Sorrento Therapeutics receives FDA clearance to initial trials with STI-1557

Sorrento Therapeutics has received clearance from the US FDA to initiate clinical trials with STI-1557, its next generation mRNA vaccine against SARS-CoV-2 Omicron variants. This mRNA vaccine incorporates a mutation in the furin cleavage site that prevents the S1 subunit cleavage from the spike protein from anchoring on the muscle cell membrane. This modification was introduced to prevent the leakage of S1 subunit from the expressed spike protein into the blood circulation, which is known in part to potentially cause undesirable side effects in vital organ tissues following administration of the current FDA-approved mRNA vaccines. The mRNA is encapsulated in a Sorrento proprietary lipid nanoparticle formulation to protect mRNAs from degradation and enable potent translation of the S protein in host cells after intramuscular delivery, thus inducing an adaptive immune response. The preclinical work that supported this investigational new drug application has been published online in Molecular Therapy Nucleic Acids, a Cell Press partner journal. The paper, titled "Chimeric mRNA-based COVID-19 vaccine induces protective immunity against Omicron and Delta variants," will appear in print in the December 2022 issue of the journal.