Enzalutamide cuts risk of death in pre-chemotherapy mCRPC

According to a media release from Medivation and Astellas issued earlier today, the companies are stopping the randomized, double-blind, Phase III PREVAIL trial early because enzalutamide has shown a 30 percent reduction in risk of death and an 81 percent reduction in risk of radiographic progression or death in this trial.

The full text of the media release is available on line. However, the basic information is as follows:

  • The Independent Data Monitoring Committee (IDMC) conducted a pre-planned interim analysis of data from the PREVAIL trial, which had enrolled > 1,700 men with metastatic, castration-resistant prostate cancer (mCRPC) who had not received chemotherapy.
  • The estimated median overall survival times were
    • 32.4 months for men treated with enzalutamide
    • 30.2 months for men treated with a placebo
  • Enzalutamide demonstrated a 30 percent reduction in risk of death compared with placebo (hazard ratio [HR] = 0.70).
  • Enzalutamide also demonstrated an 81 percent reduction in risk of either radiographic progression or death compared to a placebo (HR = 0.19).
  • The median time to radiographic progression-free survival has yet to be reached by patients in the enzalutamide arm and was 3.9 months in the placebo arm.
  • The majority of patients in this trial were still alive at the time of the interim data analysis.
    • 72 percent of patients were alive in the enzalutamide arm.
    • 65 percent of patients were alive in the placebo arm.
  • Given the overall survival benefit and the observed safety profile, the IDMC considered the overall benefit-risk ratio to favor the enzalutamide arm and recommended unequivocally that patients receiving placebo be offered treatment with enzalutamide.
  • 2/1,715 patients in the trial (0.1 percent) are reported to have experienced a seizure event.

It should be noted that, because such a high percentage of patients were still alive in each arm of the trial at the time of the analysis, ” the estimated median survivals are not as precise as the hazard ratio. The hazard ratio takes into account available information about the trial endpoint from all patients whereas the median is a single point estimate of a much smaller number of patients at risk.”

One has to assume that Medivation and Astellas will be submitting detailed data to the U.S. Food and Drug Administration and to other regulatory agencies around the world to seek an expanded indication for this product as soon as they can manage.

One Response

  1. Wow!

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