A review of new treatments for patients with castration-resistant prostate cancer

This review explores new approaches and treatments for patients with metastatic castration-resistant prostate cancer. 

Prostate cancer (PC) is the second most common cancer in men worldwide, after lung cancer. Over the last 5 years survival in these patients has been improving due to recent developments in PC screening, surgical, and radiation techniques, and increased use of hormonal therapy following surgical removal of the prostate. Hormonal therapy such as androgen-deprivation therapy or ADT decreases the amount of androgens (testosterone – the main male sex hormone which cancer cells need in order to grow and multiply) in the body. Despite these advances, many men experience a return (recurrence) of their cancer, even with ADT. This is called castration-resistant prostate cancer (CRPC), and it can take multiple forms, including metastatic disease (mCRPC), in which the cancer spreads beyond the prostate, to distant organs and tissues of the body. Until recently, the best treatment for mCRPC was docetaxel chemotherapy, which inhibits cancer growth, but several new treatments have also been tested. The current review discusses some of these new treatments. 

Treatments now being explored for mCRPC include hormonal therapies, chemotherapies, immunotherapies, and radiopharmaceuticals. Hormonal therapies, such as abiraterone acetate (AA), focus on stopping the production of testosterone. AA, when combined with the steroid prednisone, has been shown to increase survival time by one third over the use of prednisone alone and they also decreased the risk of disease progression by about 50% when given prior to chemotherapy. Enzalutamide (Xtandi) is another hormonal therapy drug for mCRPC that has proven to improve survival in these patients. It works by stopping testosterone get to the prostate gland, thus stopping the growth of PC. 

Chemotherapy has not been used often in the past for mCRPC, as the effects were not well-tolerated by patients. Docetaxel (Taxotere) is a drug which stops cancer cells from growing, and it has been shown to lead to a 48% drop in Prostate Specific Antigen or PSA (a protein produced by the prostate gland whose levels rise in PC) levels, and leads to a small increase in overall survival when compared to another chemotherapy drug, mitoxantrone. Newer chemotherapy drugs, such as cabazitaxel (Jevtana), have been found to increase survival time by approximately 30%. Other novel chemotherapy agents are currently being tested in clinical trials.

Immunotherapy vaccines such as Sipuleucel-T boost the patient’s own immune system to fight cancer, and have been found to increase overall survival by 25% over a placebo (a substance with no effect on the body, often used as a control when testing new drugs). Radiopharmaceuticals such as Radium-223, which concentrate into the bone and deliver short-range, high intensity irradiation, are given to patients with bone metastases and have been shown to improve survival by 30% in these patients. 

In summary, researchers continue to study the way in which PC grows and spreads and new treatments for mCRPC are continually being developed to help increase patients' survival and quality of life.

Talk to your doctor about which types of treatment are the most appropriate in your situation.