A revolutionary suicide gene therapy has been proven effective in combating prostate cancer, as evidenced in a recent study published on Saturday, December 12 in the journal of Radiation Oncology.
Research was conducted by experts at Houston Methodist Hospital from Texas, and included a group of 66 individuals, who suffered from prostate cancer.
Those with a more advanced form of the disease underwent treatment involving radiotherapy, coupled with androgen deprivation therapy (ADT), while those who had a milder type of prostate cancer were only given radiotherapy, without any hormone therapy.
During the course of the experiment, which unfolded between 1999 and 2003, the subjects also participated in suicide gene therapy, a newly invented type of medical procedure through which genes can be used so as to combat disease.
Patients who had more severe prostate cancer benefited from this type of treatment on 3 occasions during the trial, while the rest of the individuals underwent two such sessions.
More precisely, scientists altered prostate cancer cells so as to incorporate a herpes simplex virus gene. That DNA material was transported inside the genes by employing adenoviruses, just like the ones that transmit conditions such as bronchitis, conjunctivitis, pneumonia or the common cold.
As the herpes gene took over the cells and started releasing thymidine kinase, researchers promptly treated the subjects with valacyclovir (Valtrex), an antiviral drug used against herpes infections.
Shortly afterwards, as the immune system went in alert mode, prostate cancer cells began dying off, to the point where the disease was virtually eradicated.
Under normal conditions, tumor cells manage to disguise themselves so as to remain undetected by the body’s immune system, by increasing the activity of regulatory T cells, which prevent excessive reactions to inflammation.
However, in suicide gene therapy, cancer cells can be easily identified, and eradicated successfully, one by one.
Overall, during follow-up studies, it was determined that 97% of the subjects who had been diagnosed with less advanced forms of prostate cancer were still alive 5 years following the trial. Similarly, those who had been more critically ill had a 94% survival rate, 5 years after the diagnosis.
This means that the newly developed treatment, which forces tumor cells to self-destruct, resulted in boosting life expectancy for prostate cancer patients, by as much as 20%.
In addition, when conducting biochemical analysis to determine the risk of cancer recurrence, it was proven that between 79% and 83% of the patients who had received this type of gene therapy showed no signs that their tumor would re-emerge, 5 years upon completing their treatment.
As explained by Bin Teh, radiation oncologist at the Houston Methodist Hospital, progress that has been achieved through suicide gene therapy is substantial, especially since a few of the patients who were eventually cured had been told by their physicians that their disease was simply too advanced so as to be surmounted.
Moreover, the procedure is completely safe and highly efficient in vanquishing prostate cancer, especially when used in conjunction with intensity-modulated radiation therapy.
High success rates were recorded even in the absence of androgen deprivation therapy, which is commonly employed so as to stop prostate tumors for becoming more widespread and aggressive.
Meanwhile, experts such as professor Kevin Harrington, at the Institute of Cancer Research in London have declared that although these findings are certainly quite promising, further research should be conducted so as to test the effectiveness of this therapy.
Ideally, other viruses that can actually replicate should be used instead, so as to target and infect all tumor cells, in order to destroy them much faster.
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