A new long-term clinical trial conducted by Houston Methodist Hospital researchers has tested radiation treatment in conjunction with a technique called "suicide gene therapy," which genetically modifies prostate cancer cells so that they stimulate a patient's immune system to attack them. The results show that the technique is a safe and effective method of treating the disease - there was a 20 percent survival improvement in the group of patients that underwent the therapy.
"We strategically used an adenovirus, similar to the one that causes the common cold, to carry the therapy agent-a herpes virus gene that produces the enzyme thymidine kinase, or TK-directly into the tumor cells," Brian Butler, senior author of the paper, said in a press release. "Once the herpes virus gene was delivered and it started manufacturing TK, we gave patients a commonly used anti-herpes drug, valacyclovir. The combination attacked the herpes DNA, and the TK-producing tumor cells self-destructed, which is why the procedure is called 'suicide gene therapy.'"
Once valacyclovir, trade name Valtrex, begins to destroy tumor cells, it also signals the patient's immune system to launch an attack on the disease.
"We have created a vaccine with the patient's own cancer cells, a treatment that complements, and may even enhance, what we can achieve with traditional radiation and hormonal therapies," said Butler.
In addition to showing strong results against the cancer cells, patients enrolled in the clinical trial showed little to no side effects or complications, making it a promising option for those with previously incurable diseases.
"This is extremely pleasing to us, considering we had patients enrolled in our protocol after other physicians deemed them incurable," said Bin Ten, lead author of the paper.
The study was published in the Dec. 12 issue of The Journal of Radiation Oncology.
