Diagnosis of cancers may be one of the worst news to patients and their families. Conventional treatment options such as radiation and chemotherapies often kill not only cancer cells but also normal cells, which results in painful side effects. Radiation and chemotherapies destroy cancer cells by producing DNA double-strand breaks in their DNA. Since both treatments target DNA in both normal and cancer cells, radiation and chemo-drugs cannot distinguish between cancer and normal cells. Thus, indiscriminate killing of healthy cells and side effects are unavoidable when using these treatments. Therefore, scientists have long been searching for a method to selectively target only cancer cells without affecting normal cells, which is a crucial requirement for ideal cancer therapy.
There have been two major developments in the biomedical science fields recently. One is cancer genomics, and the other one is the discovery of a site-specific endonuclease, called CRISPR-Cas9 (commonly called genetic scissors). Cancer genomics projects have found that regardless of their origins, most cancer cells accumulate many mutations including small insertion/deletion (InDel) of several nucleotides, single nucleotide changes, and large chromosomal aberrations. CRISPR-Cas9, the discovery which was recognized by the 2020 Nobel Prize in chemistry, is a technology that can be used to make DNA double-strand breaks in a sequence-specific manner.