Last Updated

28 Jun 2022

Experimental PfSPZ vaccine in adults without malaria

Objectives

To test the safety and effectiveness of the PfSPZ vaccine.

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Rationale and Abstract

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".

Study Design

A Phase 1, Open-Label, Dose-Escalation Clinical Trial With Experimental Challenge.

  • 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.

For the pilot subjects, the 1st vaccination (V1) and 2nd vaccination (V2) will be administered no faster than one per pilot subject every 2 hours.Before administration of the first dose to the subsequent pilot Group (dose escalation), at least 5 weeks of cumulative safety data for the pilot subjects in a dosage group (i.e., 1 week past 2nd vaccination) must be submitted to the Safety Monitoring Committee (SMC) and the FDA, and protocol-specified approval received for the dose escalation.Subjects in vaccine Groups 2, 3, 4 and the Group 5 controls will be challenged by exposure to Anopheles stephensi mosquitoes infected with Pf sporozoites in a controlled setting, followed by testing for parasitemia at specified intervals through up to 28 days post-challenge

All participants from any group who receive a malaria challenge will be treated promptly for malaria when it develops.

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Date

2011 Sep - 2013 Jun

Funding Details

Project Site

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