Achieving Complete Response in Metastatic Prostate Cancer With Triplet Therapy and Local Radiation: A Case Report

Triplet therapy, consisting of androgen deprivation therapy, docetaxel, and androgen receptor signaling inhibitors, has been approved for the treatment of metastatic castration-sensitive prostate cancer (mCSPC) and is primarily recommended for high-volume disease. A 68-year-old man presented with suspected prostate cancer following the detection of lumbar spine metastases. Prostate-specific antigen (PSA) was as high as 69.76 ng/mL at the first visit. Imaging revealed widespread metastases in the bones and lungs, and a biopsy confirmed prostate cancer with a Gleason score of 4+5=9 (cT3b, N1, M1c). Triplet therapy (surgical castration, docetaxel, and darolutamide) was initiated, resulting in a rapid decline in PSA to <0.01 ng/mL within four months. Metastatic lesions progressively regressed, and a complete response was achieved on imaging 17 months after treatment initiation. However, repeat prostate biopsy revealed residual viable tumor cells (Gleason score of 4+5=9), prompting local radiation therapy to the prostate. Two months after radiation, the patient remained on darolutamide monotherapy, with PSA persistently <0.01 ng/mL. This case highlights the potential for achieving a complete response in mCSPC with triplet therapy. Even in metastatic disease, first-line treatment may lead to a complete response, underscoring the need for further studies to identify patients who may benefit most from this approach.