Cancer - A Virus to treat Cancer

• When pharmacologists develop cancer drugs, they look for compounds that will target tumor cells but not harm healthy cells. One of the fundamental properties of cancer cells is that they divide continuously while most healthy cells do not.
• Because HSV1716 is unable to make the protein ICP34.5 it does not replicate in nondividing cells.
• HSV1716 kills dividing cells because the process of viral replication results in the death of the host cell.
• The process of viral replication has the added benefit of creating more copies of HSV1716 which are able to replicate in and kill additional tumor cells to the point of tumor eradication. Therefore, the amount of virus needed to kill a large tumor may be relatively small.
• The selective replication phenotype in vivo appears to be specific to tumor cells and in vitro to actively dividing cells.

Oncolytic Herpes Viruses as Therapies

HSV1 (and other lytic viruses) are highly efficient micro-organisms that replicate at the expense of the host cell - their strategy for effectively entering human cells, avoiding detection by the immune system, replicating, and finally bursting from the host cell and thus killing ('lysing') it, have been honed by millions of years of evolution. This strategy has resulted in approximately 90% of the world's population being infected with HSV1.

If this cell-killing ability could be targeted only to selected cells, these 'killers' might be turned into effective treatments for many types of cancer - a disease in which previously healthy cells replicate at a high rate and in an uncontrolled manner.

HSV1716, our lead product, has a single gene deletion that results in a virus that can only replicate in and lyse rapidly dividing cells. This allows HSV1716 to infect and lyse rapidly dividing cancer cells while leaving normal host tissue unaffected.