This year’s meeting of the American Society of Clinical Oncology (ASCO) brought life-saving news for prostate cancer patients.
The 2017 ASCO Annual Meeting, held in Chicago over the past weekend, featured the presentation of two ground-breaking clinical trials on the drug abiraterone.
The studies, both published in The New England Journal of Medicine, offer clear evidence that this drug, typically used to treat prostate cancer once it has spread, can save lives and help patients live longer if it is administered earlier in the treatment course.
One of the studies, titled STAMPEDE, showed that adding abiraterone to the standard androgen deprivation therapy (ADT) slows advanced prostate cancer and reduces the patients’ risk of death by 37 percent.
The other study, titled LATITUDE, proved that combining abiraterone with ADT delays tumor growth by 18 months, even when it has metastasized, thereby extending prostate cancer survival.
These remarkable findings have the potential to revolutionize prostate cancer treatment, researchers agree.
“These results could transform the treatment of prostate cancer. Abiraterone can clearly help many more prostate cancer patients than was first thought,” Sir Harpal Kumar, chief executive of Cancer Research UK, said in a statement.
What Is Abiraterone?
According to the American Cancer Society, prostate cancer is the most common type of cancer among men, second only to skin cancer. The disease is more prevalent among older men, typically arising after the age of 40.
Every year, around 161,360 new cases of prostate cancer are reported in the United States.
Early prostate cancer detection increases the likelihood of the tumor being treated. Even so, prostate cancer still remains the third leading cause of cancer death among American men, after lung cancer and colorectal cancer.
The disease is fuelled by the male hormone testosterone, which feeds the prostate cancer cells and sustains their growth.
To inhibit the testicles’ production of testosterone and other similar hormones, called androgens, patients follow a standard treatment of ADT, which slows tumor growth.
However, even with ADT, other organs in the body, the prostate gland included, still produce small amounts of testosterone and androgens.
This is where abiraterone comes in. This drug, also known as Zytiga, is a hormone therapy designed to halter testosterone production throughout the body.
As opposed to chemotherapy and radiation, which work by killing cancer cells, abiraterone prevents testosterone from reaching the prostate gland.
In the absence of the hormone, tumor growth is thereby hindered and the disease’s progression is significantly slowed down. This happens even in patients whose cancer has already begun to metastasize, shows the LATITUDE study.
The STAMPEDE Trial And Increased Cancer Survival Rates
Conducted by British researchers at University College London, the STAMPEDE clinical trial looked at abiraterone as an additional treatment for patients with advanced prostate cancer who were about to start long-term hormone therapy.
The study involved nearly 2,000 patients, half of which were treated abiraterone plus ADT, while the other half received ADT alone.
The results showed that adding the drug to the standard hormone therapy lowers the relative risk of death by 37 percent. The drug increased the three-year survival rate from 76 percent (for ADT only) to 83 percent.
“This is one of the biggest reductions in death I’ve seen in any clinical trial for adult cancers,” said study leader Prof. Nicholas James, from the University of Birmingham.
James deemed this discovery “a once-in-a-career feeling”, stating these findings “are the most powerful results” he has ever encountered in a prostate cancer trial.
“Abiraterone not only prolonged life, but also lowered the chance of relapse by 70 percent and reduced the chance of serious bone complications by 50 percent,” he explained in an ASCO news release.
In view of these results, and the tremendous benefits this drug can offer to cancer patients, James believes the upfront care for men recently diagnosed with advanced prostate cancer can be significantly improved.
The LATITUDE Trial And Slowed Cancer Progression
The second trial assessing the benefits of abiraterone in addition to standard hormonal therapy involved nearly 1,200 men with newly diagnosed metastatic cancer.
The study was conducted at 235 sites in 34 countries in Europe, the Asia-Pacific region, Latin America, and Canada.
The results showed a treatment with abiraterone plus ADT for this type of patients reduces the chance of death by 38 percent.
Moreover, the addition of abiraterone more than doubled the median time until the cancer worsened, increasing the period before tumor progression from 14.8 months (for ADT alone) to 33 months.
“We had been treating metastatic prostate cancer the same way for 70 years until docetaxel chemotherapy was shown to improve survival in 2015, and now in 2017 we show abiraterone is also helping patients live longer,” lead study author Dr. Karim Fizazi, from the University Paris-Sud in Villejuif, France, said in an ASCO news release.
The results were so remarkable that the trial was stopped early so even the patients given the placebo could also receive abiraterone.
According to Dr. Fizazi, who is head of the Department of Cancer Medicine at Gustave Roussy, after being diagnosed with metastatic cancer, patients have less than five years on average to live.
“The next step is to see if adding abiraterone on top of docetaxel offers further benefit,” he added. Such a study is currently ongoing in Europe.