Chlorotoxin is a 36-amino acid peptide found in the venom of the deathstalker scorpion (Leiurus quinquestriatus) which blocks small-conductance chloride channels. The fact that chlorotoxin binds preferentially to glioma cells has allowed the development of new methods for the treatment and diagnosis of several types of cancer. TM-601 which is the synthetic version of chlorotoxin is under phase II clinical trial. Iodine-131-TM-601 is used to treat malignant glioma. TM-601 is also a candidate for targeting gliomas because it crosses blood-brain and tissue barriers and binds to malignant brain tumor cells without affecting healthy tissue.
