A Trial to Evaluate the Safety, Immunogenicity and the Optimal Dose of MOPEVAC-Las Vaccine Candidate Against Lassa Fever

NCT07833436 | Not Yet Recruiting Phase 1 DMC

• 1 other identifier: 2021-063
• Study Type: interventional
• Target: 72
• Locations: 1 country
• Sites: 1

Brief Summary

Lassa fever is an acute viral disease belonging to the category of viral hemorrhagic fevers. It is endemic in West Africa. Outbreaks occur every year, and it is estimated that between 100 000 and 300 000 individuals are infected each year, with a fatality rate for symptomatic cases that ranges between 15 and 30%. There is no efficient treatment against the disease, as ribavirin, the only licensed therapy, is at best poorly efficient. MOPEVAC-Las is a live-attenuated vaccine candidate targeting Lassa virus. The objective of this phase 1 clinical trial is to evaluate the safety of the MOPEVAC-Las vaccine candidate on healthy volunteers. It will also evaluate the immunogenicity and optimal dose of the vaccine candidate. The main questions it aims to answer are:

• What are the safety and tolerability of the MOPEVAC-Las vaccine candidate following two intramuscular injections in healthy volunteers ?
• Are cell-mediated immunity and humoral immunity induced by the MOPEVAC-Las vaccine ?
• What is the optimal dose of MOPEVAC-Las vaccine regarding safety, tolerability and immunogenicity ? Researchers will compare the MOPEVAC-Las vaccine candidate to a placebo (a look-alike substance that contains no drug).

Conditions

Lassa Fever

Keywords

Lassa fever; Phase 1; Vaccine

Outcome Measures

Primary Outcomes (1)

• Rate of solicited and unsolicited Adverse Events (AEs) during the treatment period up to 28 days after each injection.

  From each injection to 28 days later

Secondary Outcomes (4)

• Measurement of functional CD4+ and CD8+ T- cells to assess cell-mediated immunity specific for MOPEVAC-Las

  On days 14 and 28 after each injection, and 6 months and 1 year after the second injection (i.e. day 242 and 425)

• Measurement of anti-LASV antibodies determined by ELISA assay

  The day of each injection and 7, 14 and 28 days after each injection

• Quantification of functional, neutralizing antibodies via Virus Neutralization Test (VNT)

  On days 0, 14, 28, 60, 74, 88, 242 and 425

• Rate of serious adverse events (SAEs), serious adverse reactions (SARs), suspected unexpected serious adverse reactions (SUSARs) and adverse events of special interest (AESI)

  From the first injection until 1 year after the second injection

Study Arms (3)

Low dose

EXPERIMENTAL

Biological: Low dose MOPEVAC-Las vaccine; Drug: Saline Solution for Injection

Intermediate dose

EXPERIMENTAL

Biological: Intermediate dose MOPEVAC-Las vaccine; Drug: Saline Solution for Injection

High dose

EXPERIMENTAL

Biological: High dose MOPEVAC-Las vaccine; Drug: Saline Solution for Injection

Interventions

Low dose MOPEVAC-Las vaccine BIOLOGICAL

2 intramuscular injections of low dose MOPEVAC-Las vaccine candidate (5 x 10\^4 FFU per injection), on days 0 and 60

Low dose

Intermediate dose MOPEVAC-Las vaccine BIOLOGICAL

2 intramuscular injections of intermediate dose MOPEVAC-Las vaccine candidate (5 x 10\^5 FFU per injection), on days 0 and 60

Intermediate dose

High dose MOPEVAC-Las vaccine BIOLOGICAL

2 intramuscular injections of high dose MOPEVAC-Las vaccine candidate (5 x 10\^6 FFU per injection), on days 0 and 60

High dose

Saline Solution for Injection DRUG

2 intramuscular injections of placebo on days 0 and 60

High dose; Intermediate dose; Low dose

Eligibility Criteria

• Age: 18 Years - 55 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Males and females between the ages of 18 and 55 years (at the time of consent).
• Healthy participant, according to the investigator's clinical judgment, as established by medical history, vital signs, physical examination, and laboratory assessments.
• Participant with a body mass index (BMI) between 18,5 kg/m2 and 30.0 kg/m2.
• Provide written informed consent before initiation of any study procedures.
• A female participant is eligible for this study if she is not pregnant, given by a negative serum pregnancy test at screening and a negative urine pregnancy test at V1 (first injection), nor breastfeeding and if she meets any of the following criteria:
• Of non-childbearing potential (i.e., women who have had a hysterectomy or surgical tubal ligation or are postmenopausal, as defined by no menses in greater than or equal to 1 year).
• Of childbearing potential but having sexual relations exclusively with female partners.
• Of childbearing potential but has been and agrees to continue practicing highly effective contraception or abstinence (if this is the preferred and usual lifestyle of the participant) from 30 days prior to vaccination up to 6 months after the last injection (D242).
• Highly effective methods of contraception include 1 or more of the following:
• Male partner who is sterile prior to the female participants entry into the study and is the sole sexual partner for the female participant
• Compliant hormonal therapy (oral, intravaginal, transdermal, implantable or injectable)
• An intrauterine hormone-releasing system (IUS)
• An intrauterine device (IUD) with a documented failure rate of \< 1%
• A female participant is eligible if she agrees to abstain from donating oocyte from the screening visit up to 6 months after the last injection (D242)
• A male participant is eligible if he agrees to:

You may not qualify if:

• Subjects previously infected by Lassa Virus.
• Previous vaccination with an investigational Lassa fever vaccine.
• Subjects who travelled in the past 12 months prior the first injection or plan to travel during the study in a Lassa-endemic country .
• Subjects who used to live in a Lassa-endemic country, or who are regularly traveling to a Lassa-endemic country.
• History of presence of pulmonary disorders (e.g. COPD, etc.) or asthma in adulthood.
• History of or present thrombocytopenia and/or bleeding disorders.
• History of or present hearing deficiency or tympanic vulnerability (e.g. manifested by recurrent ear infections).
• A positive serum pregnancy test at screening or urine pregnancy test prior to study injection, women who are planning to become pregnant during the study, or women who are breastfeeding.
• Clinically relevant history of or current renal, hepatic, gastrointestinal, cardiovascular, respiratory, skin, hematological, endocrine, inflammatory, autoimmune, central nervous system or neurological diseases or clinically relevant abnormal laboratory values.
• Use of immunosuppressive drugs like corticosteroids (excluding topical preparations and inhalers) within 3 months prior to the first vaccination or 6 months for chemotherapies and all along the study.
• A diagnosis of schizophrenia, bipolar disease, or history of hospitalization for a psychiatric condition or previous suicide attempt.
• A history of treatment for any other psychiatric disorder in the past 3 years that increases the risk to the subject in the opinion of the investigator.
• Received immunoglobulin or other blood product within 3 months prior to enrollment or planned receipt of immunoglobulin or a blood product through study completion.
• Vaccination within 3 weeks prior to first injection or planning to receive any licensed vaccine before D88 (e.g. COVID-19 vaccine, Inactivated influenza vaccine).
• History of severe adverse reactions to vaccine administration, including anaphylaxis and related symptoms, such as urticaria, respiratory difficulty, angioedema and abdominal pain to vaccines, or history of known or suspected allergic reaction likely to be exacerbated by any component of the MOPEVAC-Las vaccine.

Sponsors & Collaborators

• Institut Pasteur: lead

Study Sites (1)

Centre d'Investigation Clinique en Vaccinologie Cochin-Pasteur

Paris, 75014, France

Location

MeSH Terms

Conditions

Lassa Fever

Interventions

Saline Solution; Injections

Condition Hierarchy (Ancestors)

Arenaviridae Infections; RNA Virus Infections; Virus Diseases; Infections; Hemorrhagic Fevers, Viral

Intervention Hierarchy (Ancestors)

Crystalloid Solutions; Isotonic Solutions; Solutions; Pharmaceutical Preparations; Drug Administration Routes; Drug Therapy; Therapeutics

Study Officials

• Sylvain Baize

  Institut Pasteur

  STUDY DIRECTOR

Central Study Contacts

Sandrine Fernandes Pellerin

CONTACT

+33145688179; sandrine.fernandespellerin@pasteur.fr

Maëlys Petit-Moreau

CONTACT

+33176535439; maelys.petit-moreau@pasteur.fr

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 16, 2026
• First Posted: September 22, 2026
• Study Start: September 15, 2026
• Primary Completion (Estimated): April 1, 2028
• Study Completion (Estimated): December 1, 2028
• Last Updated: September 25, 2026

Record last verified: 2026-09

Locations

FR (1)