Immunization With Different Doses of Plasmodium Falciparum Sporozoites Under Chloroquine Prophylaxis (ZonMw1)

Malaria is one of the major infectious diseases in the world with a tremendous impact on the quality of life significantly contributing to the ongoing poverty in endemic countries. It causes almost one million deaths per year, the majority of which are children under the age of five. The malaria parasite enters the human body through the skin, by the bite of an infected mosquito. Subsequently, it invades the liver and develops and multiplies inside the hepatocytes. After a week, the hepatocytes burst open and the parasites are released in the blood stream, causing the clinical phase of the disease.

As a unique opportunity to study malaria immunology and efficacy of immunisation strategies, a protocol has been developed in the past to conduct experimental human malaria infections (EHMIs). EHMIs generally involve small groups of malaria-naïve volunteers infected via the bites of P. falciparum infected laboratory-reared Anopheline mosquitoes. Although potentially serious or even lethal, P. falciparum malaria can be radically cured at the earliest stages of blood infection where risks of complications are virtually absent.

The investigators have shown previously that healthy human volunteers can be protected from a malaria mosquito (sporozoite) challenge by immunization with sporozoites (by mosquito bites) under chloroquine prophylaxis (CPS immunization). However, it is unknown how many mosquito bites are necessary to confer protection. Moreover, as all volunteers were protected in this study, no correlates of protection could be established. For future development of vaccines and understanding of protective immunity to malaria, it is important to investigate the lowest dose of CPS immunization that confers 100% protection and to find correlates of protection. Therefore, the present study aims to make the CPS immunization protocol more sensitive by lowering the number of infected mosquito bites, in order to study the underlying mechanisms of protection.

Study Overview

• Status: Completed
• Conditions: Plasmodium Falciparum Malaria
• Intervention / Treatment: Drug: Chloroquine prophylaxis; Biological: Immunization; Biological: Plasmodium falciparum challenge; Drug: Malarone treatment

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Netherlands
  • Leiden, Netherlands, 2300 RC
    • Leiden University Medical Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Age > 18 and < 35 years healthy volunteers (males or females)
• Good health based on history and clinical examination
• Negative pregnancy test
• Use of adequate contraception for females
• All volunteers must sign the informed consent form demonstrating their understanding of the meaning and procedures of the study
• Volunteer agrees to inform the general practitioner and agrees to sign a request to release medical information concerning contra-indications for participation in the study
• Willingness to undergo a Pf mosquito challenge
• For volunteers not living in Leiden: agreement to stay in a hotel room close to the trial center during a part of the study (Day 5 after challenge till 3 days after treatment)
• Reachable (24/7) by mobile phone during the whole study period
• Living with a third party that could contact the clinicians in case of alteration of consciousness or agreement to stay in a hotel room close to the trial center during a part of the study (Day 5 after challenge till 3 days after treatment)
• Available to attend all study visits
• Agreement to refrain from blood donation to Sanquin or for other purposes, during the study period until 337.
• Willingness to undergo HIV, hepatitis B and hepatitis C tests
• Negative urine toxicology screening test at screening visit and day before challenge
• Willingness to take a prophylactic regime of chloroquine and curative regimen of Malarone®

Exclusion Criteria:

• History of malaria
• Plans to travel to malaria endemic areas during the study period
• Plans to travel outside of the Netherlands during the challenge period
• Previous participation in any malaria vaccine study and/or positive serology for Pf
• Symptoms, physical signs and laboratory values suggestive of systemic disorders including renal, hepatic, cardiovascular, pulmonary, skin, immunodeficiency, psychiatric, and other conditions which could interfere with the interpretation of the study results or compromise the health of the volunteers
• History of diabetes mellitus or cancer (except basal cell carcinoma of the skin)
• History of arrhythmias or prolonged QT-interval
• Positive family history in 1st and 2nd degree relatives for cardiac disease < 50 years old
• An estimated, ten year risk of fatal cardiovascular disease of ≥5%, as estimated by the Systematic Coronary Risk Evaluation (SCORE) system
• Clinically significant abnormalities in electrocardiogram (ECG) at screening
• Body Mass Index (BMI) below 18 or above 30 kg/m2
• Any clinically significant deviation from the normal range in biochemistry or hematology blood tests or in urine analysis
• Positive HIV, HBV or HCV tests
• Participation in any other clinical study within 30 days prior to the onset of the study
• Enrollment in any other clinical study during the study period
• Pregnant or lactating women
• Volunteers unable to give written informed consent
• Volunteers unable to be closely followed for social, geographic or psychological reasons
• Previous history of drug or alcohol abuse interfering with normal social function during a period of one year prior to enrolment in the study
• A history of psychiatric disease
• Known hypersensitivity to Malarone® or chloroquine
• The use of chronic immunosuppressive drugs, antibiotics, or other immune modifying drugs within three months of study onset (inhaled and topical corticosteroids are allowed) and during the study period
• Contra-indications to Malarone® or chloroquine including treatment taken by the volunteer that interferes with Malarone® or chloroquine
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including asplenia
• Co-workers of the departments of Medical Microbiology, Parasitology, or Internal Medicine of the Leiden University medical Centre
• A history of sickle cell anemia, sickle cell trait, thalassemia, thalassemia trait or G6PD deficiency

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 15-15-15; This group will receive three times 15 infected mosquito bites under chloroquine prophylaxis, as we know that this dose is protective.	Drug: Chloroquine prophylaxis; The chloroquine dose used will be 300mg for the first two days, followed by 300mg per week, for 13 weeks.; Biological: Immunization; All groups will be immunised with mosquitobites. The number of infected mosquitoes differs per group, as clarified in group description.; Biological: Plasmodium falciparum challenge; Exposure to the bites of 5 Plasmodium falciparum infected mosquitoes.; Drug: Malarone treatment; When thick smear positive, of ar day 21 after challenge, all volunteers will be treated with malarone.; Other Names: atovaquon/proguanil
Experimental: 10-10-10; This group will receive three times 10 infected and 5 uninfected mosquito bites under chloroquine prophylaxis.	Drug: Chloroquine prophylaxis; The chloroquine dose used will be 300mg for the first two days, followed by 300mg per week, for 13 weeks.; Biological: Immunization; All groups will be immunised with mosquitobites. The number of infected mosquitoes differs per group, as clarified in group description.; Biological: Plasmodium falciparum challenge; Exposure to the bites of 5 Plasmodium falciparum infected mosquitoes.; Drug: Malarone treatment; When thick smear positive, of ar day 21 after challenge, all volunteers will be treated with malarone.; Other Names: atovaquon/proguanil
Experimental: 5-5-5; This group will receive three times 5 infected and 10 uninfected mosquitobites under chloroquine prophylaxis.	Drug: Chloroquine prophylaxis; The chloroquine dose used will be 300mg for the first two days, followed by 300mg per week, for 13 weeks.; Biological: Immunization; All groups will be immunised with mosquitobites. The number of infected mosquitoes differs per group, as clarified in group description.; Biological: Plasmodium falciparum challenge; Exposure to the bites of 5 Plasmodium falciparum infected mosquitoes.; Drug: Malarone treatment; When thick smear positive, of ar day 21 after challenge, all volunteers will be treated with malarone.; Other Names: atovaquon/proguanil
Placebo Comparator: 0-0-0; This group will receive three times 15 uninfected mosquitobites under prophylaxis.	Drug: Chloroquine prophylaxis; The chloroquine dose used will be 300mg for the first two days, followed by 300mg per week, for 13 weeks.; Biological: Immunization; All groups will be immunised with mosquitobites. The number of infected mosquitoes differs per group, as clarified in group description.; Biological: Plasmodium falciparum challenge; Exposure to the bites of 5 Plasmodium falciparum infected mosquitoes.; Drug: Malarone treatment; When thick smear positive, of ar day 21 after challenge, all volunteers will be treated with malarone.; Other Names: atovaquon/proguanil

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Period to thick smear positivity after challenge in groups 1, 2, 3 and 4	21 days after challenge (day 218 of study)
Parasitemia and kinetics of parasitemia as measured by PCR in groups 1, 2, 3 and 4	21 days after challenge (day 218 of study)
Frequency of signs or symptoms in groups 1, 2, 3 and 4	Day 21 after challenge (day 218 of study)

Secondary Outcome Measures

Outcome Measure	Time Frame
Cellular immune response between groups 1, 2, 3 and 4	Day 0 - day 337 of study
Antibody production between groups 1, 2, 3 and 4	Day 0 - day 337 of study
Cytokine profile in groups 1, 2, 3 and 4	Day 0 - day 337 of study

Collaborators and Investigators

• Sponsor: Radboud University Medical Center

Publications and helpful links

General Publications

• Nahrendorf W, Scholzen A, Bijker EM, Teirlinck AC, Bastiaens GJ, Schats R, Hermsen CC, Visser LG, Langhorne J, Sauerwein RW. Memory B-cell and antibody responses induced by Plasmodium falciparum sporozoite immunization. J Infect Dis. 2014 Dec 15;210(12):1981-90. doi: 10.1093/infdis/jiu354. Epub 2014 Jun 25.
• Bijker EM, Teirlinck AC, Schats R, van Gemert GJ, van de Vegte-Bolmer M, van Lieshout L, IntHout J, Hermsen CC, Scholzen A, Visser LG, Sauerwein RW. Cytotoxic markers associate with protection against malaria in human volunteers immunized with Plasmodium falciparum sporozoites. J Infect Dis. 2014 Nov 15;210(10):1605-15. doi: 10.1093/infdis/jiu293. Epub 2014 May 27.

Study record dates

Study Major Dates

• Study Start: April 1, 2011
• Primary Completion (Actual): January 1, 2012
• Study Completion (Actual): March 1, 2012

Study Registration Dates

• First Submitted: October 8, 2010
• First Submitted That Met QC Criteria: October 8, 2010
• First Posted (Estimate): October 11, 2010

Study Record Updates

• Last Update Posted (Estimate): April 2, 2012
• Last Update Submitted That Met QC Criteria: March 30, 2012
• Last Verified: March 1, 2012

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Infections; Vector Borne Diseases; Parasitic Diseases; Protozoan Infections; Malaria; Malaria, Falciparum; Molecular Mechanisms of Pharmacological Action; Anti-Infective Agents; Antirheumatic Agents; Antimetabolites; Antiprotozoal Agents; Antiparasitic Agents; Antimalarials; Amebicides; Chloroquine; Proguanil; Atovaquone, proguanil drug combination
• Other Study ID Numbers: ZonMw1