Please note that this summary only contains information from the full scientific abstract: View ESMO Scientific Abstract

New imaging tools and biomarkers to help predict when men with prostate cancer stop responding to enzalutamide

Date of summary: September 2019

Study number: NCT02677376


Study start date: June 2016


Estimated study end date: January 2021


The full title of this abstract is: Spatial-Temporal Change in Quantitative Total Bone Imaging (QTBI) and Circulating Tumor Cells (CTCs) in Metastatic Castration-Resistant Prostate Cancer (mCRPC) Treated With Enzalutamide (ENZA)

This study drug is approved to treat the condition under study that is discussed in this summary.


Researchers must look at the results of many types of studies to understand whether a study drug works, how it works, and whether it is safe to prescribe to patients


This summary reports the results of only one study. The results of this study might be different from the results of other studies that the researchers look at.

This summary reports the interim results from the study – results may not be the same when the study is complete.


More information can be found in the scientific abstract of this study, which you can access here:
View ESMO Scientific Abstract

What did this study look at?

  • Prostate cancer is one of the most common cancers in men.
    • Prostate-specific antigen (PSA for short) is a marker of how much prostate cancer is in the body.
    • PSA is an example of a biomarker. Biomarkers are biological factors (such as molecules found in blood, body fluids or tissues) that may help to predict how well treatment works.
  • Prostate cancer cells depend for their growth on male sex hormones (called androgens).
    • Treatment for prostate cancer involves lowering the amount of androgens in the body through surgical castration or androgen-deprivation therapy (known as chemical castration).
  • In some men, the cancer may not respond to androgen-deprivation therapy and will continue to grow, even without androgens.
    • This type of prostate cancer is known as castration-resistant prostate cancer (CRPC for short).
  • Enzalutamide (ENZA for short) is an approved treatment for CRPC.
    • CRPC can spread to other parts of the body, known as metastatic castration-resistant prostate cancer (mCRPC for short).
    • It is common for mCRPC to spread to the bone.
  • Doctors use special tools to measure how much and how far the cancer has spread outside of the prostate. One of these is an imaging tool called quantitative total bone imaging.
    • This type of imaging scans all the bones in a person’s body for cancer, and shows how the cancer spreads to different locations and how it changes.
  • Doctors can also look for cancer cells in the bloodstream, called circulating tumor cells. (Medical staff and researchers may refer to these as CTCs.)
    • By collecting circulating tumor cells, it is possible to measure the amounts of certain biomarkers present on the tumor cells.
  • In this study, researchers used quantitative total bone imaging to measure changes in the size or appearance of the cancer.
  • Researchers also measured the amount of biomarkers on circulating tumor cells:
    • ARV7/9 proteins
    • neuroendocrine features.
  • Researchers wanted to find out whether the imaging tools and biomarkers could help predict which tumors respond well to ENZA and how long men would continue to respond to ENZA.
  • This summary reports the results from these experiments.

Who took part in this study?

  • All 23 men were taking ENZA and androgen-deprivation therapy. The researchers used the men’s PSA levels to measure how long the cancer continued to respond to ENZA.
  • Researchers used quantitative total bone imaging to measure the cancer that had spread to the bones at 3 different times during this study:
    1. At the start
    2. After 3 months of ENZA treatment
    3. When the cancer stopped responding to ENZA, or after 2 years if the treatment continued to be successful.
  • The researchers collected circulating tumor cells from the men at the start and end of the study.

What were the results of the study?

  • In total, 23 men aged between 51 and 93 years took part in the study.
    • Of these 23 men, 22 completed the study. (One man did not complete all the planned imaging and was left out of the study.)
  • Between them, the men had an average of 58 sites of cancer metastases in the bones at the start of the study.
  • Men stayed on ENZA therapy for different lengths of time.
  • Overall, the amount of cancer seen with quantitative total bone imaging decreased between the start of the study and the second measurement at 3 months.
    • Men who have more aggressive forms of the tumor may need to stay on ENZA treatment for longer or have other types of treatment.
  • Using quantitative total bone imaging, researchers could clearly see changes in the tumors after treatment with ENZA. This is important for identifying changes in the bone that may need other types of treatment.

More results from this study can be found here:
View ESMO Scientific Abstract

What were the main conclusions reported by the researchers?

  • Although many men respond to ENZA, the length of time they continue to respond varies.
  • Using quantitative total bone imaging, researchers saw differences in the response to ENZA treatment.
    • Men who had fewer differences in tumor appearance on quantitative total bone imaging responded for longer to ENZA therapy. In these men, there was a longer time before their cancer got worse (or progressed).
    • Men who had treatment-resistant lesions (lesions that did not respond well to treatment) may be suitable for other types of treatment.
  • Based on the results of this study, measuring ARV7/9 or neuroendocrine biomarkers on circulating tumor cells did not help to predict how long men would respond to ENZA therapy.
  • More studies are needed to see if these imaging tools can help doctors to predict how long men will respond to ENZA.

Who sponsored this study?

University of Wisconsin, Madison with
National Cancer Institute (NCI) and the
Prostate Cancer Foundation
University of Wisconsin Carbone
Cancer Center, Madison, Wisconsin,
United States, 53705

Pfizer Inc.
235 East 42nd Street NY, NY 10017
Phone (United States): +1 212-733-2323

Pfizer would like to thank all of the people who took part in this study.

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