Bipolar androgen therapy (BAT)—the intermittent use of high-dose testosterone therapy—is safe and possibly effective in patients with advanced hormone-sensitive prostate cancer (PCa), according to findings of a small study that will be presented at the 2016 Genitourinary Cancers Symposium.
The study, conducted at Johns Hopkins University in Baltimore, enrolled 33 patients with advanced hormone-sensitive PCa. Twenty-two patients had undergone radical prostatectomy, 8 received radiation therapy, and 3 received no treatment. The cohort had a median PSA level of 27.6 ng/mL at study baseline.
All patients received a 6-month androgen deprivation therapy (ADT) lead-in. Patients with a PSA level below 4 ng/mL or 50% or more below baseline at the end of the lead-in went on to receive 2 rounds of alternating BAT-ADT. During rounds of BAT, testosterone cypionate or testosterone enanthate was administered intramuscularly at the FDA-approved dose of 400 mg every 28 days.
Each round of BAT-ADT consisted of 3 cycles of BAT and 12 weeks of ADT alone. The primary endpoint was the percentage of patients with a PSA level below 4 ng/mL at the end of the study.
Of the 33 patients, 29 went on to the BAT phase of the study, and 17 of these men (59%) achieved the primary endpoint, according to lead author Michael T. Schweizer, MD, now at the University of Washington/Fred Hutchinson Cancer Research Center in Seattle, and his colleagues. Three patients (10%) had an undetectable PSA level (less than 2 ng/mL).
Adverse events thought to be at least possibly related to testosterone occurred in 23 (79%) of the 29 men, although all events were low grade, the researchers stated.
The authors noted that previous research demonstrated a paradoxical anti-tumor effect in patients with castration-resistant PCa treated with BAT. An adaptive increase in androgen receptor expression following chronic ADT may underlie this effect, they stated.