Efficacy of low dose ketoconazole therapy for Chinese patients with castration resistant prostate cancer

Abstract

To assess the efficacy of low dose ketoconazole therapy for Chinese patients with castration resistant prostate cancer (CRPC) and explore possible prognosis factors. From August 2006 to August 2011, 71 patients with CRPC were analyzed retrospectively, who received oral ketoconazole 200 mg, three times a day with prednisone 5 mg, twice a day. Prostate specific antigen (PSA) response rate was defined as the percentage of patients with PSA decline ≥ 50% compared to baseline PSA level during low dose ketoconazole therapy. Multivariate Logistic regression analysis and receiver operating characteristic curve were used to assess the prognostic factors and their accuracy. The mean initial serum PSA level was (205 ± 38) ng/ml for these patients with mean age (69 ± 1) years old. After first androgen deprivation therapy failure, the prostate cancer progressed into castration resistant stage. The baseline PSA was (93 ± 24) ng/ml and the baseline serum testosterone was (0.13 ± 0.02) ng/ml. During the low dose ketoconazole therapy, 31 patients (43.7%) had PSA decrease and 22 cases (31.0%) were effective with PSA decline more than 50%. PSA doubling time and baseline serum testosterone were positive correlation with PSA response rate by multivariate Logistic regression analysis. Patients with PSA doubling time of ≥ 3.0 months had a PSA response rate of 64.3% and the PSA response rate in those with < 3.0 months decreased to 22.8%, hazard rate (HR) = 0.149 (95% confidence interval [CI] 0.029 - 0.766), P = 0.023, area under the curve (AUC) = 0.707. The PSA response rate for patients with baseline serum testosterone ≥ 0.1 and < 0.1 µg/L were 55.6% and 5.7%, respectively, HR = 0.068 (95%CI 0.012 - 0.380), P = 0.002, AUC = 0.749. The common adverse reactions included liver dysfunction (17.9%), renal dysfunction (16.4%), fatigue (11.9%), nausea (6.0%) and anorexia (4.5%) and so on. Low dose ketoconazole therapy was a moderate, low toxicity hormonal therapy option for patients with CRPC. PSA doubling time ≥ 3 months and baseline serum testosterone ≥ 0.1 µg/L were predictors of desired effect for low dose ketoconazole therapy.