Two new drugs stall progression of hard-to-treat prostate cancer

There is promising news in the world of treating men who have aggressive prostate cancer.  Two newly developed cancer drugs have been found to delay the spread of the disease by two years. 

In a pair of new trials and for the first time, researchers have results showing that two drugs, one called apalutamide and an already approved drug called enzalutamide (Xtandi), kept prostate cancer from spreading for two years in men whose disease had not yet traveled to other parts of their bodies. This provides an additional two years before the cancer may spread and further treatments needed such as chemotherapy. 

Prostate cancer is the second most common cancer in men worldwide.  The American Cancer Society estimates that in 2018, there will be more than 164,690 new cases and around 29,430 men who will die from the disease.  Worldwide, there were 1.1 million new cases and about 307,000 deaths in 2012, according to recent data from the World Health Organization. 

Generally, men newly diagnosed with prostate cancer which has not spread to other areas will be treated with androgen-deprivation therapy (ADT).  ADT is an anti-hormone therapy used in treating prostate cancer.  Prostate cancer cells usually require androgen hormones, such as testosterone to grow.  ADT reduces the levels of androgen hormones, with drugs or surgery to prevent the prostate cancer cells from growing.

Usually ADT almost always works but if it stops working, then it is referred to as nonmetastatic castration-resistant prostate cancer.  Each year, about 150,000 men worldwide will be diagnosed with this type of prostate cancer aggressive enough to resist standard hormonal therapy.  In the United States, about 30,000 to 50,000 men will have this condition.  However, the cancer will not show up on scans as having spread just yet.  This means men in this dilemma are told they will be under active surveillance, waiting to see if their cancer ends up metastasizing to their bones, lymph nodes or other organs. 

Results of the studies

The studies which included more than 1,200 patients in countries around the world used similar drugs - both androgen receptor inhibitors - which block testosterone from binding to prostate cancer cells and entering them.  Two-thirds of the men took one of the androgen receptor inhibitors, while a one-third took a placebo.  All of the men continued to receive androgen deprivation therapy. 

The men who received apalutamide took on average, 40.5 months for cancer to spread to where it could be detected on a scan while the men who received the placebo, saw their cancer spread in 16.2 months, on average.  Men using enzalutamide, metastasis took 36.6 months on average compared to men on a placebo which took 14.7 months on average.

While there is a great deal of excitement over the fact of the extension of life for these men, researchers emphasize that the two studies only show preliminary indications that they might extend a patient’s survival.  To get a better understanding of the study, researcher will need to follow the patients longer to know for sure.

During the trial, both drugs had significant side effects for some patients which included fatigue, hypertension, rashes, fractures, falls, nausea, and mild cognitive and memory slippage. 

Both of these two drugs are very similar in their chemical structure and mechanistically, operate in the same manner.  Cost wise, enzalutamide is more than $10,000 an month; a price for apalutamide has not yet been set. 

With the onset of these two new drugs looking to be a game changer for men with aggressive prostate cancer, this allows patients more options than ever while encouraging researchers to delve into more studies searching for ways to prevent prostate cancer from developing to begin with.