Capricor Therapeutics has achieved a significant milestone in vaccine development with the first-in-human dosing of subjects in a Phase 1 clinical trial evaluating its StealthX exosome-based vaccine platform. The study, funded by the National Institute of Allergy and Infectious Diseases (NIAID) under the U.S. Department of Health and Human Services' Project NextGen initiative, represents a novel approach to vaccine technology that could offer advantages over existing mRNA platforms.
The trial follows FDA clearance of the Investigational New Drug (IND) application and is being conducted by an NIAID-funded network of clinical trial sites. This first-in-human study marks a critical step in advancing Capricor's proprietary exosome-based vaccine technology beyond preclinical development.
Novel Vaccine Platform Technology
The StealthX vaccine platform utilizes exosomes engineered to display viral proteins on their surface, initially focusing on the spike (S) protein of SARS-CoV-2. According to Linda Marbán, Ph.D., Chief Executive Officer of Capricor, "StealthX potentially offers an alternative to mRNA vaccines as this platform contains no adjuvants, offers a more natural delivery system, and uses native proteins, allowing for rapid adaptability to emerging targets."
Preclinical results published in Microbiology Spectrum demonstrated that StealthX elicited robust antibody production, potent neutralizing activity, a strong T-cell response and a favorable safety profile. The platform represents a novel antigen delivery system with potential to enable rapid development of multivalent, protein-based vaccines.
Trial Design and Federal Support
The Phase 1 trial includes four dosing arms initially focused on the SARS-CoV-2 spike protein. An additional arm incorporating the nucleocapsid (N) protein is planned, pending separate FDA clearance for Capricor's StealthX multivalent vaccine formulation.
Project NextGen is a federal initiative aimed at accelerating the development of next-generation vaccine platforms that provide broader and more durable protection against respiratory viruses and other infectious threats. Capricor's vaccine is among several candidates selected for evaluation through this NIAID-sponsored program.
Broader Therapeutic Vision
Beyond the current SARS-CoV-2 focus, Capricor envisions StealthX as a versatile platform with potential across multiple therapeutic areas. "Our broader vision is to position StealthX as a versatile exosome-based platform with potential across a range of therapeutic areas, including rare diseases and other conditions requiring targeted payload delivery," Marbán stated.
The company is leveraging its exosome technology using the proprietary StealthX platform in preclinical development focused on vaccinology, targeted delivery of oligonucleotides, proteins and small molecule therapeutics with potential to treat and prevent a diverse array of diseases.
Timeline and Strategic Implications
NIAID expects initial data from the study in the first quarter of 2026. According to Marbán, "With first-in-human dosing achieved, this trial advances the platform clinically while also potentially laying the groundwork for strategic partnerships, pipeline expansion and long-term value creation."
Exosomes, originally identified as extracellular vesicles, are nano-sized particles enriched with select proteins, RNAs, and lipids that play a key role in cell-to-cell communication. This natural delivery mechanism forms the foundation of Capricor's approach to vaccine development.
The successful initiation of this trial represents a significant step forward for exosome-based vaccine technology and positions Capricor at the forefront of next-generation vaccine platform development under federal support through Project NextGen.
