Some clinical trials test a new drug to be sure that it is safe and effective, while others test whether existing treatments can be used for something different than their original purpose.
A recent clinical trial called STAMPEDE tested whether a drug called abiraterone (Zytiga), originally used to treat advanced prostate cancer, could be beneficial if used earlier in the disease. The results, published in the New England Journal of Medicine in June, showed that the drug could be combined with a standard type of hormone therapy early in treatment to dramatically improve patient survival.
How does hormone therapy for prostate cancer work?
Prostate cancer cells need male hormones called androgens (like testosterone) to grow and spread. Androgen deprivation therapy (ADT) is a standard form of hormone therapy for prostate cancer. ADT prevents androgens from working properly, and as a result, prostate cancer cells can’t use them to grow.
A different approach to hormone therapy is to prevent the body from making the androgens that prostate cancer cells need in the first place. Abiraterone is a drug that blocks the biological pathway the body uses to make androgens, preventing the body from making these hormones.
Abiraterone is currently used to treat men with advanced prostate cancer that has become resistant to ADT. But the STAMPEDE trial results show that it could be used to help even more men if it is used earlier on, at the start of hormone therapy.
Trial results showed a dramatic improvement in survival
The STAMPEDE trial was one of the largest ever clinical trials for prostate cancer, with more than 1,900 men taking part. Roughly, half of the trial participants received ADT plus abiraterone, and the other half received ADT alone. This course of treatment lasted 2 years, unless the patient’s cancer progressed sooner and then a more aggressive treatment was prescribed.
The researchers found that the combination therapy prolonged the time to when the cancer progressed by 71% and extended overall survival by 37%. Both results were significant improvements from ADT alone.
It’s rare to have a trial show such dramatic results. The lead investigator on the trial, Professor Nicholas James from the University of Birmingham in the UK, said in a press release, “These are the most powerful results I’ve seen from a prostate cancer trial – it’s a once in a career feeling.”
Success of trial could change standard of care for prostate cancer
The trial results are so significant that they have the potential to change how prostate cancer is treated around the world. The combination therapy could soon become the new standard of care and could also be combined with other treatments to be even more effective.
Since abiraterone is already an approved drug for prostate cancer treatment, the results of the trial could potentially be implemented relatively quickly.
While it’s encouraging when a new cancer drug is developed, it’s also exciting when researchers find new ways to use existing drugs. The drugs then have the potential to benefit more people and have a greater impact than initially planned.
Eileen Hoftyzer, BSc, and Carolyn Goard, PhD
