Safety and Efficacy of NF135 CPS Immunization

This is an open label, randomized, controlled clinical trial. The primary aim of this project is to determine the safety and tolerability of NF135.C10 sporozoite immunization under chemoprophylaxis against homologous and heterologous challenge infection.

A total of 49 healthy volunteers will be allocated to receive either three immunizations with 15 NF135.C10 infected Anopheles mosquitoes (n=30), 3 immunizations with 5 NF135.C10 infected mosquitoes (n=10) or no immunizations (n=6). Immunizations in cohort A (n=20) will be performed under mefloquine prophylaxis, spaced 4 weeks apart. In cohort B, volunteers will not take mefloquine prophylaxis, instead all volunteers will be treated presumptively on day 7 after each immunization with a curative regimen of artemether/lumefantrine, regardless of parasitaemia or symptoms.

Nineteen weeks after the last immunization, all volunteers plus naïve controls will be challenged either by the bites of 5 NF135.C10 (n=36) or 5 NF54 (n=13) infected mosquitoes. After challenge infection, volunteers will be followed up on an out-patient basis once daily for qPCR and safety lab measurements from day 6 until day 21 post challenge. All volunteers will be treated with a curative regimen of atovaquone/proguanil, either at the time of detection of blood stage parasitemia, or 28 days after challenge infection.

Eligibility Criteria:
Inclusion Criteria:

1. Subject is aged ≥ 18 and ≤ 35 years and in good health.
2. Subject has adequate understanding of the procedures of the study and agrees to abide strictly thereby.
3. Subject is able to communicate well with the investigator and is available to attend all study visits.
4. The subject will remain within the Netherlands during the challenge period, not travel to a malaria-endemic area during the study period, and is reachable (24/7) by mobile telephone throughout the entire study period.
5. Subject agrees to inform his/her general practitioner about participation in the study and to sign a request to release by the General Practitioner (GP), and medical specialist when necessary, any relevant medical information concerning possible contra- indications for participation in the study.
6. The subject agrees to refrain from blood donation throughout the study period and for a defined period thereafter according to current guidelines.
7. For female subjects: subject agrees to use adequate contraception and not to breastfeed for the duration of study. Acceptable forms of contraception include: established use of oral, injected or implanted hormonal contraceptives; intrauterine device or intrauterine system; barrier methods (condoms or diaphragm with additional spermicide); male partner's sterilisation (with appropriate post-vasectomy documentation of absence of sperm in the ejaculate); true abstinence when this is in line with the preferred and usual lifestyle of the subject. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception.
8. Subject agrees to refrain from intensive physical exercise (disproportionate to the subjects usual daily activity or exercise routine) during the malaria challenge period.
9. Subject agrees to avoid additional triggers that may cause elevations in liver enzymes including alcohol from baseline up to 1 week post treatment.
10. Subject has signed informed consent.

Exclusion Criteria:

1. Any history, or evidence at screening, of clinically significant symptoms, physical signs or abnormal laboratory values suggestive of systemic conditions, such as cardiovascular, pulmonary, renal, hepatic, neurological, dermatological, endocrine, malignant, haematological, infectious, immunodeficient, psychiatric and other disorders, which could compromise the health of the volunteer during the study or interfere with the interpretation of the study results. These include, but are not limited to, any of the following.

   1.1 Body weight \<50 kg or Body Mass Index (BMI) \<18 or \>30 kg/m2 at screening. 1.2 A heightened risk of cardiovascular disease, as determined by: an estimated ten year risk of fatal cardiovascular disease of ≥5% at screening, as determined by the Systematic Coronary Risk Evaluation (SCORE); history, or evidence at screening, of clinically significant arrhythmia's, prolonged QT-interval or other clinically relevant ECG abnormalities; or a positive family history of cardiovascular events (including ischemia and myocarditis) in 1st or 2nd degree relatives \<50 years old.

   1.3 A medical history of functional asplenia, sickle cell trait/disease, thalassaemia trait/disease or G6PD deficiency.

   1.4 History of epilepsy in the period of five years prior to study onset, even if no longer on medication.

   1.5 Screening tests positive for Human Immunodeficiency Virus (HIV), or active Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV).

   1.6 Chronic use of i) immunosuppressive drugs, ii) antibiotics or antimalarials, iii) or other immune modifying drugs within three months prior to study onset (inhaled and topical corticosteroids and oral anti-histamines exempted) or expected use of such during the study period.

   1.7 History of malignancy of any organ system (other than localized basal cell carcinoma of the skin), treated or untreated, within the past 5 years.

   1.8 Any history severe psychiatric disease diagnosed by a psychiatrist. 1.9 History of drug or alcohol abuse interfering with normal social function in the period of one year prior to study onset, positive urine toxicology test for cocaine or amphetamines at screening or inclusion, or positive urine toxicology test for cannabis at inclusion.
2. For female subjects: positive urine pregnancy test at screening or at inclusion.
3. Any history of malaria, positive serology for P. falciparum, or previous participation in any malaria (vaccine) study.
4. Known hypersensitivity to or contra-indications (including co-medication) for use of Mefloquine, Malarone or artemether-lumefantrine, or history of severe (allergic) reactions to mosquito bites.
5. Receipt of any vaccinations in the 3 months prior to the start of the study or plans to receive any other vaccinations during the study period or up to 90 days thereafter.
6. Participation in any other clinical study in the 30 days prior to the start of the study or during the study period.
7. Being an employee or student of the department of Medical Microbiology of the Radboudumc or the department of Internal Medicine.
8. Any other condition or situation that would, in the opinion of the investigator, place the subject at an unacceptable risk of injury or render the subject unable to meet the requirements of the protocol.