RabiesPhase 2ARPEPNCT03961555

Comparison of SYN023 to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies

A Phase 2 study testing SYN023, HRIG (HyperRab) and Rabies vaccine in people with Rabies, run by Synermore Biologics Co., Ltd. at 14 sites in 2 countries.

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
What is being tested?: SYN023, HRIG (HyperRab) and Rabies vaccine
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 448 participants
Where: 14 sitesin 2 countries
Study dates: 3 Sep 2019to 23 Dec 2021
Phase: Phase 2
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

Subjects must meet all of the following criteria at the time of subject ID assignment:
History of dog, cat, mongoose, fox, ferret, skunk, bat or raccoon bite to trunk, leg, ankle or foot, or lick or scratch with, or of broken skin or mucous membrane saliva or neural tissue contamination, unprotected physical bat contact, scratch or saliva contamination of the head or neck without broken skin all ≤ 54 hours
Has completed the written informed consent process and signed informed consent document
Males and females
Is age equal or more than 18 years on Study Day 1
Agrees to stay in contact with the study site for the duration of the study, provide updated contact information as necessary, and has no current plans to move from the study area for the duration of the study

Show all 16Show fewer

Lives within 2 hour journey by available transportation to study center
For female subjects: agrees to avoid pregnancy from Study Day 1 through Study Day 121. Women physically capable of pregnancy (not sterilized and still menstruating or within 1 year of the last menses if menopausal) in sexual relationships with men must use an acceptable method of avoiding pregnancy during this period. Acceptable methods of avoiding pregnancy include a sterile sexual partner, sexual abstinence (not engaging in sexual intercourse), hormonal contraceptives (oral, injection, transdermal patch, or implant), vaginal ring, intrauterine device (IUD), or the combination of a condom or diaphragm with spermicide
Subjects must meet all of the following criteria at the time of subject ID assignment:
History of dog, cat, mongoose, fox, ferret, skunk, bat or raccoon bite to any body part, lick or scratch with, or of broken skin, mucous membrane saliva or neural tissue contamination, or unprotected physical bat contact all ≤ 54 hours from post exposure prophylaxis (PEP)
Has completed the written informed consent process and signed informed consent document.
Males and females
Is age equal or more than 18 years on Study Day 1
Agrees to stay in contact with the study site for the duration of the study, provide updated contact information as necessary, and has no current plans to move from the study area for the duration of the study
Lives within 2 hour journey by available transportation to study center
For female subjects: agrees to avoid pregnancy from agrees to avoid pregnancy from Study Day 1 through Study Day 121. Women physically capable of pregnancy (not sterilized and still menstruating or within 1 year of the last menses if menopausal) in sexual relationships with men must use an acceptable method of avoiding pregnancy during this period. Acceptable methods of avoiding pregnancy include a sterile sexual partner, sexual abstinence (not engaging in sexual intercourse), hormonal contraceptives (oral, injection, transdermal patch, or implant), vaginal ring, intrauterine device (IUD), or the combination of a condom or diaphragm with spermicide

Who cannot join

Subjects must have had none of the following at the time of subject ID assignment:
Clinical evidence of rabies infection
Category 3 exposure > 54 hours before Study Drug receipt
History or serological evidence of previous rabies vaccination
Previous receipt of equine or human rabies globulin
History of hypersensitivity reaction to equine or human immunoglobulin.

Show all 14Show fewer

Received immunoglobulin or blood products within 42 days before Study Day 1
Received any investigational drug therapy or investigational vaccine within 60 days before Study Day 1
Planned participation in any other investigational study during the study period.
Receiving systemic immunosuppressant medication such as systemic corticosteroids but not limited to systemic corticosteroids
History or laboratory evidence of any past, present, or possible immunodeficiency state including but not limited to any laboratory indication of HIV infection
Previous medical history that may compromise the safety of the subject in the study according to the opinion of the principal investigator
History or evidence on physical examination of any systemic disease or any acute or chronic illness that, in the opinion of the investigator, may interfere with the evaluation of the safety or activity of SYN023
Pregnancy (results of the urine pregnancy test MUST be known before enrollment)

Trial locations and contacts

14 sites in 2 countries.

Country

City, postcode or hospital

14 sites in 2 countries

Philippines9 sites

Baguio General Hospital and Medical Center
Baguio City, Benguet, 2600
De La Salle Health Sciences Institute Independent Ethics Committee
Cavite City, Calabarzon, 4114
Southern Philippines Medical Center
Davao City, Davao (Region XI), 8000
Manila Doctors Hospital Institutional Review Board
Manila, National Capital Region, 1000
Mary Johnston Hospital
Manila
Asian Hospital and Medical Center
Muntinlupa, National Capital Region, 1780
Center of Excellence in Drug Research, Evaluation and Studies, Inc.
Muntinlupa, National Capital Region, 1781
Research Institute For Tropical Medicine
Muntinlupa, National Capital Region, 1781
Far Eastern University Hospital Nicanor Reyes Medical Foundation
Quezon City, National Capital Region, 1118

Other trials in Philippines

United States5 sites

University of Virginia
Charlottesville, Virginia, 22903
University of Florida
Gainesville, Florida, 32610
University of Iowa
Iowa City, Iowa, 52242
Clinical Research Solutions PC -Milan
Milan, Tennessee, 38358
Medical College of Wisconsin
Milwaukee, Wisconsin, 53226

Other trials in United States

About this study

Official title: A Phase 2b Randomized Blinded Study to Evaluate SYN023 Compared to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies in Adults With Different Rabies Exposure Risks

This is a Phase 2b, double blinded, randomized study of SYN023 compared to HyperRab® (a licensed Rabies immune globulin from human sources, HRIG) for the prevention of rabies as part of post-exposure prophylaxis (PEP). The trial will enroll sequentially two different risk substrata of WHO Category 3 rabies exposure which are Low Risk Group (LRG) and Normal Risk Group (NRG). The enrollment will be stepwise while subject's data will be reviewed by data and safety monitoring board (DSMB) to confirm the safety and permit for next enrollment. Besides, rabies vaccine would be administered within 75 minutes 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 the United States.

Conditions: Rabies
Being tested: SYN023, HRIG (HyperRab), Rabies vaccine
Keywords: Post-exposure prophylaxis of Rabies
Medical subject headings: Rabies

What participants receive

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

SYN023Biological
it is administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible
HRIG (HyperRab)Biological
it is administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible
Rabies vaccineBiological
Also called RabAvert, Rabipur
it should be administered in deltoid muscle

Study groups in NCT03961555
Study group	Role	What they receive
Low Risk Group: SYN023+Rabies vaccine	Experimental	The subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). Bites to the head, neck, genitalia arm or hand are not included in the LRG. The initial 20 subjects in the LRG were to be randomized on a 3:1 (SYN023 to Human Rabies Immune Globulin (HRIG)) ratio. The general 60 subjects in the LRG were to be allocated with a 1:1 randomization to either SYN023 or HRIG treatment arms. SYN023: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 0.3 mg/kg of SYN023 * Frequency/duration: at Day 1 Rabies vaccine: * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: Initial LRG subjects received 4 vaccine doses (Days 1, 4, 8,15); General LRG subjects received 5 vaccine doses (Days 1, 4, 8, 15, and 29). Receives: Biological: SYN023; Biological: Rabies vaccine
Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine	Active comparator	The subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). Bites to the head, neck, genitalia arm or hand are not included in the LRG. The initial 20 subjects in the LRG were to be randomized on a 3:1 (SYN023 to Human Rabies Immune Globulin (HRIG)) ratio. The general 60 subjects in the LRG were to be allocated with a 1:1 randomization to either SYN023 or HRIG treatment. HRIG: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 20 IU/kg * Frequency/duration: at Day 1 Rabies vaccine : * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: Initial LRG subjects received 4 vaccine doses (Days 1, 4, 8,15); General LRG subjects received 5 vaccine doses (Days 1, 4, 8, 15, and 29) Receives: Biological: HRIG (HyperRab); Biological: Rabies vaccine
Normal Risk Group: SYN023+Rabies vaccine	Experimental	The subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). The NRG were consisted of all WHO Category 3 exposure. Subjects were to be allocated with a 1:1 randomization to either SYN023 or Human Rabies Immune Globulin (HRIG) treatment arms. SYN023: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 0.3 mg/kg of SYN023 * Frequency/duration: at Day 1 Rabies vaccine: * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: at Day 1, 4, 8, 15, 29 Receives: Biological: SYN023; Biological: Rabies vaccine
Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine	Active comparator	The subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). The NRG were consisted of all WHO Category 3 exposure. Subjects were to be allocated with a 1:1 randomization to either SYN023 or Human Rabies Immune Globulin (HRIG) treatment arms. HRIG: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 20 IU/kg * Frequency/duration: at Day 1 Rabies vaccine (RabAvert/Rabipur): * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: at Day 1, 4, 8, 15, 29 Receives: Biological: HRIG (HyperRab); 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
Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 99
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Day 99
Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL at Study Day 99
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Day 99
Cases of Probable and Confirmed Rabies
Case Classification Human Rabies
- Suspected: A case that is compatible with the clinical case definition
- Probable: A suspected case (above) plus history of contact with a suspected rabid animal.
- Confirmed: A suspected case that is laboratory-confirmed.
Measured: Day 1 to Day 365

Secondary outcomes (2)

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 4
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Measured: Day 4
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.

3 Sep 201923 Dec 2021

First posted23 May 2019
Study start3 Sep 2019
Primary completion23 Dec 2021
Study completion23 Dec 2021

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 (1)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 2
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Quadruple blind
Who is masked: Participant, Care provider, Investigator, Outcomes assessor
Enrolment: 448 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT03961555
Sponsor's protocol ID: SYN023-004
Acronym: ARPEP
Status last verified: Jun 2026
First submitted: 16 May 2019
Last updated: 29 Jun 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No

Publications

Quiambao BP, Payumo RA, Roa C, Borja-Tabora CF, Emmeline Montellano M, Reyes MRL, Zoleta-De Jesus L, Capeding MR, Solimen DP, Barez MY, Reid C, Chuang A, Tsao E, McClain JB. A phase 2b, Randomized, double blinded comparison of the safety and efficacy of the monoclonal antibody mixture SYN023 and human rabies immune globulin in patients exposed to rabies. Vaccine. 2024 Sep 17;42(22):126018. doi: 10.1016/j.vaccine.2024.05.066. Epub 2024 Jun 4.
PubMed 38834432

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

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RecruitingObservational study
Real World Evidence Study of SYN023 in Children Exposed to Rabies
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Enrolling by invitationPhase 3
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All Rabies trials

Study at a glance

From the registry record, last updated by the sponsor on 29 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 2b Randomized Blinded Study to Evaluate SYN023 Compared to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies in Adults With Different Rabies Exposure Risks
ClinicalTrials.gov ID: NCT03961555
Acronym / sponsor ID: ARPEP / SYN023-004
Conditions: Rabies
Keywords: Post-exposure prophylaxis of Rabies
Phase: Phase 2
Study type: Interventional
Recruitment status: Completed
Enrolment: 448 participants (actual)
Lead sponsor: Synermore Biologics Co., Ltd.Industry (pharma, biotech, devices)
Collaborators: Synermore Biologics USA Limited
Study start: 3 Sep 2019 (actual)
Primary completion: 23 Dec 2021 (actual)
Study completion: 23 Dec 2021 (actual)
First posted: 23 May 2019 (actual)
Results: Posted 16 Jan 2026

Clinical summary

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

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Quadruple blind (participant, care provider, investigator, outcomes assessor)
Number of arms: 4

Arm	Type	Receives
Low Risk Group: SYN023+Rabies vaccine	Experimental	Biological: SYN023, Biological: Rabies vaccineThe subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). Bites to the head, neck, genitalia arm or hand are not included in the LRG. The initial 20 subjects in the LRG were to be randomized on a 3:1 (SYN023 to Human Rabies Immune Globulin (HRIG)) ratio. The general 60 subjects in the LRG were to be allocated with a 1:1 randomization to either SYN023 or HRIG treatment arms. SYN023: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 0.3 mg/kg of SYN023 * Frequency/duration: at Day 1 Rabies vaccine: * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: Initial LRG subjects received 4 vaccine doses (Days 1, 4, 8,15); General LRG subjects received 5 vaccine doses (Days 1, 4, 8, 15, and 29).
Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine	Active comparator	Biological: HRIG (HyperRab), Biological: Rabies vaccineThe subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). Bites to the head, neck, genitalia arm or hand are not included in the LRG. The initial 20 subjects in the LRG were to be randomized on a 3:1 (SYN023 to Human Rabies Immune Globulin (HRIG)) ratio. The general 60 subjects in the LRG were to be allocated with a 1:1 randomization to either SYN023 or HRIG treatment. HRIG: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 20 IU/kg * Frequency/duration: at Day 1 Rabies vaccine : * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: Initial LRG subjects received 4 vaccine doses (Days 1, 4, 8,15); General LRG subjects received 5 vaccine doses (Days 1, 4, 8, 15, and 29)
Normal Risk Group: SYN023+Rabies vaccine	Experimental	Biological: SYN023, Biological: Rabies vaccineThe subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). The NRG were consisted of all WHO Category 3 exposure. Subjects were to be allocated with a 1:1 randomization to either SYN023 or Human Rabies Immune Globulin (HRIG) treatment arms. SYN023: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 0.3 mg/kg of SYN023 * Frequency/duration: at Day 1 Rabies vaccine: * Interventions: should be administered in deltoid muscle * Dosage: 1 mL after reconstitution * Frequency/duration: at Day 1, 4, 8, 15, 29
Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine	Active comparator	Biological: HRIG (HyperRab), Biological: Rabies vaccineThe subjects were enrolled in the study sequentially into 2 different risk substrata of WHO Category 3 rabies exposure, which included Low Risk Group (LRG) and Normal Risk Group (NRG). The NRG were consisted of all WHO Category 3 exposure. Subjects were to be allocated with a 1:1 randomization to either SYN023 or Human Rabies Immune Globulin (HRIG) treatment arms. HRIG: * Interventions: are administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible * Dosage: 20 IU/kg * Frequency/duration: at Day 1 Rabies vaccine (RabAvert/Rabipur): * Interventions: should be administered in deltoid muscle * Dosage: 1 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 (16 listed)

History of dog, cat, mongoose, fox, ferret, skunk, bat or raccoon bite to trunk, leg, ankle or foot, or lick or scratch with, or of broken skin or mucous membrane saliva or neural tissue contamination, unprotected physical bat contact, scratch or saliva contamination of the head or neck without broken skin all ≤ 54 hours
Has completed the written informed consent process and signed informed consent document
Males and females
Is age equal or more than 18 years on Study Day 1
Agrees to stay in contact with the study site for the duration of the study, provide updated contact information as necessary, and has no current plans to move from the study area for the duration of the study

Key exclusion criteria (14 listed)

Clinical evidence of rabies infection
Category 3 exposure > 54 hours before Study Drug receipt
History or serological evidence of previous rabies vaccination
Previous receipt of equine or human rabies globulin
History of hypersensitivity reaction to equine or human immunoglobulin.

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
SYN023it is administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible	Biological	Low Risk Group: SYN023+Rabies vaccine, Normal Risk Group: SYN023+Rabies vaccine
HRIG (HyperRab)it is administered by direct injection into the wound or by subcutaneous or intramuscular injection when this is not possible	Biological	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine, Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine
Rabies vaccineAlso: RabAvert, Rabipurit should be administered in deltoid muscle	Biological	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine, Low Risk Group: SYN023+Rabies vaccine, Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies vaccine, Normal Risk 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).
Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 99
Time frame: Day 99
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL at Study Day 99
Time frame: Day 99
Rabies Virus Neutralizing Activity (RVNA) was assessed using Rapid Fluorescent Focus Inhibition Test (RFFIT).
Cases of Probable and Confirmed Rabies
Time frame: Day 1 to Day 365
Case Classification Human Rabies * Suspected: A case that is compatible with the clinical case definition * Probable: A suspected case (above) plus history of contact with a suspected rabid animal. * Confirmed: A suspected case that is laboratory-confirmed.

2 secondary outcomes

Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 4
Time frame: Day 4
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 16 Jan 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Low Risk Group: SYN023+Rabies Vaccine	45	45
Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine	35	34
Normal Risk Group: SYN023+Rabies Vaccine	184	178
Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine	184	178

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

Time frame: Day 8. Geometric mean (Geometric Coefficient of Variation). Unit: IU/mL

Measure	Low Risk Group: SYN023+Rabies Vaccine n = 40	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 31	Normal Risk Group: SYN023+Rabies Vaccine n = 153	Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 156
Value	4.70 (0.37)	0.13 (0.10)	3.30 (0.61)	0.17 (1.39)

Population analysed: The primary efficacy analyses were performed and summarized for the for the Normal Risk Group per-protocol population. Results for the Low Risk Group per-protocol population are only presented in-text tables. The per-protocol population included all as-treated subjects without any major protocol deviation who had met all inclusion/exclusion criteria and received complete study treatment.

Primary outcome: Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 99

Time frame: Day 99. Geometric mean (Geometric Coefficient of Variation). Unit: IU/mL

Measure	Low Risk Group: SYN023+Rabies Vaccine n = 40	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 31	Normal Risk Group: SYN023+Rabies Vaccine n = 153	Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 152
Value	0.66 (1.13)	1.72 (1.83)	0.97 (1.21)	1.47 (1.60)

Population analysed: The primary efficacy analyses were performed and summarized for the for the Normal Risk Group per-protocol population. Results for the Low Risk Group per-protocol population are only presented in-text tables. Per-protocol population: all subjects who were randomly assigned, received the correct study drug, met inclusion/exclusion criteria, completed all rabies scheduled vaccinations, lacked major protocol deviations, had adequate wound treatment and study drug injection of all exposure sites.

Primary outcome: Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL at Study Day 99

Time frame: Day 99. Count of participants. Unit: Participants

Measure	Low Risk Group: SYN023+Rabies Vaccine n = 40	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 31	Normal Risk Group: SYN023+Rabies Vaccine n = 154	Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 156
Value	30	28	138	142

Population analysed: The primary efficacy analyses were performed and summarized for the for the Normal Risk Group per-protocol population. Results for the Low Risk Group per-protocol population are only presented in-text tables. Per-protocol population: all subjects who were randomly assigned, received the correct study drug, met inclusion/exclusion criteria, completed all rabies scheduled vaccinations, lacked major protocol deviations, had adequate wound treatment and study drug injection of all exposure sites.

Primary outcome: Cases of Probable and Confirmed Rabies

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

Measure	Low Risk Group: SYN023+Rabies Vaccine n = 40	Low Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 31	Normal Risk Group: SYN023+Rabies Vaccine n = 154	Normal Risk Group: Human Rabies Immune Globulin (HRIG)+Rabies Vaccine n = 156
Value	0	0	0	0

Population analysed: The primary efficacy analyses were performed and summarized for the for the Normal Risk Group per-protocol population. Results for the Low Risk Group per-protocol population are only presented in-text tables. Per-protocol population: all subjects who were randomly assigned, received the correct study drug, met inclusion/exclusion criteria, completed all rabies scheduled vaccinations, lacked major protocol deviations, had adequate wound treatment and study drug injection of all exposure sites.

2 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
LRG: SYN023+Rabies Vaccine	0 of 45 (0%)	9 of 45 (20%)	0 of 45
LRG: HRIG+Rabies Vaccine	1 of 35 (2.9%)	11 of 35 (31.4%)	1 of 35
NRG: SYN023+Rabies Vaccine	1 of 183 (0.5%)	40 of 183 (21.9%)	0 of 183
NRG: HRIG+Rabies Vaccine	2 of 184 (1.1%)	30 of 184 (16.3%)	0 of 184

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 29 Jun 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 38834432Quiambao BP, Payumo RA, Roa C, Borja-Tabora CF, Emmeline Montellano M, Reyes MRL, Zoleta-De Jesus L, Capeding MR, Solimen DP, Barez MY, Reid C, Chuang A, Tsao E, McClain JB. A phase 2b, Randomized, double blinded comparison of the safety and efficacy of the monoclonal antibody mixture SYN023 and human rabies immune globulin in patients exposed to rabies. Vaccine. 2024 Sep 17;42(22):126018. doi: 10.1016/j.vaccine.2024.05.066. Epub 2024 Jun 4.
Individual participant dataSharing planned: No

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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.

The record lists no contact. Use the official record to reach the sponsor.

14 sites in 2 countries: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing SYN023, HRIG (HyperRab) and Rabies vaccine in people with Rabies, run by Synermore Biologics Co., Ltd. at 14 sites in 2 countries.

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 16 inclusion and 14 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 29 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 14 sites in Philippines, United States. 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 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

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 16 Jan 2026). 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 4 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 NCT03961555, which also lists 1 linked publication.

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 29 Jun 2026.