Laser-activated drug offers new hope for prostate cancer treatment

A new laser-based treatment for prostate cancer has shown promise as a new therapy, without the need for surgery.

In a new study, published Tuesday in the Lancet Oncology, scientists at UCL in the UK injected cancer patients with a light-sensitive chemical that, on entry into the prostate, could be activated by lasers to kill cancerous cells, while avoiding the surrounding healthy cells and tissue.

Prostate cancer is the fourth most common cause of cancer worldwide, and the second most common cancer among men. It’s estimated that there were more than 180,000 new cases of prostate cancer in the US in 2016, with more than 26,000 deaths, according to the American Cancer Society.

Current care for prostate cancer patients often involves monitoring them closely until their cancer has become more severe, at which point their prostate is either removed or completely irradiated, bringing with it the risk of long-term side-effects, including erectile problems or incontinence.

But this new treatment, known as vascular-targeted photodynamic therapy (VPDT), offers hope to go in earlier. Nearly half of the patients receiving it went into complete remission, as opposed to just 13% in the control group after two years of follow-up.

“These results are excellent news for men with early localised prostate cancer, offering a treatment that can kill cancer without removing or destroying the prostate,” said Professor Mark Emberton, dean of UCL Medical Sciences and consultant urologist at University College London Hospital who led the research.

The therapy was trialed on 413 patients with low-risk prostate cancer across 10 European countries. Participants were randomly assigned to either receive the new light-based therapy or standard care – in this case, active surveillance.

“This is truly a huge leap forward for prostate cancer treatment, which has previously lagged decades behind other solid cancers, such as breast cancer,” Emberton said in a statement, adding that while breast cancer can often be treated today without the need of a mastectomy to remove the breast, the main options for prostate cancer patients remain removal of their prostate or total irradiation of the gland.

The new therapy also shortened the duration of side-effects, with most cases being resolved within three months, and all patients no longer experiencing side effects after two years.

“The success of this new tissue-preserving treatment is welcome news indeed,” he said.

‘I didn’t want to wait’

A patient in his 60s, known only as Gerald, was one of the first people to receive the new laser therapy, according to the researchers. He explained he didn’t want to have to wait for his cancer to get worse before receiving treatment and that this new therapy has changed his life in terms of survival, but also quality.

“The treatment I received on the trial changed my life. I’m now cancer-free with no side-effects and don’t have to worry about needing surgery in (the) future. I feel so lucky to be in this position,” he said in a statement.

He met others with the same condition that had undergone therapy and had to stay in the hospital for several days, with one person experiencing severe incontinence. Gerald, however, could go home the day after his procedure and had minimal side effects, he said.

I had some minor side effects for a few weeks after the operation, but I’m back to normal now,” he said. “When I was diagnosed with early prostate cancer, I had the option of active surveillance but I didn’t want to wait until it got worse so when I was offered a place on the trial I signed up straight away.”

How it works

This targeted form of photodynamic therapy was developed by scientists at the Weizmann Institute of Science in Israel in collaboration with biotechnology company, STEBA Biotech.

The process involves infusion of a light-sensitive drug – or dye – into the blood stream to reach the affected lobe of the prostate. After the chemical is localized, optical fibers are inserted into the same affected region to deliver light.

Laser light at a specific wavelength of light is then given through the optical fibers that are then absorbed by the light-sensitive drug to activate it. Once activated, the drug blocks blood flow around the tumor cells, causing them to die.

“It’s basically like putting a dye inside a tumor and then shining a light on it to make it vanish,” said Mustafa Djamgoz, professor of oncology at Imperial College London, who was not involved in the study. “(This) technology does it through the blood supply … which makes it less invasive.”

In the trial, patients receiving the therapy saw a range of improvement in addition to the increased chances of remission. Their chances of cancer progressing to a more dangerous stage were three times lower, treatment doubled the average time to progression to 28 months, and only 6% of patients needed radical therapy – where their prostate would either be removed or completely irradiated – compared to 30% in the control group.

A further benefit was the lack of long-lasting side-effects. “A big problem in cancer is targeting the cancer and not affecting the rest of the body … and this technique does that,” said Djamgoz, adding that although this is a significant step toward a new therapy, “it didn’t happen overnight.” More than a decade of research has gone into this result.

“New procedures are generally associated with a learning curve, but the lack of complications in the trial suggests that the treatment protocol is safe, efficient and relatively easy to scale up,” said Emberton who also hopes that more recent developments in MRI scanning and targeted biopsies, that occurred after this trial began, could further improve his new treatment.

“We could accurately identify men who would benefit from VPDT and deliver treatment more precisely to the tumor,” he said. “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.”

The team believes this technique could one day be applied to other forms of cancer, such as breast and liver cancer. But for now, prostate cancer is the priority. “Prostate cancer needs major changes in treatment,” said Djamgoz. “So if there is another way of destroying the tumor (like this), it’s welcome.”

“It’s exciting to see photodynamic therapy being used for prostate cancer,” said Malcolm Mason, professor of clinical oncology at Cardiff University and Cancer Research UK’s prostate cancer expert. Mason was not involved in the research and highlighted that many questions remain before this can become a widespread treatment.

“While the results show that this technology can effectively kill prostate cancer cells, it’s not clear yet if it could improve the quality of life for men with the disease or save lives. With longer follow up, it could have long-term benefits that we can’t see yet,” he said.

The treatment is currently under review by the European Medicines Agency, so it will be some time before it becomes readily available to patients. “It’s important that these types of trials are done so that we can assess and improve treatment for low risk prostate cancer patients,” said Mason.