(UroToday.com) During bipolar androgen therapy (BAT), intramuscular testosterone is administered, which results in rapid cycling of serum T levels from supraphysiologic to near-castrate in men with metastatic castration resistant prostate cancer (mCRPC).1 It has previously been observed that anecdotal clinical responses to immune checkpoint blockade in mCRPC patients previously treated with BAT occur and it has been hypothesized that a BAT/ immune checkpoint blockade combination would be synergistic. At the American Society of Clinical Oncology (ASCO) 2021 Annual Meeting, Dr. Mark Markowski and colleagues reported the results of a prospective phase 2 study of men with mCRPC treated with BAT in combination with nivolumab.