Clinical trials

A randomized double blind, placebo-controlled study to assess the safety, tolerability, immunogenicity, and protective efficacy of 1, 6, 29-day PfSPZ-LARC2 Vaccine regimen given at a dose of 2 x10\^5 PfSPZ or placebo in healthy WOCBP, who are on pregnancy prevention during vaccination, but report plans to become pregnant in the near future. Participants will be randomized into two arms. Arm 1: (n= 150) will receive 3 doses of PfSPZ-LARC2 Vaccine (2x10\^5 PfSPZ) via direct venous inoculation (DVI) at 1, 6, 29 days. Arm 2: (n= 150) will receive 3 doses of normal saline (placebo) injection via DVI at 1, 6, 29 days. All volunteers will receive antimalarial treatment with artemether/lumefantrine (AL) \~2 to 4 weeks prior to 1st (study day -14 to -28) and \~2 weeks prior to 3rd injection (study day 44). Participants will be monitored for safety, tolerability, immunogenicity, and malaria infection during the follow-up period. Participants will also be monitored closely for pregnancy as well post 3rd injection through the entire planned study duration (2 years post dose 1). If pregnant, women will be followed during the course of their pregnancy and for at least 1 year post-delivery (as well as their offspring) for safety and malaria infection. Malaria infections in participants and their offspring will be classified as asymptomatic or symptomatic (clinical cases).

This is a randomized, double-blind, placebo-controlled Phase 1 trial of Plasmodium falciparum (Pf) sporozoite (SPZ) late-arresting replication-competent (LARC) malaria vaccine (PfSPZ-LARC2 Vaccine) administered to healthy, malaria-naive study participants in Germany by direct venous inoculation (DVI) to determine safety, tolerability, and vaccine efficacy (VE) against controlled human malaria infection (CHMI). PfSPZ-LARC2 Vaccine contains a deletion of two genes, the Mei2 and LINUP genes, and undergoes developmental arrest in the late liver stages without releasing merozoites into the blood stream (blood stage parasites). The primary objective of the study is to assess the safety and tolerability of administration of PfSPZ-LARC2 Vaccine, with special attention to the adequacy of attenuation, in the intention-to-treat (ITT) population.

This is a phase 2 clinical trial of a Plasmodium falciparum (Pf) late liver stage-arresting replication-competent (LARC) sporozoite (SPZ) vaccine (Sanaria® PfSPZ-LARC2 Vaccine) that will assess field efficacy in Africa. The PfSPZ comprising PfSPZ-LARC2 Vaccine contain a double deletion of the genes encoding the Mei2 and LINUP proteins, both of which are required for transition from liver to blood stage malaria. As a result, mei2-/linup- parasites undergo developmental arrest in the late liver stages without releasing merozoites into the blood stream. No blood stage parasites are produced, either asexual or sexual, and the parasite life cycle does not progress. Because Pf parasites with the LARC phenotype replicate in the liver before disintegrating, they amplify and diversify parasite protein expression and are expected to be a potent immunogen to induce anti-malarial immunity, equaling or exceeding the potency and efficacy of the replication-competent chemo-attenuated Sanaria® PfSPZ-CVac (chloroquine) vaccine approach. Because the parasites are intrinsically attenuated, they are expected to be safe and well tolerated, similar to radiation-attenuated Sanaria® PfSPZ Vaccine, to the replication deficient, early arresting PfSPZ-GA1 Vaccine, and to the single-gene(mei2)-deleted GA2 (LARC1) parasites tested at the Leiden University Medical Center that provided 90% protection against CHMI after a single dose. The active treatments to be assessed for efficacy are one immunization of 6.0x10\^5 PfSPZ or two immunizations with 4.0x10\^5 PfSPZ of PfSPZ-LARC2 Vaccine four weeks apart, timed so that the immunization of the one dose regimen coincides with the second immunization of the two dose regimen. The alternative treatment is immunization with normal saline (placebo group), which is indistinguishable from the test article. The primary variable of interest is whether and when trial participants develop Pf malaria parasitemia during surveillance. Malaria parasitemia will be detected by thick blood smear (TBS), which will be performed every two weeks starting two weeks after the second vaccination (to allow time for the vaccine to work) and extending to week 26 after the second vaccination (24-week surveillance period). Surveillance will continue for 40 weeks but the primary outcome will be determined at 24 weeks of surveillance so the data are comparable to other studies of PfSPZ vaccines.