Vaccine for Lassa Fever

Overseen By Sarah Litts, MS, BSN, RN

Age: 18 - 65

Sex: Any

Trial Phase: Phase 1

Sponsor: Wilbur Chen, MD, MS

Must not be taking: Immunosuppressants, Allergy injections

Disqualifiers: Anaphylaxis, Pregnancy, Rabies vaccine, others

Stay on Your Current Meds You can continue your current medications while participating

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 2

Duration: 8 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests a new vaccine for Lassa fever, a serious disease similar to Ebola, spread by rodents. The vaccine, LASSARAB+ aPHAD-SEat 1400rU, uses a modified rabies virus to help the body build immunity against both Lassa fever and rabies. Participants will receive different doses to determine the most effective one. Ideal candidates are generally healthy individuals without significant health issues who have not previously received a rabies or Lassa fever vaccine. As a Phase 1 trial, this research focuses on understanding how the treatment works in people, offering participants the unique opportunity to be among the first to receive this new vaccine.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you are using medications that may impair immune response.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that the LASSARAB vaccine, developed to combat Lassa fever, has yielded promising results in animal studies. Animals such as monkeys that received the vaccine developed strong immune responses and survived exposure to the Lassa virus. However, limited information exists about its safety in humans, as this is its first test on people.

In other studies with similar vaccines, such as the rVSVΔG-LASV-GPC vaccine, participants experienced mild, temporary side effects like soreness and minor flu-like symptoms. No serious side effects were reported, which is reassuring.

Since this trial is in its early stages (Phase 1), it aims to gather safety data. Early trials like this one focus on understanding how well people can tolerate the treatment. While the animal studies are encouraging, human trials will provide more concrete safety information. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising?

Researchers are excited about the LASSARAB+ aPHAD-SE vaccine for Lassa Fever because it represents a novel approach compared to existing treatments, which mainly focus on supportive care and antiviral drugs like ribavirin. Unlike these current options, the LASSARAB+ aPHAD-SE vaccine is designed to actively prevent infection by stimulating the immune system to produce a protective response against the Lassa virus. This vaccine incorporates a unique adjuvant, aPHAD-SE, which could enhance the immune response, potentially offering more robust and long-lasting protection. If successful, this vaccine could significantly reduce the incidence of Lassa Fever, offering a proactive solution rather than relying on treatments after infection occurs.

What evidence suggests that this vaccine might be an effective treatment for Lassa fever?

Research has shown that the LASSARAB+ aPHAD-SE vaccine could help protect against Lassa fever. In studies with mice and monkeys, this vaccine provided strong protection after exposure to the Lassa virus. In a human study, all participants who received two doses of the vaccine achieved a 100% seroconversion rate, indicating their immune systems reacted to the vaccine. This reaction was measured by a test for specific antibodies. Importantly, the vaccine was well tolerated by all participants, indicating safety. While these early results are promising, more research is needed to confirm its effectiveness in humans. Participants in this trial will receive different dosages of the LASSARAB+ aPHAD-SE vaccine or an active comparator as part of the various treatment arms. ^{1 4 5 6 7}

Are You a Good Fit for This Trial?

This trial is for healthy adults aged 18 to 50 who can understand and agree to the study procedures. They must be in good general health without significant medical or psychiatric conditions, and able to attend all study visits.

Inclusion Criteria

I understand and agree to follow the study's procedures and attend all visits.

I have signed the consent form for this trial.

I am in good health without major medical or psychiatric conditions.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive the LASSARAB vaccine with aPHAD-SE adjuvant in a dose-escalation study

8 weeks

2 visits (in-person) for vaccinations

Follow-up

Participants are monitored for safety and effectiveness after treatment

56 weeks

Regular follow-up visits

What Are the Treatments Tested in This Trial?

Interventions

• LASSARAB+ aPHAD-SEat 1400rU

Trial Overview The trial is testing a new Lassa fever vaccine using an altered rabies virus that carries the Lassa glycoprotein complex. It's given with an adjuvant that boosts immune response. The vaccine's effectiveness against both Lassa fever and rabies will be assessed.

How Is the Trial Designed?

Group I: Cohort 4 - LASSARAB+ aPHAD-SE Vaccine at 1400rU (single) or AC/Placebo Experimental Treatment 3 Interventions

11:3 randomization to investigational vaccine (2 doses) at 14rU or active comparator and normal saline placebo

Group II: Cohort 3 - LASSARAB+ aPHAD-SE Vaccine at 1400rU Single or Double or AC or AC/Placebo Experimental Treatment 3 Interventions

11:2:4:1 randomization to investigational vaccine single dose at 1400rU or investigational vaccine (2 doses) at 14rU or active comparator or active comparator and normal saline placebo

Group III: Cohort 2 - LASSARAB+ aPHAD-SE Vaccine at 700rU or 1400rU or AC Experimental Treatment 3 Interventions

11:4:3 randomization to investigational vaccine dose 700rU or 1400rU or active comparator (n=18)

Group IV: Cohort 1 - LASSARAB+ aPHAD-SE Vaccine at 700rU or Active Comparator (AC) Experimental Treatment 2 Interventions

4:1 randomization to investigational vaccine or active comparator (n=5)

Who Is Running the Clinical Trial?

Wilbur Chen, MD, MS

Lead Sponsor

Trials

1

Recruited

60+

Published Research Related to This Trial

The MV-LASV vaccine candidate demonstrated an acceptable safety profile in a phase 1 trial with 60 healthy adults, showing similar rates of adverse events between the vaccine and placebo groups, with no serious adverse events reported.

The vaccine induced strong immune responses, with significant levels of LASV-specific IgG antibodies observed, indicating its potential effectiveness in providing immunity against Lassa fever.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Immunogenicity, safety, and tolerability of a recombinant measles-vectored Lassa fever vaccine: a randomised, placebo-controlled, first-in-human trial. Tschismarov, R., Van Damme, P., Germain, C., et al.[2023]

A single injection of the ML29 reassortant vaccine for Lassa fever was found to induce low levels of virus in the blood and tissues of common marmosets, but it effectively triggered strong immune responses that completely protected them from severe disease.

Gene expression analysis in human immune cells exposed to ML29 confirmed its safety profile, suggesting that ML29 is a promising candidate for further development as a vaccine against Lassa fever.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety, immunogenicity, and efficacy of the ML29 reassortant vaccine for Lassa fever in small non-human primates. Lukashevich, IS., Carrion, R., Salvato, MS., et al.[2021]

Lassa virus (LASV) causes significant health issues in West Africa, with hundreds of thousands of infections and thousands of deaths each year, highlighting the urgent need for an effective vaccine.

Current vaccine development for Lassa fever is challenged by high costs of animal models and strict biocontainment requirements, necessitating innovative approaches to evaluate vaccine candidates and induce strong immunity against various LASV lineages.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The search for animal models for Lassa fever vaccine development. Lukashevich, IS.[2021]

The LASSARAB vaccine candidate, which combines inactivated Lassa virus and rabies components, successfully generates a strong and lasting immune response in both mice and guinea pigs, providing protection against Lassa fever.

A key mechanism of protection identified is the role of non-neutralizing antibodies targeting the Lassa virus glycoprotein, which enhance immune response through antibody-dependent cellular functions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Non-neutralizing antibodies elicited by recombinant Lassa-Rabies vaccine are critical for protection against Lassa fever. Abreu-Mota, T., Hagen, KR., Cooper, K., et al.[2020]

Four Lassa fever vaccine candidates have reached clinical trials, with five phase 1 trials and one phase 2 trial registered, indicating progress in vaccine development.

Current trials primarily focus on healthy adults, with one trial including a broader age range, suggesting a cautious approach to assessing safety and efficacy in diverse populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Lassa fever vaccine candidates: A scoping review of vaccine clinical trials. Sulis, G., Peebles, A., Basta, NE.[2023]

Citations

1. medrxiv.org medrxiv.org/content/10.1101/2025.10.16.25338178v1

interim results of a first-in-human Phase 1 trial All doses were well tolerated. After two doses, Lassa GPC ELISA seroconversion rates were 100% in all LASSARAB groups and 0% in the control ...

2. clinicaltrials.gov clinicaltrials.gov/study/NCT06546709

NCT06546709 | DMID 23-0015; Lassa Fever CVD 1000 This study proposes the evaluation of a novel, first-in-human Lassa fever vaccine based on the complete Lassa glycoprotein complex (GPC) antigen.

3. researchgate.net researchgate.net/publication/396620592_Immunogenicity_of_an_adjuvanted_combination_inactivated_rabies-vectored_Lassa_fever_vaccine_in_healthy_adults_interim_results_of_a_first-in-human_Phase_1_trial

interim results of a first-in-human Phase 1 trial All doses were well tolerated. After two doses, Lassa GPC ELISA seroconversion rates were 100% in all LASSARAB groups and 0% in the control ...

4. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/41191941/

Safety and Immunogenicity of an rVSV Lassa Fever ... Results: A total of 114 adults were enrolled. No serious vaccine-related adverse events were reported. The vaccine caused minimal local ...

5. iavi.org iavi.org/fact-sheet/about-iavis-lassa-virus-vaccine-program/

Lassa virus vaccine development program multidisciplinary Lassa Fever Vaccine Efficacy and. Prevention for West Africa ... Interim results found the candidate to be safe and immunogenic ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11315998/

Inactivated rabies-based Lassa fever virus vaccine ... NHPs immunized with LASSARAB developed strong humoral responses to LASV-GPC. Upon challenge, NHPs vaccinated with LASSARAB survived to the study endpoint, ...

7. withpower.com withpower.com/trial/phase-1-lassa-fever-9-2024-82a30

Vaccine for Lassa Fever · Info for Participants The LASSARAB vaccine has been tested in animals and shown to be effective, but human safety data is not detailed in the provided research. ... Group II: Cohort 3 ...