FDA Expands Approval for Enzalutamide
In December 2019, the U.S. FDA expanded its approval of the drug enzalutamide to include treatment of men with metastatic castration-sensitive prostate cancer.
Enzalutamide (brand name Xtandi) is an androgen receptor inhibitor that patients take orally. The drug is now approved to treat three forms of advanced prostate cancer: non-metastatic castration-resistant (no longer responding to hormonal therapy) prostate cancer, metastatic castration- sensitive prostate cancer, and metastatic castration-resistant prostate cancer.
The new approval, for men with metastatic castration-sensitive prostate cancer, gives men with advanced prostate cancer the chance to use enzalutamide earlier, before their disease becomes resistant to hormone therapy.
The FDA based its approvals on results from the ARCHES clinical trial. In ARCHES, 1,150 patients with metastatic castration-sensitive prostate cancer undergoing hormone therapy were randomly divided into two groups: patients who either took enzalutamide or did not. For men in the study, enzalutamide reduced the risk of disease progression or death by 61% within a two-year period.
The study’s authors hope to report on future results comparing survival rates between the two groups of men.
QUEST has previously reported on results from the ARCHES trial. See “ARCHES Trial: Better Results for Patients with Metastatic Hormone- Sensitive Prostate Cancer” in the Spring 2019 issue for more details.
Hormone Therapy for Prostate Cancer and Supplemental Drugs
Men with advanced prostate cancer often undergo hormone therapy, also known as androgen-deprivation therapy (ADT), available via medication or a surgical treatment. These therapies are designed to lower levels of testosterone in the body, as these hormones can promote tumor growth. Lowering the hormones can slow or stop the disease spread.
However, most patients eventually develop resistance to hormone therapy, putting these patients at high risk for further disease spread.
Newer supplemental treatments, such as enzalutamide and apalutamide, could offer a second line of defense to patients in this situation. In addition, new FDA approvals for men with castration- sensitive prostate cancer could give certain patients the chance to take these drugs before their disease is resistant to hormone therapy.
Types of Advanced Prostate Cancer
Non-metastatic castration-resistant prostate cancer: the disease has not spread beyond the prostate, yet the cancer is no longer responding to hormone therapy.
Metastatic castration-sensitive prostate cancer: the disease has already spread beyond the prostate, but the cancer is still responding to hormone therapy.
Metastatic castration-resistant prostate cancer: the disease has already spread beyond the prostate, and the cancer is no longer responding to hormone therapy.