Abiraterone Shows Impressive Long Term Survival Benefits

Prostate Cancer Drug Abiraterone Shows Impressive Long Term Survival Benefits

New UK research confirms the groundbreaking cancer drug abiraterone provides significant benefit for up to two-thirds of men upon long term treatment for advanced and aggressive prostate cancer, according to a study published online in the Journal of Clinical Oncology.

The drug, discovered by Professor Gerry Potter at The Institute of Cancer Research (ICR) in the Cancer Research UK Centre for Cancer Therapeutics, made headlines in July 2008 when the first UK Phase I clinical trial reported significant shrinkage of patients’ tumours and reduction in pain. Scientists hailed it as one of the most significant developments in prostate cancer in 60 years. There is an 8 year survivor from the first Phase I trial started in 2004.

The second publication of a Phase I/II study, reporting on 54 patients, confirmed the Phase I results. In addition, ICR scientists have worked out how to delay drug resistance and developed a test to identify the men most likely to benefit from abiraterone. There are several 6 year survivors from recruitment in 2006 for the Phase II trials.

These Phase I/II studies were undertaken by the Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust and were funded by Cougar Biotechnology Inc. The lead researchers on the study were funded by Cancer Research UK.

Lead researcher Dr Gert Attard says:

“Phase I/II results showed that up to 70 per cent of men responded to the drug, abiraterone. About two-thirds of men experienced significant benefits for an average of eight months, with scans showing their tumours decreased in size and their PSA levels dropped substantially.

“Our latest study also shows that by combining abiraterone with a steroid treatment when abiraterone stops working, we can reverse resistance and extend the response to this treatment by another 12 months.

 “We have also noticed that the majority of patients who had very significant shrinkage of their tumours had an abnormality of a gene called ERG that was probably driving their cancer. We have developed a test for this ERG gene so we can identify the men most likely to benefit from abiraterone.”

Chief investigator Dr Johann de Bono is extremely optimistic about these results:

“Almost all these men had cancer that had spread to the bones, lymph glands and elsewhere. Many were in pain and not enjoying life. The patients involved in this trial remained pain-free for an average of about eight months, a brilliant result for those with aggressive prostate cancer and their families. For about a third of men – those who carried the ERG gene - the benefit lasted for more than 18 months.

“In addition, this 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. 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.”

Mike Torr, 73 from Sheffield, was involved in the original Phase II abiraterone clinical trial in 2007. He says: "Five years ago, I was in severe pain as my prostate cancer had spread to my bones. I was involved in the earlier trials and received the additional steroid treatment to combat resistance. This drug has given me over five years of life, symptom-free. I have been able to go back to fully enjoying my retirement and travelling with my wife to places such as India."

Abiraterone is currently in Phase III prostate cancer trials at more than 200 hospitals across the world, in one of the largest ever trials for end-stage prostate cancer. More than 1500 men have been treated with the drug and it is hoped that, should the trials continue to show a benefit, abiraterone may be available for general use as a prostate cancer treatment in 2011.

Professor Peter Johnson, chief clinician at Cancer Research UK, which helped fund the lead investigators on the study, said: “These early results hold great promise for treating a problem which affects many men with prostate cancer and give us real hope for the future. We are keen to see the results of the larger trials now underway, to find out whether abiraterone should be made generally available. This 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.”