Dengue fever affects as many as 400 million people annually, according to the U.S. Centers for Disease Control and Prevention (CDC). It is caused by one of four related viruses transmitted by mosquitoes. Symptoms usually start four to seven days after the mosquito bite and usually last three to 10 days. About 2.5 billion people, 40 percent of the world’s population, live where there is a risk of dengue transmission. About 20,000 people die each year from the disease.
Primary symptoms of dengue are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild blooding, usually from the nose or gums. At its worst, the capillaries start to leak, which allows the fluid in blood into the peritoneum and pleural cavity, which can lead to circulatory system failure and shock, followed by death.
TAK-003 is a tetravalent dengue vaccine based on a live-attenuated dengue serotype 2 virus. In Phase I and II trials, children and adolescents given the vaccine showed an immune response against all four dengue serotypes. It was found to be safe and well tolerated.
The Tetravalent Immunization against Dengue Efficacy Study (TIDES) Phase III trial showed the vaccine was efficacious in preventing dengue fever by any of the four serotypes. The TIDES trial is still ongoing and more results are expected later this year with data from other Phase III trials. The TIDES trial has enrolled more than 20,000 healthy children and adolescents from the ages of four to 16 years that live in dengue-endemic areas. The trial is in patients who have been exposed to dengue and who have not been exposed.
Rajeev Venkayya, Takeda’s president of the company’s Global Vaccine Business Unit, stated, “We are very encouraged by the performance of our dengue vaccine candidate in the study. This brings us one step closer to helping the world tackle the massive burden of dengue.”
The vaccine is administered in two doses three months apart. The first data about efficacy included 11 months of follow-up. The second part of the trial will include another six months of patient data and will review the vaccine’s performance in each of the four different serotypes in addition to how it affected people with previous exposure compared to those who are dengue-naïve.
That data will be used for regulatory filings. A third part of the trial will evaluate long-term safety by following participants for three more years.
The first dengue vaccine, Dengvaxia, was developed by Sanofi Pasteur and was first registered in Mexico in December 2015. Dengvaxia is a live recombinant tetravalent dengue vaccine. The World Health Organization (WHO) indicates there are at least five other vaccine candidates being studied in clinical trials.
There is some controversy related to Dengvaxia, at least in the Philippines, where the vaccine has been banned for the last year. The vaccine is not recommended for people who have been previously infected by dengue virus, and Sanofi Pasteur indicated in December 2017 that it planned to update its label.
A version of Dengvaxia is being evaluated by the U.S. Food and Drug Administration (FDA) under the name Dengaviia. It has a target action date of May 1, 2019.
In December, Merck and Co. signed a research collaboration deal with Instituto Butantan, based in Sao Paulo, Brazil, to develop vaccines against dengue virus disease. Merck and Instituto Butantan have licensed specific rights from the U.S. National Institutes of Health (NIH)’s National Institute of Allergy and Infectious Diseases (NIAID), related to the development of live attenuated tetravalent vaccines (LATV).
The Instituto Butantan also has a dengue vaccine candidate, TV003, which is in an ongoing Phase III clinical trial in Brazil. The trial expects to enroll almost 17,000 healthy individuals between the ages of 2 and 59 years in 15 cities. All patients in the trial will be monitored for five years by way of in-person visits to the health clinic and telephone or text communications.