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Malaria vaccine candidate PAMVAC passes test in humans
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A recent phase 1 clinical trial of the malaria vaccine candidate PAMVAC, designed to protect against pregnancy-associated malaria, or PAM, found that the vaccine is safe, well tolerated and induced functionally active antibodies in humans.
Two other vaccine candidates, PfSPZ and RTS,S/AS01, are also in being tested in adults, but neither provides specific protection against PAM, which results in 20,000 maternal and 200,000 infant deaths globally each year.
“In the present study, we show that the vaccine is safe and prepares the immune system by developing antibodies, which interfere with binding to the special sugar in placental tissue called chondroitin sulfate A,” Morten Agertoug Nielsen, MD, associate professor of the department of infectious diseases at the University of Copenhagen, told Infectious Disease News. “By targeting the disease-causing or pathogenic stage of the parasite, we hope to avoid disease.”
In a randomized, double-blind study, researchers tested healthy, malaria-naive adults with intermuscular injections of PAMVAC adjuvanted with Alhydrogel, Glucopyranosyl Lipid Adjuvant in stable emulsion (GLA-SE), or liposomal formulation with QS21. Volunteers were assigned a 20-g or 50-g dose, randomly allocated one of the three formulas and immunized three times at 4-week intervals by an independent pharmacist. The participants were monitored for 6 months following their last immunization.
PAMVAC was immunogenic in all participants, and researchers found the antibody levels specific to PAMVAC were highest in the PAMVAV-GLA-SE adjuvant. Throughout the study, 292 adverse events (AEs) occurred in all 36 volunteers, 94 of which were at least possibly related to the vaccine. Of those, there were 10 Grade 2 and two Grade 3 AEs. The distribution and severity of AEs were similar in all formulas.
“The drawback of targeting this stage is that the parasite has evolved many different variants of these surface antigens. Therefore, we have to do further testing of the vaccine in women living in endemic areas. This will tell whether the vaccine-induced antibodies target enough variants to warrant further testing,” said Nielsen. – by Erin Michael
Disclosure: Nielsen is the co-inventor of a novel technology to develop capsid-like particle vaccines, which may be used in the further development of the PAMVAC vaccine. This technology is licensed by AdaptVac, of which Nielsen is a co-owner. The company had no influence on the study.
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