LONDON – A non-surgical treatment of low-risk prostate cancer, in which doctors inject a light-sensitive drug derived from deep-sea bacteria in a patient’s bloodstream was shown in a trial to kill cancer cells without destroying healthy tissue.
Results from a trial in 413 patients showed that the drug, which is activated with a laser to destroy tumor tissue in the prostate, was so effective that half of the patients went into remission, compared with 13.5 percent in a control group.
“These results are excellent news for people with early localized prostate cancer, offering a treatment that can kill cancer without removing or destroying the prostate,” said Mark Emberton, University College London consultant urologist who led the study. “This is really a huge leap forward.”
The treatment, the so-called vascular-targeted photodynamic therapy or VTP, developed by scientists of the Weizmann Institute of Science in Israel, in cooperation with the private property STEBA Biotech.
The light-sensitive drug that is used, the so-called WST11, is derived from the bacteria on the bottom of the ocean. To survive with little sunlight, they have evolved to convert light into energy with incredible efficiency, Emberton, the team said in a study published in the journal Lancet Oncology.
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The Weizmann scientists exploited this feature to develop WST11, a substance that release free radicals to kill surrounding cells activated by the laser light.
Men with low-risk prostate cancer are currently under active surveillance, where the disease is monitored and treated only when it becomes more severe. Radical therapy, in which surgical removal or irradiation of the entire prostate gland, has significant long-term side effects so is only used for the treatment of high-risk tumors.
While radical therapy causes a lifelong erectile problems and incontinence, VTP only caused short-term urinary and erectile problems that are resolved within three months, the researchers said. No significant side effects remained after two years.
In the test, only 6 percent of patients treated with VTP need radical therapy compared with 30 percent of the patients in the control arm, which is under active surveillance.
The trial involved 47 treatment sites in 10 European countries, most of which were running VTP for the first time.
“The fact that the treatment was performed with so much success by non-specialised centres in the different health systems is truly remarkable,” Emberton said.
The VTP treatment is now being reviewed by the European Medicines Agency (EMA) for possible license, but probably for a number of years before it can be offered to patients more widely.