Prostate Cancer: Biomarker Testing

Biomarker Testing for People with Prostate Cancer

This section covers the following topics:

Tumor biomarker testing	Biomarkers for treatment selection
Tests to measure prognosis	Genetic testing for treatment selection

What is prostate cancer biomarker testing?

Biomarker tests look at samples of blood, tumor or other tissue for changes or abnormalities caused by cancer. These tests can give doctors clues about the cancer, including:

• how fast the cancer is growing
• which treatments are most likely to work
• whether or not the cancer is responding to treatment or growing
• whether or not the cancer has come back after remission

Biomarker tests may be used to select treatments, and help patients avoid side effects from treatments that will not work for them. Biomarker tests used to select a treatment are sometimes called "companion diagnostic tests." See our Biomarker Testing section for more information. 

Biomarkers for treatment selection

Biomarker tests may be used to select treatments, and help patients avoid side effects from treatments that will not work for them. Biomarker tests used to select a treatment are sometimes called "companion diagnostic tests." See our Biomarker Testing section for more information. 

The biomarker tests below are most often used in treatment selection for metastatic prostate cancer. Additional tumor biomarker testing may help people learn if they are eligible for certain clinical trials. 

Biomarkers for PARP inhibitor selection

PARP inhibitors are a type of targeted therapy that work best for treating cancers with certain abnormalities. Several different PARP inhibitors have been approved for treating metasatic prostate cancer. 

• People with tumor mutations in these genes may benefit from treatment with a PARP inhibitor:
  • ATM, BARD1,BRCA1, BRCA2,  BRIP1, CDK12, CHEK2, FANCA, FANCL, MLH1, PALB2, RAD51B, RAD51C, RAD51D, MRE11A or NBN

Other biomarkers for targeted therapies

Additional biomarker tests that may be used for metastic castration-resistant prostate cancer (mCRPC) include: 

• AR-V7 testing is a blood test that looks for a form of the androgen receptor that makes androgen therapy less effective. AR-V7 testing can help identify patients who would not benefit from androgen receptor therapies.
• An imaging test uses a PET scan to find tumors with the biomarker PSMA. Tumors with PSMA are more likely to respond to the treatment Pluvicto.  
• HER2-positive tumors may respond to treatment with Enhertu (trastuzumab deruxtecan). 
• Tumors that test positive for a RET gene fusion may respond to the drug Retevmo (selpercatinib). 
• A biomarker known as an NTRK fusion can  predict who might benefit from the targeted therapy Vitrakvi (larotrectinib).

Biomarkers for immunotherapy selection

• An abnormality known as “microsatellite instability" (MSI-H or MSI-high) also known as "mismatch repair deficiency" (dMMR or MMR-D).
  • MSI-high cancers are common in people with a Lynch syndrome gene mutations. People with advanced/metastatic MSI-high prostate cancer may respond well to an immunotherapy agent. 

Genetic testing for inherited mutations to guide treatment selection

People diagnosed with metastatic prostate cancer should be offered genetic testing for an inherited mutation. Genetic test results  may be used to guide treatment selection.  

• People with advanced prostate cancer who test positive for an inherited BRCA1 or BRCA2 mutation may benefit from treatment with a type of targeted therapy known as a PARP inhibitor.
• People who test positive for other inherited gene mutations may qualify for clinical trials looking at targeted therapies to treat hereditary ovarian cancer. 
• People who test positive for a Lynch syndrome gene mutation may benefit from treatment with an immunotherapy agent.

Genetic testing offers additional benefits for people with prostate cancer. You can read more about genetic testing for prostate cancer here.