Pick Your Poison

Arsenic, a poison, has been cleared by the U.S. Food and Drug Administration (FDA) to treat promyelocytic leukemia in the form of arsenic compound arsenic trioxide (ATO).

The compound may benefit patients with certain brain and connective-tissue tumors.

Brain tumors called medulloblastomas and connective-tissue tumors known as Ewing sarcoma (both characterized by incorrect activation of the signaling pathway Hh/GLI1) were both suppressed by ATO in a recent study conducted with mice at Georgetown University Medical Center.

The study authors suggest ATO as a potential therapy for tumors that exhibit the incorrectly activated Hh/GLI1 signaling pathway, predominately found in childhood cancers.

Praveen Raju of Weill Cornell Medical College, New York, cautioned in an accompanying commentary that the Hh pathway is crucial for both embryonic and postnatal development. ATO's effects on the pathway could potentially result in severe side effects for child patients.