Bipolar Androgen Therapy (BAT) State of the Art Explained by Dr. Antonarakis

Bipolar androgen therapy (BAT) is a paradoxical treatment strategy for metastatic androgen pathway modulation–resistant prostate cancer (mAPMR), formerly known as metastatic castration‑resistant prostate cancer (mCRPC), that replaces continuous androgen suppression with cyclical, supraphysiologic testosterone exposure, aiming to exploit the tumor’s dependence on an overactive androgen receptor (AR). The approach was pioneered by Samuel Denmeade and John Isaacs at Johns Hopkins and has been advanced through multiple prospective trials and translational studies led in part by Emmanuel Antonarakis, now Clark Endowed Professor of Medicine at the University of Minnesota. In BAT, patients remain on medical or surgical castration but receive monthly intramuscular testosterone cypionate or enanthate to reach serum testosterone levels around 1,500 ng/dL, creating repeated swings between castrate and supraphysiologic androgen states.

Clinical experience across cohorts totaling roughly 150–200 men shows that BAT produces PSA50 responses in about 30–40% of asymptomatic, low‑ to intermediate‑burden mCRPC patients, with an additional subset achieving stable disease. A consistent caution is an approximately 10% risk of disease acceleration, which is why BAT has been restricted to minimally symptomatic patients without bone pain requiring narcotics or impending complications such as urinary obstruction or spinal cord compression. Quality‑of‑life signals are favorable in many men, with reports of improved energy and sexual function during treatment cycles.

A multi‑site consortium analysis presented by Antonarakis integrated next‑generation sequencing (NGS) performed within 30 days of the first BAT dose to define biomarkers of sensitivity and resistance. AR amplification emerged as a predictor of greater BAT sensitivity, consistent with the therapy’s mechanism of AR stimulation. Perhaps most strikingly, pathogenic TP53 mutations (typically adverse in other systemic therapy contexts) were associated with improved PSA50 rates and longer progression‑free survival on BAT. The combination of AR amplification plus a TP53 mutation, seen in about 20% of the cohort, identified a high‑response subgroup with roughly a 70% PSA50 rate and significantly prolonged disease control.
Conversely, SPOP mutations and AR ligand‑binding domain (LBD) mutations were linked to resistance and shorter progression‑free survival; among LBD mutations, the classic 875/878 alterations portended resistance more strongly than H702Y. These findings refine patient selection and highlight the need for clinical assays that quantify AR copy number rather than reporting only presence/absence, especially given the risk of undercalling AR amplification in liquid biopsies with low tumor fraction.

Looking ahead, Antonarakis and collaborators are exploring ways to make BAT more practical and tunable. Because the current monthly intramuscular schedule was chosen empirically around 2015, there is interest in testing alternative cycle lengths and in developing oral, short‑half‑life AR agonists that could mimic or improve BAT while allowing rapid reversal and finer pharmacokinetic control. Such agents could enable more precise modulation between supraphysiologic and castrate/near‑castrate states and potentially broaden BAT’s applicability. While BAT is not yet FDA‑approved, the accumulating clinical and biomarker data provide a clear path toward better‑selected candidates and next‑generation formulations that preserve efficacy while reducing the risk of unpredictable progression.

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