In MDA-MB-231 triple negative breast cancer cells, Targaprimir-96 shows a dose-response (IC50 of ~50 nM) by assessing the reduction of mature miR-96 levels. Targaprimir-96 (50 nM) boosts the amount of the pri-miRNA and decreases the levels of the pre-miRNA and mature miRNA in a dose-dependent manner. In breast cancer cell line 4175, Targaprimir-96 (50 nM; 48 hours) increases FOXO1 levels and triggers apoptosis . Targaprimir-96 binds RNA3 (contains both the Drosha site and the adjacent 1×1 nt GG internal loop) with a Kd of 85 nM. Targaprimir-96 binds RNA1, RNA2, RNA4, and RNA5 with Kd values of 1.2, 0.9, 1.2, and 1.5 μM, respectively. Thus, Targaprimir-96 is highly RNA-selective and recognizes both the 1×1 nt GG and 1×1 nt UU loops to provide high affinity, effectively discriminating against a variety of related targets.

Tumor growth in a mouse model of triple-negative breast cancer (TNBC) inhibited by Targaprimir-96 (10 mg/kg; i.p.; every other day for 21 days). In FVB/n mice,The amount of Targaprimir-96 (2 or 7 mg/kg; i.p.) in plasma peaks is ~4 h. Importantly, even 48 hours postinjection, the concentration of Targaprimir-96 remaining in plasma is much greater than the 50 nM cellular concentration that triggered apoptosis: 1.6 μM for the 2 mg/kg dosage and 1.9 μM for the 7 mg/kg dosage.