First-in-human, randomized, double-blind clinical trial of differentially adjuvanted PAMVAC, a vaccine candidate to prevent pregnancy-associated malaria

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Benjamin Mordmüller, Mihály Sulyok, Diane Egger-Adam, Mafalda Resende, Willem A de Jongh, Mette H. Jensen, Helle Holm Smedegaard, Sisse B Ditlev, Max Soegaard, Lars Poulsen, Charlotte Dyring, Carlos Lamsfus Calle, Annette Knoblich, Javier Ibáñez, Meral Esen, Philippe Deloron, Nicaise Ndam, Saadou Issifou, Sophie Houard, Randall F Howard & 7 more Steven G Reed, Odile Leroy, Adrian J F Luty, Thor G Theander, Peter G Kremsner, Ali Salanti, Morten A Nielsen

BACKGROUND: Malaria in pregnancy has major impacts on mother and child health. To complement existing interventions, such as intermittent preventive treatment and use of impregnated bed nets, we developed a malaria vaccine candidate with the aim of reducing sequestration of asexual "blood-stage" parasites in the placenta, the major virulence mechanism.

METHODS: The vaccine candidate PAMVAC is based on a recombinant fragment of VAR2CSA, the Plasmodium falciparum protein responsible for binding to the placenta via chondroitin sulfate A (CSA). Healthy, adult malaria-naive volunteers were immunized with 3 intramuscular injections of 20 μg (n = 9) or 50 μg (n = 27) PAMVAC, adjuvanted with Alhydrogel or glucopyranosyl lipid adjuvant in stable emulsion (GLA-SE) or in a liposomal formulation with QS21 (GLA-LSQ). Allocation was random and double blind. The vaccine was given every 4 weeks. Volunteers were observed for 6 months following last immunization.

RESULTS: All PAMVAC formulations were safe and well tolerated. A total of 262 adverse events (AEs) occurred, 94 (10 grade 2 and 2 grade 3) at least possibly related to the vaccine. No serious AEs occurred. Distribution and severity of AEs were similar in all arms. PAMVAC was immunogenic in all participants. PAMVAC-specific antibody levels were highest with PAMVAC-GLA-SE. The antibodies inhibited binding of VAR2CSA expressing P. falciparum-infected erythrocytes to CSA in a standardized functional assay.

CONCLUSIONS: PAMVAC formulated with Alhydrogel or GLA-based adjuvants was safe, well tolerated, and induced functionally active antibodies. Next, PAMVAC will be assessed in women before first pregnancies in an endemic area.

CLINICAL TRIALS REGISTRATION: EudraCT 2015-001827-21; ClinicalTrials.gov NCT02647489.

Original languageEnglish
JournalClinical infectious diseases : an official publication of the Infectious Diseases Society of America
Volume69
Issue number9
Pages (from-to)1509-1516
Number of pages8
ISSN1058-4838
DOIs
Publication statusPublished - 2019

Bibliographical note

© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America.

ID: 228814489