An non-surgical approach, called vascular-targeted photodynamic therapy (VTP), may be a new way of treating early stage and localized prostate cancer, according to a study published in The Lancet Oncology.
The technique involves injecting a light-sensitive drug, called WST11, into the bloodstream and then activating it with a laser, via optical fibers inserted directly into the prostate. The laser causes WST11 to release free radicals that kill surrounding cancerous cells in the prostate tissue.
A Phase 3 clinical trial (NCT01310894) led by Mark Emberton, dean of Medical Sciences at University College London and a consultant urologist at University College London Hospitals, and funded by Steba Biotech, tested the approach in 413 patients with low-risk prostate cancer at 47 different sites in 10 countries across Europe.
Results of the study, “Padeliporfin vascular-targeted photodynamic therapy versus active surveillance in men with low-risk prostate cancer (CLIN1001 PCM301): an open-label, phase 3, randomised controlled trial,” showed that almost half (49%) of the men treated with VTP went into complete remission, compared to 13.5 percent in the control group under active surveillance.
In addition, only 6 percent of the patients in the VTP group required radical therapy, which involves complete removal or irradiation of the prostate, compared to 30 percent in the control group.
The risk of the cancer progressing to a more advanced stage was also three times lower in the VTP group, and the average time for progression to the next stage was more than two years (28 months) in patients treated with VTP compared to just more than one year (14 months) in the active surveillance group.
“These results are excellent news for men with early localized prostate cancer, offering a treatment that can kill cancer without removing or destroying the prostate,” said Emberton in a press release.
Currently, active surveillance, which involves close monitoring, is the routine treatment for men with low-risk prostate cancer. Radical therapy is only initiated if the disease becomes more severe. But serious side effects are associated with radical therapy, including life-long erectile problems and incontinence. VTP treatment was found to cause only short-term erectile and urinary problems, which disappeared fully after two years, according to the study.
The approach was developed by researchers at the Weizmann Institute of Science in Israel in collaboration with Steba Biotech, which holds the commercial license for this technology, and has been tested in Phase 1, 2, and 3 studies worldwide.
According to Emberton, it is remarkable that the treatment has been successfully performed by non-specialists working different health systems. “[T]he lack of complications in the trial suggests that the treatment protocol is safe, efficient and relatively easy to scale up,” he said, adding that the treatment is increasingly precise “as technology has come a long way since the study began in 2011.”
Clinicians can now “pinpoint prostate cancers using MRI scans and targeted biopsies, allowing a much more targeted approach to diagnosis and treatment,” he added.
“This means we could accurately identify men who would benefit from VTP and deliver treatment more precisely to the tumour. With such an approach we should be able to achieve a significantly higher remission rate than in the trial and send nearly all low-risk localized prostate cancers into remission,” Emberton said.
The treatment is currently under review by the European Medicines Agency (EMA) for approval. In the U.S., VTP has been tested at Memorial Sloan Kettering Cancer Center in New York, where preclinical work into more advanced cancers is also underway.