Relugolix Rapidly Suppresses Testosterone Levels in Advanced Prostate Cancer
by Dr. C.H. Weaver M.D. 12/2020
On December 18, 2020 the U.S. Food and Drug Administration approved Orgovyx (relugolix) for the treatment of advanced prostate cancer. Orgovyx is the first oral anti-androgen therapy and its availability reduces the need for in person clinic visits which is especially beneficial in helping patients with cancer stay home and avoid exposure during the coronavirus pandemic. (2)
According to the results of a clinical trial published in the New England Journal of Medicine comparing standard Lupron (leuprolide) therapy to Orgovyx in patients with advanced prostate cancer, Orgovyx was associated with sustained testosterone level suppression and a lower risk for major cardiovascular adverse events than Lupron. (1)
Lupron is an injectable luteinizing hormone-releasing hormone agonist which is a standard treatment for achieving androgen deprivation therapy (ADT) in men with prostate cancer. Lupron has some disadvantages including an initial testosterone surge and an associated delay in therapeutic effect. It is also known to have longer term side effects to the heart.
The American Cancer Society estimates that in 2020, there will have been more than 190,000 men diagnosed with prostate cancer in the U.S. One of the treatment options for advanced prostate cancer is androgen deprivation therapy, which uses drugs to lower levels of the hormones that help prostate cancer cells grow. Current FDA-approved treatments of this type are injected or placed as small implants under the skin.
The safety and efficacy of Orgovyx was evaluated in a randomized, open-label trial in men with advanced prostate cancer. The patients randomly received either Orgovyx once daily or injections of leuprolide, another hormone-targeting drug, every three months for 48 weeks. The objective was to determine if Orgovyx achieved and maintained low enough levels of testosterone (castrate levels), by day 29 through end of the treatment course. In the 622 patients who received Orgovyx, the castration rate was 96.7%.
About Orgovyx (relugolix)
Orgovyx is an orally administered small molecule, gonadotropin-releasing hormone (GnRH) receptor antagonist As a GnRH receptor antagonist, Orgovyx binds to and blocks the GnRH receptor (GnRHR) in the anterior pituitary gland. Blocking GnRH receptors decreases the release of gonadotropins – luteinizing hormone (LH) and follicle-stimulating hormone (FSH) – thereby decreasing the downstream production of estrogen and progesterone by the ovaries in women and testosterone by the testes in men
A clinical trial of 930 patients with advanced prostate cancer was conducted to directly compare Lupron and Orgovyx. Participants were treated with either Orgovyx 120 mg once daily or Lupron injection every 3 months for 48 weeks and their outcomes directly compared.
Overall 97% of Orgovyx treated patients maintained castration levels of testosterone for 48 weeks compared to 89% of Lupron recipients demonstrating the non inferiority of Orgovyx. In the Orgovyx and Lupron treatment groups patients castrate levels of testosterone on day 4 were 56.% and 0%, respectively. The incidence of major cardiovascular adverse events was 2.9% and 6.2% with Orgovyx and Lupron, respectively.
A lead author of the study Dr. Shore concluded that “In this trial involving men with advanced prostate cancer, Orgovyx achieved rapid, sustained suppression of testosterone levels that was superior to that with leuprolide, with a 54% lower risk of major adverse cardiovascular events.”
While Orgovyx offers an oral alternative to Lupron injection and has some potential therapeutic benefits some doctors have expressed concerns about compliance and convenience between the requirement to take a pill daily compared to an injection every 3-4 months. Reducing the need for in person clinic visits however provides appropriate patients an oral treatment alternative and the ability to stay home and avoid unwanted trips to the doctor and exposure during the coronavirus pandemic.
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- N Engl J Med. 2020 May 29. Epub ahead of print.
- FDA Approves First Oral Hormone Therapy for Treating Advanced Prostate Cancer