Real-world evidence of triplet therapy efficacy in patients with metastatic castration-sensitive prostate cancer: a Japanese multicenter study

Abstract Background Two randomized trials demonstrated that the survival benefits afforded by triplet therapy were greater than those of doublet therapy, thus changing the treatment paradigm for metastatic castration-sensitive prostate cancer (mCSPC). This is the first study to assess the real-world use, performance, and safety of triplet therapy in Japanese patients. Methods This retrospective multicenter study included 45 consecutive mCSPC patients who received triplet therapy composed of androgen deprivation therapy (ADT), docetaxel, and darolutamide between January 2023 and June 2024. Baseline patient characteristics and their clinical parameters during triplet therapy were collected. Adverse events (AEs) were graded using Common Terminology Criteria for Adverse Events version 5.0, and imaging responses were evaluated following the RECIST criteria. The prostate-specific antigen (PSA) nadir was defined as the lowest PSA value during follow-up, and the PSA decrease was the initial PSA value minus the PSA nadir. Results The median patient age was 70 years and the median follow-up duration was 10 months. High-volume disease was present in 82.2% of patients. Concurrent administration of docetaxel and darolutamide was scheduled for 22.2% of cases. The incidence of any AE was 86.7%, with 55.5% of patients experiencing grade 3–4 AEs. Neutropenia was common, but prophylactic granulocyte colony-stimulating factor (G-CSF) significantly reduced the incidence of neutropenia of grade 3 or higher. Febrile neutropenia occurred in four patients (8.9%); these patients had not received prophylactic G-CSF. A decline in PSA of 90% was observed in 95.6% of patients, and an imaging response was seen in 97.8%. Conclusions Triplet therapy with ADT, darolutamide, and docetaxel was highly efficacious and tolerable in Japanese mCSPC patients, particularly those with high-volume disease. Prophylactic G-CSF prescription is crucial to manage neutropenia effectively. Further studies with longer follow-ups are needed to confirm these findings and explore the long-term outcomes.