Safety, tolerability, and Plasmodium falciparum transmission-reducing activity of monoclonal antibody TB31F: a single-centre, open-label, first-in-human, dose-escalation, phase 1 trial in healthy malaria-naive adults. Issue 11 (November 2022)

• Record Type: Journal Article
• Authors: van der Boor, Saskia C; Smit, Merel J; van Beek, Stijn W; Ramjith, Jordache; Teelen, Karina; van de Vegte-Bolmer, Marga; van Gemert, Geert-Jan; Pickkers, Peter; Wu, Yimin; Locke, Emily; Lee, Shwu-Maan; Aponte, John; King, C Richter; Birkett, Ashley J; Miura, Kazutoyo; Ayorinde, Morolayo A; Sauerwein, Robert W; ter Heine, Rob; Ockenhouse, Christian F; Bousema, Teun; Jore, Matthijs M; McCall, Matthew B B
• Is Part Of: Lancet infectious diseases. Volume 22:Issue 11(2022)
• Page Start: 1596
• Page End: 1605
• Publication Date: 2022-11
• Subjects: Communicable diseases -- Periodicals; Infection -- Periodicals; Communicable Diseases -- Periodicals; Infection -- Periodicals; Maladies infectieuses -- Périodiques; Infection -- Périodiques; Communicable diseases; Infection; Periodicals; 616.905
• DOI: 10.1016/S1473-3099(22)00428-5
• Languages: English
• ISSNs: 1473-3099

Abstract

Summary: Background: Malaria elimination requires interruption of the highly efficient transmission of Plasmodium parasites by mosquitoes. TB31F is a humanised monoclonal antibody that binds the gamete surface protein Pfs48/45 and inhibits fertilisation, thereby preventing further parasite development in the mosquito midgut and onward transmission. We aimed to evaluate the safety and efficacy of TB31F in malaria-naive participants. Methods: In this open-label, first-in-human, dose-escalation, phase 1 clinical trial, healthy, malaria-naive, adult participants were administered a single intravenous dose of 0·1, 1, 3, or 10 mg/kg TB31F or a subcutaneous dose of 100 mg TB31F, and monitored until day 84 after administration at a single centre in the Netherlands. The primary outcome was the frequency and magnitude of adverse events. Additionally, TB31F serum concentrations were measured by ELISA. Transmission-reducing activity (TRA) of participant sera was assessed by standard membrane feeding assays with Anopheles stephensi mosquitoes and cultured Plasmodium falciparum gametocytes. The trial is registered with Clinicaltrials.gov, NCT04238689 . Findings: Between Feb 17 and Dec 10, 2020, 25 participants were enrolled and sequentially assigned to each dose (n=5 per group). No serious or severe adverse events occurred. In total, 33 grade 1 and six grade 2 related adverse events occurred in 20 (80%) of 25 participants across all groups. Serum of all participants administered 1 mg/kg, 3 mg/kg, or 10 mg/kg TB31F intravenously had more than 80% TRA for 28 days or more, 56 days or more, and 84 days or more, respectively. The TB31F serum concentration reaching 80% TRA was 2·1 μg/mL (95% CI 1·9–2·3). Extrapolating the duration of TRA from antibody kinetics suggests more than 80% TRA is maintained for 160 days (95% CI 136–193) following a single intravenous 10 mg/kg dose. Interpretation: TB31F is a well tolerated and highly potent monoclonal antibody capable of completely blocking transmission of P falciparum parasites from humans to mosquitoes. In areas of seasonal transmission, a single dose might cover an entire malaria season. Funding: PATH's Malaria Vaccine Initiative.