Ketoconazole and liarozole in the treatment of advanced prostatic cancer

Abstract

Background: Ketoconazole, an imidazole derivative, is an orally active antifungal agent. In high doses (400 mg three times a day), it inhibits the biosynthesis of testicular and adrenal androgens and may therefore be useful for the treatment of hormone dependent diseases such as advanced prostatic cancer. Similarly, a new imidazole derivative, liarozole, was recently found to interfere with testicular and adrenal steroid biosynthesis in animals and healthy volunteers.

Methods: The therapeutic and endocrine effects of ketoconazole and liarozole in patients with disseminated prostatic cancer are discussed, including data from the literature and personal experience.

Results: Using high-dose ketoconazole, medical castration with the expected clinical response was achieved easily in previously untreated patients in all clinical series (personal data include seven patients). In patients with prostatic cancer who had relapses after castration, few objective remissions were achieved. By contrast, long-lasting subjective remissions, especially pain relief, were seen in more than half of the patients (personal data include 20 patients). Gastrointestinal intolerance, which was the main side effect, severely limits the routine use of the drug. Recently, the authors studied the effect of liarozole on adrenal steroid production in castrated patients whose disease was progressive after first-line treatment. Unlike ketoconazole therapy, adrenal androgen and cortisol levels were not modified. A Phase I-II trial was then done in 44 patients with metastatic prostatic cancer in clinical relapse. In patients with measurable disease, objective responses, including tumoral volume reduction, occurred in approximatively 30%. A prostate specific antigen reduction of 50% or more was noted in approximatively 50% of patients. Pain relief occurred in most patients. Mucocutaneous side effects were observed in most patients--dryness of the skin and onychomalacia. Raised tissue retinoic acid levels suggested a possible pathway by which this drug might exert its cytotoxic effects.

Conclusions: Ketoconazole in high doses is effective in first-line and second-line therapy for advanced prostatic cancer, but gastrointestinal side effects limit its routine use. Liarozole is a new imidazole that is also effective in second-line therapy for prostatic cancer and has fewer side effects. Unlike ketoconazole, its effect is not mediated by inhibition of steroid biosynthesis.