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ACTIVE_NOT_RECRUITINGPHASE2

Study to Assess the Safety and Immunogenicity of TPOXX® When Administered Orally for 28 Days With JYNNEOS

A Phase 1, Open-Label (JYNNEOS®), Double-Blind (TPOXX® And Placebo), Multicenter, Randomized, Placebo-Controlled, Drug-Vaccine Interaction Study To Evaluate the Impact of TPOXX on JYNNEOS Immunogenicity

NCT04957485•SIGA Technologies

View on ClinicalTrials.gov

Summary

This study is designed to evaluate the immunogenicity profile of JYNNEOS® when 2 doses are administered subcutaneously (SC) 4 weeks apart; and potential immunological interference while concomitantly administering TPOXX or placebo orally twice daily (BID) for 28 days.

Detailed Description

This is a Phase 2, open-label (JYNNEOS), double-blind (TPOXX and placebo), multicenter, randomized, placebo-controlled, drug-vaccine interaction study to examine whether administering TPOXX with JYNNEOS concomitantly affects JYNNEOS immunogenicity in healthy adult subjects. A total of 100 subjects (approximately 50 subjects per treatment group), ages 18 to 42, inclusive, will be enrolled and randomly assigned to 1 of 2 treatment groups.

Eligibility

Age

18 - 42 years

Sex

ALL

Healthy Volunteers

Yes

Inclusion Criteria

•Each subject must meet all of the following criteria to be enrolled in this study:
•1. Subject is a healthy male or female between 18 and 42 years of age, inclusive, at the time of informed consent.
•2. Subject has a resting heart rate \>40 beats per minute (bpm) or \<110 bpm at screening.
•3. Subject has negative test for HIV antibodies, hepatitis B surface antigen, and hepatitis C virus antibody.
•4. Subject has white blood cells ≥2500/mm3 and \<11,000/mm3.
•5. Subject has hemoglobin within normal limits.
•6. Subject has platelets ≥ lower normal limits.
•7. Subject has adequate renal function defined as a calculated creatinine clearance \>60 mL/min as estimated by the Cockcroft-Gault equation.
•8. Creatinine in males ≤1.7 mg/dL and in females ≤1.4 mg/dL (1.3 times the upper laboratory reference range).
•9. Subject has adequate hepatic function in the absence of other evidence of significant liver disease defined as:
+20 more criteria

Exclusion Criteria

•Subjects meeting any of the following criteria will be excluded from the study:
•1. Subject is a female who is pregnant or breastfeeding or planning to become pregnant within 3 months after the second JYNNEOS injection.
•2. Subject has a history or suspected exposure of smallpox, monkeypox or cowpox disease, or previous vaccination with any poxvirus-based vaccine.
•3. Subject has received any vaccinations within 28 days prior to Day 1 or plans to receive a vaccination at any time during the treatment period or within 28 days after Day 29.
•4. Subject weighs 120 kg or more.
•5. Subject has been administered or plans to be administered immunoglobulins and/or any blood products during a period starting from 3 months prior to administration of the vaccine and ending at trial conclusion.
•6. Subject has used any investigational or nonregistered drug or vaccine other than the trial vaccines within 28 days preceding the first dose of the trial vaccine or planned administration of such a drug /vaccine during the trial period, including the COVID-19 vaccine prior to marketing approval by the FDA.
•7. Subject has a known or suspected history of smallpox vaccination defined as visible vaccination scar or documentation of smallpox vaccination or as reported by the subject.
•8. Subject has had a previous anaphylactic reaction, severe systemic response, or serious hypersensitivity to a prior immunization.
•9. Subject has a history of any clinically significant conditions including the following:
+39 more criteria

Locations (2)

Meridian Clinical Research

Omaha, Nebraska, United States

Aventiv Research Inc

Columbus, Ohio, United States

Key Dates

Start Date

April 5, 2022

Primary Completion Date

January 1, 2026

Completion Date

January 1, 2026

Last Updated

May 15, 2025

Enrollment

100

ACTUAL participants

Conditions

Smallpox

Interventions

Tecovirimat

DRUG

Smallpox and Mpox Vaccine

DRUG

Placebo

OTHER

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Mpox (Monkeypox)Smallpox+1 more

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COMPLETEDPHASE1/PHASE2

A Study to Investigate The Safety, Tolerability, And Immune Response of a Range of Doses of mRNA-1769 Compared With Placebo in Healthy Participants From ≥18 Years of Age to <50 Years of Age

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SmallpoxMpox

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Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: May 15, 2025Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

Neither the United States Government nor Clareo Health make any warranties regarding the data. Check ClinicalTrials.gov frequently for updates.

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Study to Assess the Safety and Immunogenicity of TPOXX® When Administered Orally for 28 Days With JYNNEOS

Inclusion Criteria

Exclusion Criteria

A Randomized Clinical Trial Investigating the Safety, Reactogenicity, and Immunogenicity After Immunization With an mRNA-based Mpox Vaccine Candidate in Africa

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A Phase 4, Observational Field Study to Evaluate TPOXX in Patients With Smallpox

A Randomized, Double-blind, Placebo-controlled Study on Immunogenicity and Safety of MVA-BN (IMVAMUNE™) Smallpox Vaccine in Healthy Subjects