Sustained exposure to the investigational Kisspeptin analog, TAK-448, down-regulates testosterone into the castration range in healthy males and in patients with prostate cancer: results from two phase 1 studies

J Clin Endocrinol Metab. 2014 Aug;99(8):E1445-53. doi: 10.1210/jc.2013-4236. Epub 2014 Apr 24.


Background/objective: Kisspeptin-54, an endogenous naturally occurring ligand of the G protein-coupled receptor-54, stimulates GnRH-gonadotropin secretion and suppresses metastases in animal models of cancer but is subject to rapid degradation and inactivation. TAK-448 is an investigational oligopeptide analog of the fully active 10-amino acid C terminus of kisspeptin-54. This phase 1 study evaluated the safety, pharmacokinetics, and pharmacodynamics of TAK-448 in healthy subjects and patients with prostate cancer (PC).

Design: Healthy subjects aged 50 years or older received TAK-448 sc as a single-bolus or 2-hour infusion (0.01-6 mg/d; part A) and as a 14-day sc administration (0.01-1 mg/d; part B). In a subsequent, open-label, phase 1 study in PC patients aged 40-78 years, TAK-448 was given as a 1-month depot formulation.

Results: Eighty-two healthy subjects received TAK-448; 30 received placebo. Grades 1-2 adverse events were reported in 26% of subjects during TAK-448 treatment. All dosing regimens resulted in dose-proportional exposures. The maximum observed plasma concentration occurred after 0.25-0.5 hours, and median terminal elimination half-life was 1.4-5.3 hours. T increased approximately 1.3- to 2-fold by 48 hours after a single bolus or 2 hour injections, whereas during the 14-day infusion, at doses above 0.1 mg/d, T dropped to below-baseline values by 60 hours and reached a subsequently sustained below-castration level by day 8. In PC patients, T decreased to less than 20 ng/dL in four of five patients dosed with 12 or 24 mg TAK-448 sc-depot injections. The prostate-specific antigen decreased greater than 50% in all patients dosed with 24 mg.

Conclusions: Continuous TAK-448 infusion was well tolerated by healthy males and resulted in sustained T suppression. Depot injection in patients with PC similarly reduced T and resulted in prostate-specific antigen responses.

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Dose-Response Relationship, Drug
  • Down-Regulation / drug effects
  • Drug Administration Schedule
  • Drugs, Investigational / administration & dosage*
  • Drugs, Investigational / adverse effects
  • Drugs, Investigational / pharmacokinetics
  • Health
  • Humans
  • Kisspeptins / administration & dosage*
  • Kisspeptins / adverse effects
  • Kisspeptins / pharmacokinetics
  • Luteinizing Hormone / blood
  • Male
  • Middle Aged
  • Orchiectomy*
  • Placebos
  • Prostatic Neoplasms / blood*
  • Prostatic Neoplasms / metabolism
  • Testosterone / blood*


  • Drugs, Investigational
  • Kisspeptins
  • Placebos
  • metastin (46-54), acetyl-tyrosyl(46)-hydroxypropyl(47)-threonyl(49)-azaglycyl(51)-methylarginyl(53)-tryptophyl(54)-
  • Testosterone
  • Luteinizing Hormone