Bicalutamide in advanced prostate cancer. A review

Bicalutamide is a nonsteroidal antiandrogen with a long elimination half-life (t1/2) that permits once-daily administration. When combined with a gonadorelin (gonadotrophin releasing hormone; GnRH) agonist in maximum androgen blockade (MAB) regimens, bicalutamide 50 mg once daily is at least as effective as flutamide 250 mg 3 times daily, as shown in a large randomised trial. Rate of treatment failure, the primary end-point, was significantly lower at 49 weeks with bicalutamide in this study, mainly because of a lower rate of withdrawal due to adverse events. Final results at a median follow-up of 160 weeks revealed longer median times to progression and death with bicalutamide than flutamide, but between-group differences were not significant overall. Although early trials demonstrated clinical benefits with bicalutamide 50 mg/day as monotherapy, the drug in this dosage is less effective than castration. Increasing the dosage to 150 mg/day has improved its efficacy in patients with non-metastatic disease: combined data from 2 trials demonstrate similar survival with bicalutamide in this dosage compared with castration. Accumulating evidence from these and other studies indicates that sexual interest appears to be better preserved with bicalutamide than with castration. The tolerability profile of bicalutamide is characteristic of antiandrogens, with breast pain and gynaecomastia occurring most often. Bicalutamide has not been causally associated with problems such as interstitial pneumonitis and difficulty with light/dark adaptation seen with nilutamide, and in a 50 mg/day dosage causes a lower incidence of diarrhoea than flutamide 750 mg/day. Changes in hepatic function are generally transient and resolve or improve during therapy or after bicalutamide treatment is withdrawn.

Bicalutamide, with its once-daily regimen and good tolerability, is an attractive option when combined with a GnRH agonist in patients with advanced prostate cancer who are suitable to receive MAB regimens. The role of bicalutamide as monotherapy in the management of this common malignancy is currently being assessed.