Experience of bipolar androgen therapy (BAT) in Argentinian oncology centres

Background: Previous studies with bipolar androgen therapy (BAT) have shown clinical activity in metastatic Castration Resistant Prostate Cancer (mCRPC) as well as the poten-tial to re-sensitise prostate cancer cells to prior androgen receptor-targeted agents. None of these studies had tested BAT after chemotherapy. In this study, we gathered real-world evidence from three centres in Argentina where BAT is being used in castration-resistant prostate cancer (CRPC), not only prior to chemotherapy but also after several lines of treatment. Materials and methods: This retro-prospective nonrandomised multicentre cohort study included patients with mCRPC, who received BAT in different scenarios defined by the treating physician at three centres in Argentina. Results: A total of 21 asymptomatic patients with mCRPC were included. There was a median of two lines before BAT, with nine patients (42.8%) receiving three or more lines, and 13 patients (61.9%) receiving chemotherapy previously. Previous lines included next-generation hormonal agents (NHA) in 100% (abiraterone 33.3% and enzalutamide 71.4%), chemotherapy in 61.9%, Radium-223 in 47.6% and others in 4.8%. The progres-sion free survival (PFS) after BAT was 3.5 months (95% CI: 3.06-7.97). PSA50 response rate (RR) was 28.5% and the overall RR was 14.3%. Of the 17 patients who had disease progression, 9 had a rechallenge to NHA, achieving a 55% RR, 6 received other treatment (chemotherapy in 5 and 177Lu-PSMA in 1) with a 66% RR and 2 best supportive care. The PFS2, calculated after the initiation of BAT in the 15 patients who received further ther-apy, was 7.93 months (95% CI: 6.73-NR). Treatment was overall well tolerated, with only two patients requiring hospitalisation and treatment interruption due to worsening pain.Conclusion: To the authors' knowledge, this is the first publication of BAT in later lines of therapy in mCRPC. BAT showed clinical activity in this scenario. Our data supports that BAT may play a role in CRPC re-sensitisation after multiple treatment lines.