In addition, recent challenges in the development of bone-targeted delivery systems and strategies for the treatment of bone metastasis have been summarised in this review.242 One of the studies reported that RNA aptamer (APT) A10-3.2 has been used as a ligand to target PCa cells that express PSMA.243 APT was investigated as a PSMA-targeting ligand in the design of an ATE-based microRNA (miRNA; miR-15a and miR-16-1) vector to PCa bone metastasis. The gene discussed is FOLH1; the disease is posterior cortical atrophy.