Prostate cancer patients, whose disease has spread to other organs, can now expect to live on average two years longer when the drug enzalutamide is added to their treatment.
This is according to the latest findings emerging from the global ENZAMET trial, involving 1,100 patients, including about 150 patients in Ireland.
The EU lead for the trial is Ray McDermott, Professor of Medical Oncology at Tallaght University Hospital.
The Irish and European part of the global trial was sponsored by Cancer Trials Ireland, with Prof McDermott as its Chief Investigator
“They haven’t reached the final figures yet, but the people who got the enzalutamide, as opposed to the previous standard, are living for an average of two years longer,” said Prof McDermott.
“It confirms a survival advantage for the people who got the new drug – enzalutamide – as opposed to those who got the prior standard of care.
“That means the new combination now becomes the new standard of care.”
Updated results of the ENZAMET trial – which began in 2019 – were reported at the 2022 American Society for Clinical Oncology (ASCO) annual meeting in Chicago.
They confirmed earlier findings that suggested enzalutamide was effective in treating metastatic prostate cancer.
The trial compared patients who received the standard treatment with those who received the same treatment in addition to enzalutamide.
The ASCO meeting heard the latter group saw a significant increase in survivability.
The delegates also heard that patients with metastatic cancer who received enzalutamide had a 67pc chance of being alive after five years.
Those who received standard care had a 57pc chance.
The male hormone testosterone helps prostate cancer grow, and without it, the cancer will stop growing. Enzalutamide works by blocking the growth effects of testosterone on cancer cells.
The standard treatment for metastatic prostate cancers for many years has been to put patients on androgen deprivation therapy – an androgen being a male hormone, such as testosterone.
“The way androgen deprivation therapy works is it takes away most of your body’s production of testosterone, and testosterone feeds the cancer,” said Prof McDermott.
“It doesn’t take it (testosterone) all away; it takes about 90pc but the remaining 10pc is still there.
“The tumour becomes very sensitive to very low levels of testosterone and keeps growing.
“The enzalutamide sits on the receptor in the cell where the testosterone works and stops it from activating the cell.
“It works in a completely different way to other treatments and that means it stops the cancer cells from growing and dividing.”
Patients who present with metastatic prostate cancer and have yet to be treated, and those who have been treated but whose cancer has relapsed, are likely to see the most benefits from the drug.
“For patients with metastatic disease, this is really a huge step forward. It means these drugs are going to be used much earlier in the disease process,” said Prof McDermott.
“Previously, we were using them when the androgen deprivation therapy stopped working.
"The reality is that you get much less benefit from them than in the earlier years.”