TheraPHIX™: Enabling global vaccine equity with thermostable RNA formulations

The rapid development of RNA vaccines during the COVID-19 pandemic saved millions of lives. However, one major challenge remains: RNA degrades quickly when exposed to heat, enzymes, or physical stress. This means that current RNA vaccines require deep freezing (-50°C or lower) to remain stable, making global distribution costly and logistically complex.

At RNAssist, we have been working to change this. Through our collaboration with CPI, funded by Innovate UK, we have developed TheraPHIX™, a thermostable formulation that enables RNA vaccines to be stored at ambient temperatures. This breakthrough has the potential to revolutionise vaccine distribution worldwide, especially in regions with limited cold storage infrastructure.

Developing thermostable RNA vaccines

To address RNA instability, our team at RNAssist partnered with CPI to explore the use of deep eutectic solvents (DES)—non-aqueous, non-organic solid solvents that become liquid when mixed. Together, we developed two innovative workflows:

• Internal DES: Encapsulating DES within RNA-LNPs (lipid nanoparticles) to enhance stability from within.

• External DES: Applying DES after the RNA vaccine-LNP complex has already been formed, providing an external protective layer.

By leveraging CPI’s cutting-edge formulation expertise and world-class facilities at the National Formulation Centre and National Biologics Manufacturing Centre, we optimised these approaches, scaling up production six-fold and demonstrating the effectiveness of DES in maintaining RNA purity under high-temperature conditions.

Key advancements in RNA vaccine stability

• Successfully encapsulated DES in RNA-LNPs, developing two distinct stabilisation approaches.

• Demonstrated that external DES formulations maintain RNA purity after three months at 37°C.

• Initial potency testing showed that internal DES RNA-LNPs exhibit higher biological activity than standard LNP formulations.

• Provided stabilised materials for further in vitro and in vivo testing.

A step towards vaccine accessibility

With TheraPHIX™, vaccine manufacturers can significantly reduce the reliance on deep-freeze storage, allowing vaccines to be transported more easily into remote regions. By eliminating the need for large-scale refrigeration and freezer units, this technology has the potential to expand vaccine coverage to isolated communities, improving access and ensuring a more equitable global response to infectious diseases.

What’s next?

RNAssist has filed for additional patent protection in respect of this groundbreaking technology. We are also launching a range of stabilisation reagents for RNA-LNPs to further support pharmaceutical manufacturers in improving RNA vaccine stability.

We believe that TheraPHIX™ will transform the landscape of RNA vaccine distribution, helping to overcome one of the greatest logistical challenges in modern medicine.

To learn more about our work with CPI and the full case study, visit CPI’s website