Shanghai's Stemirna Therapeutics plans to start a Phase III trial in Brazil of its mRNA vaccine for COVID-19. The unnamed vaccine has already completed a Phase I trial in Laos, and a Phase II test is underway. In June 2021, Stemirna raised $200 million in venture capital to expand its operations and underwrite development of the COVID vaccine. The company now has the capacity to produce 400 million vaccines per year. Stemirna is developing a portfolio of mRNA vaccines for more than 10 immunoncology and infectious disease indications.

“We will publish data for the Phase 1 trial (conducted in Laos) soon,” said Hangwen Li, co-founder and CEO of Stemirna in an interview with the South China Morning Post. “Our Phase II trial is going smoothly there. We have high confidence in our vaccine’s efficacy and safety based on the data.”

Stemirna's COVID vaccine joins another mRNA vaccine under development in China -- ARCoVax -- which is currently in ex-China Phase III trials. It is being developed by the Academy of Military Medical Sciences, Suzhou Abogen Biosciences and Walvax Biotechnology. 

China's other COVID vaccines (not mRNA) are based on a dead or weakened form of the virus, the traditional mechanism for vaccines. The mRNA vaccines, like the BioNTech and Moderna products, are surprisingly effective compared to older types of vaccines. 

In addition, Stemirna believes its mRNA vaccine may be better than these other mRNA vaccines. Stemirna's LPP (lipopolyplex) nano-delivery platform is a core-shell structure, with polymer-mixed mRNA as the core and lipids as the shell. Moderna and Pfizer, on the other hand, use a lipid nanoparticle (LNP) technology to deliver a variety of nucleic acids in vivo and in vitro.

“Compared with traditional LNP platforms that most companies are adopting, the core-shell structured LPP particle is better at protecting mRNA, and is able to release mRNA gradually as the polymers are degraded,” said Shen Haifa, Stemirna's chief technology officer.  

Stemirna CEO Li obtained his doctorate in cancer biology from MD Anderson Cancer Center of the University of Texas in 2010,. He founded Stemirna in Zhangjiang Hi-tech Park in 2016. The COVID-19 will probably be the company first commercialized product. Stemirna has a staff of 500 employees. 

See our other articles on Stemirna.

 Disclosure: none.