An experimental virus could open a new path in the fight against pancreatic cancer, one of the most formidable cancers that patients and doctors must fight against. During a preliminary clinical trial conducted in the United States, this treatment stopped the progression of the disease in three patients. Although these results have yet to be confirmed on a larger scale, they already raise great hope.
The treatment relies on a genetically modified virus, designed to specifically target cancer cells. A feat all the more impressive when we know that the researchers only administered a very low dose, equivalent to a tenth of that planned in the long term, in order to first test the safety of the protocol. Despite this, the observed effectiveness exceeds initial expectations.
Pancreatic cancer is particularly difficult to treat, recalls New Scientist. It is often diagnosed late, when the tumor has already spread and surgery is no longer possible. Under these conditions, life expectancy after diagnosis is generally limited to a few months. Another difficulty lies in the very structure of pancreatic tumors: very dense and fibrous, they prevent chemotherapy drugs from penetrating effectively. In addition, these tumors manage to evade the immune system, rendering traditional immunotherapies largely ineffective.
In the current trial, treated patients had localized tumors, which had not yet spread to other organs. Since administration of the virus, no tumor progression has been observed, the patients are still alive and their condition is considered clinically stable.
Cascading beneficial effects
To administer the treatment, doctors inject the virus directly into the tumor using a thin tube inserted through the throat into the pancreas and guided using an ultrasound imaging system. Although the tumors did not decrease in size, they stopped growing, which could be explained by the low dose administered. It is possible that with higher doses or longer action time, tumors may shrink.
Furthermore, this treatment could have a beneficial indirect effect by activating the immune system. As they disintegrate, cancer cells release signals that alert the body, which could then learn to recognize and attack other tumor cells, including those that have migrated elsewhere in the body.
Researchers are now considering combining this viral approach with immunotherapies, including immune checkpoint inhibitors, to strengthen the body’s response against cancer.
This use of viruses to treat cancer is not new, and we find work dating back to the 1950s having already explored this avenue. Today, thanks to advances in genetic engineering, these treatments can be designed to precisely target diseased cells, and new engineered viruses could join the only such treatment now approved in the United States: a modified herpes virus used against certain skin cancers.
