MSA-2 是一種口服非核苷酸 STING 激動(dòng)劑，以具有納摩爾親和力的非共價(jià)二聚體形式與 STING 結(jié)合。MSA-2 對(duì)人的 STING 亞型 WT 和 HAQ 的 EC₅₀ 分別為 8.3 和 24 μM。MSA-2 在同基因小鼠腫瘤模型中顯示抗腫瘤活性，刺激腫瘤分泌干擾素-β，誘導(dǎo)腫瘤消退，具有持久的抗腫瘤免疫，并與抗 PD-1 協(xié)同作用。

    體外研究：

   MSA-2 dosed via either PO or SC regimens achieved comparable exposure in both tumor and plasma. MSA-2 also exhibits dose-dependent antitumor activity when administered by IT, SC, or PO routes, and dosing regimens were identified that induced complete tumor regressions in 80 to 100% of treated animals^[1].
MSA-2 (PO: 60 mg/kg or SC: 50 mg/kg; single dose) that effectively inhibits tumor growth induced substantial elevations of IFN-β, interleukin-6 (IL-6), and TNF-α in tumor^[1].