Touted as the most significant development in the field of prostate cancer therapy in 70 years, will abiraterone finally end the scourge of prostate cancer?
By: Ringo Bones
As the results of the early stage trials were published in the Journal of Clinical Oncology, abiraterone instantly gained rave reviews as the miracle drug to treat prostate cancer. The mainstream media immediately pounced on the story during the middle of July 2008, hailing the drug as the most significant development in the field of prostate cancer therapy in 70 years. Despite the promising results during its early trials, abiraterone might have rightfully earned its bragging rights. Given that in the history of prostate cancer research shows that on a worldwide basis, almost a third of men diagnosed with the disease die from it.
Prostate cancer usually affects men who have reached their fifties, and the risk increases the older they get. To detect or examine suspected prostate cancer cases, the doctor usually starts with a prostate specific antigen or PSA bloodwork then a biopsy when a check up shows positive indicators for the disease. At present, only early detection guarantees recovery in most prostate cancer cases.
The male hormone testosterone – even though it performs a vital function in the male anatomy – stimulates prostate cancer tumors to grow. Current therapeutic methods used to cure prostate cancer usually involve stopping the body making testosterone. This method can slow down the growth of preexisting tumors, or even shrink it. Most of the testosterone in the male anatomy is made by the testes but a significant – though small amount – is synthesized by other tissues in the body, including the cancer itself. To synthesize or create testosterone, the body needs an enzyme called cytochrome P17, usually referred to as CYP17 in the research’s “White Paper”.
Abiraterone, whose chemical name is abiraterone acetate, also known as CB7630 works differently in comparison to other current hormone treatments for prostate cancer. Abiraterone acetate has a broad-spectrum effect in blocking the enzyme CYP17, thus preventing the testes and other tissues in the body from synthesizing testosterone. Abiraterone has just been recently used on clinical trials as an experimental treatment for prostate cancer. These early clinical trials focused on men with advanced prostate cancer whose previous treatments no longer works and also men with advanced prostate cancer that has spread or metastasized beyond the prostate gland.
Results of the phase 1 trial have recently been published in the Journal of Clinical Oncology. During the abiraterone trials, 80% of the men had a fall in their levels of prostate specific antigen (PSA) in their blood accompanied by tumor shrinkage. A fall in PSA levels usually that the number of cancerous cells had gone down. Some of the men who were suffering from chronic pain resulting from their prostate cancer tumors were able to take much lower doses of painkillers, a sure sign of improvement. PSA level reduction lasted from just over two months in some men while on other subjects, level reductions lasted for 18 months.
Side effects were generally mild but are reminiscent of patients under hormone replacement therapy. These include a change in the levels of sodium and potassium in the blood, a build-up of fluid in the ankles / joint edema, a rise in blood pressure, headaches, loss of appetite, fatigue, and hot flushes.
Phase 2 trials are currently being carried out but the results are yet to be published. It focused on the men whose previous hormone therapy no longer works. These men were given abiraterone and when the abiraterone no longer worked, they were then given a steroid called dexamethasone. The early results were announced in June 2008, and because they looked promising, were hailed by the media as the greatest advance in prostate cancer research. Men who were taking abiraterone alone – most of them – show a fall in their PSA levels. A sure sign of the treatment stopped the cancer from growing or developing. In 50% of the men with tumors could be measured on the scan, the cancer shrank or didn’t grow further. The PSA levels were cut in half in almost 70% of the men taking part in the clinical trials even though the PSA levels of the men taking part rose again after 7 months. Despite the promising results, abiraterone is currently only available to men who will take part in a clinical trial.
Based on early tentative results, the latest abiraterone trial participants must be screened as a precaution. Because the drug changes the levels of sodium and potassium in the blood and raises blood pressure, men with a history of heart disease and high-blood pressure are not allowed to participate in abiraterone trials. So do men who had undergone treatment using a drug called ketoconazole, have history of liver disease or currently have another type of cancer and /or secondary cancer in the brain. Experts say that all hormone-based therapy to cure prostate cancer – including abiraterone – carries the risk of impotence, urinary tract problems and incontinence.
In the past, prostate cancer awareness was usually spearheaded when someone famous overcame the disease helped only by the existing treatment regimen of the period. Back in November 1987, then US President Ronald Reagan underwent transurethral prostate surgery because of benign prostatic hypertropy, thus causing a flurry of prostate cancer awareness. In the entertainment world, Bill “The Fox” Foster emcee of Comedy Central’s “The Man Show” died of prostate cancer in May 10, 2000. His family asks that we (The Man Show fans) honor his memory by urging male viewers to get their prostates examined regularly by their doctor. Many opined that with early detection, Bill “The Fox” Foster’s death could have been prevented.