RTS,S/AS01E Hypo-immuno-responsiveness Study
Plasmodium Falciparum
About this trial
This is an interventional other trial for Plasmodium Falciparum focused on measuring RTS,S/AS01E, hypo-immuno-responsiveness, open-label randomized study, Phase 2b, Kenyan adults, anti-malarials, fractional dose RTS,S/AS01E
Eligibility Criteria
Inclusion Criteria:
- Provision of signed or thumb printed and dated informed consent form
- Stated willingness to comply with all study procedures and availability for the duration of the study
- Male or female between 18 and 55 years of age, inclusive
- In good general health as evidenced by medical history and clinical examination before entering the study
- Ability to take oral medication and be willing to adhere to the medication regimen
- For females, she must be of non-childbearing potential or use appropriate measures to prevent pregnancy for 30 days prior to vaccination through 2 months after completion of the vaccine series. Non-childbearing potential means she is surgically sterilized or at least one year post-menopausal. Appropriate measures to prevent pregnancy include abstinence or adequate contraceptive precautions (i.e. intrauterine contraceptive device; oral contraceptives; diaphragm or condom in combination with contraceptive jelly, cream or foam; Norplant or Depo-Provera). Clinical trial site staff will assist with provision of acceptable birth control for study entry and will discuss with volunteer at screening visit.
Exclusion Criteria:
Planned administration/administration of a vaccine not foreseen by the study protocol from within 30 days before the first dose of study vaccine until 30 days after the last dose of study vaccine.†
† In the context of the COVID-19 pandemic, the administration of the COVID-19 vaccine will be allowed as an exception to this exclusion criteria as follows. The study team will work with the participant to attempt to have any COVID-19 vaccine administration occur 30 days or more before or after study vaccinations. When this is not possible, COVID-19 vaccination will be allowed 10 days or more before or after study vaccination. Intervals shorter than 10 days can be allowed on a case-by-case basis in discussion with the sponsor.
- Any prior receipt of any rabies vaccine or experimental malaria vaccine.
- Confirmed or suspected significant immunosuppressive or immunodeficient condition as determined by the investigator, including clinical stage 3 or 4 human immunodeficiency virus (HIV) infection.
- A family history of congenital or hereditary immunodeficiency.
- History of allergic reactions, significant immunoglobulin E (IgE)-mediated events or anaphylaxis to previous immunizations.
- History of any neurologic disorders.
- Acute disease (defined as the presence of a moderate or severe illness with or without fever), including acute malaria, at the time of enrolment. All vaccines can be administered to persons with a minor illness, such as diarrhea or mild upper respiratory infection without fever, i.e. Oral temperature < 37.5°C*. Individuals excluded with acute disease, including acute malaria, can become eligible again after complete recovery of the illness, including appropriate treatment as applicable, and can be rescreened at a later date. *Temperature readings may be taken by site staff either using either oral, axillary, or infrared thermal thermometers during clinic or field visits, while subjects enrolled in the reactogenicity cohort will be supplied with oral thermometers for the purposes of recording their own temperature measurements in the memory aid over 7 days after each vaccination.
- Acute or chronic, clinically significant pulmonary, cardiovascular (including cardiac arrythmias) , hepatic or renal functional abnormality, as determined by medical history, physical examination or laboratory screening tests.
- History of homozygous sickle cell disease (Hgb SS).
- Any clinically significant laboratory abnormalities as determined by the investigator on screening labs.
- History of splenectomy.
- Administration of immunoglobulins, blood transfusions or other blood products within the three months preceding the first dose of study vaccine or planned administration during the study period.
- Pregnant (i.e. a positive pregnancy test) or lactating female during immunization phase of the study (refer to section 2.3 for rationale). If a woman becomes pregnant after all vaccinations are complete, she will not be excluded from the remainder of the study.
- Female planning to become pregnant or planning to discontinue contraceptive precautions during the vaccination phase.
- History of chronic alcohol consumption and/or drug abuse.
- Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose (for corticosteroids, this will mean prednisone, or equivalent, ≥ 0.5 mg/kg/day. Inhaled and topical steroids are allowed).
- Major congenital defects or serious chronic illness.
- Simultaneous participation in any other clinical trial [apart from participation in the Health and Demographics Surveillance System (HDSS) network].
- Any other findings that the investigator feels would increase the risk of having an adverse outcome from participation in the trial.
Sites / Locations
- Lucas O Tina
Arms of the Study
Arm 1
Arm 2
Arm 3
Arm 4
Arm 5
Experimental
Experimental
Experimental
Placebo Comparator
Placebo Comparator
Group 1: Positive baseline parasitemia, antimalarial treatment, RTS,S/AS01E vaccine
Group 2: Negative baseline parasitemia, antimalarial prophylaxis, RTS,S/AS01E vaccine
Group 3: Positive baseline parasitemia, RTS,S/AS01E vaccine
Group 4: Positive baseline parasitemia, antimalarial treatment, rabies vaccine
Group 5: Negative baseline parasitemia, antimalarial prophylaxis, rabies vaccine
Group 1 subjects have detectable P. falciparum parasitemia at baseline measured by PCR. Anti-malarial treatment with Dihydroartemisinin-piperaquine (DHA/Pip) to clear asexual stage and young gametocyte parasites plus low dose primaquine (LD PQ) to clear mature gametocytes will be given 4 weeks prior to immunization with RTS,S/AS01E. A 2nd course of DHA/Pip plus Primaquine will be given 2 weeks before second RTS,S/AS01E immunization. One week before 3rd RTS,S/AS01E immunization, a three-day course of Artemether/lumefantrine (A/L) plus Primaquine will be administered to clear infection. Rationale for administration of A/L is its preferred shortened half-life allowing for evaluation of vaccine efficacy thereby excluding any confounder effect due to prolonged anti-malarial effect of drug.
Group 2 subjects have no detectable P. falciparum parasitemia as measured by PCR at enrolment. It is proposed to initiate anti-malarial chemoprevention to subjects (prophylaxis effect) with DHA/Pip plus LD PQ 4 weeks prior to immunization with RTS,S/AS01E. A 2nd course of DHA/Pip plus Primaquine will be given 2 weeks before second RTS,S/AS01E immunization. One week before 3rd RTS,S/AS01E immunization, a three-day course of A/L plus Primaquine will be administered to clear infection.
Group 3 subjects have detectable P. falciparum parasitemia at baseline measured by PCR but will not receive any anti-malarial medications to clear PCR-positive parasites. This group includes 35 subjects and is included only for immunological assessment and not for vaccine efficacy. Subjects in Group 3 will be administered RTS,S/AS01E three times on a 0, 1, 7 month schedule.
Group 4 subjects have detectable P. falciparum parasitemia at baseline measured by PCR (note any positive result from PCR will be considered positive for purposes of group selection and study endpoints as with Group 1) and will receive DHA/Pip , Primaquine, and A/L on the same schedule as subjects in group 1. Subjects in Group 4 will be administered Abhayrab rabies vaccine on a 0, 1, 7 month schedule.
Group 5 subjects have no detectable P. falciparum parasitemia as measured by PCR at enrolment and will receive DHA/Pip, Primaquine, and A/L on the same schedule as subjects in group 2. Subjects in Group 5 will be administered Abhayrab rabies vaccine on a 0, 1, 7 month schedule.