Could Toxin From The Bacteria That Causes Diphtheria Be Used To Treat Cancer?

New research suggests that it could. Scientists investigating ways of encouraging the immune system to recognise and kill tumour cells have found that a drug containing parts of the diptheria toxin appears to work well in patients with advanced skin cancer.

In the first part of a clinical trial to test the drug denileukin diftitox five out of seven patients with stage IV melanoma showed significant regression or stabilisation of both tumours and metastases (secondary tumours). The cancer progressed in the other two patients but these were on a lower dose of the drug. All the patients were expected to live only 8 months but were still alive after 12 months.

Denileukin diftitox is a fusion protein made up of amino acid sequences for the diptheria toxin and the T cell growth factor, interleukin 2. T cells are cells of the immune system but only some respond to cancer cells and tumours and try to destroy them. Others try to damp down this response. The drug is taken inside T cells that do this damping down; it then stops protein synthesis and kills the cells. Without the damping down T cells, the body's immune system goes into full swing against the tumour.