A 71-year-old man with castration-resistant prostate cancer demonstrated a flare phenomenon on 99mTc-MDP and CT after 10 weeks of enzalutamide. Prostate-specific membrane antigen–targeted 18F-DCFPyL PET/CT demonstrated minimal uptake at sites of baseline bone and lymph node disease with increasing uptake at sites of osseous disease following therapy. Although this is likely related in part to decreased androgen receptor activity and a consequent increase in prostate-specific membrane antigen expression, other mechanisms (neovascularization, cell infiltration from the bone repair process, osteoblastic turnover, or minimal radiotracer impurity) may also be involved in causing the increased 18F-DCFPyL uptake at sites of osseous flare.
From the Departments of *Medicine and Radiology, and †Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario; ‡Department of Molecular Oncology, University of British Columbia, Vancouver, British Columbia, Canada; §The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD; ‖Department of Medicine, Hanyang University College of Medicine, Seoul, South Korea; ¶Harvard Medical School, Boston, MA; and **Department of Radiology, University of Wisconsin, Madison, WI.
Received for publication December 3, 2017; revision accepted December 7, 2017.
Conflicts of interest and sources of funding: M.G.P. is a coinventor on a US patent covering 18F-DCFPyL and as such is entitled to a portion of any licensing fees and royalties generated by this technology. This arrangement has been reviewed and approved by the Johns Hopkins University in accordance with its conflict-of-interest policies. S.P.R. and M.G.P. receive research support from Progenics Pharmaceuticals, the licensee of 18F-DCFPyL. S.Y.C. is a consultant for Imaging Endpoints LLC. The following grants are acknowledged: EB024495, CA134675, CA184228, CA183031 and the Movember Foundation (GAP2). No other potential conflict of interest relevant to this article was reported.
Correspondence to: Katherine A. Zukotynski, MD, 1200 Main St W, Room 1P11, Hamilton, Ontario, Canada L8N 3Z5. E-mail: firstname.lastname@example.org.