Experimental P. aeruginosa Vaccine Bites the Dust

FDA approval is unlikely any time soon

The French company Valneva has cancelled development of an investigational vaccine against hospital-acquired infection with Pseudomonas aeruginosa. The vaccine was positioned to be picked up by GlaxoSmithKline, but weak phase 2/3 data killed both that possibility and Valneva’s interest in forging ahead with development, according to FierceBiotech.

In June, Valneva announced that the phase 2/3 trial results for its P. aeruginosa vaccine candidate (VLA43) did not confirm prior phase 2 and interim findings, which had shown a clinically meaningful reduction in all-cause mortality. As a result, the company has decided to discontinue the program.

The randomized, placebo-controlled, double-blind study was conducted in 800 mechanically ventilated patients in intensive care units (ICUs) in six European countries. The patients were vaccinated twice with either the P. aeruginosa vaccine candidate or placebo at a seven-day interval, in conjunction with standard-of-care treatments for ICU patients. While the trial confirmed the vaccine’s immunogenicity and acceptable safety profile, the trial’s primary endpoint was not met. Overall survival, a secondary endpoint in the study, also did not differ between the VLA43 group and the placebo group.

The failure of VLA43 scuttles hopes that a prophylactic vaccine against P. aeruginosa will gain FDA approval in the foreseeable future. The bacterium is estimated to cause 51,000 health care-associated infections and 400 deaths each year in the United States.

GlaxoSmithKline also rejected another Valneva vaccine, this one aimed at Clostridium difficile. Valneva is now on the verge of starting phase 3 trials of the vaccine without a partner.

Sources: FierceBiotech, September 1, 2016; Valneva, June 2 and August 31, 2016.