Safety, Reactogenicity, and Immunogenicity Trial of STX-S SARS-CoV-2 Vaccine in Adults

NCT07095231 | Completed Phase 1 FDA Drug

• 1 other identifier: 24-1104
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 3

Brief Summary

This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. The study is designed as a non-randomized, open-label, dose-escalation clinical trial evaluating three dose levels of STX-S. A sample size of 60 participants (20 participants per dose cohort) is anticipated. The primary objective is to evaluate the safety and reactogenicity of a single intramuscular injection of three different dose levels (25 ng, 50 ng, and 125 ng) of STX-S in previously vaccinated healthy adults

Conditions

COVID-19

Keywords

Booster Dose; Capricor; coronavirus; Dose-Escalation; NextGen; phase 1; STX-S; vaccine

Outcome Measures

Primary Outcomes (8)

• Occurrence of abnormal clinical safety laboratory adverse events (AEs).

  Through Day 8

• Occurrence of adverse events of special interest (AESI)

  Through 6 months post study product administration

• Occurrence of medically attended adverse events (MAAEs)

  Through 6 months post study product administration

• Occurrence of new onset chronic medical conditions (NOCMCs)

  Through 6 months post study product administration

• Occurrence of serious adverse events (SAEs)

  Through 6 months post study product administration

• Occurrence of solicited local adverse events (AEs).

  Through Day 7 post study product administration

• Occurrence of solicited systemic adverse events (AEs).

  Through Day 7 post study product administration

• Occurrence of unsolicited adverse events (AEs).

  Through Day 28 post study product administration

Secondary Outcomes (5)

• Nasal mucosal anti-spike binding IgA antibodies

  Day 1 through Day 91

• Nasal mucosal anti-spike binding IgG antibodies

  Day 1 through Day 91

• Serum Anti-spike binding Immunoglobulin A (IgA) antibody

  Day 1 through Day 181

• Serum Anti-spike binding Immunoglobulin G (IgG) antibody

  Day 1 through Day 181

• Serum Anti-spike neutralizing antibodies

  Day 1 through Day 181

Study Arms (3)

Cohort 1

EXPERIMENTAL

Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 25 ng at a volume of 0.25 mL. Three sentinel participants, aged \< 50, will be enrolled over at least 2 days. The Protocol Safety Review Team (PSRT) will conduct a safety review before enrolling the remainder of the cohort. N=20

Biological: STX-S

Cohort 2

EXPERIMENTAL

Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 50 ng at a volume of 0.5 mL. N=20

Biological: STX-S

Cohort 3

EXPERIMENTAL

Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 125 ng at a volume of 0.5 mL. N=20

Biological: STX-S

Interventions

STX-S BIOLOGICAL

A proprietary vaccine developed internally by Capricor utilizing exosomes that were engineered to express spike proteins on the surface

Cohort 1; Cohort 2; Cohort 3

Eligibility Criteria

• Age: 18 Years - 64 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Provides written informed consent before initiation of any study procedures.
• Able to understand and agree to comply with planned study procedures and be available for all study visits.
• Non-pregnant adults, 18 through 64 years of age at the time of study product administration.
• Participants of childbearing potential\* must agree to use or have practiced true abstinence\*\* or use at least one acceptable primary form of contraception\*\*\*
• \*These criteria apply to females who are in a heterosexual relationship who are of childbearing potential. Not of childbearing potential include post-menopausal females (defined as having a history of amenorrhea for at least one year) or a documented status as being surgically sterile (hysterectomy, bilateral oophorectomy, or tubal ligation/salpingectomy).
• \*\*True abstinence is 100% of the time, no sexual intercourse (penis enters the vagina). Periodic abstinence \[e.g., calendar, ovulation, symptothermal, post-ovulation methods\] and withdrawal are not acceptable methods.
• \*\*\*Acceptable forms of primary contraception include a monogamous relationship with a vasectomized partner who has been vasectomized for 180 days or more before the participant's study product administration, intrauterine devices, birth control pills, and injectable/implantable/insertable/transdermal hormonal birth control products. Must have used at least one acceptable primary form of contraception for at least 30 days before study product administration and agree to continue at least one acceptable primary form of contraception through 60 days after study product administration.
• Male participants must use acceptable contraception\* or be vasectomized and must refrain from donating sperm for 60 days following study product administration.
• \*Acceptable contraception includes abstinence from intercourse with a female participant of childbearing potential or use of a male condom. Contraception use does not apply to males in an exclusively same-sex relationship.
• Participants of childbearing potential must have a negative urine pregnancy test at screening and within 24 hours before study product administration.
• Receipt of a complete primary authorized or approved COVID-19 vaccine series and at least one booster\* with the last vaccination at least 16 weeks before study product administration.
• \*Booster may be either homologous or heterologous to the primary vaccine series. It must be a Food and Drug Administration (FDA)-authorized/licensed vaccine, though doses may have been received during a clinical trial.
• Must agree to have samples stored for secondary research.

You may not qualify if:

• Positive SARS-CoV-2 PCR at screening.
• Abnormal vital signs (Grade 1 or higher)\*:
• \*Grade 1 or higher is equivalent to: Systolic blood pressure (SBP) \>/= 141 mmHg or \</= 89 mmHg Diastolic blood pressure (DBP) \>/= 91 mmHg Heart rate (HR) is \>/= 101 beats per minute or \</= 54 beats per minute Oral temperature \>/= 38.0 degrees Celsius (100.4 degrees Fahrenheit)
• History of SARS-CoV-2 infection or receipt of any COVID-19 vaccine \< 16 weeks prior to study product administration.
• Participant who is pregnant or breastfeeding.
• Blood or plasma donation within 4 weeks before study product administration.
• Receipt of antibody or blood-derived products within 90 days before study product administration.
• Any self-reported or documented significant medical or psychiatric diseases\* or any other condition that, in the opinion of the site Principal Investigator (PI) or appropriate sub-investigator, precludes study participation.
• \*Significant medical or psychiatric conditions include but are not limited to significant kidney disease, liver disease, ongoing malignancy, or recent diagnosis of malignancy in the last five years, excluding treated basal and squamous cell carcinoma of the skin and cervical carcinoma in situ, which are allowed.
• Neurological or neurodevelopmental conditions\*
• \*Including history of Bell's palsy, history of four or more migraine headaches in the past 12 months that interfered with normal daily activity or any migraine headache in the past 5 years that required emergency or inpatient medical care, epilepsy, seizures in the last 5 years, encephalopathy, focal neurologic deficits, Guillain-Barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, Creutzfeldt-Jakob disease, or Alzheimer's disease.
• History of significant respiratory disease requiring daily medications currently, history of asthma in the past 5 years, or any treatment of respiratory disease exacerbations in the last 5 years.
• History of cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), including any history of myocarditis, pericarditis, or uncontrolled cardiac arrhythmia.
• Any autoimmune disease, including hypothyroidism, without a defined non-autoimmune cause.
• Has an acute illness determined by the site Principal Investigator or appropriate sub-investigator within 72 hours before study product administration\*.

Sponsors & Collaborators

• National Institute of Allergy and Infectious Diseases (NIAID): lead

Study Sites (3)

University of Rochester Medical Center - Vaccine Research Unit

Rochester, New York, 14642-0001, United States

Location

Kaiser Permanente Washington Health Research Institute

Seattle, Washington, 98101-1466, United States

Location

The University of Washington - Virology Research Clinic

Seattle, Washington, 98104, United States

Location

MeSH Terms

Conditions

COVID-19; Coronavirus Infections

Condition Hierarchy (Ancestors)

Pneumonia, Viral; Pneumonia; Respiratory Tract Infections; Infections; Virus Diseases; Coronaviridae Infections; Nidovirales Infections; RNA Virus Infections; Lung Diseases; Respiratory Tract Diseases

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SEQUENTIAL
• Sponsor Type: NIH
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 24, 2025
• First Posted: July 31, 2025
• Study Start: August 11, 2025
• Primary Completion: June 16, 2026
• Study Completion: June 16, 2026
• Last Updated: June 26, 2026

Record last verified: 2025-07-17

Locations

US (3)