Endocrine studies with a gonadotropin-releasing hormone analogue to achieve withdrawal of testosterone in prostate carcinoma patients.

This investigation on 12 well-defined patients with untreated, advanced prostatic adenocarcinoma establishes the gonadotropin-releasing hormone analogue [D-Ser(But)6](1-9)-nonapeptide-ethylamide (Hoe 766) as an effective, safe and non-toxic form of medical castration. Hoe 766 was given either as subcutaneous injections of 2 x 200 micrograms/day over 14 days and pernasal application (3 x 400 micrograms/day) thereafter, or as subcutaneous injections of 3 x 1,000 micrograms/day over 6 days and pernasal application thereafter in the dosage mentioned above. Both dose regimens were equally effective: pituitary overstimulation between days 3 and 6 with a rise of serum HL and testosterone; pituitary and testicular desensitization with LH and testosterone decline between days 6 and 14; medical castration with average serum testosterone levels maintained around 0.5 ng/ml for up to 12 weeks. Except for transient hot flashes in 4 patients, no clinical or laboratory side effects were observed. It is concluded from this study that the gonadotropin-releasing hormone analogue. Hoe 766, is a valuable alternative to conventional contrasexual measures for prostate cancer palliation. To improve the patient's compliance, however, the smallest single pernasal dosage effective for maintenance of down-regulation and steroidogenic arrest has still to be determined.