Combining testosterone-blocking drugs in patients with prostate cancer relapse prevents the spread of cancer higher than treatment with a single drug, a multi-institution, Phase 3 clinical trial led by UC San Francisco researchers has found.

The approach can extend the time between debilitating drug treatments without prolonging the time it takes to get better from each treatment.

Prostate cancer affects 1 in 8 men and causes 34,000 deaths annually in the USA. It is normally treated with one in every of several testosterone-lowering drugs for a set time frame.

This adds to a growing body of evidence in favor of more intensive testosterone-blocking therapy in patients with higher-risk prostate cancer.”

Rahul Aggarwal, MD, professor within the UCSF School of Medicine and lead writer of the paper

The researchers’ findings were published on Jan. 23, 2024, within the Journal of Clinical Oncology. They were first announced in September 2022 on the annual meeting of the European Society for Medical Oncology.

A case for intensifying prostate cancer treatment

The brand new study focused on patients who had surgery for prostate cancer, and yet the cancer relapsed and was detected through a sudden jump within the blood levels of a protein called prostate-specific antigen (PSA).

“We checked out patients who had a quick rise of their PSA – an indicator of a higher-risk type of relapsed prostate cancer,” Aggarwal said. “Our goal was to check several different hormone therapy strategies to seek out one of the best approach when it comes to delaying the cancer’s progression.”

Between 2017 and 2022, 503 patients were randomly assigned to take a single testosterone-lowering therapy chosen by their oncologist, or to mix it with one or two other testosterone-lowering drugs. The extra drugs were already FDA-approved for other cancers but hadn’t been tested in this manner with prostate cancer.

The patients stayed on the assigned therapy for a yr. Whether given singly or together, the drugs caused their testosterone to plummet. That put the brakes on their cancer but in addition caused fatigue, hot flashes, decreased libido and other problems for patients, based on Aggarwal.

In comparison with the prostate cancer patients who only received a single drug therapy during their yr of treatment, patients who received either one or two additional drugs stayed cancer-free, with low PSA levels, for longer.

Once off the treatment, patients who took the mix therapies saw their testosterone levels get better just as fast as others who took the only drug.

The researchers are following up with a more detailed evaluation of how patients fared on the various treatments – which unwanted side effects they experienced and for the way long, and the way they felt overall as they recovered.

“Latest cancer therapies must clear a high bar to make their strategy to patients,” Aggarwal said. “With the evidence on this study and others, combination hormone therapy must be considered a regular of care in prostate cancer patients with high-risk relapse after prior treatment.”