FDA Grants Priority Review to Relugolix for Men With Advanced Prostate Cancer

An oral 120 mg dose of relugolix (Relumina) has received a priority review designation from the FDA for the treatment of patients with advanced prostate cancer, Myovant Sciences announced in a press release. The target FDA action date has been set for December 20, 2020.¹

“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,” said Lynn Seely, MD, chief executive officer, Myovant Sciences. “As recently published in the New England Journal of Medicine, relugolix demonstrated superior efficacy and a 54% lower risk of major adverse cardiovascular events (MACE) compared to the current standard of care, leuprolide acetate injections, in the Phase 3 HERO study.”

The priority review is supported by data from the phase 3 HERO study, which demonstrated relugolix is superior over leuprolide (Lupron) in men with advanced prostate cancer in findings presented during the 2020 American Society of Clinical Oncology Virtual Scientific Meeting.

The study drug achieved castration as early as day 4, which suggests the potential for this agent to become a new standard of care for testosterone-suppression.²

Oral relugolix induced a response rate of 96.7% (95% CI, 94.9-97.9) in men who had castrate levels (≤50 ng/dL) that were sustained from week 5 through week 48. Investigators also noted an 88.8% response rate for men treated with leuprolide acetate, and the difference between the 2 groups was 7.9% (95% CI, 4.1%-11.8%; P <.0001).

All secondary end points in HERO demonstrated superiority with relugolix compared with leuprolide acetate. The median T-levels among a subgroup of patients evaluated for testosterone recovery were 270.76 ng/dL in the relugolix group compared with 12.26 ng/dL in the control group 90 days after discontinuation of therapy.

In a prespecified analysis, the incidence of MACE was lower with relugolix therapy compared with leuprolide (2.9% vs 6.2%, respectively). The safety of these 2 agents was generally similar, investigators noted.

Adverse events (AEs) occurring in >10% of patients treated with relugolix versus leuprolide included hot flush (54.3% vs 51.6%), fatigue (21.5% vs 18.5%), constipation (12.2% vs 9.7%), diarrhea (12.2% vs 6.8%), arthralgia (12.1% vs 9.1%), and hypertension (7.9% vs 11.7%), respectively. AEs of diarrhea were only of grades 1/2 and did not result in study discontinuation.

HERO is a randomized, open-label, parallel-group multinational clinical study evaluating the safety and efficacy of this agent in 934 men with androgen-sensitive prostate cancer. These patients have received at least 1 year of continuous androgen deprivation therapy (ADT) to be included in the study. Patients were randomized 2:1 to receive either a single loading dose of relugolix at 360 mg followed by a 120 mg dose daily or leuprolide acetate in a 3-month depot injection.

The primary end point of the study was sustained castration rate defined as the cumulative probability of testosterone suppression to ≤50 ng/dL. Secondary end points in this study included castration rate by visit, profound castration rate, PSA, PSA response rate, time to PSA progression, and quality of life. Quality of Life total scores and each subdomain score, castration resistance-free survival, composite of safety, the pharmacokinetics of relugolix, testosterone recovery, and sustained profound castration rate were also evaluated in the HERO study.

To be included in the study, patients had to have a histologically or cytologically confirmed diagnoses of adenocarcinoma of the prostate and were good candidates for 1 year on continuous ADT. They were also required to have an ECOG performance status of 0 or 1 at the time of both initial screening and baseline, a serum testosterone level of ≥150 ng/dL and a serum PSA concentration of >2.0 ng/mL (2.0 μg/L).

Patients who required chemotherapy or surgery were excluded from the study, as well as those with brain metastases or a history of surgical castration. Patients who had been treated with GnRH analog, another form of ADT, or had prior systemic cytotoxic treatment for prostate cancer were also excluded from the study.

Data from the key secondary end points, including castration resistance-free survival, are expected to be announced during the third quarter of 2020.¹

_References

1. _{Myovant Sciences Announces Priority Review and FDA Acceptance of New Drug Application for Once-Daily, Oral Relugolix for Advanced Prostate Cancer. News Release. Myovant Sciences. June 22, 2020. Accessed June 22, 2020. https://bit.ly/2NiGw8K}
2. _{Shore ND, George DJ, Saad F, et al. HERO phase III trial: Results comparing relugolix, an oral GnRH receptor antagonist versus leuprolide acetate for advanced prostate cancer. Presented at: 2020 ASCO Virtual Scientific Program. Abstract 5602.}