ZD1839 (gefitinib) and hormone resistant (HR) prostate cancer - final results of a double blind randomized placebo-controlled phase II study

4698 Background: The epidermal growth factor receptor (EGFR) is expressed in most prostate cancers. We investigated the effect of gefitinib (ZD1839), an orally active EGFR tyrosine kinase inhibitor, on the slope of changing prostate specific antigen (PSA) levels. Methods: We conducted a placebo-controlled, double blind, randomized Phase II study of gefitinib (500 mg/day) in patients with prostate cancer and hormone-independent PSA progression. To calculate sample size, the method of Schlesselman (J Chron Dis 1973; 26: 561–70) was applied; 24 patients per group were necessary to detect a change in slope of 0.25 (ie to zero slope) with 90% power using a two-sided significance level of alpha = 0.05. Asymptomatic patients with PSA progression after castration or under luteinizing hormone-releasing hormone treatment (excluding antiandrogens and recent radiotherapy) were eligible. Unblinding took place after 6 months or in the case of medical emergencies. Secondary endpoints included PSA response rate at 6 mont...