RESEARCHERS have harnessed a drug based on chlorophyll, the pigment that reacts with sunlight to produce energy in plants and make them green, to develop a treatment for prostate cancer.
The scientists injected the drug into patients and then “activated” it using tiny lasers inserted into the prostate gland. The chemically modified chlorophyll attacked and blocked the blood vessels that fed the tumours, killing the cancerous cells within days.
The technique remains experimental but trials at University College London (UCL) and in Canada suggest it has strong potential. “This is one of the most promising treatments for prostate cancer I’ve seen,” said John Trachtenberg, director of the prostate centre at Princess Margaret hospital in Toronto, who is overseeing the trials.
Prostate tumours are among the most common and deadliest of cancers in men with 30,000 new diagnoses and 10,000 deaths a year in Britain alone.
Sufferers of the disease have included Lord Runcie, the late Archbishop of Canterbury, Nelson Mandela and Bob Monkhouse, the late comedian.
The cancer can be cured if caught early but it is difficult to discriminate between cancerous and normal tissue using conventional therapies such as surgery or radiotherapy. Patients are often left incontinent and impotent because the nerves controlling urination and sexual function pass through the prostate and are destroyed along with the cancerous tissue.
The new research was prompted by these drawbacks. The technique was devised by Avigdor Scherz, in collaboration with Yoram Salomon from the department of Biological regulation. Professor Scherz is a plant biochemist based at the Weizmann Institute of Science in Israel. One of his family was stricken by cancer.
He knew that when chlorophyll was struck by light it could be induced to release a surge of “free radicals” — highly reactive molecules capable of destroying nearby cells. He reasoned that, in the darkness of the human body, a drug based on chlorophyll would remain inert unless hit by light.
“By illuminating a tumour with intense light we could activate the drug only around the cancerous cells, leaving the rest of the body unaffected,” he said.Scherz tested different chlorophyll molecules from plants and micr