There are many trials and tribulations facing new drug approvals for men with prostate cancer. This is particularly true for men the drugs that are designed to fight metastatic castration-resistant prostate cancer (mCRPC) because of the many new treatments, all with life extending ability, that we now have available to use.
The good news is that we currently do have these agents, but paradoxically, this is also the bad news. These agents include drugs that prevent the production of androgens, drugs that block the androgen’s ability to make its way to the cell’s nucleus and then feed the cancer, toxic drugs that work by poisoning the fastest growing cells (which usually are the cancer cells, hair and nails) and drugs that sensitize the immune system to prostate cancer. All of these drugs extend life, so it becomes very difficult to demonstrate that an investigational drug also has the ability to provide a statistically significant survival gain because the trial subjects will go on and take these other life extending drugs.
The other good news, but also another complication, is that we have made prostate cancer more like a chronic disease. This also creates major challenges in the way that phase III trials will now have to be designed. The common belief is that the median survival for men with mCRPC is about 3 years. This makes designing, running, and reading out a phase III trial approximately a 5-to 7-year endeavor. This very expensive and can become discouraging to a pharmaceutical development company.
The only way to really deal with this problem is to develop and have the FDA approve new surrogate biomarkers for survival. This should help to speed the ultimate approval of new drugs and bring down the staggering costs of running new phase III clinical trials.