ST12 is a lipid-conjugated DMXAA prodrug designed for temporally controlled STING activation in mRNA vaccine formulations. Its structure integrates a mouse-specific STING agonist, a biodegradable ester linker, an RNA-interacting tertiary amine domain, and two hydrophobic tails. When incorporated as a partial replacement for SM-102, ST12 preserves early antigen mRNA translation and subsequently releases DMXAA to activate STING. This delayed activation supports localized type I interferon signaling, enhanced antigen-specific CD8-positive T-cell responses, and improved antitumor immunity. In preclinical OVA and HPV tumor models, ST12-based Syn-STING vaccines suppressed tumor growth and prolonged survival. ST12 remains a preclinical research lipid developed specifically around DMXAA-sensitive STING systems.

Providing storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 24 months.
Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.

Qin P, Qin Q, Hao Y, et al. Enhanced antitumor immunity of mRNA vaccines by bioorthogonal-like delayed activation of exogeneous STING. Nature Biotechnology. 2026.