The invention generally relates to compositions and methods for targeted delivery of a Cas endonuclease or nucleic acid encoding a Cas endonuclease to a fusion sequence in a cancer cell but not in a healthy cell of a subject. The Cas endonuclease or nucleic acid encoding the Cas endonuclease may be complexed with a guide RNA complementary to a fusion sequence identified based on differences between a mutated sequence obtained from a cancer cell and a wild-type sequence obtained from a healthy cell of the subject. For example, the Cas endonuclease may be a Cas9 and cut DNA or a Cas13a and cut RNA. The Cas endonuclease complexes may induce cell death or cancerous cells or cause other beneficial effects.
