A new type of drug could revolutionise the treatment of therapy-resistant prostate cancer, early research suggests. The “cyclic peptoid” molecules block the action of genes that drive prostate cancer growth.

Importantly, they do not target the hormone signalling pathways that are central to standard therapies. Hormone treatments for prostate cancer have life-changing side effects including loss of sex drive, muscle weakness, brittle bones and abnormal breast growth.

Currently, when these drugs stop working the only other option is chemotherapy. This can have even worse side effects including immune system suppression, anaemia, and the risk of brain bleeds.

In laboratory tests, cyclic peptoids reduced the growth of prostate cancer cells by up to 95%. Animal studies showed how they blocked a key cancer-driving growth signal. Senior researcher Professor Kent Kirshenbaum, from New York University, said:

“We designed our peptoids specifically to hit targets that are currently ‘undruggable’, such as those causing treatment-resistant prostate cancer.”

The compounds interfere with the interaction between beta catenbin protein and T-Cell Factor (TCF) transcription factors. These are proteins that turn on genes and cause cells to multiply.

The gene activity involved is critical to the early development of prostate tissue, but is normally dialled-down in adulthood. Changes that re-activate the genes can lead to cancer.

The drugs showed no evidence of toxicity when given to zebrafish at a dose relatively equivalent to what would be used in humans. Next the peptoids will be tested on human prostate tumours grown in mice.

Each year, around 47,000 UK men are diagnosed with prostate cancer and more than 11,000 die from the disease. The research is published in the journal Nature Communications.