A method of producing nanovesicles comprising an oligonucleotide inhibitor to an oncogene or a proto-oncogene or the gene product thereof, said method comprises a) introducing a DNA sequence encoding an oligonucleotide capable of inhibiting a human oncogenic or proto-oncogenic transcription factor, into a mammalian cell; b) allowing the cell to express said inhibitor oligonucleotide; and c) obtaining nanovesicles containing said inhibitor oligonucleotide from said cell. Nanovesicles produced by the claimed method can be effectively and specifically targeted to e.g. cancer cells to deliver the inhibitor oligonucleotide.