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Results from ongoing Phase 3 trial announced
RTS,S malaria vaccine candidate reduces malaria by approximately one-third in African infants
Results from a pivotal, large-scale Phase 3 trial, published online on November 9, 2012, in the New England Journal of Medicine, show that the RTS,S malaria vaccine candidate can help protect African infants against malaria. The trial is being conducted by GlaxoSmithKline (which invented RTS,S), the PATH Malaria Vaccine Initiative, and 11 trial sites in seven sub-Saharan African countries. The study found that infants (aged 6 to 12 weeks at first vaccination) vaccinated with RTS,S had one-third fewer episodes of both clinical and severe malaria, when compared to immunization with a control vaccine, and had similar reactions to the injection. In this trial, RTS,S demonstrated an acceptable safety and tolerability profile.
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Vaccinations completed in large-scale Phase 3 RTS,S trial
The ongoing, large-scale Phase 3 trial of the RTS,S malaria vaccine candidate reached a milestone on November 30, 2012, when the last booster dose of the trial was administered at the Lambaréné trial site in Gabon. This safety and efficacy trial began at the trial site in Bagamoyo, Tanzania, in May 2009. The trial is being conducted by GlaxoSmithKline (which invented RTS,S), the PATH Malaria Vaccine Initiative, and 11 trial sites in seven sub-Saharan African countries. Enrollment comprises 15,460 participants, in two age groups: 5 to 17 months and 6 to 12 weeks of age, at the time of the first vaccination. Results of the RTS,S Phase 3 trial for efficacy, safety, and immunogenicity during the first 12 months of follow-up were published by the
New England Journal of Medicine in October 2011 (children aged 5 to 17 months) and November 2012 (infants aged 6 to 12 weeks). It is anticipated that efficacy and safety findings related to the booster dose, as well as data on longer-term protection, will be published by the end of 2014.
Collaboration with Inovio on new vaccine delivery technologies
The PATH Malaria Vaccine Initiative has entered into a follow-on agreement with Inovio Pharmaceuticals to conduct a clinical trial using new vaccine delivery technologies. Researchers will test whether a novel vaccine approach that combines genetically engineered DNA with an innovative vaccine delivery technology called electroporation could induce an immune response in humans against the malaria parasite.
Electroporation deploys controlled electrical impulses to create temporary pores in a cell membrane, allowing uptake of the synthetic DNA vaccine. The cell then uses the DNA’s instructions to produce proteins that mimic the presence of the malaria pathogen, with the aim of inducing an immune response to provide future protection against malaria.
The Phase 1/2a clinical trial, which will begin in early 2014, will test Inovio’s plasmid DNA and electroporation technology in approximately 30 individuals, as part of what is known as a challenge trial by controlled human malaria infection. If successful, this trial would provide valuable information that may further the development of a highly efficacious vaccine against malaria.
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Perceptions of vaccines and malaria in Mozambique districts
A PATH Malaria Vaccine Initiative-supported qualitative study in two malaria-endemic districts in southern Mozambique looks at some of the perceptions, beliefs, and attitudes that are held in relation to malaria and vaccines at the community level, the information gaps that may exist, and the household decision-making processes and treatment-seeking patterns related to malaria and vaccination.
This and similar studies are part of the work underway on the policy front to pave the way for decisions on possible malaria vaccine introduction. To facilitate the planning process, several African countries and their international partners are using a malaria vaccine decision-making guide, which lays out the range of data that would be needed for timely decisions on whether or not to introduce a particular malaria vaccine. The range of data include sociocultural and health communication information from communities that could inform the development of communications strategies and facilitate discussions with communities prior to vaccine introduction.
Visit the Malaria Vaccine Decision-Making Framework website to read more.
MVI at ASTMH
Transmission-blocking vaccine assays symposium
The PATH Malaria Vaccine Initiative (MVI) hosted a symposium on November 14, 2012, as part of the
American Society of Tropical Medicine and Hygiene (ASTMH) 61st Annual Meeting, titled “Bridging Membrane Feeding Assays with Direct Feeds to Test Malaria Transmission Blocking Vaccines.” The symposium was chaired by Dr. David Kaslow, Director of MVI, and co-chaired by Dr. Vasee Moorthy, Malaria Vaccine Focal Point for the World Health Organization. On the panel were Dr. Robert Sinden, Imperial College London, Dr. Carole Long, National Institute of Allergy and Infectious Diseases (NIAID), Dr. Robert Sauerwein, Radboud University, Dr. Yimin Wu, NIAID, and Dr. Jetsumon Prachumsri, Mahidol University. Dr. Kaslow provided an introduction to the symposium, setting the stage for the topic of discussion. He described the assays used to determine the
potential efficacy of a transmission-blocking vaccine and the importance of the assays within the context of seeking licensure of a vaccine. He also highlighted the differences between assays and the need to better understand both laboratory and field assays.
The speaker presentations included a broad range of topics—from a historical analysis of the standard membrane-feeding assay, to a qualification of the assay, comparisons of data from the laboratory and field, and a discussion of how studies for Plasmodium vivax are performed in contrast to ones for Plasmodium falciparum. The symposium culminated with a Q&A session, at which questions were posed to the panel in order to garner their feedback on how the laboratory and field assays can be bridged.
While more work may be needed to generate a consensus on how to perform and interpret the results of the assays, there was consensus that when reporting results, all data need to be reported. This will allow for better comparison of results between studies and between different laboratories.
Prioritizing new malaria vaccine candidates symposium
At the ASTMH annual meeting, Dr. Kaslow also participated in a Walter Reed Army Institute of Research-sponsored symposium, titled “Prioritizing New Malaria Vaccine Candidates for Further Development.” In his remarks, Dr. Kaslow noted the need to prioritize projects on an ongoing basis in order to maximize the impact of limited resources. He described the portfolio management approach as one of the most efficient and effective ways to deploy those resources. Dr. Kaslow suggested that leveraging controlled human malaria infection models in translational research and translational development in a learn-confirm-apply paradigm was one way to define and manage the risk inherent in the development of malaria vaccines. He also discussed the Malaria Vaccine Technology Roadmap—the global health community’s blueprint for accelerating the development of malaria vaccines. The
Roadmap, which seeks to maintain a shared vision, strategic goals, and landmarks for the development of malaria vaccines, is undergoing a strategic update that should be completed in 2013.
To find more information about the two symposia discussed above, please click here.
RTS,S results session
The second set of results from the large-scale Phase 3 clinical trial of RTS,S was also presented at ASTMH. Dr. John Lusingu, principal investigator for the clinical trial site in Korogwe, Tanzania, and chair of the RTS,S Clinical Trials Partnership Committee, presented efficacy data for the 6- to 12-week-old infants who were vaccinated during this trial. Dr. Patricia Njuguna, principal investigator for the trial site in Kilifi, Kenya, presented safety data on this cohort. For more information about the results, please click here.
Malaria Vaccine Technology Roadmap under review
For the first time since its publication in 2006, the Malaria Vaccine Technology Roadmap is being updated. The Roadmap—launched at the World Health Organization (WHO) Global Vaccine Research Forum—established a shared Vision, Strategic Goal (2025), and Landmark (2015) for development of malaria vaccines. At a WHO Scientific Forum held in Geneva in February 2012, a consensus was reached on the need to update the Roadmap Vision and 2025 Strategic Goal in response to a number of changes since 2006, including changes in the strategic role of malaria vaccines and changes in malaria epidemiology and control status.
Through a broad consultative process led by WHO, efforts are being made to update the Roadmap Vision and Strategic Goal(s), culminating in review and endorsement by an appropriate WHO mechanism. It is anticipated that the updating process will conclude in the second quarter of 2013, culminating in the launch of an updated Roadmap. Please refer to the WHO website for more information on this process.
Watch our website...
Requests for proposals (RFPs) are one way that the PATH Malaria Vaccine Initiative identifies the best partners with whom to work. We expect a number of RFPs to be issued in 2013, including one this month to improve upon the assays used for detecting antibody-mediated responses against Plasmodium falciparum pre-erythrocytic antigens. Once posted, RFPs can be found by going to our website at www.malariavaccine.org/rd-rfps.php.
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