After decades of deaths from all varieties of cancer, hope is on the horizon.
Some amazing results have come from Phase I Clinical Trials for Recurrent Glioblastoma patients at the Preston Robert Tisch (PRT) Brain Tumor Center at Duke University. The bottom line is that the cure for all cancers is not set in concrete, but the recipe for the concrete is known as PVS-RIPO and has been successfully set in targeting an aggressive form of brain cancer.
PVS-RIPO is a genetically engineered poliovirus that was being investigated as a new anti-cancer agent at the PRT Brain Tumor Center. Even though the idea of targeting cancer with viruses has been around for about a century, legitimate strategies of using cancer-fighting viruses emerged only recently. Technological advances in genetic engineering of viruses have opened this door for medical science.
Safe oncolytic (cancer-fighting) viruses must be introduced into cancer cells and do two things: (1) destroy or render useless the cancer shield that keeps the immune system from attacking the cancer cells and (2) actually attack the cancer cells. But most importantly, they must be safe. Physicians cannot introduce a Trojan horse that will successfully destroy the enemy, but will also attack the host.
Accomplishing this was very difficult since only a few viruses were considered safe. However, researchers utilized genetic engineering to remove the poliovirus’ dangerous disease-causing ability. An innocuous piece of a cold-causing rhinovirus was spliced into the poliovirus genome. This poliovirus kills cancer cells, but does not harm normal cells. Safety testing in both monkeys and human patients have shown: (1) no nerve cell killing, (2) no ability to cause poliomyelitis, and (3) no ability of PVS-RIPO to change back to a wild type poliovirus that can cause poliomyelitis.
The FDA approved clinical trials with PVS-RIPO in brain tumor patients recently. Since May of 2012, five brain tumor patients have been treated. There have been no toxic side effects with PVS-RIPO whatsoever, even at the highest possible dose of 10 billion particles.
These patients have done extremely well in fighting their cancers. The first patient was treated in May of 2012 and she is now symptom free. The other patients have had similar good results with a cancer that is aggressive usually resulting in a prognosis of the patient having a short life span after diagnosis. One patient died six months following the PVS-RIPO infusion, due to tumor regrowth.
PVS-RIPO is infused directly into a patients’ tumor, assuring that the maximum amount of virus is delivered directly to the tumor. Once inside the tumor, PVS-RIPO infects and kills tumor cells. Although this tumor cell killing alone may have tumor-fighting results, the likely key to therapy with PVS-RIPO is its ability to enable the immune response against the cancer. The human immune system is trained to recognize virus infections so will respond to the PVS-RIPO.
Currently, Phase I clinical trials of PVS-RIPO against recurrent glioblastoma brain tumors are ongoing at Duke. Phase II/III will be future phases to establish PVS-RIPO as a possible therapy for brain tumors. The exciting news is that PVS-RIPO has the potential to work for other types of cancers. The mechanisms responsible for PVS-RIPO’s effects against brain tumors broadly apply to almost all cancers. Because PVS-RIPO naturally targets and destroys cancer cells from most common cancer types (pancreas, prostate, lung, colon, and many others), it can be directed against these cancers as well. To establish this in the clinic, future clinical trials are planned for patients with cancers other than brain tumors.
The key to better cancer care is a better understanding of the disease and the mechanisms that may work to fight it. We already have much information about PVS-RIPO, because of a very successful research effort in the Gromeier Laboratory that now spans over 10 years. Scientists will continue to identify why anti-tumor responses occur in brain tumor patients infused with PVS-RIPO.
Research currently ongoing in the Gromeier Laboratory is designed to a) explain why/how PVS-RIPO kills cancer cells selectively; b) unravel how the patients’ immune system responds to tumor infection with PVS-RIPO; and c) how this immune response fights the tumor itself.
In several years, we may look back on this day as a banner day to celebrate the discovery of the cure for all types of cancers.