Maria da Graça Salomão, Maria do Carmo Sampaio Tavares Timenetsky, Stephen S. Whitehead, João Luiz Miraglia, Jorge Kalil, Anna P. Durbin, Alexander Roberto Precioso, Sylvia Costa Lima Farhat, Tazio Vanni, Neuza Maria Frazatti Gallina, Isaias Raw, Ricardo Palacios, Heloisa Maxímo Espinola, Raphaella Goulart, Alvino Maestri, Lucia M.A. Campos, Joane do Prado Santos, Gabriela Mondini, Adriana M. E. Sallum, Priscilla R. Costa, Beatriz Thomé, Rafael Tavares Salles, Alessandro Sette, Anderson da Silva, Daniela Weiskopf, Lilian Ferrari, Neusa Keico Sakita, Patrícia Emília Braga, Cassia G. T. Silveira, Esper G. Kallas, Juliana Carvalho Ferreira, and Cecília L. S. Santos
Summary Background The Butantan Institute has manufactured a lyophilised tetravalent live-attenuated dengue vaccine Butantan-DV, which is analogous to the US National Institutes of Health (NIH) TV003 admixture. We aimed to assess the safety and immunogenicity of Butantan-DV. Methods We did a two-step, double-blind, randomised placebo-controlled phase 2 trial at two clinical sites in Sao Paulo, Brazil. We recruited healthy volunteers aged 18–59 years; pregnant women, individuals with a history of neurological, heart, lung, liver or kidney disease, diabetes, cancer, or autoimmune diseases, and individuals with HIV or hepatitis C were excluded. Step A was designed as a small bridge-study between Butantan-DV and TV003 in DENV-naive participants. In step A, we planned to randomly assign 50 dengue virus (DENV)-naive individuals to receive two doses of Butantan-DV, TV003, or placebo, given 6 months apart. In step B, we planned to randomly assign 250 participants (DENV-naive and DENV-exposed) to receive one dose of Butantan-DV or placebo. Participants were randomly assigned, by computer-generated block randomisation (block sizes of five); participants in step A were randomly assigned (2:2:1) to receive Butantan-DV, TV003, or placebo and participants in step B were randomly assigned (4:1) to receive Butantan-DV or placebo. Participants and study staff were unaware of treatment allocation. The primary safety outcome was the frequency of solicited and unsolicited local and systemic adverse reactions within 21 days of the first vaccination, analysed by intention to treat. The primary immunogenicity outcome was seroconversion rates of the DENV-1-4 serotypes measured 91 days after the first vaccination, analysed in the per-protocol population, which included all participants in step A, and all participants included in step B who completed all study visits with serology sample collection. This trial is registered with ClinicalTrials.gov , NCT01696422 . Findings Between Nov 5, 2013, and Sept 21, 2015, 300 individuals were enrolled and randomly assigned: 155 (52%) DENV-naive participants and 145 (48%) DENV-exposed participants. Of the 155 DENV-naive participants, 97 (63%) received Butantan-DV, 17 (11%) received TV003, and 41 (27%) received placebo. Of the 145 DENV-exposed participants, 113 (78%) received Butantan-DV, three (2%) received TV003, and 29 (20%) received placebo. Butantan-DV and TV003 were both immunogenic, well-tolerated, and no serious adverse reactions were observed. In step A, rash was the most frequent adverse event (16 [845] of 19 participants in the Butantan-DV group and 13 [76%] of 17 participants in the TV003 group). Viraemia was similar between the Butantan-DV and TV003 groups. Of the 85 DENV-naive participants in the Butantan-DV group who attended all visits for sample collection for seroconversion analysis and thus were included in the per-protocol analysis population, 74 (87%) achieved seroconversion to DENV-1, 78 (92%) to DENV-2, 65 (76%) to DENV-3, and 76 (89%) to DENV-4. Of the 101 DENV-exposed participants in the Butantan-DV group who attended all visits for sample collection for seroconversion analysis, 82 (81%) achieved seroconversion to DENV-1, 79 (78%) to DENV-2, 83 (82%) to DENV-3, and 78 (77%) to DENV-4. Interpretation Butantan-DV and TV003 were safe and induced robust, balanced neutralising antibody responses against the four DENV serotypes. Efficacy evaluation of the Butantan-DV vaccine is ongoing. Funding Intramural Research Program US NIH National Institute of Allergy and Infectious Diseases, Brazilian National Bank for Economic and Social Development, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, and Fundacao Butantan.