Prostate Cancer Drug Abiraterone Shows Impressive New Research Results

Main Category: Prostate / Prostate Cancer
Also Included In: Cancer / Oncology
Article Date: 28 May 2009 - 6:00 PDT

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

The drug, discovered 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.

This second publication of a phase I/II study, reporting on 54 patients, confirms 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.

These phase I/II studies were undertaken by the ICR and The Royal Marsden Hospital 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 tumors 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, 70, from Sheffield, was involved in the phase II abiraterone clinical trial. He says: "Two 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 two 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 150 hospitals across the world, in one of the largest ever trials for end-state prostate cancer. More than 1300 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 by 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."

The Phase III abiraterone trial in prostate cancer patients has reached full recruitment.

Abiraterone was discovered and developed in the Cancer Research UK Cancer for Cancer Therapeutics at The Institute of Cancer Research and is licensed to Cougar Biotechnology, Inc.

This study was funded by Cougar Biotechnology, Inc. the Medical Research Council (MRC), Prostate Cancer Foundation (USA), Cancer Research UK, the ICR and the Royal Marsden Hospital.

Notes

- Selective inhibition of CYP17 with abiraterone acetate is highly active in the treatment of castration-resistant prostate cancer was published online in the Journal of Clinical Oncology on 26 May 2009

- Phase I Clinical Trial of a Selective Inhibitor of CYP17, Abiraterone Acetate, Confirms That Castration-Resistant Prostate Cancer Commonly Remains Hormone Driven was published online in the Journal of Clinical Oncology on 22 July 2008.

- Molecular Characterization of Circulating Tumor Cells from Patients with Castration-Resistant Prostate Cancer (ERG gene paper) was published in Cancer Research on 1 April 2009

This trial is a phase I/II study with a phase II expansion.
Abiraterone is also in an early clinical trial for women with advanced breast cancer, who have exhausted all other treatments. This trial is being run and funded by Cancer Research UK.

For patient information about the breast cancer study involving abiraterone and other treatments, please visit CancerHelp UK (www.cancerhelp.org.uk) or call the Cancer Research UK team of specialist nurses on 0808 800 40 40. Lines are open Monday to Friday, between 9am and 5pm.

Prostate Cancer

- Prostate cancer has overtaken lung cancer to become the most common cancer in men affecting more than 35,000 men every year in the UK. One man dies of prostate cancer in the UK every hour.

- For the majority the majority of men, prostate cancer is not a life-threatening disease, however about 10,000 men die of the aggressive form of the disease each year.

Source
Institute of Cancer Research