FDA grants relugolix priority review for advanced prostate cancer

The FDA has granted a priority review designation to a new drug application (NDA) for relugolix for the treatment of patients with advanced prostate cancer, according to Myovant Sciences, the manufacturer of the oral GnRH receptor antagonist.¹

The NDA is based on data from the phase 3 HERO study, which compared oral relugolix to standard leuprolide acetate injection in men with advanced prostate cancer. Among patients randomized to relugolix, 96.7% (95% CI, 94.9-97.9) maintained castration through 48 weeks, compared with 88.8% (95% CI, 84.6-91.8) of patients in the leuprolide cohort. The benefit was statistically significant (P <.001).²

Beyond meeting this primary study end point, the benefit with relugolix was sustained across all major secondary end points (P <.001). Relugolix was also associated with a 54% lower risk of major adverse cardiovascular events compared with leuprolide (HR, 0.46; 95% CI, 0.24-0.88).

Under the Prescription Drug User Fee Act, the FDA is scheduled to decide on the NDA on or before December 20, 2020. The FDA indicated in its acceptance letter to Myovant that it is not currently planning to review the NDA at a meeting of its Oncologic Drugs Advisory Committee. Myovant noted in a press release that relugolix is slated to become the first FDA-approved oral GnRH receptor antagonist for the treatment of patients with 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, chief executive officer of Myovant Sciences, stated in the press release. “As recently published in the New England Journal of Medicine, relugolix demonstrated superior efficacy…compared to the current standard of care, leuprolide acetate injections, in the Phase 3 HERO study.”

The open-label international phase 3 HERO trial included 930 patients treated at 155 clinical sites. The median patient age was 71 years (range, 47-97), with 28.6% of patients being aged ≥75 years. Overall, 31.7% of patients had metastatic disease, 15.5% of patients had a Gleason score of 5-6, 38.6% of patients had a Gleason score of 7, and 43.1% of patients had a Gleason score of 8-10. Half (50.2%) of patients had evidence of biochemical or clinical relapse after local primary intervention with curative intent.

The median PSA level at baseline was 10.8 ng/ml and the average testosterone level at baseline was 427.5 ± 156.2 ng/ml. The ECOG performance status was 0 in 88.1% of patients, 11.9% of patients, had prior androgen-deprivation therapy, and 30.3% had prior radiotherapy.

Patients were randomized in a 2:1 ratio to relugolix at 120 mg orally once daily or leuprolide injections every 3 months. Treatment was administered for 48 weeks, with a primary end point of sustained testosterone suppression to castrate levels (<50 ng/dL) through 48 weeks.

On day 4 of treatment, 56% of the relugolix cohort had castrate levels of testosterone versus 0% of the leuprolide group. On day 15, the rates were 98.7% versus 12%, respectively. Also on day 15, 79.4% of the relugolix arm had a confirmed PSA response, compared with 19.8% of patients on the leuprolide arm (P <.001). 

Among a subgroup of men followed for testosterone recovery (n = 184), the mean testosterone levels 90 days following discontinuation of treatment were288.4 ng/dL versus 58.6 ng/dL, respectively.

The incidence of adverse events (AEs) was similar across the study arms. In the relugolix group, all-grade AEs occurred in 92.9% of patients compared with 93.5% in the leuprolide arm. Grade 3/4 AEs occurred in 18% versus 20.5% of the 2 arms, respectively. There were 7 AE-related deaths in the relugolix cohort compared with 9 in the leuprolide arm.

The most common AE across all grades in both arms was hot flash, occurring in 54.3% and 51.6% of the relugolix and leuprolide cohorts, respectively. There was a higher incidence of all-grade diarrhea with relugolix at 12.2% versus 6.8% with leuprolide. All diarrhea cases were grade 1/2 and did not lead to any patient discontinuations.

Major adverse cardiovascular events occurred in 2.9% of the relugolix arm compared with 6.2% of the leuprolide cohort. The study defined major adverse cardiovascular events as nonfatal stroke or myocardial infarction, or death due to any cause.

References

1. Myovant Sciences Announces Priority Review and FDA Acceptance of New Drug Application for Once-Daily, Oral Relugolix for Advanced Prostate Cancer. Published June 22, 2020. https://bit.ly/2NmocMg. Accessed June 22, 2020.

2. Shore ND, Saad F, Cookson MS, et al. Oral relugolix for androgen-deprivation therapy in advanced prostate cancer. N Engl J Med. 2020;382(23):2187-2196. doi: 10.1056/NEJMoa2004325.