Slowing cancer progression before chemotherapy

This study examined the benefit of enzalutamide (Xtandi) in treating patients with advanced prostate cancer requiring chemotherapy.

Researchers concluded that enzalutamide treatment results in delayed disease progression and increased overall survival.

Hormone therapy is commonly used to treat prostate cancer. By reducing levels of androgens (male sex hormones such as testosterone) cancer progression can be delayed and survival increased. Many patients, however, continue to progress despite hormonal treatment. According to current standard of care, such patients are treated with chemotherapy, in addition to new anti-androgen drugs such as enzalutamide (Xtandi). While enzalutamide has been shown to improve survival following chemotherapy, the efficiency of enzalutamide in patients not receiving chemotherapy has not been fully studied.

This trial included 1,717 men with metastatic prostate cancer, not previously treated with chemotherapy. Men were randomly assigned to receive either treatment with enzalutamide or a placebo (a control drug with no active effect). All patients were offered chemotherapy if signs of cancer progression were noted.

As shown by imaging tests, men receiving treatment with enzalutamide were 81% less likely show cancer progression compared to the placebo group. Cancer progression was stopped in 65% of men after one year of treatment with enzalutamide, compared to 14% of men receiving placebo. Enzalutamide treatment was also associated with significantly less metastatic damage to other organs.

On average, the time until chemotherapy was required due to cancer progression was significantly longer with enzalutamide (28 months), compared to placebo (11 months). Overall survival was also improved with enzalutamide therapy. Men receiving treatment with enzalutamide were 29% more likely to survive the duration of the study (average follow-up of 2 years). Average survival time was 32.4 months in the enzalutamide treatment group and 30.2 months in the placebo group.

Fatigue and high blood pressure were the most common side-effects associated with enzalutamide treatment. However, the overall rate of side effects was similar between treatment groups.

The authors concluded that enzalutamide is a safe and effective treatment for delaying disease progression in men with advanced prostate cancer requiring chemotherapy.