RabiesPhase 3NCT04644484

A Phase III Clinical Study to Evaluate SYN023's Efficacy and Safety

A Phase 3 study testing SYN023, Human Rabies Immune Globulin (HRIG) and Rabies Vaccine in people with Rabies and Communicable Disease, run by Synermore Biologics (Suzhou) Co., Ltd. at 1 site in China.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 18 years and older
Conditions the study is for: Rabies, Communicable Disease, Virus Diseases
What is being tested?: SYN023, Human Rabies Immune Globulin (HRIG) and Rabies Vaccine
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 1,000 participants
Where: 1 siteChina
Study dates: 23 Sep 2020to 16 Dec 2022
Phase: Phase 3
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

Is age ≥18 years, on Study Day 1 with legal identification documents, and plan to live in the local administration area during the study;
Category III rabies exposure within 24 hours before Study Drug receipt ;
Completed written informed consent process, and signed the informed consent forms;
Subjects with the ability to understand the study procedure. And agreed to complete all follow-ups;
Female subjects are not in pregnancy (with negative results of urine pregnancy tests before vaccination) and are not in the period of breast feeding, and agree to avoid pregnancy within 121 days after administration;
Those who have an armpit temperature ≤ 37.0 °C.

Who cannot join

Previous receipt of equine or human (rabies) globulin or rabies vaccination prior to randomization;
Clinical evidence of rabies infection;
Category I and Category II rabies exposure;
Had fever (armpit temperature ≥ 38.5 °C) within 3 days before Study Day 1, or in the acute episode of any chronic diseases;
Received immunoglobulin or blood products (except for the anti-tetanus immunoglobulin) within 43 days before Study Day 1, or plan to use any such product (except for the anti-tetanus immunoglobulin) during the study;
Received systemic immunosuppressant medication such as systemic corticosteroids but not limited to systemic corticosteroids within 43 days before Study Day 1;

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History of any immunodeficiency disease (for example: AIDS, systemic lupus erythematosus, etc.); or Laboratory evidence of previous or current immunodeficiency disease, including, but not limited to, any laboratory evidence of HIV infection;
History of spleen function deficiency or function injury, such as no spleen caused by any cause (such as splenectomy);
History of any severe allergy for vaccination, such as systemic urticaria, allergic laryngeal edema, anaphylactoid purpura, local allergic necrosis (Arthus reaction), angioedema, anaphylactic shock, etc., or allergic to any ingredient of the study drug/vaccine;
Previous receipt of any study product (drug, vaccine, biological product or medical device) within 6 months before Study Day 1, or plan to participate in any other clinical study during this study period;
History of or clinical evidence of any systemic disease, acute disease or chronic disease (such as convulsions, epilepsy, encephalopathy, nephrotic syndrome, etc.) that the investigator considers to be likely to interfere with safety or efficacy assessment of the study;
Previous medical history that may compromise the safety of the subject in the study according to the opinion of the principal investigator.

Trial locations and contacts

1 site in 1 country.

China1 site

Yunnan Province Center for Disease Control and Prevention (CDC)
Kunming, 650022

Other trials in China

About this study

Official title: A Phase III Randomized Blinded Study to Evaluate SYN023 Compared to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies in Adults With Category III Rabies Exposure Risks

This is a Phase 3, blinded, randomized study of SYN023 compared to a China licensed Human Rabies Immunoglobulin (a Rabies immune globulin from human sources, HRIG) for the prevention of rabies as part of post-exposure prophylaxis (PEP). The trial will enroll the World Health Organization (WHO) Category III rabies exposure subjects. The subject's death and rabies data will be reviewed by Data and safety monitoring board (DSMB) to confirm the safety. Besides, rabies vaccine would be administered after Study Drug in each group.

This trial is proposed to further the licensure of SYN023 to provide an effective PEP alternative available to those exposed persons who need such a product. A placebo-controlled rabies trial is unethical thus HRIG is selected as the control group. Rabies immune globulin from equine and human sources (HRIG) have been evaluated in many trials and HRIG is the standard of care in China.

Read the detailed description

This is a Phase 3, randomized, blinded, and active controlled study of SYN023 compared with a China licensed HRIG for PEP of patients who have been confirmed to have met all inclusion/exclusion criteria for their treatment group.

1000 patients aged 18 and above with the World Health Organization (WHO) Category III rabies exposure should be enrolled as planned and randomly assigned to the experimental group and the control group based on a ratio of 3: 1 through on-site stratification as part of PEP.

All subjects should receive wound infiltration injection of SYN023 or HRIG on Study Day 1 (wound conditions should be described and recorded before injection, including diameter, depth, expansion treatment, etc.), and should also simultaneously receive intramuscular injection of one dose of the freeze-dried rabies vaccine for human use (Vero cells) into the deltoid muscle. In accordance with the Essen Scheme, each subject also needs to receive one dose of the freeze-dried rabies vaccine for human use (Vero cells) on Study Days 4, 8, 15, and 29 respectively.

3.0 mL of venous blood samples should be collected 8 times from each subject prior to administration and on Study Day 4, 8, 15, 43, 99, 183, and 365 post administration of study drug. Relevant information should be collected from the subjects through follow-up visits, such as occurrence of rabies and survival conditions.

RVNA should be assayed through rapid fluorescence focus inhibition test (RFFIT).

Local adverse events related to the SYN023 injection sites and injection sites of the first dose and second dose of rabies vaccine, and systemic adverse events (AE) other than injection sites should be collected within 7 days after administration; local adverse events related to the injection sites of the third dose, fourth dose and fifth dose of rabies vaccine, and systemic adverse events (AE) other than the injection sites should be collected 7 days after administration. In addition, all adverse events occurring within 43 days after administration should be collected, and pregnancy conditions in 6 months after administration and all serious adverse events (SAE) occurring during the study period should be collected.

Conditions: Rabies, Communicable Disease, Virus Diseases, Rhabdoviridae Infections, Mononegavirales Infections, RNA Virus Infections
Being tested: SYN023, Human Rabies Immune Globulin (HRIG), Rabies Vaccine
Keywords: Post-exposure prophylaxis of Rabies
Medical subject headings: Rabies, Communicable Diseases, Virus Diseases, Rhabdoviridae Infections, Mononegavirales Infections, RNA Virus Infections

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

SYN023Biological
Also called A Humanized Anti-Rabies Molecular antibodies cocktails
The finished product of SYN023 is a mixture of 3.0 mg/mL CTB011 and 3.0 mg/mL CTB012 at a ratio of 1:1. SYN023 is a sterile and preservative-free injection, and the excipient contains 25 mM histidine (3.879 mg/mL), 150 mM sodium chloride (8.766 mg/mL) and 0.02% polysorbate 80 (0.2 mg/mL) and pH of 6.0. Each vial contains 2.15 mL of SYN023, or 6.45 mg of monoclonal antibody. The glass bottle was closed with a 13 mm bromobutyl rubber stopper, a 13 mm aluminum crimping cap and a polypropylene flip-open lid.
Human Rabies Immune Globulin (HRIG)Biological
The HRIG is a Chinese licensed Human Rabies Immunoglobulin, which are derived from human plasma, and then purified and filled in the injectable vial form. The HRIG is indicated for the Post-exposure Prophylactic (PEP) of Rabies
Rabies VaccineBiological
Also called Freeze-dried Rabies Vaccine for Human Use (Vero Cells)
Interventions: The Chinese licensed rabies vaccine should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 milliliters (mL) before use Dosage: 0.5 mL after reconstitution Frequency/duration: at Day 1, 4, 8, 15, 29

Study groups in NCT04644484
Study group	Role	What they receive
Experimental Group: SYN023+Rabies Vaccine	Experimental	SYN023: Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible SYN023 is an equal mass mixture of CTB011 and CTB012, two monoclonal antibodies that exhibit a wide spectrum of activity against various wild-type rabies strains in vitro. Dosage form: 6mg/2mL, liquid; Dosage: 0.3 mg/kg of SYN023; Frequency/duration: at Day 1 Rabies vaccine : Interventions: should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 mL before use Dosage: 0.5 mL after reconstitution Frequency/duration: at Day 1, 4, 8, 15, 29 Receives: Biological: SYN023; Biological: Rabies Vaccine
Control Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine	Active comparator	Human Rabies Immune Globulin (HRIG): Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible Dosage form: 100 IU/mL, liquid; Dosage: 20 IU/kg; Frequency/duration: at Day 1 Rabies vaccine : Interventions: should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 mL before use; Dosage: 0.5 milliliters (mL) after reconstitution; Frequency/duration: at Day 1, 4, 8, 15, 29 Receives: Biological: Human Rabies Immune Globulin (HRIG); Biological: Rabies Vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Day 8
Number of Probable or Confirmed Rabies Cases
WHO's Classification of Rabies Cases:
1. Suspected case: refers to a case that satisfies the definition of clinical case;
2. Probable case: refers to a suspected case with a reliable medical history of contact with any suspected animal infected with the rabies virus;
3. Confirmed case: refers to a suspected or probable case that is proved to be infected based on the lab test result.
Measured: Day 1 to Day 365

Secondary outcomes (3)

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC)
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Days 4, 15, 43, 99, 183 and 365
Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Days 4, 8, 15, 43, 99, 183 and 365
Area Under the Efficacy Curve for the Geometric Mean Concentration (GMC) of Rabies Virus Neutralizing Activity (RVNA)
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT). Area Under the Efficacy Curve for the GMC of RVNA from Study Day 1 to Day 15 after administration (AUEC1-15)
Measured: Day 1 to Day 15

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

23 Sep 202016 Dec 2022

First posted25 Nov 2020
Study start23 Sep 2020
Primary completion24 Jun 2022
Study completion16 Dec 2022

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (4)Papers the sponsor has linked to this study.
Other trials for RabiesStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 3
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Model description: In this study, 1000 subjects aged 18 and over who had Grade 3 exposure to rabies virus were intended to be enrolled, and randomly assigned to the experimental group and the control group (3:1). Both groups were immunized according to PEP procedures for rabies.
Masking: Quadruple blind
Who is masked: Participant, Care provider, Investigator, Outcomes assessor
Enrolment: 1,000 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT04644484
Sponsor's protocol ID: SYN023-006
Status last verified: Mar 2023
First submitted: 16 Nov 2020
Last updated: 21 Apr 2023
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No

Publications

McClain JB, Chuang A, Reid C, Moore SM, Tsao E. Rabies virus neutralizing activity, pharmacokinetics, and safety of the monoclonal antibody mixture SYN023 in combination with rabies vaccination: Results of a phase 2, randomized, blinded, controlled trial. Vaccine. 2021 Sep 24;39(40):5822-5830. doi: 10.1016/j.vaccine.2021.08.066. Epub 2021 Sep 3.
PubMed 34483020
Ding Y, Wu M, Zhang H, Zhu X, Hu Y, Li X, Liu J, Tsao E, Liu M, Li C. Safety, pharmacokinetics and pharmacodynamics of SYN023 alone or in combination with a rabies vaccine: An open, parallel, single dose, phase 1 bridging study in healthy Chinese subjects. Antiviral Res. 2020 Dec;184:104956. doi: 10.1016/j.antiviral.2020.104956. Epub 2020 Oct 19.
PubMed 33091433
Liu X, Zha Y, Wang Z, Jiang Y, Zhang X, Guo J, Li J, Zhang Q, Tsao E. The pharmacokinetics and safety comparison of Zamerovimab and Mazorelvimab monoclonal antibodies vs. HRIG in category III rabies post-exposure prophylaxis: a stratified analysis by wound characteristics. Biologicals. 2025 Nov;92:101852. doi: 10.1016/j.biologicals.2025.101852. Epub 2025 Aug 13.
PubMed 40812204
Liu X, Li J, Zha Y, Wang Z, Jiang Y, Zhang X, Guo J, Yu J, Li X, Zhang Q, Reid C, McClain JB, Tsao E. The efficacy and safety of SYN023 (Zamerovimab and Mazorelvimab injection), the recombinant humanized anti-rabies virus monoclonal antibody mixture, combined with rabies vaccine in a WHO category III rabies post-exposure population: A randomized, double-blind, positive control, phase III clinical trial. Vaccine. 2025 Aug 13;61:127289. doi: 10.1016/j.vaccine.2025.127289. Epub 2025 Jun 5.
PubMed 40479926

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

Active, not recruitingObservational study
Real-World Effectiveness of Zamerovimab and Mazorelvimab and Vaccine for Rabies Grade III Exposure in Nanyang
Rabies Post-exposure Prophylaxis, Rabies
RecruitingObservational study
Real World Evidence Study of SYN023 in Children Exposed to Rabies
Rabies Post-exposure Prophylaxis
Active, not recruitingPhase 3
A Clinical Trial of Rabies Vaccine（Human Diploid Cell）for Human Use,Freeze-dried in a Population Aged 10 to 60 Years
Rabies
Enrolling by invitationPhase 3
A Phase III Clinical Trial on Immunogenicity and Safety of Lyophilized Rabies Vaccine for Human Use (Human Diploid Cell)
Rabies Prevention
Not yet recruitingPhase 3
Boostability Assessment of Three Rabies Pre-Exposure Regimens in Healthy Volunteers 5 Years Following Priming.
Rabies (Healthy Volunteers)

All Rabies trials

Study at a glance

From the registry record, last updated by the sponsor on 21 Apr 2023. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase III Randomized Blinded Study to Evaluate SYN023 Compared to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies in Adults With Category III Rabies Exposure Risks
ClinicalTrials.gov ID: NCT04644484
Acronym / sponsor ID: SYN023-006
Conditions: Rabies, Communicable Disease, Virus Diseases, Rhabdoviridae Infections, Mononegavirales Infections, RNA Virus Infections
Keywords: Post-exposure prophylaxis of Rabies
Phase: Phase 3
Study type: Interventional
Recruitment status: Completed
Enrolment: 1,000 participants (actual)
Lead sponsor: Synermore Biologics (Suzhou) Co., Ltd.Industry (pharma, biotech, devices)
Collaborators: Simoon Record Pharma Information Consulting Co., Ltd.
Study start: 23 Sep 2020 (actual)
Primary completion: 24 Jun 2022 (actual)
Study completion: 16 Dec 2022 (actual)
First posted: 25 Nov 2020 (actual)
Results: Posted 21 Apr 2023

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

RVNA should be assayed through rapid fluorescence focus inhibition test (RFFIT).

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Quadruple blind (participant, care provider, investigator, outcomes assessor)
Number of arms: 2
Model description: In this study, 1000 subjects aged 18 and over who had Grade 3 exposure to rabies virus were intended to be enrolled, and randomly assigned to the experimental group and the control group (3:1). Both groups were immunized according to PEP procedures for rabies.

Arm	Type	Receives
Experimental Group: SYN023+Rabies Vaccine	Experimental	Biological: SYN023, Biological: Rabies VaccineSYN023: Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible SYN023 is an equal mass mixture of CTB011 and CTB012, two monoclonal antibodies that exhibit a wide spectrum of activity against various wild-type rabies strains in vitro. Dosage form: 6mg/2mL, liquid; Dosage: 0.3 mg/kg of SYN023; Frequency/duration: at Day 1 Rabies vaccine : Interventions: should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 mL before use Dosage: 0.5 mL after reconstitution Frequency/duration: at Day 1, 4, 8, 15, 29
Control Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine	Active comparator	Biological: Human Rabies Immune Globulin (HRIG), Biological: Rabies VaccineHuman Rabies Immune Globulin (HRIG): Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible Dosage form: 100 IU/mL, liquid; Dosage: 20 IU/kg; Frequency/duration: at Day 1 Rabies vaccine : Interventions: should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 mL before use; Dosage: 0.5 milliliters (mL) after reconstitution; Frequency/duration: at Day 1, 4, 8, 15, 29

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (6 listed)

Is age ≥18 years, on Study Day 1 with legal identification documents, and plan to live in the local administration area during the study;
Category III rabies exposure within 24 hours before Study Drug receipt ;
Completed written informed consent process, and signed the informed consent forms;
Subjects with the ability to understand the study procedure. And agreed to complete all follow-ups;
Female subjects are not in pregnancy (with negative results of urine pregnancy tests before vaccination) and are not in the period of breast feeding, and agree to avoid pregnancy within 121 days after administration;

Key exclusion criteria (12 listed)

Previous receipt of equine or human (rabies) globulin or rabies vaccination prior to randomization;
Clinical evidence of rabies infection;
Category I and Category II rabies exposure;
Had fever (armpit temperature ≥ 38.5 °C) within 3 days before Study Day 1, or in the acute episode of any chronic diseases;
Received immunoglobulin or blood products (except for the anti-tetanus immunoglobulin) within 43 days before Study Day 1, or plan to use any such product (except for the anti-tetanus immunoglobulin) during the study;

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
SYN023Also: A Humanized Anti-Rabies Molecular antibodies cocktailsThe finished product of SYN023 is a mixture of 3.0 mg/mL CTB011 and 3.0 mg/mL CTB012 at a ratio of 1:1. SYN023 is a sterile and preservative-free injection, and the excipient contains 25 mM histidine (3.879 mg/mL), 150 mM sodium chloride (8.766 mg/mL) and 0.02% polysorbate 80 (0.2 mg/mL) and pH of 6.0. Each vial contains 2.15 mL of SYN023, or 6.45 mg of monoclonal antibody. The glass bottle was closed with a 13 mm bromobutyl rubber stopper, a 13 mm aluminum crimping cap and a polypropylene flip-open lid.	Biological	Experimental Group: SYN023+Rabies Vaccine
Human Rabies Immune Globulin (HRIG)The HRIG is a Chinese licensed Human Rabies Immunoglobulin, which are derived from human plasma, and then purified and filled in the injectable vial form. The HRIG is indicated for the Post-exposure Prophylactic (PEP) of Rabies	Biological	Control Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine
Rabies VaccineAlso: Freeze-dried Rabies Vaccine for Human Use (Vero Cells)Interventions: The Chinese licensed rabies vaccine should be administered in deltoid muscle Dosage form: >=2.5 IU, freeze-dried vaccine, reconstitute into 0.5 milliliters (mL) before use Dosage: 0.5 mL after reconstitution Frequency/duration: at Day 1, 4, 8, 15, 29	Biological	Control Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine, Experimental Group: SYN023+Rabies Vaccine

Primary outcome

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8
Time frame: Day 8
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Number of Probable or Confirmed Rabies Cases
Time frame: Day 1 to Day 365
WHO's Classification of Rabies Cases: 1. Suspected case: refers to a case that satisfies the definition of clinical case; 2. Probable case: refers to a suspected case with a reliable medical history of contact with any suspected animal infected with the rabies virus; 3. Confirmed case: refers to a suspected or probable case that is proved to be infected based on the lab test result.

3 secondary outcomes

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC)
Time frame: Days 4, 15, 43, 99, 183 and 365
Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL
Time frame: Days 4, 8, 15, 43, 99, 183 and 365
Area Under the Efficacy Curve for the Geometric Mean Concentration (GMC) of Rabies Virus Neutralizing Activity (RVNA)
Time frame: Day 1 to Day 15

Results and safety

Results posted to the registry on 21 Apr 2023, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Experimental Group: SYN023+Rabies Vaccine	750	750
Control Group: Human Rabies Immune Globulin (HRIG)+Rabie Vaccine	250	250

Primary outcome: Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8

Time frame: Day 8. Geometric mean (95% Confidence Interval). Unit: IU/mL

Measure	Experimental Group: SYN023+Rabies Vaccine n = 507	Control Group: Human Rabies Immune Globulin (HRIG)+Rabie Vaccine n = 165
Value	4.346 (4.111 to 4.595)	0.232 (0.198 to 0.271)

Population analysed: The primary analysis set of the outcome measure data is Per-Protocol Analysis Set (PPS). The PPS included all subjects who were randomized, received the correct study drug, passed the confirmation of the inclusion/exclusion criteria \*, completed the rabies vaccination schedule as required by the protocol on Day 29 of the study, had no major protocol violations impacting efficacy evaluation, received adequate wound treatment of all exposed sites, and received study drug injection.

Primary outcome: Number of Probable or Confirmed Rabies Cases

Time frame: Day 1 to Day 365. Number. Unit: participants

Measure	Experimental Group: SYN023+Rabies Vaccine n = 750	Control Group: Human Rabies Immune Globulin (HRIG)+Rabie Vaccine n = 250
Value	0	0

3 secondary outcomes are reported in the full results.

Adverse events

Time frame: 365 days. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Experimental Group: SYN023+Rabies Vaccine	41 of 750 (5.5%)	315 of 750 (42%)	0 of 750
Control Group: HRIG+Rabie Vaccine	14 of 250 (5.6%)	138 of 250 (55.2%)	0 of 250

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 21 Apr 2023.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Results publication: PubMed 34483020McClain JB, Chuang A, Reid C, Moore SM, Tsao E. Rabies virus neutralizing activity, pharmacokinetics, and safety of the monoclonal antibody mixture SYN023 in combination with rabies vaccination: Results of a phase 2, randomized, blinded, controlled trial. Vaccine. 2021 Sep 24;39(40):5822-5830. doi: 10.1016/j.vaccine.2021.08.066. Epub 2021 Sep 3.
Results publication: PubMed 33091433Ding Y, Wu M, Zhang H, Zhu X, Hu Y, Li X, Liu J, Tsao E, Liu M, Li C. Safety, pharmacokinetics and pharmacodynamics of SYN023 alone or in combination with a rabies vaccine: An open, parallel, single dose, phase 1 bridging study in healthy Chinese subjects. Antiviral Res. 2020 Dec;184:104956. doi: 10.1016/j.antiviral.2020.104956. Epub 2020 Oct 19.
Derived from this study: PubMed 40812204Liu X, Zha Y, Wang Z, Jiang Y, Zhang X, Guo J, Li J, Zhang Q, Tsao E. The pharmacokinetics and safety comparison of Zamerovimab and Mazorelvimab monoclonal antibodies vs. HRIG in category III rabies post-exposure prophylaxis: a stratified analysis by wound characteristics. Biologicals. 2025 Nov;92:101852. doi: 10.1016/j.biologicals.2025.101852. Epub 2025 Aug 13.
Derived from this study: PubMed 40479926Liu X, Li J, Zha Y, Wang Z, Jiang Y, Zhang X, Guo J, Yu J, Li X, Zhang Q, Reid C, McClain JB, Tsao E. The efficacy and safety of SYN023 (Zamerovimab and Mazorelvimab injection), the recombinant humanized anti-rabies virus monoclonal antibody mixture, combined with rabies vaccine in a WHO category III rabies post-exposure population: A randomized, double-blind, positive control, phase III clinical trial. Vaccine. 2025 Aug 13;61:127289. doi: 10.1016/j.vaccine.2025.127289. Epub 2025 Jun 5.
Individual participant dataSharing planned: No

Related trials for Rabies

Active, not recruitingObservational study
Real-World Effectiveness of Zamerovimab and Mazorelvimab and Vaccine for Rabies Grade III Exposure in Nanyang
Rabies Post-exposure Prophylaxis, Rabies
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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Xiaoqiang Liu, MD, PhD principal investigator

Yunnan Province CDC

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 21 Apr 2023. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 21 Apr 2023). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8 (time frame: Day 8). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04644484, which also lists 4 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Apr 2023.