Japanese Case of Enzalutamide-Resistant Prostate Cancer Harboring a SPOP Mutation With Scattered Allelic Imbalance: Response to Platinum-Based Therapy

Genomic analysis of tumor biopsy specimens is critical for precision medicine, but there are no consensus guidelines on treatment plans for specific mutations. Herein we present a case of enzalutamide-resistant prostate cancer (PC) harboring a speckle-type pox virus and zinc finger protein (SPOP) mutation with scattered allelic imbalance successfully treated using platinum-based treatment. A 71-year-old man was diagnosed with castration-resistant PC and bone metastases. He was initial treated using enzalutamide and denosumab, and subsequently administrated radium-223. His prostate-specific antigen level initially decreased during treatment, but eventually began to rise. Magnetic resonance imaging revealed progressive PC invading the bladder, so we performed channeling transurethral resection of bladder tumor. The pathological diagnosis was adenocarcinoma with neuroendocrine differentiation. Carboplatin with etoposide therapy was initiated and no obvious tumor progression was detected thereafter. Genetic sequencing identified a SPOP p.Y87N mutation with scattered allelic imbalance. These findings suggest that enzalutamide-resistant PC with SPOP loss of function might be highly responsive to platinum-based therapy. Mutational analyses might provide useful information for treatment guidance of refractory PC. (C) 2019 Elsevier Inc. All rights reserved.