[Cancer of the prostate: biologic bases for the use of an antiandrogen in its treatment].

Although orchiectomy, estrogens and LHRH agonists suppress testicular androgens, they are without effect on adrenal androgens which are converted into dihydrotestosterone in the prostate. It is therefore necessary to develop substances able to block the action of all androgens, whatever their source, on target organs. The non-steroid, Anandron (RU 23908), when administered orally, gives rise to a high and sustained plasma level of intact compound that inhibits testosterone binding to its receptor. This inhibition, however, occurs not only in the prostate but also in the pituitary. The negative feedback action of androgens is thus inhibited by Anandron resulting in an increased secretion of testosterone and explaining the necessity of combining Anandron with castration (whether surgical or medical by an LHRH agonist). Anandron opposes, on the one hand, the action of adrenal androgens and, on the one other, of the testosterone surge that occurs during the early days of treatment with the LHRH analog. The efficacy of the combined treatment has been demonstrated experimentally. Clinical trials are presently underway.