BC-819 uses the H19 gene to target susceptible tumor cells. A vehicle is constructed to gain access to the targeted cell, and the host cell's internal machinery is directed to produce Diptheria Toxin (DTA). BC-819 enters all dividing cells, but while it will destroy the cancerous cells that express H19 it will be just a strand of non-functional DNA in non-cancerous cells.

DTA is one of the most lethal toxins known to mankind, and has proved to be the most efficient agent for the targeted destruction of cancerous growths. Because of this, it has been a frequently-used component of targeted approaches to cancer therapy, including immunotoxins and gene therapies, and has been approved by the FDA for a number of cancer treatments. There are two strong safety factors protecting the patient receiving DTA. The first is that Western societies are fully immunized against Diphtheria Toxin. The second is that the technology only utilizes the ‘A' fragment of the toxin, not the ‘B' fragment that would allow the toxin to replicate itself.