Retrospective Analysis of the Consequences of Acid Suppressive Therapy on Ketoconazole Efficacy in Advanced Castration-Resistant Prostate Cancer

Background:The area under the curve of a single ketoconazole dose has been shown to decrease significantly when administered with acid suppressive therapy. No published studies have examined the clinical impact of concurrent ketoconazole and acid suppressive therapy in patients with castration-resistant prostate cancer (CRPC).Objective:To evaluate the effect of acid suppressive therapy on prostate-specific antigen (PSA) response rate in CRPC patients receiving ketoconazole.Methods:This retrospective study evaluated CRPC patients treated with ketoconazole 3 times daily between January 1, 1999, and September 30, 2009. Patients included in the analysis had failed androgen deprivation therapy, and were subsequently initiated on ketoconazole. Response (PSA decline ≥50% maintained ≥4 weeks) was evaluated in patients receiving ketoconazole with (group 1 [G1]) or without (group 2 [G2]) concurrent acid suppressive therapy.Results:Thirty patients (G1: 11 patients; G2: 19 patients) were included in the analysis. Mea...