Immunotoxins May be Effective to Treat Colon Cancer

the Cancer Therapy Advisor take:

According to a study published in Oncotarget, immunotoxins, cancer-targeted antibodies bound to toxins like ricin, can attach to key receptors on the surface of colon cancer cells, thereby delivering the toxin to the cancer and killing them. In the study, researchers administered the immunotoxin to lung metastases from colon cancer in mice and found that the metastases were reduced by more than 80% after only six doses.

Scott Waldman, MD, PhD, discovered GUCY2C receptors on colon cancer cells in 1993. Although the receptors are also found on normal cells, they are hidden from the immune system. In the study, researchers found that colon cancer cells absorb the GUCY2C receptors via endosomes. When the immunotoxins bind to the GUCY2C receptors on cancer cells, the cancer cells absorb the receptors, antibodies, and toxins. When lysosomes free the toxin from the antibody, the toxin destroys the cancer cell from the inside.

Waldman has used ricin, but the findings from this study show demonstrate that various agents can be used to create immunotoxins. He also notes that those with esophageal, gastric, and pancreatic cancers could also benefit, as those cancers express GUCY2C receptors as well. Phase 2 clinical trials are currently underway to test the method in those with esophageal and prostate cancers.