Experimental PfSPZ Vaccine in Adults Without Malaria
- Malaria parasites are carried by mosquitoes, which spread the infection by biting people. Currently, there is no effective malaria vaccine. However, studies show that volunteers bitten many times by mosquitoes that carry weakened malaria parasites could fight off getting sick with malaria when later exposed to normal malaria parasites. Malaria parasites are weakened by exposing them to radiation when they are in the stage of development called sporozoites . Only the mosquitoes are irradiated and study volunteers are not exposed to radiation. The radiation stops the parasites from being able to cause disease but still promote protection. For many years, it was not possible to give these sporozoites to people as a vaccine since they could not be adequately purified from the mosquito. Scientists have recently figured out how to produce and isolate the weakened sporozoites so that they can be given in an injected vaccine. This vaccine is known as the "PfSPZ vaccine".
- A malaria challenge will be used to test whether the vaccine will prevent infection. In a malaria challenge, mosquitoes that have the malaria parasite will be allowed to bite a participant's arm. In the event that the vaccine does not work, the malaria parasite used for the challenge can be treated completely with common anti-malaria medications. Participants will be treated immediately if they develop malaria symptoms.
- To test the safety and effectiveness of the PfSPZ vaccine.
- Healthy volunteers between 18 to 45 years of age.
- Participants will be screened with a physical exam, medical history, and blood tests. There will be five different groups of study participants, all of whom will be monitored with frequent blood tests.
- Group 1 will have two vaccines with the lowest amount of the vaccine given 4 weeks apart, with regular clinic visits up to 24 weeks after the second vaccine. This group will not have a malaria challenge.
- Group 2 will have four or six vaccines given 4 weeks apart at a higher dose than group 1. A malaria challenge will be given about 3 weeks after the last vaccine. Follow-up visits will continue through 24 weeks after the last vaccine.
- Group 3 will have four or six vaccines given 4 weeks apart at a higher dose than group 2. A malaria challenge will be given about 3 weeks after the last vaccination, as for Group 2. Follow-up visits will continue through 24 weeks after last vaccine.
- Group 4 will have four or six vaccines given 4 weeks apart at a higher dose than group 3. A malaria challenge will be given about 3 weeks after the last vaccination. Follow up visits will continue through 24 weeks after last vaccine.
- Group 5 will serve as a control group and will not receive the vaccine, but will have the malaria challenge. Follow-up visits will continue through 8 weeks after the challenge.
All participants from any group who receive a malaria challenge will be treated promptly for malaria when it develops.
Prevention and Control
|Study Design:||Allocation: Non-Randomized
Endpoint Classification: Safety Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Prevention
|Official Title:||VRC 312: A Phase 1, Open-Label, Dose-Escalation Clinical Trial With Experimental Challenge to Evaluate Intravenous Administration of the PfSPZ Vaccine in Malaria-Naive Adults|
- The primary objectives of the study are related to the safety and tolerability of the vaccine at the 4 dosage levels when administered IV.
- The secondary objectives are related to PfSPZ vaccine-mediated protection against Plasmodium falciparum (Pf) challenge at the 3 higher dosage levels.
|Study Start Date:||September 2011|
|United States, Maryland|
|National Institutes of Health Clinical Center, 9000 Rockville Pike|
|Bethesda, Maryland, United States, 20892|
|Principal Investigator:||Robert A Seder, M.D.||National Institute of Allergy and Infectious Diseases (NIAID)|