PTK7 and cancer: In 2009, the first ApDC was constructed by conjugating the protein tyrosine kinase 7 (PTK7)-targeted aptamer Sgc8c with doxorubicin, demonstrating the homing capacity of aptamers conjugated with drugs to selectively kill cancer cells in vitro and validating the feasibility of aptamer-based targeted drug delivery.12 Since then, various ApDCs have been designed and synthesized for targeted cancer therapies.