Compositions comprising a polymeric micellar nanoparticle composition comprising a block or graft copolymer comprising at least one polycationic polymer and at least one polyethylene glycol (PEG) polymer having an average molecular weight less than 1 kDa, and at least one nucleic acid, wherein the graft or block copolymer and at least one nucleic acid are complexed and condensed into a shaped micellar nanoparticle that is stable in biological media are disclosed. The presently disclosed subject matter also provides a method for preparing the presently disclosed polymeric micellar nanoparticle compositions, a method for targeting at least one metastatic cancer cell in a subject, and a method for treating a disease or condition using the presently disclosed polymeric micellar nanoparticle compositions.