The approval comes ahead of its June 20, 2011 regulatory date due to the significant increase in overall survival shown by arbiraterone treatment. In a Phase III study, patients who received abiratone in combination with prednisone had a median overall survival of 14.8 months, compared to 10.9 for patients in the placebo group. Treatment with abiratone also resulted in a 35% reduction in the risk of death.

“While 3.9 months may not seem like much, in the history of prostate cancer, only 4 drugs have ever shown a survival benefit” said abiraterone investigator, Johann de Bono, MD., putting into perspective the apparent modest increase in survival.

The results of the trial were found by an independent panel to be so successful that it was considered unethical to keep the placebo patients without the drug. The study was stopped earlier than planned and placebo patients were crossed over to abiraterone treatment.

Abiraterone inhibits the enzyme CYP17A1 which is found in testicular, adrenal and prostate tumor tissues. The enzyme plays an important role in the production of testosterone which has been found to stimulate prostate tumor growth. Abiraterone works by ”[ultimately blocking] the cancer cell from making its own hormones” said Johann de Bono, resulting in tumor shrinkage.

Abiratone also seems promising in the treatment of breast cancer. A Phase I/II clinical trial evaluating the effectiveness of abiratone in late-state breast cancer patients is underway in the U.K.

Sources: MedScape; April 28, 2011, FDA Press Release,  Investor’s Business Daily; September 24, 2010, ESMO 2010 interview by Oncology Tube: Johann de Bono, MD, GEN; September 10, 2010.

Author: Karla Robleto, Ph.D.

In the first of these studies, a drug called abiraterone shrank tumors by 30% in one-fourth of 31 men whose prostate cancer did not respond to standard therapies and continued to grow. In 35% of the patients taking the experimental drug, their tumors stopped growing.

Standard PSA (prostate-specific antigen) measurements were able to give accurate indications of each response to the new treatment. PSA levels after 12 weeks of treatment with abiraterone lowered PSA levels by 50% or more in 71% of the patients. In two men, the PSA fell so dramatically, it was undetectable.

A leading medical authority at the Cedars-Sinai Medical Center in Los Angeles Radiation Oncology Department called abiraterone currently the most promising prostate cancer drug on the horizon. He explained that the new hormone therapy appears to be active in men not responsive to other hormone treatments.

Abiraterone works differently from other hormone treatments in wide use today. The new drug targets an enzyme called CYP17 that is needed to produce male hormones throughout the body. Current hormonal treatments can only prevent production of male hormones in the testes. Other parts of the body are still able to produce testosterone and related hormones called androgens that fuel the growth of prostate cancer.

The first study involved men who were initially treated surgically or medically to prevent testosterone production in the testes. None had received chemotherapy, sometimes administered when the cancer does not respond well to hormone therapy. Men in the study took abiraterone orally once a day and generally tolerated the drug without serious side effects.

In a second study, men who were given chemotherapy after their hormone treatment no longer worked showed similar encouraging results after taking the experimental drug. Cougar Biosciences is the manufacturer of abiraterone, and they funded this study.

Researchers have begun enrolling men in a larger and longer study. Patients will be randomly assigned to abiraterone or a placebo (sugar pill). If results continue to be promising, the company will apply to the FDA for approval of the drug. Unfortunately, these studies and the approval process can take several years.

In the U.S., prostate cancer was diagnosed in over 180,000 men and 28,000 men died of the disease in 2008. It is the second most common cause of cancer death in the U.S.

Source: WebMD Health News; 3/1/09 written by Charlene Laino and reviewed by Louise Chang, M.D. blog article by Anna Dabney

Taking vitamins will not help those most at risk for prostate cancer to keep from getting it. In fact, a recent study shows it can have the opposite effect.

Researchers followed nearly 300,000 men over a five-year period to uncover a potential link between multivitamins and prostate cancer.  They found no relationship with slow-growing prostate cancer. However, men who took an excessive amount of multivitamins were found to have developed aggressive prostate cancer that had spread beyond the gland or had proved fatal. This association was strongest in men who had a family history of prostate cancer and men who also took selenium, beta-carotene or zinc supplements.

About a third of the men studied took a daily multivitamin, while 5% were heavy users taking more than the recommended doses. Overall, no link was found between multivitamin use and early stage prostate cancer.  The theory is that high-dose vitamins have little effect until a tumor appears, but that their intake then encourages cancer’s rapid growth.

Those who took more than the prescribed dosage on the bottle, one multivitamin a day, increased their risk of aggressive prostate cancer by one-third, and the risk of fatal prostate cancer doubled compared to men who did not take multivitamins.

This year over 250,000 men will be diagnosed and 30,000 will die of prostate cancer.

This study was published in May 2007 and appears in the Journal of the National Cancer Institute.

Sources:  Associated Press; MSNBC

In recent studies of 385 men, those with elevated EPCA-2 test results were found to have cancer 94% of the time, compared with 19% of those showing elevated PSA results. Only 3% showed false positive results and about 6% of existing cancers were missed using the new EPCA-2 blood protein markers. These results compare more favorably than the PSA test, which misses about 15% of existing cancers and gives a high level of false positives.

Every year, about 1.6 million men have unnecessary biopsies because of elevated PSA scores, whereas only about 230,000 of them actually are shown to have cancer. The digital rectal exam (DRE) is also not definitive in detecting this common cancer of men.

Prostate cancer is diagnosed in 230,000 new cases annually, and about 27,000 men die of the disease. The current PSA and DRE detection procedures are also deficient in that they cannot distinguish between cancer’s aggressive form, which is frequently fatal, and a slow-growing variety where “watchful waiting” may be the best strategy.

The new test could revolutionize the treatment of prostate cancer. It could save many lives and spare men with the slow-growing form of cancer from having unnecessary treatments in the future. Its manufacturer Onconome Inc., a Seattle Biomedical company, is developing the EPCA-2 test and expects the FDA to approve it by early next year.

Source:  San Francisco Chronicle; Sunday, April 26, 2007; reporter Susan Brink of the Los Angeles Times

A study at a Philadelphia Cancer Center compared results in 216 men who received IMRT to 158 men who received the more traditional radiation seed implant therapy. Before treatment, all had a cancer at low risk of spreading beyond the prostate.

In radiation seed implant therapy, or brachytherapy, tiny radioactive seeds are implanted by surgeons into the prostate glad where high-dose radiation is delivered for a specified length of time.

Both treatments are effective and safe. The side effects and quality of life are important factors in choosing a therapy. In general, men with enlarged prostates or who have poor urinary function or diabetes do better with IMRT than radiation seed implants.

Men treated with the newer method of therapy were less likely to need catheters to help them urinate, researchers determined. After three months, only 0.5% of men on IMRT compared to 4% with radioactive seeds still needed a urinary catheter.

In another comparison, 97% of those receiving IMRT were cancer-free four years later, compared to 86% of men who had radioactive seeds. These results were measured by blood tests for prostate specific antigen (PSA), in which rising levels can signal a recurrence of cancer. The PSA levels in the second group were negligible or not significant.

Both IMRT and seed implant therapy offer excellent outcomes with low toxicity, according to a lead researcher at the Cancer Center.
Source:  WebMD

The variant gene was discovered in men in Iceland, Sweden, and in two populations in the U.S. The gene variant, carried by about 13% of men of European ancestry, raises the risk of getting prostate cancer by 60%, compared with a 13% risk in those who did not carry it. Men with this recently found gene were discovered to make up about 8% of all cases of prostate cancer.

The variant in African-American men is twice as common as in men of other ancestry. For this reason, prostate cancer may be more prevalent and have a higher mortality rate in black males in the U.S. than in white males. Early detection and aggressive treatment could lead to better outcomes for black males.

According to Dr. Kari Stefansson, DeCode’s chief executive, this was the first major gene in prostate cancer found in widespread populations.

Source:  Oakland Tribune, reprinted from New York Times writer Nicholas Wade’s article; May 8, 2006

Additional Resources:
What You Need to Know About Prostate Cancer