Efficacy of treatment with a GnRH antagonist in prostate cancer patients previously treated with a GnRH agonist

Taisuke Ezaki, Takeo Kosaka, Ryuichi Mizuno, Toshiaki Shinojima, Eiji Kikuchi, Akira Miyajima, Mototsugu Oya

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Purpose: The efficacy of switching from a GnRH agonist to a GnRH antagonist for prostate cancer patients resistant to treatment with the GnRH agonist has not been fully characterized yet. We aimed to evaluate the efficacy of the switch to a GnRH antagonist in patients with PSA failure after hormonal therapy with a GnRH agonist. Methods: We retrospectively examined 18 patients with prostate cancer who received androgen-deprivation therapy and who were treated with a GnRH antagonist (degarelix) after they showed an elevated PSA while on GnRH agonist therapy. We evaluated the characteristics of the patients and analyzed some clinical factors for their potential association with the patient response to the switch. Results: The median PSA at the switch was 7.9 (0.37-1709) ng/ml, and the median testosterone level was 0.17 (<0.08-0.81) ng/ml. Three months after the switch, the median PSA level was 11.3 (0.22-2636) ng/ml, and the median testosterone level was 0.14 (<0.08-0.23) ng/ml. The PSA decreased in six patients (33.3 %) 1 month after the switch, and in three of them it decreased by more than 50 % by 3 months after the switch. Univariate analyses revealed that the lower number of prior treatment lines for prostate cancer before the switch was associated with a favorable decrease in PSA. Conclusions: Switching from GnRH agonist to GnRH antagonist therapy was effective for some prostate cancer patients with PSA failure. The small number of prior treatment lines for prostate cancer before the switch was significantly associated with a good PSA response.

Original languageEnglish
Pages (from-to)301-306
Number of pages6
JournalCancer Chemotherapy and Pharmacology
Volume76
Issue number2
DOIs
Publication statusPublished - 2015 Aug 27

Keywords

  • Androgen-deprivation therapy
  • GnRH antagonist
  • PSA failure
  • Prostate cancer

ASJC Scopus subject areas

  • Oncology
  • Toxicology
  • Pharmacology
  • Cancer Research
  • Pharmacology (medical)

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