There is growing evidence that a drug developed to treat late-stage prostate cancer may be a game changer if used earlier. The drug is Zytiga (abiraterone). The FDA first approved its use a decade ago. It was initially to be used only when the horses were out of the barn: metastatic, “castration-resistant” prostate cancer after treatment with the chemo drug docetaxel failed. This is a grim picture. But new research suggests that abiraterone (ABI) could make a big difference for men with aggressive prostate cancer if they are treated early.
The STAMPEDE Trial: Abiraterone Is A Winner!
A study of men with high-risk prostate cancer found that adding ABI to conventional treatment reduces the likelihood of metastasis and improves the chance of survival (ESMO OncologyPro presentation, Sept. 19, 2021). The research, conducted in the UK, randomly assigned 988 men to conventional hormone suppression plus radiation. Another 986 men were assigned to take ABI in addition to radiation and anti-androgen hormone treatment.
Six years later, 82 percent of the men on the triple treatment regimen (containing abiraterone) had no metastases. Those on standard treatment did not do quite so well. About 69 percent of them did not have cancer beyond the prostate.
Flipping those numbers, 18% of the men taking ABI along with conventional treatment had metastases after six years. 31% of the men on standard therapy had their prostate cancer spread through their bodies over the same time period.
Abiraterone also improved survival. After six years, 86 percent of the men in that treatment group were still alive. That is significantly more than the 77 percent of the control group who survived six years.
How Does Abiraterone Work?
Prostate cancer thrives on testosterone, which is why the conventional treatment suppresses this hormone. ABI, also known by the brand name Zytiga, prevents the cancer cells from creating their own testosterone.
The lead author, Professor Gerhardt Attard, was quoted:
“This translates into a very significant improvement in life expectancy for men with high-risk prostate cancer that’s not spread beyond the prostate on conventional imaging.”
“Based on these results, all men with high-risk non-metastatic prostate cancer should be considered for two years of abiraterone.”
Professor Nick James, another author on the paper went further:
“The results were spectacular – that is really the only word for it.”
Other Abiraterone Research:
This is not the first research involving ABI in high-risk, early-stage prostate cancer.
“The combination of RT [radiation therapy] and 6 months of ADT [androgen-deprivation therapy] and AAP [abiraterone acetate plus prednisone] demonstrated acceptable toxicity and a high rate of testosterone recovery with restoration of quality of life and excellent disease control in men with low-volume, intermediate- or high-risk localized prostate cancer.”
Zytiga is a pricey drug. Fortunately, the generic is much more affordable. Hopefully, the FDA will give ABI the green light for early treatment of prostate cancer and insurance companies will help pay for the costs of this valuable drug. I hope that urologists and prostate cancer specialists pay attention to the STAMPEDE trial results.