There are now several drugs for advanced prostate cancer that are available. Taxotere, Zytiga, Jevtana, and Provenge have received a great deal of attention because they represent breakthroughs for men with prostate cancer that has spread beyond the prostate and is no longer able to be controlled by hormone therapy. Learn more about these important drugs here.
There are several recent drugs for prostate cancer that that show some effectiveness in treating prostate cancer that no longer responds to hormone therapy.
Docetaxel (Taxotere) is a medication used to treat advanced prostate cancer. It is a form of chemotherapy that has been used extensively for years to treat other cancers as well, including breast, ovarian and certain forms of lung cancer.
How Does Docetaxel Work?
Docetaxel works by disrupting cell division (called mitosis). Since cancer cells are some of the most rapidly dividing cells in the body, these cells are particularly affected by the action of docetaxel and die at high rates when the drug is administered.
Why Is It Used for Prostate Cancer?
Docetaxel is used to treat advanced prostate cancer; specifically, in men whose prostate cancer has spread beyond the prostate and that has become resistant to hormone therapy.
For men at this stage of cancer, there are not many treatment choices, as they have likely already undergone radiation therapy or surgery, and have also tried and then developed resistance to hormone therapy.
Docetaxel was brought into the mainstream of prostate cancer therapy after a study was published in the New England Journal of Medicine in 2004, which showed that docetaxel in combination with the steroid prednisone resulted in improved survival when compared to the then-standard drug for advanced prostate cancer, mitoxantrone. The New England Journal article also showed that men treated with docetaxel had overall better quality of life and improved pain control.
What Are the Side Effects
As with all chemotherapy drugs, there are a wide variety of side effects that can occur when taking docetaxel. More information about these side effects is available here.
Cabazitaxel (Jevtana) has been approved by the U.S. Food and Drug Administration (FDA) for use in combination with prednisone, only after treatment with docetaxel (also with prednisone) has already been completed. Docetaxel is a widely used chemotherapy drug that was approved by the FDA several years ago.
Cabazitaxel received FDA approval in large part due to the positive results that came out of a Phase III clinical study comparing the drug with mitoxantrone, the then-standard drug for advanced prostate cancer. The study showed that Cabazitaxel resulted in a roughly three-month increased survival in men with advanced prostate cancer that was resistant to hormone therapy when compared to mitoxantrone.
Cabazitaxel represents an important step forward for men who are facing advanced prostate cancer that has become resistant to hormone therapy and docetaxel. Cabazitaxel's ability to increase survival in men who have few other options offers them a dose of hope.
One point of controversy that has arisen since FDA approval of Cabazitaxel and other drugs for advanced prostate cancer is the high cost of these treatments. They can cost tens of thousands of dollars over the course of just a few months.
The prostate cancer vaccine Provenge now has FDA approval. Many doctors believe that this treatment represents a big step forward for prostate cancer therapy.
How Does the Prostate Cancer Vaccine Work?
First of all, Provenge is considered a "vaccine" because it puts the body's immune system to use to fight prostate cancer.
The vaccine is made for each individual who is going to be treated with it. To make the vaccine, a sample of the patient's immune cells (specifically dendritic cells) is sent to a laboratory where they are "taught" to attack cancerous prostate cells by exposing them to proteins found only on prostate cancer cells.
After a few days, the patient's cells are re-injected into his body, where they will hopefully begin attacking his cancer. The process is repeated three times overall at two-week intervals between doses.
Is the Prostate Cancer Vaccine Like Other Vaccines?
Yes and no.
Childhood immunizations are what typically come to mind when the word "vaccine" is used.
The prostate cancer vaccine is similar to other vaccines in that a substance is injected into the body that stimulates the immune system to attack something in the body that is not supposed to be there (in this case, prostate cancer cells).
The prostate cancer vaccine differs from other vaccines in an important way, however. Childhood vaccines are intended, nearly always, to prevent a future illness - such as measles, mumps, the flu, etc. The prostate cancer vaccine, on the other hand, is not used to prevent prostate cancer, but is used as a treatment in men who already have the disease. In fact, the prostate cancer vaccine is currently only being used in men with very advanced prostate cancer.
Abiraterone (Zytiga) is a drug that treats prostate cancer that is no longer confined to the prostate and that has become resistant to hormone therapy. The drug works by blocking the action of an enzyme called 17 α-hydroxylase/C17,20 lyase (CYP17A1). This enzyme is important for the formation of testosterone within the body. When blocked, overall testosterone production drops.
While other drugs have been developed that block the production of testosterone, they have mostly worked to stop testicular production of testosterone. Abiraterone works by essentially eliminating production of testosterone in the testicles, adrenal glands and the cancerous tumors themselves.
Because prostate cancer is known to grow in response to testosterone, lowering testosterone levels can result in slowing or sometimes shrinking the cancer.
Is It Approved for Use?
Abiraterone is a relatively new drug and has only recently been approved by the FDA for use in a subset of men with prostate cancer. Specifically, the FDA has approved its use in men who have prostate cancer that has spread beyond the prostate and that has become resistant to conventional hormone therapy. Patients must already have tried docetaxel.
Abiraterone is typically prescribed along with prednisone, as these drugs were used together in the clinical trials that led to Abiraterone FDA approval. Studies have shown increased survival, lowered PSA levels, decreased tumor size and improved quality of life in men taking the drug.
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de Bono JB. Oudard S, Ozguroglu M, et al. Prednisone plus cabazitaxel or mitoxantrone for metastatic castration-resistant prostate cancer progressing after docetaxel treatment: a randomised open-label trial. The Lancet, Volume 376, Issue 9747, Pages 1147 - 1154, 2 October 2010
FDA Press Release April 29, 2010
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