16 Aug 2012

Phase 1/2a trial aims to induce CD8+ T cells to target liver-stage malaria parasites

OXFORD, UK/WASHINGTON, DC August 16, 2012 – The PATH Malaria Vaccine Initiative (MVI)—with support from the United States Agency for International Development (USAID)—and the University of Oxford (Oxford) have entered into an agreement to conduct a Phase 1/2a clinical trial of a malaria vaccine prime-boost approach to immunization involving two viral vectors. The research will expand on previous studies indicating that the approach induces CD8+ T cells (cells that recognize antigens on the surface of an infected cell and can bind to and kill the infected cell) that target malaria parasites during the liver stage of development. The study will also involve a control human malaria infection component. After they are vaccinated, volunteers will be infected under controlled conditions by the bite of an infected mosquito in order to assess the efficacy of this vaccine approach.

The Phase 1/2a trial is to take place at the Centre for Clinical Vaccinology and Tropical Medicine, part of the Jenner Institute, at Oxford and the Wellcome Trust Clinical Research Facility at Southampton General Hospital. The human infection portion of the trial is to take place at the Infection and Immunity Section of the Imperial College London. Two groups of volunteers will be immunized. The first will receive the prime-boost combination (adenovirus vector ChAd63, followed by poxvirus vector MVA) expressing a malaria antigen called ME-TRAP. The second will receive the same viral vector combination expressing the circumsporozoite protein (CSP), which is a parasite surface protein that helps the parasite invade liver cells. Both regimens are expected to induce an immune response that targets liver-stage parasites. Oxford, responsible for running the trial as trial sponsor, received the ChAd63 vaccine vector from Okairos, an Italian company.

Funding for this trial was provided by MVI, USAID, National Institute for Health Research Oxford Biomedical Research Centre (NIH Oxford BRC), and the Wellcome Trust. Additional funding for generation and manufacture of some of the vaccine vectors used was provided by the European Vaccine Initiative.