The U.S. Food and Drug Administration (FDA) has granted priority review to the new drug application (NDA) Myovant Sciences submitted earlier this year requesting the approval of relugolix for the treatment of men with advanced prostate cancer.
The priority review status will shorten relugolix’s regulatory review for this indication from the standard 10 months to six months. The FDA has set a prescription drug user fee act (PDUFA) action date for Dec. 20. That means that the agency must decide by then whether to approve relugolix, which is given as a 120 mg tablet once per day.
If approved, relugolix will become the first and only oral gonadotrophin-releasing hormone (GnRH) receptor inhibitor to win regulatory approval in the U.S. for the treatment of advanced prostate cancer.
“We are delighted that the FDA has accepted for Priority Review our New Drug Application for relugolix, bringing us one step closer to providing a one pill, once a day potential new treatment option to men with advanced prostate cancer,” Lynn Seely, MD, CEO of Myovant Sciences, said in a press release.
Relugolix is a small molecule inhibitor of the GnRH receptor that lowers the production of testosterone in men, and is being investigated as a form of treatment for prostate cancer. It also lowers estrogen production in women, for whom it is being investigated for uterine fibroids — noncancerous growths that can lead to heavy menstrual bleeding, pelvic pain, and endometriosis.
The NDA filing was based on data from the HERO Phase 3 trial (NCT03085095). That data showed that relugolix is superior to standard of care leuprolide acetate, a conventional androgen deprivation therapy (ADT), at reducing the levels of testosterone in men, while also lowering the risk of major cardiovascular events by more than half.
HERO aims to enroll approximately 1,100 patients with advanced, hormone-sensitive prostate cancer, who required at least one year of continuous ADT treatment. The trial is still recruiting men, ages 18 and older, at locations in China.
So far, 934 men have been enrolled and randomly assigned to receive either relugolix or leuprolide acetate. Relugolix is given as a single loading dose of 360 mg followed by daily 120 mg tablets, while leuprolide acetate is administered via slow-acting, slow-release (depot) injections every three months.
The study’s main goal was to determine the percentage of men from each group achieving a sustained castration, defined as having testosterone levels lower than 50 ng/dL from week 5 through to week 48.
Secondary goals included the effects of both therapies on testosterone suppression, on the levels of the prostate cancer marker prostate-specific antigen (PSA), and on testosterone recovery following treatment discontinuation (subset of patients).
The findings announced last year showed that HERO met its main goal, with 96.7% of men on relugolix and 88.8% of those on leuprolide acetate achieving sustained castration levels through 48 weeks.
More recently, the results of a detailed analysis of key secondary goals of the HERO trial have been announced by the company.
That data was simultaneously presented at the 2020 American Society of Clinical Oncology (ASCO) Virtual Scientific Program, recently held online, and published in The New England Journal of Medicine. Men who received relugolix were found to have a 54% lower risk of experiencing serious cardiovascular adverse events compared with those treated with leuprolide acetate (2.9% vs. 6.2%).
“Cardiovascular disease is the leading cause of death in men with prostate cancer,” Neal Shore, MD, medical director of the Carolina Urologic Research Center, who presented data at ASCO, and authored the NEJM paper, said in a press release.
“An oral therapeutic option with strong efficacy that also reduces cardiovascular risk compared to that of conventional GnRH agonist therapy would be a critical achievement for men with advanced prostate cancer,” Shore said.
Additionally, analyses showed that relugolix lowered the levels of testosterone to castrate levels faster and more effectively than leuprolide acetate, with over half (56%) of men in the relugolix group achieving this goal by day four, compared to none in the leuprolide acetate group. By day 15, 98.7% on relugolix had attained testosterone suppression compared with 12.1% of those on leuprolide acetate.
A higher percentage of patients in the relugolix group experienced a 50% reduction in their PSA levels (79.4% vs. 19.8%) after five weeks, and saw their testosterone levels return to normal after discontinuing treatment for 90 days (54% vs. 3%).
“A faster effect in lowering testosterone for prostate cancer patients can be clinically significant — likewise, a more rapid testosterone recovery after stopping treatment, could potentially improve a patient’s quality of life,” Shore said.
“Both of these findings could make a meaningful difference in the treatment journey for men with advanced prostate cancer,” he added.
Myovant also is working toward a new treatment for heavy menstrual bleeding in women with uterine fibroids. The company recently submitted another NDA to the FDA requesting the approval of a combination tablet containing relugolix, estradiol, and norethindrone acetate as a therapy for this condition, which is estimated to affect up to 5 million women in the U.S.
A marketing authorization application requesting the approval of the relugolix combination tablet in women with moderate-to-severe symptoms caused by uterine fibroids is currently being reviewed by the European Medicines Agency.
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