogenicity of the vaccine candidate in healthy adults aged between 65 and 85 years.

Pfizer senior vice president and Vaccine Research and Development head Kathrin Jansen, Ph.D. said: “Despite improved infection control measures, C. difficile disease continues to rise, further augmenting an already urgent public health threat with particular negative impact on older adults.

“We are very encouraged by these interim immunogenicity and safety results demonstrating robust increases in vaccine-elicited neutralizing antibodies to both toxins, that we believe could provide protection against C. difficile disease.”

Designed to help prevent C. difficile infection (CDI), PF-06425090 induces a functional antibody response that can neutralize the two primary toxins produced by C. difficile - toxins A and B that cause the disease. The vaccine candidate has been designed to cover both life-threatening diarrhea and pseudomembranous colitis associated with CDI as per Pfizer.

In August 2014, the vaccine candidate secured the Fast Track designation from the US Food and Drug Administration (FDA).

C. difficile, a spore-forming pathogen, typically results in symptoms in individuals having modified gut microbial flora. The pathogen releases toxins that can create different disease manifestations from asymptomatic colonization to diarrhea, toxic megacolon, pseudomembranous colitis, intestinal perforation, and can also cause death in most severe cases.