Disclosed herein are drug delivery molecules that comprise a ligand that targets a cell surface molecule； a membrane penetration domain； and a payload binding domain； and pharmaceutical compositions comprising the same. Also disclosed are methods of treating cancer, inhibiting the progression of cancer, preventing cancer metastasis, and delivering a therapeutic compound to the brain in a subject in need thereof, the methods comprising identifying a subject in need thereof； providing a composition comprising the drug delivery molecule as disclosed herein； and administering an effective amount of the composition to the subject.
