Experimental PfSPZ Vaccine in Adults Without Malaria

Completed · Phase 1

Conditions studied: Malaria, Prevention and Control, Acquired Immunity

In brief

Background: * 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. Objectives: \- To test the safety and effectiveness of the PfSPZ vaccine. Eligibility: \- Healthy volunteers between 18 to 45 years of age. Design: * 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.

Key facts

Study ID

NCT01441167

Run by

National Institute of Allergy and Infectious Diseases (NIAID)

People needed

64

Starts

2011-09-14

Expected to finish

2013-06-05

Last updated by the study team

2018-07-05

Who can join

Age: 18 and older, up to 45. Sex: any. Healthy volunteers: not accepted.

You may not qualify if…

• A volunteer will be excluded if one or more of the following conditions apply:
• Woman who is breast-feeding or planning to become pregnant during the time interval needed to complete the study.
• Receipt of a malaria vaccine in a prior clinical trial.
• Any history of malaria infection.
• Evidence of increased cardiovascular disease risk; defined as >10% five year risk by the non-laboratory method.
• Screening EKG showing pathologic Q waves and significant ST-T wave changes; left ventricular hypertrophy; any non-sinus rhythm (except isolated premature atrial contractions); left bundle branch block; or advanced (secondary or tertiary) A-V heart block.
• Current use of systemic immunosuppressant pharmacotherapy.
• History of a splenectomy, sickle cell disease or sickle cell trait.
• Plan for major surgery between enrollment and challenge.
• Known allergy to any component of the vaccine formulation; history of anaphylactic response to mosquito-bites; or known allergy to chloroquine phosphate, atovaquone or proguanil.
• Participation in any study involving another investigational vaccine or drug within 12 weeks prior to enrollment, or plan to participate in another investigational vaccine/drug research during the study.
• Personal beliefs that prohibit the receiving of vaccine product containing human serum albumin within the diluent.
• Use or planned use of any drug with anti-malarial activity that would coincide with study vaccination or challenge.
• History of psoriasis or porphyria, which may be exacerbated after treatment with chloroquine.
• Anticipated use of medications known to cause drug reactions with chloroquine or atovaquone-proguanil (Malarone) such as cimetidine, metoclopramide, antacids, and kaolin.
• Psychiatric condition that precludes compliance with the protocol; past or present psychoses; disorder requiring lithium; or within five years prior to enrollment, history of a suicide plan or attempt.
• Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer s ability to give informed consent.

Where it is running

• National Institutes of Health Clinical Center, 9000 Rockville Pike — Bethesda, Maryland, United States

Full record on ClinicalTrials.gov

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