The World Health Organization recommended the first vaccine for malaria on October 6 for sub-Saharan African and other areas with moderate to high transmission rates, bringing hope to parts of the world where it kills more than 400,000 people a year. That doesn’t mean the search for even better vaccines is over. For more than three decades, the Walter Reed Army Institute of Research (WRAIR) has remained steadfast in search of vaccines to rid the world of malaria—including playing a role in the testing of RTS,S/AS01.
Over the years, WRAIR has developed a controlled human malaria infection (CHMI) model which tests vaccine effectiveness in healthy adult volunteers, prior to testing in the countries where the disease is found. In this CHMI model, volunteers receive the malaria vaccines and are then bitten by malaria-infected mosquitoes at the WRAIR Entomology Branch. Volunteers who develop parasitemia are then cured very early in the infection with a commonly used malaria drug.
Currently, a research team at WRAIR is testing a new malaria vaccine candidate—known as FMP013/ALFQ—using this CHMI model. Volunteers who received the vaccine underwent the mosquito-bite challenge along with six unvaccinated control volunteers. In the coming weeks, these volunteers will be carefully monitored to determine if the vaccine protected them against malaria.
“We have reached this point because of a vast amount of teamwork and significant contributions from many different people,” Lieutenant Colonel Paul Robben, the principal investigator for the clinical trial said. “It’s been a privilege to work alongside so many talented and hardworking individuals as we move forward in this effort.”
This immunization and challenge study follows an earlier clinical study that evaluated the safety of the same malaria vaccine at the Clinical Trial Center at the WRAIR in 2020; researchers found no significant safety concerns.
The FMP013 vaccine directs the human immune system to develop antibodies to the circumsporozoite protein (CSP) of the malaria parasite Plasmodium falciparum, the same protein that is the basis for the RTS,S/AS01 vaccine. “We also included portions of the CSP protein in this vaccine that were not present in RTS,S,” said the inventor of the FMP013 antigen, Dr. Sheetij Dutta, who heads the Structural Vaccinology Laboratory at the Malaria Biologics Branch. “We are hopeful that the trial will answer key questions that will allow us to determine if these extra regions of CSP will broaden the immune response and improve protection or longevity of protection against malaria and aid in the development of next-generation vaccines with improved efficacy over RTS,S,” Dr. Dutta said.
The vaccine also contains the adjuvant Army Liposome Formulation with QS-21, or ALFQ which stimulates the immune response, making the vaccine as a whole more effective. ALFQ was developed by the Military HIV Research Program (MHRP) at WRAIR. Scientists in WRAIR’s Laboratory of Adjuvant and Antigen Research began developing adjuvants in the 1980s. The newest ALF adjuvants, ALFQ and ALFA, have generated strong immune responses in preclinical studies, and the Army was awarded a patent for ALFQ in 2019.
“ALF is an Army-owned product that can be flexibly utilized with any vaccine, including those for emerging infectious diseases”, said Dr. Gary Matyas, Chief of the Adjuvants and Formulation Section. “In addition to this malaria vaccine, ALFQ is being used in candidate vaccines to combat COVID-19, bacterial diarrhea, and HIV.”
The vaccine product development and clinical trials were funded jointly by the United States Agency for International Development (USAID) Malaria Vaccine Development Program and the U.S. Military Infectious Diseases Research Program (MIDRP). The Congressionally Directed Medical Research Programs (CDMRP) Joint WarFighter grant partly funded the adjuvant development.