Prostate cancer: oral relugolix rapidly achieves castration in phase 2

  • Deanaley DP & et al.
  • Eur Urol
  • 6 Apr 2020

  • curated by Deepa Koli
  • Univadis Clinical Summaries
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Takeaway

  • In patients with prostate cancer undergoing radiotherapy, relugolix was well tolerated in this phase 2 trial, achieved testosterone suppression to castrate levels, maintained it during treatment, and showed rapid recovery after discontinuation.

Why this matters

  • Testosterone recovery can take up to 100 days after degarelix discontinuation.

Study design

  • Phase 2 study: 103 patients with intermediate-risk prostate cancer were randomly assigned to 24-week treatment with either daily oral relugolix (n=65) or 4-week subcutaneous depot degarelix (n=38).
  • Funding: Millennium Pharmaceuticals, Inc.

Key results

  • Relugolix and degarelix groups showed:
    • Conventional castration rates: 95% and 89%, respectively.
    • Profound castration rates for the lower threshold of 0.7 nmol/L: 82% and 68%, respectively.
    • Median time to castration: 4 and 3 days, respectively.
  • At 12 weeks after treatment discontinuation:
    • Relugolix group: testosterone recovery to baseline or >9.8 nmol/L occurred in 52% of patients.
      • 8.3-point improvement in sexual activity scores.
    • Degarelix group: median testosterone remained well below 1.73 nmol/L; recovery to baseline levels occurred in 16% of patients.
      • No improvement in sexual activity score.
  • In relugolix and degarelix groups:
    • Most common toxicity was hot flush: 57% and 61%, respectively.
    • Grade ≥3 toxicities: 2% and 11%, respectively.
  • Degarelix group showed high rates of increased alanine aminotransferase (13%) and injection-site erythema (11%).

Limitations

  • Nonblinded.