No safety concerns were observed with EXG‑5003 administration
The data suggest a priming effect by EXG-5003 on the long-term cellular immunity of approved SARS-CoV-2 mRNA vaccines.
The Company is exploring the use of the c-srRNA platform for the development of vaccines, cell therapies and immunotherapies for several indications
BALTIMORE, October 16, 2023 – Elixirgen Therapeutics, Inc., a clinical-stage biotechnology company focused on the discovery, development and commercialization of therapies using its mRNA platforms, today announced promising data from a Phase 1/2 trial (NCT04863131) evaluating EXG-5003, a SARS-CoV-2 vaccine developed with the Company’s temperature controllable self-replicating RNA (c-srRNA) technology. The data, published on medRxiv, demonstrate no safety concerns with EXG-5003 and induction of cellular (T cell-mediated) immunity. With clinical evidence that the c-srRNA platform is safe and can produce a T cell-mediated response, the Company is exploring its potential for the development of vaccines, cell therapies and immunotherapies for several indications.
“Current RNA vaccines have demonstrated clear efficacy benefits, but challenges remain with the need for multiple booster doses due to neutralizing antibodies with limited cross-reactivity across variants,” said Yohei Doi, a Principal Investigator of this clinical trial and Professor of Fujita Health University School of Medicine and University of Pittsburgh School of Medicine. “Importantly, it’s been demonstrated that T cell-mediated immunity results in strong cross-reactivity across variants, but the T cell response by approved mRNA vaccines wanes rapidly. The results from this trial suggest a priming effect by EXG-5003 on the long-term cellular immunity of approved SARS-CoV-2 mRNA vaccines. Altogether, data show the unique and beneficial features of EXG-5003.”
Akihiro Ko, chief executive officer of Elixirgen Therapeutics, added, “Our self-replicating RNA platform allows for expression to be temperature-controllable, which helps to improve efficacy while reducing off-target effects. EXG-5003 is active at around 33°C (skin temperature) but does not function at 37°C (core body temperature). This allows for the vaccine to be delivered intradermally, which is a method that’s been shown to induce strong T cell-mediated immunity. Additionally, EXG-5003 is delivered without lipid nanoparticles (LNPs), which may reduce local reactogenicity in the skin. We are pleased with the safety and immune data from this study and are exploring the potential of the c-srRNA platform for other indications.”
A Phase 1/2 clinical trial of intradermal, controllable self-replicating RNA vaccine EXG-5003 against SARS-CoV-2
- This was a double-blind, placebo-controlled Phase 1/2 trial to evaluate the safety, tolerability and immunogenicity of EXG‑5003.
- EXG-5003 is a vaccine that encodes the receptor binding domain (RBD) of SARS-CoV-2.
- Forty (40) healthy participants were enrolled in Cohort 1 (5 µg per dose, n = 16; placebo, n = 4) and Cohort 2 (25 µg per dose, n = 16; placebo, n = 4). The participants were followed for 12 months.
- No safety concerns were observed with EXG‑5003 administration. It is noteworthy that the reactogenicity and systemic adverse events associated with EXG-5003 were much lower than the approved mRNA vaccines and other srRNA/saRNA vaccines.
- SARS-CoV-2 RBD antibody titers and neutralizing antibody titers were not elevated in either cohort by EXG-5003 alone.
- Elicitation of antigen-specific cellular immunity was observed in the EXG-5003 recipients in Cohort 2.
- At the 12-month follow-up, participants who had received an approved mRNA vaccine (BNT162b2 or mRNA-1273) >1 month after receiving the second dose of EXG-5003 showed higher cellular responses compared to equivalently vaccinated participants in the placebo group.
- Data suggest a priming effect by EXG-5003 on the long-term cellular immunity of approved SARS-CoV-2 mRNA vaccines.
About Elixirgen Therapeutics, Inc.
Elixirgen Therapeutics, Inc. is a clinical-stage biotechnology company focused on the discovery, development and commercialization of therapies using its mRNA platforms and ZSCAN4 technology. The company has one ongoing (NCT04211714) and one completed (NCT04863131) Phase 1/2 clinical trials. For more information, visit ElixirgenTx.com.
This press release may contain “forward-looking” statements. Actual results may differ materially from those set forth in this press release due to the risks and uncertainties inherent in pharmaceutical research and development. Any forward-looking statements in this press release speak only as of the date of this press release, and Elixirgen Therapeutics undertakes no obligation to update or revise the statements in the future, even if new information becomes available.
Slavena Salve Nissan, M.D.