Ad35.CS.01 - RTS,S/AS01 heterologous prime boost vaccine efficacy against sporozoite challenge in healthy malaria-naïve adults

Christian F. Ockenhouse, Jason Regules, Donna Tosh, Jessica Cowden, April Kathcart, James Cummings, Kristopher Paolino, James Moon, Jack Komisar, Edwin Kamau, Thomas Oliver, Austin Chhoeu, Jitta Murphy, Kirsten Lyke, Matthew Laurens, Ashley Birkett, Cynthia Lee, Rich Weltzin, Ulrike Wille-Reece, Martha SedegahJenny Hendriks, Isabella Versteege, Maria Grazia Pau, Jerold Sadoff, Yannick Vanloubbeeck, Marc Lievens, Dirk Heerwegh, Philippe Moris, Yolanda Guerra Mendoza, Erik Jongert, Joe Cohen, Gerald Voss, W. Ripley Ballou, Johan Vekemans

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Methods: In an observer blind, phase 2 trial, 55 adults were randomized to receive one dose of Ad35. CS.01 vaccine followed by two doses of RTS,S/AS01 (ARR-group) or three doses of RTS, S/AS01 (RRR-group) at months 0, 1, 2 followed by controlled human malaria infection. Results: ARR and RRR vaccine regimens were well tolerated. Efficacy of ARR and RRR groups after controlled human malaria infection was 44% (95% confidence interval 21%-60%) and 52% (25%-70%), respectively. The RRR-group had greater anti-CS specific IgG titers than did the ARR-group. There were higher numbers of CS-specific CD4 T-cells expressing > 2 cytokine/activation markers and more ex vivo IFN-γ enzyme-linked immunospots in the ARR-group than the RRR-group. Protected subjects had higher CS-specific IgG titers than non-protected subjects (geometric mean titer, 120.8 vs 51.8 EU/ml, respectively; P = .001). Conclusions: An increase in vaccine efficacy of ARR-group over RRR-group was not achieved. Future strategies to improve upon RTS,S-induced protection may need to utilize alternative highly immunogenic prime-boost regimens and/or additional target antigens. Trial Registration: ClinicalTrials.gov NCT01366534.

Original languageEnglish
Article numbere0131571
JournalPLoS ONE
Volume10
Issue number7
DOIs
StatePublished - 6 Jul 2015
Externally publishedYes

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