Original Article: GenitourinaryAn Open-Label, Single-Arm Phase Two Trial of Gefitinib in Patients With Advanced or Metastatic Castration-Resistant Prostate CancerPezaro, Carmel, MBChB*†; Rosenthal, Mark A., MBBS, PhD, FRACP†‡; Gurney, Howard, MBBS, FRACP§¶; Davis, Ian D., MBBS, PhD, FRACP, FAChPM†∥; Underhill, Craig, MBBS, FRACP**††; Boyer, Michael J., MBBS, FRACP‡‡; Kotasek, Dusan, MBBS, FRACP§§; Solomon, Benjamin, MBBS, PhD, FRACP*†¶¶; Toner, Guy C., MBBS, MD, FRACP*†¶¶Author Information From the *Department of Medical Oncology, Peter MacCallum Cancer Centre, East Melbourne; †Cancer Trials Australia, VIC; ‡Department of Medical Oncology, Royal Melbourne Hospital, Parkville, VIC; §Department of Medical Oncology, Westmead Hospital, Westmead; ¶University of Sydney, NSW; ∥Ludwig Institute Oncology Unit, Austin Health, Heidelberg; **Border Medical Oncology, Wodonga, VIC; ††University of New South Wales; ‡‡Department of Medical Oncology, Sydney Cancer Centre, Camperdown, NSW; §§Ashford Cancer Centre, Ashford, SA; and ¶¶University of Melbourne, VIC, Australia. Supported in part by a Victorian Cancer Agency Clinician Researcher Fellowship (to I.D.D.). AstraZeneca Pharmaceuticals sponsored the trial, supplied study drug, and coordinated data collection and analysis. AstraZeneca study number: 1839IL/0076. AstraZeneca had no input into data interpretation and production of the manuscript. American Journal of Clinical Oncology: August 2009 - Volume 32 - Issue 4 - p 338-341 doi: 10.1097/COC.0b013e31818b946b Buy Metrics Abstract Objective: To determine whether the oral epidermal growth factor receptor (EGFR) inhibitor gefitinib (ZD1839, Iressa®) has clinical efficacy in patients with castration-resistant prostate cancer (CRPC). Methods: Multicenter open-label phase 2 study. Fifty-one male patients with CRPC and rising PSA levels were enrolled to obtain the target enrollment of 38 patients who completed at least 3 months of treatment with continuous gefitinib 500 mg/d. The primary end point was the prostate-specific antigen (PSA) response rate, as defined by a confirmed 50% decline in serum PSA. Results: One patient had a confirmed PSA response, giving a response rate of 2.0% (95% CI 0.1–10.4%). The median time to progression was 28 days and the median time on study was 85 days. The majority of patients had a stable performance status while on study. Of the 51 patients who received at least 1 dose of gefitinib, 13 patients had a dose reduction and 9 patients withdrew because of an adverse event. Conclusions: There was minimal evidence of single-agent gefitinib activity in CRPC. The treatment was associated with clinically relevant toxicities, which responded to dose interruption or reduction. © 2009 Lippincott Williams & Wilkins, Inc.