Phase III HERO Study Meets Primary Efficacy Endpoint in Men with Advanced Prostate Cancer

The phase III HERO study of relugolix met its primary efficacy endpoint and all 6 secondary end points in men with advanced prostate cancer, according to Myovant, the drug’s developer.¹

These results support a new drug application (NDA) submission to the FDA in the second quarter of 2020 and future regulatory submissions in Europe and Japan.

“If approved, relugolix would become the first-of-its-kind oral option for men with advanced prostate cancer,” steering committee member Neal Shore, MD, Carolina Urologic Research Center, said in a press release issued by the company.

The randomized, open-label, parallel-group, multinational clinical study evaluated the safety and efficacy of oral relugolix in men with androgen-sensitive advanced prostate cancer who required at least 1 year of continuous androgen deprivation therapy.

Patients were randomized in a 2:1 ratio to receive either a single loading dose of 360 mg relugolix followed by 120 mg relugolix once daily, or leuprolide acetate 3-month depot injection.

The primary end point was to achieve and maintain testosterone suppression to castrate levels (< 50 ng/dL) through 48 weeks.

Overall, 96.7% of men receiving relugolix achieved sustained testosterone suppression to castrate levels (95% CI, 94.9%-97.9%).

Moreover, relugolix demonstrated superiority to leuprolide acetate in regards to rapid suppression of testosterone at day 4 and day 15, profound suppression of testosterone at day 15, rapid suppression of prostate-specific antigen (PSA) at day 15, and suppression of follicle-stimulating hormone (FSH) at Week 24 (P <.0001).

In addition, relugolix demonstrated non-inferiority to leuprolide acetate on sustained testosterone suppression through 48 weeks (96.7% vs. 88.8%, respectively) with a between-group difference of 7.9% (95% CI, 4.1%-11.8%).

Lastly, pharmacodynamic results showed no testosterone flare after initiation of relugolix and mean testosterone levels returned to normal levels within 90 days after treatment discontinuation, according to the release.

The most frequently reported adverse events, reported in at least 10% of men in the relugolix group, were hot flashes, fatigue, constipation, diarrhea, and arthralgia.

“We are now closer to our goal of bringing a precision oral medicine to the broad spectrum of men with advanced prostate cancer,” Lynn Seely, MD, president and CEO of Myovant Sciences, said in the release.

Relugolix is a small molecule, gonadotropin-releasing hormone (GnRH) receptor antagonist that reduces testicular testosterone production and ovarian estradiol production.

Approximately 1,100 patients are planned to be enrolled in this study, including approximately 430 patients with metastatic prostate cancer to support the analysis of a secondary endpoint of castration resistance-free survival, data which are expected in the third quarter of 2020.

References:
1. Myovant Sciences Announces 97% Response Rate in Positive Phase 3 HERO Study of Once-Daily, Oral Relugolix in Men with Advanced Prostate Cancer [news release]. Basel, Switzerland. November 19, 2019. investors.myovant.com/news-releases/news-release-details/myovant-sciences-announces-97-response-rate-positive-phase-3. Accessed November 19, 2019.