Researchers from the Weizmann Institute of Science and Steba Biotech have reportedly developed a light-sensitive drug derived from deep-sea bacteria that has been shown to kill cancer cells in low-risk prostate cancer patients without affecting healthy tissue. The team’s work was published in Lancet Oncology.

Vascular-targeted photodynamic therapy, VTP, utilizes a drug called WST11 which was derived from bacteria that survive with very little sunlight at the bottom of the ocean. The bacteria have evolved to efficiently convert light into energy. This property enables WST11 to release free radicals and kill surrounding cells when exposed to a laser light.

“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,” lead researcher Mark Emberton said, according to Reuters. “This is truly a huge leap forward.”

The trial enrolled 413 patients at 47 treatment sites across 10 European countries. Half of the patients who received VTP went into remission, while 13.5% of the control group went into remission.

Normally, men with low-risk prostate cancer are actively observed by their doctors and only treated when the cancer progresses. High-risk cancer patients sometimes undergo radical therapy, surgically removing or irradiating the prostate, which can cause lifelong erectile problems and incontinence.

The researchers found that VTP only caused short-term urinary and erectile problems and that no significant side effects remained after 2 years. Just 6% of patients who received VTP required radical therapy, compared to 30% of the patients in the control arm.

The European Medicines Agency is reviewing VTP as a possible treatment method for low-risk prostate cancer patients, but the process is expected to take several years.