Anti-androgen drugs block the effects of male hormones on the prostate gland and slow cancer growth. However, in a small number of individuals, these medications lead to an advanced stage known as castration-resistant prostate cancer (CRPC). Researchers at the Dana-Farber Cancer Institute and Harvard Medical School recently conducted a mouse study that suggests that genetic mutations, perhaps in the PTEN gene, may be responsible for worsening prostate cancer in individuals with CRPC and that they may benefit from gene targeted therapy.
Two studies evaluated the potential side effects of proton therapy for prostate cancer using quality-of-life scores. Urinary and bowel scores were similar to those of healthy men and satisfaction rates were high. Sexual function was affected, but results may be related to other factors.
A recent study evaluated the molecular urine test PROGENSA PCA3 as a prostate cancer screening tool. The test is currently approved in conjunction with PSA testing to determine the need for repeat biopsies in individuals with a prior negative biopsy. The study found that when PROGENSA PCA 3 was used with prostate-specific antigen (PSA) testing in individuals without a prior biopsy, unnecessary biopsies were avoided for 20% of the patients.
A recent clinical study compared therapy with 50 mg of docetaxel administered every 2 weeks versus standard therapy of 75 mg every 3 weeks for the treatment of castration-resistant prostate cancer (CRPC). Treatment failure occurred later and was associated with less frequent side effects in study participants receiving the drug every 2 weeks.
A recent study found a genetic change, or ‘signature,’ in cancer cells from 13 patients with metastatic prostate cancer. The signature, which is not a DNA sequence mutation, but still alters the function of a gene, was found consistently throughout an individual’s metastatic tumors and was unique to each individual. The researchers hope to use epigenetic ‘marks’ as biomarkers to identify cancer.
A recent study evaluated the effects of IP6, an important component of high-fiber diets, on prostate tumor growth in mice. The study found a major decrease in the size of prostate tumors in mice who were given IP6 for 24 weeks. The researchers believe IP6 decreases tumor size and prevents tumor growth by blocking prostate cancer cells from using glucose for energy and by preventing blood vessel formation within the tumors. This study outlines the importance of a high-fiber diet as part of a prostate cancer treatment strategy.
Two drugs, abiraterone (sold as Zytiga) and enzalutamide (sold as Xtandi), improve overall survival in patients with castration-resistant prostate cancer (CRPC). Research is ongoing to determine ways to prevent resistance to these drugs and to find strategies to treat prostate cancer at earlier stages using these drugs.
In the last 2 years, the FDA has approved several new active metastatic prostate cancer therapies. This progress was made after researchers discovered that the available androgen deprivation therapies (ADT) had failed patients and that castration-resistant prostate cancer (CRPC) is not actually resistant to hormonal manipulation. Rather, ADT reduces levels of circulating hormones by 95%, but only by 75% within the prostate. Advanced prostate tumors are adept at making their own testosterone. Therefore, tumors seemingly resistant to androgen deprivation remain dependent on androgen receptor signaling for their growth—these tumors still rely on hormone signaling.
About 70 years ago, researcher Charles B. Huggins discovered that male hormones (androgens) are important for the growth and survival of prostate cancer tumors. In 1966, Huggins was awarded the Nobel Prize for Physiology or Medicine for his work on using hormones to control prostate cancer. In the last 10 years, studies have shown that castrate-resistant prostate tumors can continue to make their own hormones and can also increase the expression of androgen receptors on prostate cancer cells. This continued hormone signaling allows for continued tumor growth and cancer progression.
New oral androgen receptor signaling therapies have taken advantage of this latest research, targeting either hormones themselves or their receptors. These drugs provide new opportunities for patients who, just a few years ago, would have run out of treatment options. Continue reading…