Background
We developed a 13-mer locked nucleic acid (LNA) inhibitor of miR-221 (LNA-i-miR-221) with a full phosphorothioate (PS)-modified backbone. This agent downregulated miR-221, demonstrated anti-tumor activity against human xenografts in mice, and favorable toxicokinetics in rats and monkeys. Allometric interspecies scaling allowed us to define the first-in-class LNA-i-miR-221 safe starting dose for the clinical translation.