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Targeted Therapies
Cytotoxic therapy
As opposed to hormonal therapy, which is primarily cytostatic (prevents cancer cells from growing), cytotoxic therapy is designed to kill the cancer cells. Radiation therapy and chemotherapy are examples of cytotoxic treatments.
Heretofore, the treatment of advanced stage, metastatic disease centered around palliation because there was no recognized therapy that provided any survival benefit to the patient. Prior to recent developments, the only approved treatment for advanced prostate cancer was the combination of mitoxantrone (Novantrone) and prednisone, which didn't improve survival but provided significant relief from the pain associated with advanced stage disease.
Chemotherapy
Chemotherapy, like radiation, does not distinguish between healthy cells and cancer cells in the cytotoxic process with sometimes resulting side effects. This has caused researchers to focus on the development of therapies that address specific cellular or systemic approaches to better target the cancer.
The Food and Drug Administration has approved Taxotere® (docetaxel) for use in combination with prednisone as a treatment for men with androgeni-independent (hormoner-efractory) metastatic prostate cancer. Even more exciting is the research being done using Taxotere as an early stage treatment for prostate cancer either as a single agent or neoadjuvantly prior to radical prostatectomy surgery. A commentary by Dr. Michael Carducci of Johns Hopkins can be seen here.
Some examples of these new protocols are:
Endothelin blocker - a drug that blocks a protein called endothelin, that is thought to help spread cancer cells, has been shown to improve quality of life by delaying the onset of bone pain and disease progression.
Vaccine Therapy - a mechanism for altering the patient's immune
system to make it better able to fight the cancer; one example is
Provenge, details of which can be viewed at www.dendreon.com.
Androgen Receptor targeting agents - Antiandrogens inhibit the androgen receptor and have an important role in the treatment of prostate cancer. Flutamide, nilutamide and bicalutamide, which were designed to target the androgen receptor, were developed primarily for use in combination with castration to provide combined androgen blockade. With increased knowledge of androgen receptor structure and its biological functions a new generation of antiandrogens without agonist activity was designed to provide more potent inhibition of the androgen receptor. Randomized clinical trials in patients with metastatic, castration resistant prostate cancer showed significant survival benefits. Currently approved agents are: enzalutamide, abiraterone, and apalutamide.
Testing these new agents earlier in the course of prostate cancer may further improve the survival and quality of life of patients with current local and/or systemic treatment modalities.
Clinical trials on these and other new protocols can be found through
listings on the sites noted on the Clinical Trials page.
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Additionally there are several research studies in work utilizing the new standard with various agents; however, it is important to understand the imperatives associated with advanced stage therapeutic approaches. An interview with Dr. David Agus (seen here) should help to achieve the perspective necessary for informed choice. |
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