Study to Evaluate ctDNA of mCSPC Patients Receiving Apalutamide in Japan

Inclusion Criteria: * Men aged ≥20 years. * Participant has documented diagnosis of metastatic PC with histologically or cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small cell histology. * Participant has metastatic PC that is castration naïve or castration sensitive and is permitted to receive less than 6-months ADT or CAB before registration and less than 36-months neoadjuvant or adjuvant hormonal therapy. * If a participant is treated with ADT or CAB, he has maintained a response to hormonal therapy of stable disease or better, by investigator assessment of imaging and PSA. * Participant is willing to receive apalutamide for mCSPC in the participating site of this study. * Participant is of Japanese nationality. * Participant must sign an ICF indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study. Exclusion Criteria: * Participant does not agree to assess ctDNA including 73 PC driver genes, SNPs, and HLA typing. * Participant has received any prior therapy of abiraterone, docetaxel, enzalutamide, apalutamide or darolutamide. * Participant has known allergies, hypersensitivity, or intolerance to apalutamide or its excipients (refer to the package insert). * Participant has contraindications to the use of ADT based on routine treatment. * Participant has any condition for which, in the opinion of the investigator, participation would not be…