[The malaria vaccine candidate RTS,S/AS is in phase III clinical trials]

This review paper describes the development of the RTS,S/AS vaccine, from concept to phase III testing. The rationale for selection of the circumsporozoite protein (CSP) as the target antigen and the preclinical development history of the vaccine are described. The RTS,S/AS candidate vaccine has been evaluated in multiple phase I/II studies and was shown to have a favorable safety profile and to be well tolerated in both adults and children. Consistent and significant efficacy has been observed in the target population of infants and children against Plasmodium falciparum infection and disease in different transmission settings, in different age groups, with or without Expanded Program of Immunization (EPI) vaccine co-administration. The RTS,S/AS01(E) malaria vaccine candidate has recently entered phase III testing. Reaching this important milestone is the culmination of more than 20 years of research and development by GlaxoSmithKline, their partners and collaborators. If the phase III results confirm the observations made during phase II testing, the RTS,S/AS01(E) vaccine, when broadly implemented and judiciously integrated with other malaria-prevention measures, would have a major public-health impact in sub-Saharan Africa.