Relugolix approved in Canada for advanced prostate cancer

Health Canada has approved the oral GnRH receptor antagonist relugolix (Orgovyx ) for the treatment of patients with advanced prostate cancer.¹

The approval is based on results from the phase 3 HERO study, which showed that 96.7% of patients randomized to relugolix maintained castration through 48 weeks, compared with 88.8% of patients receiving leuprolide (P <.001).² The benefit with relugolix was sustained across all major secondary end points (P <.001).

"Roughly 1 in 8 Canadian men will develop prostate cancer in their lifetime, and the ability to suppress testosterone, primarily achieved through androgen deprivation therapy (ADT), is foundational in the treatment of the advanced stages of the disease," Fred Saad, MD, FRCS, professor and chairman of the Department of Surgery and director of Genitourinary Oncology at the University of Montreal, stated in a news release.¹ "In the HERO study, Orgovyx demonstrated rapid, sustained, and profound testosterone suppression when compared to leuprolide. Orgovyx is the first approved ADT in Canada that can be administered orally, and once daily, offering a safe and effective option for advanced prostate cancer patients in the country."

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.²

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 were 288.4 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 Receives Positive CHMP Opinion for ORGOVYX® (relugolix) for the Treatment of Advanced Prostate Cancer. Published online February 25, 2022. Accessed February 28, 2022. https://bit.ly/3vqLTdj

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.