Oncology The Effects of Enzalutamide Monotherapy on Multiparametric 3T MR Imaging in Prostate Cancer Rosanne CV. Van der Roest a, * , Petra J. van Houdt b , Stijn WTPJ. Heijmink c , Jeroen de Jong d , André M. Bergman e , Wilbert Zwart f , Uulke A. van der Heide b , Henk G. van der Poel a a Department of Urology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands b Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands c Department of Radiology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands d Department of Pathology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands e Department of Medical Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands f Department of Molecular Pathology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands article info Article history: Received 8 April 2016 Accepted 13 April 2016 Keywords: Antiandrogen Enzalutamide Histology MRI Prostate cancer abstract The effects of enzalutamide monotherapy on prostate tumor downsizing and multiparametric MRI are currently unknown. Here we present the first case in literature of a patient with high-grade prostate cancer who underwent 3 months of neoadjuvant enzalutamide, for which the effects on mpMRI and histology were determined. Tumor size reduction and downstaging were noted. Neoadjuvant enzalutamide resulted in an increase in ADC value on the DWI-MRI sequences. Histological changes were also observed. Ó 2016 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction Androgen ablation is the cornerstone of systemic prostate cancer treatment. This can either be achieved by (chemical) castration with GnRH/LH-RH-analogues alone or in combination with androgen receptor inhibitors. Over time, multiple androgen re- ceptor inhibitors have been developed, with increasing efficacies in blocking androgen action. Initially, flutamide was developed as a non-steroidal antiandrogen. Subsequently, other non-steroidal antiandrogens such as nilutamide and bicalutamide were intro- duced, with longer half-lives and reduced toxicity. 1 Second gen- eration antiandrogens such as enzalutamide (Xtandi, Astellas Pharma; Medivation) showed increased androgen receptor blockade, inhibition of receptor nuclear translocation and diminished DNA-binding 2 that resulted in a survival benefit in men with castration resistant cancer. 3,4 The effects of enzaluta- mide monotherapy on cell growth have not extensively been studied in hormone-naïve prostate cancer patients. Neoadjuvant androgen ablation prior to prostatectomy has shown to result in tumor downstaging, reduction in surgical positive margin-rates, decreased lymph node invasion and reduced blood loss. 5e7 Although generally found not to affect overall survival, 6 in men with PSA > 20 ng/mL neoadjuvant cyproterone acetate treat- ment was found to improve recurrence-free survival. 4 Therefore, we started a phase II window study on the efficacy of enzalutamide in hormone-naïve patients in the preoperative setting; tissue is analyzed before and after 3 months of neoadjuvant 160 mg daily enzalutamide monotherapy (NL47463.031.14). In this study, potential tumor downstaging is assessed in men who undergo prostatectomy for intermediate or high-risk prostate cancer. Multiparametric (mp) MRI is presently used to grade and stage men with prostate cancer preoperatively. Androgen ablation was Sources of support: none * Corresponding author. Tel.: þ31 20 5122553; fax: þ31 20 5122459. E-mail address: r.vd.roest@nki.nl (R.CV. Van der Roest). Contents lists available at ScienceDirect Urology Case Reports journal homepage: www.elsevier.com/locate/eucr 2214-4420/Ó 2016 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). http://dx.doi.org/10.1016/j.eucr.2016.04.010 Urology Case Reports 7 (2016) 67e69