Chlorotoxin is a 36-amino acid peptide found in the venom of the deathstalker scorpion (Leiurus quinquestriatus) which blocks small-conductance chloride channels.

[2] The fact that chlorotoxin binds preferentially to glioma cells has allowed the development of methods for the treatment and diagnosis of several types of cancer.

Chlorotoxin exerts a dual effect on MMP-2: it inhibits the enzymatic activity of MMP-2 and causes a reduction in the surface expression of MMP-2.

This result implies the use of chlorotoxin as a highly effective drug of therapeutic potential for diseases that involve the activity of MMP-2.

[9] Phase II trials are being conducted on the use of chlorotoxin for imaging and radio therapy in glioma.

Studies in mouse models have shown that CTX:Cy5.5 can identify tumors with as few as 2000 cancer cells, making it 500 times more sensitive than MRI.

Treated animals exhibited no neurologic or behavioral deficits, and postmortem studies revealed no evidence of neuropathy.