Hopes for a new, effective treatment for prostate cancer are growing after the experimental drug abiraterone was shown to shrink tumours and reduce pain in around two-thirds of patients with a particularly aggressive form of the disease.

A Cancer Research UK-funded Phase I/II trial of the drug, which was discovered by scientists at The Institute of Cancer Research, showed that 70% of patients responded to treatment with abiraterone and that two-thirds experienced improvements – including tumour shrinkage and reduced levels of the prostate specific antigen disease marker – for eight months.

Importantly, the scientists also discovered that combining the drug with a steroid extends its efficacy for a further 12 months. In addition, they also found that patients demonstrating the most extreme tumour shrinkage had an abnormality on the ERG gene, which has enabled them to develop a test to identify which patients are most likely to benefit from abiraterone therapy.

According to chief investigator Dr Johann de Bono, the drug has changed the way the science community looks at prostate cancer. “It can block the production of male hormones, including hormones produced by the tumour itself [and] the more we learn about how this drug works the more we will be able to find further ways of counteracting a patient’s potential genetic resistance to it.”

And Professor Peter Johnson, chief clinician at Cancer Research UK, said the drug is “an excellent example of how research which leads to better understanding of the biology of a cancer can give us new opportunities for its treatment”.

All eyes will now be on the outcome of a large-scale Phase III trial of abiraterone involving more than 1,300 men in 150 hospitals around the world. If successful, the researchers hope that the drug could be available for use in all patients in as little as two years.