Combination therapy for recurrent prostate cancer may slow progression and extend survival

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CANCER DIGEST – Oct. 21, 2023 – Men with aggressive recurrent prostate cancer who were given a combination therapy aimed at hormone reduction had a significantly lower risk of further cancer spread and death, the results of new clinical trial in the Oct. 19, 2023 New England Journal of Medicine show.

In the phase 3 trial led by researchers at Cedars-Sinai Cancer Center, 1,068 prostate cancer patients from 244 cancer centers in 17 countries were randomly assigned to one of three treatments. One-third received the standard treatment of androgen deprivation therapy (ADT), one-third received ADT plus a new drug called enzalutamide, and the third group received enzalutamide alone.

Patients with aggressive recurrent prostate cancer are often treated with hormone therapy to block male sex hormones including testosterone because prostate cancer growth is stimulated by such hormones. ADT has long been used in certain prostate cancer patients, the drugs include Eligard®, Lupin®, Fensolvi® and others.

“When you go on ADT, the testosterone level in the blood is reduced, but not completely eliminated,” said Stephen Freedland, MD in a press release. He is lead author of the study and the Warschaw, Robertson, Law Families Chair in Prostate Cancer at Cedars-Sinai. “And the concern is that the testosterone that remains may still be enough to stimulate tumor growth. Also, patients don’t love the idea of being on hormones.”

Eligard® and similar drugs work by reducing the production of testosterone. Enzalutamide (Xtandi®) is in a class of medications called androgen receptor inhibitors. It works by blocking the effects of androgen (a male reproductive hormone) to stop the growth and spread of cancer cells.

After following the men in the study for five years, 83 percent of the men in the combination group survived metastasis-free compared to 71.4 percent of them taking Eligard® alone, and 80 percent of those taking Xtandi® alone group.

Put another way, the combination of ADT and enzalutamide reduced the risk of metastasis or death by 58 percent compared to ADT alone. Enzalutamid alone reduced the risk of metastasis or death by 37 percent compared to ADT alone.

The next step is for the pharmaceutical companies Pfizer and Astellas Pharma, which co-developed enzalutamide and funded the trial, to apply to the FDA for approval.

Sources: Cedars-Sinai Medical Center press release and the New England Journal of Medicine