Phase 2
N=448
Comparison of SYN023 to Human Rabies Immune Globulin in Post Exposure Prophylaxis of Rabies
Rabies
Bottom Line
View on ClinicalTrials.gov: NCT03961555 ↗Enrolled (actual)
448
Serious AEs
0.9%
Results posted
Jan 2026
Primary outcome: Primary: Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8 — 4.70; 0.13; 3.30; 0.17 IU/mL
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 2
- Interventions
- SYN023 (Biological); HRIG (HyperRab) (Biological); Rabies vaccine (Biological)
- Age
- Adult, Older Adult · 18+ yrs
- Sex
- All
- Sponsor
- Synermore Biologics Co., Ltd.
- Primary completion
- Dec 2021
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 8 |
4.70; 0.13; 3.30; 0.17 | — |
| PRIMARY Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 99 |
0.66; 1.72; 0.97; 1.47 | — |
| PRIMARY Percentage of Participants With Rabies Virus Neutralizing Activity (RVNA) ≥0.5 IU/mL at Study Day 99 |
30; 28; 138; 142 | — |
| PRIMARY Number of Probable or Confirmed Rabies Cases |
0; 0; 0; 0 | — |
| SECONDARY Rabies Virus Neutralizing Activity (RVNA) of Geometric Mean Concentration (GMC) at Study Day 4 |
3.30; 0.12; 3.30; 0.14 | — |
| SECONDARY Area Under the Efficacy Curve for the Geometric Mean Concentration (GMC) of Rabies Virus Neutralizing Activity (RVNA) |
42.91; 5.79; 46.00; 9.81 | — |
| SECONDARY Maximum Observed Serum Concentration (Cmax) |
903; 700; 916.5; 628 | — |
| SECONDARY Time of Maximum Observed Serum Concentration (Tmax) |
2.93; 2.89; 2.87; 2.89 | — |
Summary
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.
Eligibility Criteria
Inclusion Criteria (Low Risk Group):
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
- 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
Inclusion Criteria (Normal Risk Group)
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
Exclusion Criteria
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.
- 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
Data sourced from ClinicalTrials.gov (NCT03961555). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.