In this study BAT produced high rates of PSA responses (7 of 14 evaluable patients) and radiographic responses (5 of 10 evaluable patients). Eventually all men showed PSA progression, but 4 patients remained on BAT for 1 year or longer.
Because these patients demonstrated PSA reductions upon receiving androgen ablative therapies after BAT, BAT may help restore sensitivity to ADT.
Of the 10 men whose metastatic cancers could be measured with imaging scans, five experienced tumor shrinkage by more than half, including one man whose cancer completely disappeared.
Two patients did not complete the study. One patient died of pneumonia and sepsis due to the etoposide and the second patient experienced prolonged erection.
Dr. Denmeade said future studies are warranted and BAT may turn out to be an effective treatment that could lower mortality rates by helping men to overcome resistance to androgen ablative therapies. He said this type of treatment could lead to a meaningfully improvement in quality of life, functional activity, and sexual function in some men with CRPC.
Dr. Denmeade stressed the importance of timing testosterone therapy and warned men with CRPC against self-medicating their cancers with testosterone supplementation.
Studies have shown that taking testosterone at the wrong time can make the disease worse, particularly in men who are symptomatic and have not yet received testosterone-blocking therapy.
James Mohler, MD, who is chair of urology at Roswell Park Cancer Institute in Buffalo, NY, stated that this is a very carefully thought out study and offers significant promise.
“It is exciting. I don’t think they are trying to cure anybody, but they are trying to resensitize the castration-resistant cells. It is a two-pronged approach to remove some of the bad actors and to reprogram the old actors,” said Dr. Mohler in an interview with Cancer Therapy Advisor. “It is like intermittent androgen deprivation therapy on steroids.”
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Medical oncologist Alicia Morgans, MD, an assistant professor of medicine at Vanderbilt University in Nashville, TN, said this study raises significant questions about the current dogma surrounding the use of ADT in men with asymptomatic CRPC.
“Intermittent therapy is generally thought of as many months on and many months off―this is significantly different. There are a lot of questions that remain. It raises questions about how we approach hormone therapy,” Dr. Morgans said in an interview with Cancer Therapy Advisor. “I would love for this to pay off. I am optimistic about this approach.”
However, she cautioned that much further investigation is warranted to elucidate which patients may be the optimal candidates.
- Schweizer MT, Antonarakis ES, Wang H, et al. Effect of bipolar androgen therapy for asymptomatic men with castration-resistant prostate cancer: results from a pilot clinical study. Sci Transl Med. 2015;7(269):269ra2.