Due to its high prevalence in the human population, cancer represents one of the fundamental areas of biomedical research, with surgery, chemotherapy, and radiotherapy remaining the primary methods used in the curative and palliative treatment of malignant diseases. However, lack of specificity and side effects associated with these therapies have a profound impact on the patient’s quality of life. Thus, the investigation of alternative therapies that target only the malignant cells, without affecting the normal cells, remains a goal to be achieved. Emerging from the defense mechanism of bacteria against invading phages, CRISPR/Cas9 showed to be a promising player in treatment of human diseases, due to its flexibility and ease of achieving precise modification in the genome of human cells. Despite the numerous efforts made to improve the function and specificity of CRISPR/Cas9 genome editing capabilities, lack of safe and efficient delivery systems into the diseased cells still poses a major limitation of increasing the clinical applicability for CRISPR/Cas9. In this chapter, we present the state of the art of delivery platforms, emphasizing on tumor targeting systems, and nonetheless their shortcomings for clinical use.