Virus Capable of Killing Prostate Cancer Cells Shows Treatment Promise
The root terms “onco” means cancer and “lytic” means to burst open. This describes the effect that oncolytic viruses have on target cells. Once the virus enters the host cancer cell it hijacks the cell processes so that it mistakenly copies the viral acids instead of its own nucleic acids. Eventually, the cell becomes so full of virus copies that it bursts and releases its surrogate offspring to infect other cells, thus spreading the anti-cancer infection.
Newcastle disease is a virus that kills chickens but is harmless to humans. It is also an oncolytic virus that seeks out tumor cells and has shown promise in human clinical trials for the treatment of various cancer types. Normal cells have an antiviral system that becomes active when the Newcastle disease virus enters the cell, effectively preventing infection. Cancer cells however, have defective antiviral systems that the Newcastle disease virus exploits to use them as replicating agents.
Previously, clinical trial results with the Newcastle disease virus have not been promising enough because successful treatment requires large injections of the virus. This is likely because not enough of the virus was successfully able to reach the solid tumors so the infection did not spread effectively to other cancer cells.
For the study, corresponding author Subbiah Elankumaran and researchers addressed the problem by altering the viruses fused to their host cell. The researchers modified the Newcastle disease virus’ protein so that it could be activated by prostate specific antigen.
The authors write, “We engineered the F protein of NDV and generated a recombinant NDV (rNDV), whose F protein is cleavable exclusively by prostate specific antigen (PSA).The rNDV replicated efficiently and specifically in prostate cancer (CaP) cells and three-dimensional prostaspheres but failed to replicate in the absence of PSA.
Elankumaran emphasizes that the Newcastle disease virus can potentially offer major advantages over other cancer treatments. First, since it only targets prostate cancer cells and not normal health cells, it’s possible to avoid the numerous unpleasant side effects of conventional cancer therapies. Second it offers an alternative for patients whose disease progresses despite hormone therapy, without the side effects of testosterone suppression that follows hormone treatment.
Currently it is estimated that 1 in 6 men will be diagnosed with prostate cancer during their lifetime, with the disease killing about 1 in 36 men.