Pharmacokinetics, Tolerability and Safety of Favipiravir Compared to Ribavirin for the Treatment of Lassa Fever

Study Overview
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Brief Summary
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This exploratory, prospective, controlled, multisite, open label, randomized clinical trial with two treatment arms aims to compare favipiravir, a new treatment candidate for Lassa fever (LF), with the current standard of care, ribavirin. The primary endpoints of this research are (1) the description of classical pharmacokinetic parameters of favipiravir in comparison with ribavirin standard treatment in patients suffering from LF and (2) the safety and tolerability of both study drugs in the investigated regimens.

Detailed Description
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The currently used antiviral for the treatment of LF, which is also recommended by the World Health Organization (WHO) and the Nigeria Center for Disease Control, is ribavirin. However, evidence for ribavirin efficacy in LF patients adds up to the results of a single study with serious limitations. A promising new treatment candidate that showed efficacy against LF in preclinical studies is Favipiravir. It has further been evaluated for the treatment of Ebola Virus disease during the West-African Ebola outbreak and is approved for treatment of pandemic influenza virus infections in Japan. The study will be conducted at two study sites in Nigeria: the Irrua Specialist Teaching Hospital (ISTH) and the Federal Medical Center of Owo (FMCO). Lassa fever patients of 18 years and older with LF confirmed by reverse-transcription polymerase chain reaction (RT-PCR) hospitalized at either ISTH or FMCO will be asked to participate in this study. A total of 40 evaluable participants will be randomized to two treatment arms (20 participants per arm): intravenous ribavirin standard of care treatment (Irrua regimen), oral favipiravir. Patients will be included in the study after giving written informed consent and if all inclusion criteria and no exclusion criteria are met. Multiple blood draws with the purpose of virologic, serologic and immunological analyses, hematological and biochemical analyses as well as pharmacokinetic analyses will be performed throughout the study duration of ten days. Adverse events (AEs), serious adverse events (SAEs) and pregnancy will be captured, monitored and followed-up. A medical monitor will be available for study investigators to assist with any clinical and safety related questions. An external data safety monitoring board (DSMB) will conduct periodic safety reviews. Data will be captured on source documents and electronic case report forms (eCRFs). Informed consent forms will be stored in a lockable cabinet. Participants data will only be linked to the unique identifier to ensure pseudonymity. Statistical analysis of study endpoints and pharmacokinetic parameters will be performed descriptively. Missing data will be treated as such, no imputation will be applied. The study will be conducted in compliance with the protocol, the Declaration of Helsinki, the International Conference on Harmonisation-Good Clinical Practice (ICH-GCP) guideline and the Nigerian National Code for Health Research Ethics, in particular concerning the submission to the ethics committees and the protection of personal data as well as other national and regulatory requirements.

Official Title
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Pharmacokinetics, Tolerability and Safety of Favipiravir Compared to Ribavirin for the Treatment of Lassa Fever: A Randomized Controlled Open Label Phase II Clinical Trial

Conditions
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Lassa Fever

Intervention / Treatment
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* Drug: Ribavirin iv
* Drug: Favipiravir


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years LF confirmed by RT-PCR (reverse-transcription polymerase chain reaction) Written informed consent Exclusion Criteria: Inability to give consent (e.g. unconscious patients/ cognitively impaired patients) Pregnancy/lactation (evidenced by negative urine pregnancy test in women of child-bearing potential) Women who plan to get pregnant within the upcoming 6 months Severe malnutrition (BMI<16) Known intolerance to ribavirin or favipiravir History of hemoglobinopathies (i.e., sickle-cell anaemia or thalassemia major) and/or haemophilia Organ failure as evidenced by: Creatinine ≥ 3x upper limit of normal (ULN) Aspartate aminotransferase (AST/GOT) > 150 IU/l Alert, confusion, voice, pain, unresponsive (ACVPU) score = V or P or U (corresponds to Glasgow Coma Scale (GCS) ≤ 12) Severe central nervous system features (e.g. seizures, restlessness, confusion and coma) O2 Saturation < 90% Hematocrit <30 % Severe anaemia requiring blood transfusion Inability to take oral drug (e.g. encephalopathy, severe vomiting) Patients who already received ribavirin or favipiravir within the preceding 7 days

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Exploratory, prospective, controlled, multisite, open label, randomized clinical trial with two arms
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Intravenous ribavirin<br>standard treatment: Irrua regimen 100 mg/kg Day 1 (dose is divided: 2/3 stat, 1/3 8 hours later, maximum dose is 7g/day) 25 mg/kg days 2-7 12.5 mg/kg days 8-10 | Drug: Ribavirin iv<br>* 100 mg/kg Day 1 (dose is divided: 2/3 stat, 1/3 8 hours later, maximum dose is 7g/day), then 25 mg/kg days 2-7, 12.5 mg/kg days 8-10<br>* Other names: Irrua regimen;|
| Experimental: Oral favipiravir<br>Oral favipiravir Day 1 2400mg(H0)-2400mg(H8)-1200mg(H16) Day 2-10 1200mg twice daily (BD) | Drug: Favipiravir<br>* Day 1 2400mg(H0)-2400mg(H8)-1200mg(H16), Day 2-10 1200mg twice daily<br>* Other names: Avigan;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pharmacokinetic parameter of favipiravir: Maximum plasma concentration (Cmax) | Maximum plasma concentration (Cmax) of favipiravir | Day 1, Day 2, Day 4, Day 6, Day 7, Day 8 and Day 10 of the study conduct | 
| Pharmacokinetic parameter of favipiravir: Time to maximum concentration (Tmax) | Time to maximum concentration (Tmax) of favipiravir | Day 1, Day 2, Day 4, Day 6, Day 7, Day 8 and Day 10 of the study conduct | 
| Pharmacokinetic parameter of favipiravir: Area under the concentration-time curve (AUC) | Area under the concentration-time curve (AUC) of favipiravir | Day 1, Day 2, Day 4, Day 6, Day 7, Day 8 and Day 10 of the study conduct | 
| Pharmacokinetic parameter of favipiravir: Half life (T1/2) | Half life (T1/2) of favipiravir | Day 1, Day 2, Day 4, Day 6, Day 7, Day 8 and Day 10 of the study conduct | 
| Proportion of drug related AEs and SAEs of both study treatments | Safety and tolerability of ribavirin and favipiravir in investigated regimens by investigating the proportion of drug related AEs and SAEs | throughout study completion (10 days per participant) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mutagenicity | Mutagenicity of ribavirin and favipiravir measured via nucleotide exchange rate in individual Lassa virus genomes | 10 days | 
| Change from baseline in Viral RNA loads | Description of viral loads during treatment Relative Lassa virus RNA concentrations in RNA copies per milliliters (RNA copies/ml). | Day of enrollment - Day 10 | 
| Change from baseline in Lassa virus titers | Description of infectious titers during treatment. Infectious titers expressed as focus forming units per milliliters or FFU/ml using immuno-focus assay for Lassa virus. | Day of enrollment - Day 10 | 
| Change from baseline in Lassa virus serological status | Description of antibody response during treatment. To evaluate the presence or absence of Lassa virus immunoglobulin M (IgM) and G (IgG) antibodies; qualitative results | 10 days | 
| Pharmacokinetic (PK) modelling and simulations | Dosing regimen (mg/frequency/day) resulting in optimal PK/PD target attainment | Day 1, Day 2, Day 4, Day 6, Day 7, Day 8 and Day 10 of the study conduct | 
| Correlation between drug exposure and different parameters | Correlation between drug exposure (AUC, Cl/F) and i. Viral elimination dynamics (elimination rate constant), including time to viral clearance (time to negative RT-PCR blood for Lassa virus), regression analysis of viral loads in function of time ii. Length of hospital stay: duration of hospitalization as defined by the enrollment date to discharged data iii. Number of deaths: mortality records iv. Blood component therapy use as concomittant medication | 10 days | 
| Co-variates impacting on drug exposure | Co-variates impacting on drug exposure: demographices, biological, clinical and virologic data captured in patient case files and sources documents may be assessed as convariates on drug exposure | 10 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ribavirin, Favipiravir, viral hemorrhagic fever