Prominent response to platinum‐based chemotherapy in a patient with BRCA2 mutant‐neuroendocrine prostate cancer and MDM2 amplification

INTRODUCTION: Genomic profiling provides useful information for diagnosis, treatment, and prognosis, and detection of certain defects, such as DNA repair gene aberrations or microsatellite instability, can possibly lead to optimal treatment, but this testing has not been widely used to inform prostate cancer treatment. CASE PRESENTATION: A 55‐year‐old man sequentially treated for prostate cancer was diagnosed as neuroendocrine prostate cancer from prostate specimens resected because of urinary retention. Subsequently, he received five cycles of platinum‐based chemotherapy in total and responded well. We also performed next‐generation sequencing of a sample from the prostate specimen and identified a breast cancer susceptibility gene mutation with Murine Double Minute 2 amplification and loss of heterozygosity in retinoblastoma 1. CONCLUSION: We report a neuroendocrine prostate cancer patient with Murine Double Minute 2 amplification who experienced an aggressive course and for whom platinum‐based chemotherapy was effective, and one of the reasons for the good response might be the breast cancer susceptibility gene mutation.