Enzalutamide, also known under the branded name Xtandi, has recently received a new FDA approval. In 2012, Enzalutamide was approved for the treatment of Non-Metastatic Castration-Resistant Prostate Cancer. On December 16, 2019, FDA approved the use of Enzalutamide for the treatment of metastatic hormone-sensitive (aka, “castration-sensitive”) prostate cancer (mHSPC).
What is metastatic hormone-sensitive prostate cancer?
First of all, cancer metastasizes when the tumor spreads outside the prostate gland, affecting the nearby organs or structures. Prostate cancer usually metastasizes to the near lymph nodes, bones or other organs, such as the bladder.
Metastatic prostate cancer is advanced cancer that can be kept under control by means of medication and therapies. Most patients with advanced prostate cancer had a life expectancy of many years and were able to control the symptoms.
When metastatic prostate cancer is hormone-sensitive, it means that the tumor is responsive to testosterone-lowering agents. Researchers have discovered a link between high levels of androgens (male sex hormones), including testosterone, and a higher risk of aggressive prostate cancer. That is why scientists have developed androgen-deprivation therapies to help control the levels of testosterone in advanced prostate cancer patients. ADT (Androgen Deprivation Therapy) slows the growth of prostate cancer by lowering the levels of androgens or by blocking them to fuel the prostate tumor.
Hormone therapy is recommended for patients whose cancer has recurred after receiving treatment or who have been initially diagnosed with advanced prostate cancer.
Castration-resistant prostate cancer
On the other side, castration-resistant prostate cancer is the type of cancer that has already developed resistance to ADT. Castration-resistant cancers keep growing even though the amount of testosterone is reduced, due to ADT therapy. Enzalutamide drug has already been approved for the treatment of non-metastatic castration-resistant prostate cancer and has proved its efficiency.
A new clinical trial was conducted in order to analyze Enzalutamide’s effects on metastatic hormone-sensitive prostate cancer.
New study on the effectiveness of Enzalutamide on metastatic hormone-sensitive prostate cancer
The results of the clinical trial were presented in February 2019 at the Genitourinary Cancers Symposium and were published in The New England Journal of Medicine.
The ARCHES Trial tested a combined treatment medication for 1.150 patients with mHSPC. Researchers have compared the effects of Enzalutamide addition to ADT versus placebo addition.
The outcomes were impressive. Patients who received Enzalutamide combined with ADT had a 61% reduced risk of radiographic disease progression (the growth of tumors on scans and imaging tests) and also a reduced risk of prostate cancer death.
Subsequent analysis showed that Enzalutamide was beneficial even for patients who have been on ADT or docetaxel chemotherapy prior to the clinical trial. What is more, there were important positive effects for both low and high volume tumors.
PSA progression was delayed by 81% and the time for the next anticancer therapy was also delayed by 72% compared to placebo!
The overall survival rate can not be already evaluated, as a median has not yet been reached for either treatment group, enzalutamide group or placebo group.
The results from this trial were consistent with those of the previous trials on the effectiveness of Enzalutamide on castration-resistant prostate cancer.
The overall side effects of ADT + Enzalutamide were not highly different from those of placebo + ADT, but they included: hot flush, asthenic conditions, hypertension, fractures, and musculoskeletal pain.
Since its first FDA approval in 2012, Enzalutamide (Xtandi) has been worldwide used to treat more than 142.000 prostate cancer patients.
“This approval in metastatic castration-sensitive prostate cancer means physicians can now offer XTANDI to men earlier in their advanced prostate cancer treatment journey”, said Andrew Krivoshik, M.D., Ph.D., Senior Vice President and Oncology Therapeutic Area Head at Astellas.
Patients with metastatic hormone-sensitive prostate cancer have to cope with complex treatment decisions and need in-depth information from their physicians. This new clinical trial is proof that many other improvements await us in the near future.