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Tetravalent dengue vaccine candidate safe effective in phase 2 trial
DENVax, a tetravalent, live-attenuated and recombinant dengue vaccine candidate, was safe and effective in patients aged 18 months to 45 years, according to recent study data.
“This phase 2 study involved the first use of tetravalent dengue vaccine [TDV; Takeda Pharmaceutical] in children and adolescents, and its first use in dengue-endemic regions,” Chukiat Sirivichayakul, MD, associate professor of tropical pediatrics at Mahidol University in Bangkok, Thailand, and colleagues wrote. “The vaccine was well-tolerated by all age groups, and substantial increases in all immunogenicity endpoints were observed for all four dengue virus serotypes after one or two doses.”
Dengue vaccine development has focused on tetravalent vaccines that protect against all four dengue virus serotypes in order to prevent subsequent and more severe infections, according to the researchers.
The multicenter, double blind study was performed in Puerto Rico, Colombia, Singapore and Thailand from November 2011 to August 2013. In the trial’s first stage, the researchers enrolled 148 volunteers, aged 18 months to 45 years, and randomly assigned them in a 2:1 ratio to the vaccine or placebo. In the second stage, the researchers enrolled 212 volunteers, aged 18 months to 11 years, and assigned them in a 3:1 ratio to vaccine or placebo. The patients assigned vaccine received it in two doses 90 days apart. The researchers followed up for safety, seropositivity and neutralizing antibodies to each serotype.
After both doses, seropositivity was greater than 95% in serotypes 1 through 3, and it exceeded 72.7% for serotype 4. Geometric mean neutralizing antibody titers (GMTs) ranged from 582 to 1,187 for serotype 1, 582 to 1,187 for type 2, 196 to 630 for type 3, and 41 to 210 for type 4. The only adverse events were injection-site pain, itching and mostly mild erythema.
The GMT values and seropositivity rates for multiple serotypes after a single dose were “encouraging,” according to Sirivichayakul and colleagues.
“These increases in GMTs can reflect an increase in the number of seropositive subjects and/or an increase in titer for those subjects that already were seropositive,” the researchers wrote. “To further explore these observations, an ongoing clinical study of TDV is comparing immune responses after one or two doses in children in endemic countries.” – by Will Offit
Disclosure: The study was funded by Inviragen. Sirivichayakul reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
