Abstract
INTRODUCTION: A certain proportion of prostate cancers have alterations in homologous recombination repair (HRR)- related genes. poly ADP-ribose polymerase (PARP) inhibitors have been approved for metastatic castration-resistant prostate cancer (mCRPC) with mutations in the BRCA1/2 gene. For other HRR-related genes, there is insufficient evidence to determine whether PARP inhibitors are effective or not. CASE PRESENTATION: The patient was a 59-year-old man with mCRPC. FoundationOne CDx was performed using surgical specimens and detected a pathogenic variant of the RAD54L gene, and the expert panel recommended administration of niraparib by patient-proposed healthcare services. Therefore, the patient was enrolled in the BELIEVE Trial and started on niraparib, which showed a marked decrease in PSA and a reduction in metastatic lesions. However, PSA subsequently began to rise and metastatic lesions were enlarged, so treatment was discontinued at 25 weeks. CONCLUSION: Niraparib was effective for mCRPC with RAD54L gene mutation. TRIAL REGISTRATION: The prospective trial of patient-proposed healthcare services with multiple targeted agents based on the results of gene profiling by multigene panel test (BELIEVE) (NCCH1901/jRCTs031190104).