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Positron Emission Tomography and Organ-Specific Changes in Participants Co-Enrolled in NIH Studies of Plasmodium Vivax Controlled Human Malaria Infection

Background:

Malaria is a serious disease caused by parasites spread by mosquitoes. To better diagnose and treat malaria, researchers need to learn more about where the parasites go when they enter a person's body. They want to see if they can locate the malaria parasites in the body using imaging scans.

Objective:

To learn whether imaging scans can locate parasites in people with malaria.

Eligibility:

Healthy people aged 18 to 54 years. They must be enrolled in protocol IRB001970 or IRB002627 for controlled malaria infection.

Design:

Participants will be screened. They will have blood drawn and a physical exam, including an abdominal exam to check the size of their spleen.

Participants for this study will have 2 or 3 positron emission tomography/computed tomography (PET/CT) scans: The first will be about 3 days before they are deliberately infected with malaria for a different study. The second will be about 13 days later, while they have the disease. The third scan is optional; it will be done about 3 and 1/2 weeks after the second scan.

For each scan, participants will receive a radioactive tracer called fluorodeoxyglucose (FDG). FDG will be injected through a tube inserted into a vein. They will lie on a table that slides through a doughnut-shaped machine. PET/CT uses x-rays to create images of the inside of the body.

All participants will have a follow-up visit about 3 and 1/2 weeks after the second scan. The blood draw and physical exam will be repeated. This visit may be combined with the third scan for those who choose it.

Přehled studie

Detailní popis

Study Description:

Participants who are enrolled in a Plasmodium vivax challenge model protocol at the NIH Clinical Center (CC) may be co-enrolled in this single-site study to undergo a 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) scan of their chest, abdomen, and pelvis at baseline before controlled human malaria infection (CHMI) inoculation and again at the expected time of peak parasitemia. FDG uptake will be used to visualize organ-specific changes as a result of malaria infection. Other assessments will include inflammatory labs, signs of bone marrow activation, compete blood count (CBC), reticulocyte counts, and transcriptional analysis.

Objectives:

Primary Objectives:

-To measure changes in spleen standardized uptake value (SUV) from baseline in participants undergoing P. vivax CHMI using PET/CT imaging

Secondary Objectives:

  • Key secondary: To measure changes in organ-specific uptake of FDG from baseline in participants undergoing P. vivax CHMI using PET/CT imaging.
  • Explore the relationship between dyserythropoiesis, hematological abnormalities, and bone marrow/splenic involvement in acute P. vivax malaria.

Exploratory Objectives:

  • To better understand the biomass and sequestration of P. vivax malaria.
  • Improve understanding of timing and location of P. vivax sequestration in tissues.
  • Measure host and parasite factors that lead to organ-specific P. vivax disease.
  • Improve understanding of convalescent changes for expected or unexpected changes in organ size or SUV due to P. vivax after treatment

Endpoints:

Primary Endpoint:

-Percentage change in mean spleen SUV from baseline to post CHMI

Key Secondary Endpoints:

  • Percentage change in max spleen SUV
  • Percentage change in peak spleen SUV
  • Percentage change in spleen volume

Additional Secondary Endpoints:

  • Percentage change in liver volume
  • Percentage change in mean, max, and peak liver SUV
  • Percentage change in mean, max and peak bone marrow SUV
  • CBC with differential, reticulocyte count, and erythropoietin (EPO) at baseline, at the time of the second FDG-PET/CT, and at the end of the CHMI-related activities performed under the co-enrolled study.

Exploratory Endpoints:

  • Describe the relationship between parasitemia/gametocytemia and organ size changes and SUV on FDG-PET/CT with exploratory labs like Plasmodium vivax-specific LDH and others.
  • Other exploratory studies may include but are not limited to proteomic and metabolomic analysis, 10x genomics, and immunophenotyping using flow cytometry or immunohistochemistry (IHC) on peripheral blood mononuclear cells (PBMCs), cytokine levels.
  • Percentage change in organ volume and mean SUV after treatment compared to baseline and compared to the time of peak parasitemia

Typ studie

Intervenční

Zápis (Odhadovaný)

45

Fáze

  • Nelze použít

Kontakty a umístění

Tato část poskytuje kontaktní údaje pro ty, kteří studii provádějí, a informace o tom, kde se tato studie provádí.

Studijní kontakt

Studijní místa

    • Maryland
      • Bethesda, Maryland, Spojené státy, 20892
        • National Institutes of Health Clinical Center
        • Kontakt:

Kritéria účasti

Výzkumníci hledají lidi, kteří odpovídají určitému popisu, kterému se říká kritéria způsobilosti. Některé příklady těchto kritérií jsou celkový zdravotní stav osoby nebo předchozí léčba.

Kritéria způsobilosti

Věk způsobilý ke studiu

18 let až 54 let (Dospělý)

Přijímá zdravé dobrovolníky

Ne

Pohlaví způsobilá ke studiu

Všechno

Popis

  • INCLUSION CRITERIA

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

  1. Aged >=18 and <=54 years.

  2. Able to provide informed consent.

  3. Co-enrolled in NIH protocol IRB001970, "Phase 1 study of induced blood-stage malaria in healthy malaria-naive adults to assess the safety and infectivity of Plasmodium vivax challenge agent and evaluate transmission in mosquito feeding assays" or IRB002627, "Phase 1/2 study of transmission-blocking vaccine Pvs230D1-EPA/Matrix-M in healthy malaria-naive adults using a Plasmodium vivax controlled human malaria infection model."

  4. Willing to allow long-term storage of study samples for future research.

  5. Individuals of childbearing potential must agree to use an acceptable method of contraception from 1 month prior to the first FDG-PET/CT scan through the end of the study. Participants will also be expected to adhere to the strictest of the contraception

    requirements of any studies they are co-enrolled in. Acceptable methods of contraception include the following:

    • A barrier method (e.g., consistent condom use) combined with an oral contraceptive pill, hormonal patch, or ring.
    • Parenteral hormonal contraceptive implant or an intrauterine device.

    Participants who otherwise are not at risk of becoming pregnant, at the judgement of the investigator will not be required to use contraception. Such participants may include those:

    • Having undergone hysterectomy, bilateral oophorectomy, or bilateral fallopian tube ligation.
    • Having reached menopause (age >=45 years plus no menses for 12 consecutive months without an alternative medical cause).
    • Having exclusive same-sex relations or committed longstanding abstinence due to a serious life choice.
    • Having an exclusive male partner who has undergone vasectomy at least 4 months prior.
  6. Participants need to have established medical care with a primary care doctor or be willing to establish care in case medically relevant findings on their imaging require follow-up.

EXCLUSION CRITERIA

An individual who meets any of the following criteria will be excluded from participation in this study:

  1. Pregnancy or lactation.
  2. History of splenectomy.
  3. History of diabetes or poorly controlled blood sugar, in the judgement of the investigators, would prevent completion of FDG-PET/CT scan.
  4. Currently undergoing therapy with drugs that, in the judgment of the investigators, may interfere with biodistribution of FDG (e.g., insulin that cannot be held or metformin that cannot be stopped for 48 hours prior to each FDG-PET/CT.).
  5. Any other finding that, in the judgment of the investigator, would interfere with, or serve as a contraindication to, protocol adherence, assessment of safety, or a participant s ability to give informed consent, or increase the risk of having an adverse outcome from

participating in the study.

Co-enrollment guidelines: Co-enrollment in other trials is restricted, other than enrollment on the LMIV CHMI trials described above and NIH protocol 17I0122, NIAID Centralized Sequencing Protocol. Study staff should be notified of co-enrollment on any other protocol as it may require the approval of the principal investigator.

Studijní plán

Tato část poskytuje podrobnosti o studijním plánu, včetně toho, jak je studie navržena a co studie měří.

Jak je studie koncipována?

Detaily designu

  • Primární účel: Základní věda
  • Přidělení: N/A
  • Intervenční model: Přiřazení jedné skupiny
  • Maskování: Žádné (otevřený štítek)

Zbraně a zásahy

Skupina účastníků / Arm
Intervence / Léčba
Experimentální: Healthy Volunteers who are co-enrolled in a P. vivax CHMI study

Healthy Volunteers are co-enrolled in a Plasmodium vivax challenge model protocol at the NIH Clinical Center.

Participants are co-enrolled in a Plasmodium vivax challenge model protocol at the NIH Clinical Center. These participants will undergo up to 3 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) scans of their chest, abdomen, and pelvis. PET/CT scans will occur at baseline (before controlled human malaria infection (CHMI) inoculation), and at the expected time of peak parasitemia. Participants may have an optional 3rd PET/CT scan at day 34 after the CHMI inoculation. FDG uptake will be used to visualize organ-specific changes as a result of malaria infection.

Co je měření studie?

Primární výstupní opatření

Měření výsledku
Popis opatření
Časové okno
To measure changes in spleen standardized uptake value (SUV) from baseline in participants undergoing P. vivax CHMI using PET/CT imaging
Časové okno: 34 (+/- 5 days) days post CHMI Inoculation

Percentage change in mean spleen SUV from baseline to post-CHMI

34 (+/- 5 days) days post CHMI Inoculation

Sekundární výstupní opatření

Měření výsledku
Popis opatření
Časové okno
To measure changes in organ specific uptake of FDG from baseline in participants undergoing P. vivax CHMI using PET/CT imaging
Časové okno: 34 (+/- 5 days) days post CHMI Inoculation

Percentage change in max spleen SUV Percentage change in peak spleen SUVPercentage change in spleen volume Percentage change in liver volumePercentage change in liver SUVPercentage change in bone marrow SUV

34 (+/- 5 days) days post CHMI Inoculation
Explore the relationship between dyserythropoiesis, hematological abnormalities, and bone marrow/splenic involvement in acute P. vivax malaria.
Časové okno: 34 (+/- 5 days) days post CHMI Inoculation

CBC with differential, reticulocyte count, and erythropoietin (EPO) at baseline, at the time of the second FDG-PET/CT, and at the end of the CHMI-related activities performed under the co-enrolled study.

34 (+/- 5 days) days post CHMI Inoculation

Spolupracovníci a vyšetřovatelé

Zde najdete lidi a organizace zapojené do této studie.

Vyšetřovatelé

  • Vrchní vyšetřovatel: Shanan R Immel, M.D., National Institute of Allergy and Infectious Diseases (NIAID)

Publikace a užitečné odkazy

Osoba odpovědná za zadávání informací o studiu tyto publikace poskytuje dobrovolně. Mohou se týkat čehokoli, co souvisí se studiem.

Termíny studijních záznamů

Tato data sledují průběh záznamů studie a předkládání souhrnných výsledků na ClinicalTrials.gov. Záznamy ze studií a hlášené výsledky jsou před zveřejněním na veřejné webové stránce přezkoumány Národní lékařskou knihovnou (NLM), aby se ujistily, že splňují specifické standardy kontroly kvality.

Hlavní termíny studia

Začátek studia (Odhadovaný)

8. listopadu 2026

Primární dokončení (Odhadovaný)

1. listopadu 2030

Dokončení studie (Odhadovaný)

1. listopadu 2030

Termíny zápisu do studia

První předloženo

3. října 2026

První předloženo, které splnilo kritéria kontroly kvality

5. října 2026

První zveřejněno (Aktuální)

6. října 2026

Aktualizace studijních záznamů

Poslední zveřejněná aktualizace (Aktuální)

3. listopadu 2026

Odeslaná poslední aktualizace, která splnila kritéria kontroly kvality

2. listopadu 2026

Naposledy ověřeno

8. října 2026

Více informací

Termíny související s touto studií

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