Hormone Inhibitor Promising For Hard-To-Treat Prostate Cancer

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology
Article Date: 09 Jul 2007 - 1:00 PDT

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For prostate cancer patients whose tumors have continued to grow despite medical or surgical castration, a new drug candidate that inhibits production of male hormones anywhere in the body is showing promise in early trials.

Two poster presentations at the ESMO Conference Lugano this week show that the drug, called abiraterone, reduced levels of "prostate specific antigen", a marker of cancer activity, and shrank tumors in patients in whom hormone therapy had stopped working and also in patients who had previously been treated with chemotherapy.

Male hormones such as testosterone are produced mainly in the testes, but are also produced by the adrenal gland and elsewhere in the body. These hormones can stimulate prostate cancer cells to grow, so the first treatment option for all men with prostate cancer that has spread, is to use chemical suppressants or surgery to inhibit testicular synthesis of male hormones. However, this treatment does not block the production of male hormones elsewhere in the body. Abiraterone, a drug that is taken orally, inhibits an enzyme called CYP450c17, which is critical to the production of the male hormones - not only in the testes, but also at other sources.

Dr. Alison Reid from The Institute of Cancer Research and Dr. Gerhardt Attard from The Institute and The Royal Marsden NHS Foundation Trust in London described two ongoing Phase II trials of the drug in men with advanced prostate cancer.

Men in both studies were given 1000mg of abiraterone daily. The first study treated men who had not previously received chemotherapy. So far 34 men have been treated, of whom 22 have seen their PSA levels drop at least 50% after 2 months. Some patients have also had shrinkage of their tumors (partial response).

This represents "significant anti-tumor activity," the researchers say.

In the second study, the UK team studied 28 men whose cancer was growing despite treatment with the chemotherapy drug docetaxel. Ten of these men have seen PSA declines of more than 50% that have lasted at least 3 months from the start of taking abiraterone, with no major toxicities or adverse events.

Overall, the results are significant, the authors say. The drug has produced PSA decline rates by greater than 50% in 60% of pre-docetaxel patients and 50% of post-docetaxel patients. These results are supported by evidence of tumour shrinkage on scans, drops in circulating tumor cell counts and improvements in symptoms.
A Phase III trial of abiraterone is planned for next year.

About the European Society for Medical Oncology (ESMO)

The European Society for Medical Oncology (ESMO) is the leading European non-profit, professional organization for medical oncology with a focus on promoting multidisciplinary cancer treatment around the world.

ESMO unites medical oncologists, oncology specialists, healthcare professionals, caregivers, patients and policy makers in a global alliance committed to eradicating cancer and ensuring equal access to high quality treatment for all patients. Thanks to its state-of-the-art education and training programs, ESMO plays an instrumental role in providing the oncology community with the most up-to-date scientific research and information available. Through its flagship journal, Annals of Oncology, ESMO publishes articles on all aspects of clinical oncology. ESMO is dedicated to educating and supporting oncologists, optimizing patient care, disseminating cancer-specific information to the public, and advocating patient rights. As an authoritative voice in the fight against cancer, ESMO provides both the platform and the consultative expertise to influence national and international organizations as well as European authorities, in order to establish common standards for a multidisciplinary approach to cancer treatment.

For more information about ESMO, please visit http://www.esmo.org

About ESMO Conference Lugano (ECLU)

ECLU 2007 represents the new direction ESMO has given to the scientific and educational meeting previously known as the ESMO Summer Educational Conference (ESEC). It will be held every July under the auspices of the City of Lugano, hometown to the European Society for Medical Oncology (ESMO). Around 1000 young oncologists, senior oncologists and cancer healthcare professionals will attend sessions on the latest developments in multidisciplinary oncology which will cover progress in cancer research and promising new technologies. International cancer specialists will highlight progress on important topics such as pharmacogenomics, molecular diagnostics, molecular-targeted therapies, new frontiers in response evaluation, cancer prevention and state-of-the-art oncology at its finest. Each Conference will also include a session on a specific topic, which in 2007 is the important issue of cancer prevention.

The 6th ESMO Patient Seminar, 7 July 2007, will also take place during ECLU. The Patient Seminar provides patients, their families and caregivers the opportunity to interact with international and local oncologists and learn more about the most recent developments and options in cancer treatment. More information about ECLU is available at http://www.esmo.org/activities/ecluconference/