By Mark Scholz, MD
My dad always told me that good ideas are a dime a dozen. The trick is to put the good ideas into motion so that by perseverance and hard work they come to fruition. This is true of the pharmaceutical industry. Massive investment in basic research has yielded a much better understanding of how cancer “works,” creating opportunities for biochemists to design specific pharmaceuticals that will inhibit cancer growth and spread. However, the fact remains that multi-million dollar clinical trials must be performed before a new medicine can be approved and released by the FDA.
One pharmaceutical company that is making fast progress is OncoGenex. They have developed an elegant solution for blocking an overactive enzymatic pathway that cancer cells use to protect themselves from chemotherapy. For example, blocking the effectiveness of one popular type of chemotherapy commonly used to treat prostate cancer is called Taxotere. The specific overactive enzyme the scientists at OncoGenex have identified is called clusterin. Cancer cells over-produce clusterin to protect themselves from chemotherapy.
OncoGenex has designed a medicine that accurately targets clusterin. This new medicine, called Custirsen, sharply reduces the amount of clusterin inside the cancer cells. A preliminary trial, using Custirsen was added to the regimen of 82 men with advanced metastatic prostate cancer being treated with Taxotere (a chemotherapy drug that is commonly used to treat prostate cancer), showed a 40% improvement in survival rate when Custirsen was added to Taxotere--compared to the survival in men receiving Taxotere alone. Clinicaltrials.gov reports that 141 centers around the country are currently participating in a larger trial combining Custirsen and Taxotere. This larger trial, involving hundreds of men with advanced prostate cancer, is aimed at proving the effectiveness of Custirsen and getting approval by the FDA for commercial availability. Custirsen is administered as a weekly intravenous infusion.
Over the course of my 20 years as an oncologist many of the common cancer medicines have proven to be major disappointments—not very effective and overly toxic. These earlier agents were discovered and developed through a slow and cumbersome process of trial and error. In that era we had only a vague idea of how the new treatments actually worked. Most of those agents were broad spectrum inhibitors of cellular growth that resulted in considerable collateral damage on the faster growing normal cells of our body like the hair follicles and the white blood cells.
Research leading to the discovery and development of newer agents like Custirsen is completely different. These agents are rationally designed and targeted to attack and destroy a very specific part of the cancer cells. As a result, they are not only more effective, they also have fewer side effects.
At last, it appears to be technology to the rescue.
A board-certified medical oncologist, Mark C. Scholz, MD, serves as medical director of Prostate Oncology Specialists Inc. in Marina del Rey, CA, a medical practice exclusively focused on prostate cancer. He is also the executive director of the Prostate Cancer Research Institute. He received his medical degree from Creighton University in Omaha, NE. Dr. Scholz completed his Internal Medicine internship and Medical Oncology fellowship at University of Southern California Medical Center. He is the co-author of the book Invasion of the Prostate Snatchers: No More Unnecessary Biopsies, Radical Treatment or Loss of Potency. He is a strong advocate for patient empowerment.