A Rockville biotech firm whose malaria vaccine works by triggering an immune response with the saliva from 1,000 irradiated mosquitoes, is safe and shows promise, according to a research study published in the journal Science.
Sanaria Inc. published the phase I trial study last week in collaboration with Center for Vaccine Development at the University of Maryland School of Medicine, the U.S. Military Malaria Vaccine Program at the Naval Medical Research Center and the Vaccine Research Center at the National Institutes of Health.
Testing on human volunteers showed the vaccine to be safe, but the method of administration — a single hypodermic needle meant to mimic a mosquito bite — did not invoke protection levels as high as expected. But when administered intravenously during testing on rhesus monkeys, the vaccine did elicit a strong immune response.
“Our challenge is to find a way to best mimic how a mosquito delivers the malaria parasite,” said study co-author Dr. Kirsten Lyke, associate professor of medicine and a research scientist at the Center for Vaccine Development at the University of Maryland School of Medicine. “The IV test was surprising and showed an unexpected, higher result of protection.”
Sanaria’s PfSPZ vaccine differs from other malaria vaccines as it is a “whole body” vaccine, using a treated form of the entire parasite. Other treatments have used engineered portions of proteins from the malaria parasite.
Sanaria is not the only company in the hunt for a malaria vaccine. GlaxoSmithKline Biologicals’ drug candidate RTS,S is already in Phase III testing. In earlier testing, the RTS,S vaccine reduced episodes of malaria by 53 percent over an eight-month period.
The hope is that whole body vaccines like Sanaria’s can reduce episodes of malaria by up to 90 percent, which was hinted at in the animal testing.
“The kind of immune response has been sought by malaria researchers for 20 years, it’s the gold standard,” said Sanaria founder and CEO Dr. Stephen Hoffman. “We still have plenty of work to do, but there is no other malaria vaccine in development with these results.”
Noted malaria researcher Dr. Fred Binka, dean of the School of Public Health, University of Ghana, praised the results, which if it works as expected could provide up to 90 percent protection from the parasite.
“This is the first indication that a highly effective malaria vaccine may be available that can be used to eliminate Plasmodium falciparum malaria in geographically defined areas and prevent malaria in travelers,” Binka said in a statement.
Sanaria’s vaccine is derived from the saliva of infected mosquitoes specially grown in aseptic rooms in the basement of the company’s Rockville headquarters. The mosquitoes are infected with the malaria parasite and later dosed with low levels of a commonly used radioactive isotope, which stunts the development of the parasite and prevents it from fully developing and causing malaria symptoms.
When introduced in enough strength, the weakened parasites invoke an immune response from T-cells in the liver without causing major side effects. The technology dates back nearly four decades, but was discounted as unviable.
“We knew this technology was successful in the past, but we had no way to give it to people other than having them be bitten by a thousand mosquitoes,” Lyke said. “There was no ability to mass produce a similar treatment before Sanaria.”
Sanaria was started in 2002 by Hoffman, who was previously the director of the Malaria Program at the Naval Medical Research Center for 14 years and spent his career working on diseases like malaria, dengue fever and typhoid fever.
After retiring from the Navy in 2001, Hoffman joined Celera Genomics. There, he organized the successful sequencing of the genome of the mosquito responsible for most transmissions of malaria in Africa. He left Celera in 2002 to found Sanaria, which means “good air” in Latin. Malaria means “bad air.”
“Our focus is to provide high-level protection with the vaccine and then work on getting it to people who need it the most,” Hoffman said. “Today, more than 2,000 kids will die of malaria, and that’s not something we should be abiding by.”
According to the U.S. Centers for Disease Control and Prevention, nearly 3,000 people die daily in Africa of the disease. And close to half the world’s population lives in areas at risk for malaria infection. Even though malaria is officially classified as “eradicated” in the U.S., about 1,500 cases are reported each year in this country. From 1957 to 2009, the U.S. had 63 outbreaks of locally transmitted malaria, most occurring when an infected traveler returned home and was bitten by a mosquito, which then spread the parasite further.
Malaria causes infected red blood cells to stick to blood vessel walls. According to the CDC, the most common symptoms include: “A cold stage (sensation of cold, shivering); a hot stage (fever, headaches, vomiting; seizures in young children) and finally a sweating stage (sweats, return to normal temperature, tiredness).”
Hoffman said the next phase of testing will begin in October. He said the testing is being fully funded through collaboration with the National Institutes of Health.