A Case of Metastatic Castration-Resistant Prostate Cancer With RAD54L Mutation Responding to Niraparib.

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. 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. Niraparib was effective for mCRPC with RAD54L gene mutation. 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).