The Test

Small amounts of HER2/neu are shed into the bloodstream and can be detected by an ELISA immunoassay. HERTEST provides a new look at HER2/neu blood testing using state-of-the-art recombinant rabbit monoclonal antibodies.  This highly sensitive test requires only a small amount of blood.  That blood is processed (serum separated from the blood sample) by your hospital's clinic and then sent to our lab where HERTEST can be performed.  Patient results are then submitted to your oncologist in as little as 24 hrs.


Clinical Background

The human epidermal growth factor receptor 2 (HER2/neu, ErbB2) is a transmembrane receptor protein with an extracellular domain (ECD) and intracellular tyrosine kinase activity. Potentially 50,000 HER2/neu molecules may be present on a single cancer cell, when overexpressed or amplified. These molecules then associate and activate cell growth. 


Approximately 20% of invasive primary breast cancers and a significantly higher proportion of metastatic tumors overexpress HER2 enough to “drive” the cancer. HERTEST results with levels of sHER2 (serum HER2) beyond an upper limit of normal indicate the presence of a HER2 tumor—false positive results are very rare. A rising sHER2 concentration may be an indicator of recurrence, preceding clinical or radiological evidence by months. Elevated HERTEST values in the absence of a positive tissue test may signal a role for targeted therapeutics in refractory breast cancer despite an earlier negative tissue test.

Given the high cost and limitations of targeted therapy, oncologists are seeking ways to reduce drug use yet improve outcomes and the quality of life. HERTEST monitoring provides useful information to support cancer treatment de-escalation. 

Clinical Utility

Immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) provides a measurement of a patient's HER2 status at initial diagnosis of breast cancer.  HERTEST complements tissue tests when a tumor spreads by monitoring response to therapy or disease progression.  Clinical data indicates that serum levels of HER2 reflect disease progression and response to therapy and that serial monitoring of serum HER2 may be a valuable tool in creating a more efficient treatment regimen.  HERSTEST offers the following advantages:

  • HERTEST is minimally invasive (requiring only a small amount of blood)

  • HERTEST can monitor metastatic breast cancer patients receiving most common therapies

  • HERTEST was developed specifically to follow metastatic breast cancer patients to help determine any change in serum HER2 status

  • HERTEST simplifies routine monitoring of metastatic breast patients with elevated serum HER2

To be of maximum value, blood (serum) tests should fulfill four specific criteria—HERTEST scores high in all four measures.

  1. PROGNOSTIC—A high serum HER2 correlates with a smaller likelihood of pathological complete response and with a shorter disease-free survival.

  2. PREDICTIVE—An elevated serum HER2 predicts response to targeted and cytotoxic drugs.


  4. Serum HER2 must be considered INDEPENDENTLY OF TISSUE HER2—Tissue negative primary tumors give rise to HER2 positive metastases, often called a phenotypic shift.

  Free of Recurrence     Recurrence        Poor Prognosis

Each of the above criteria has been studied extensively. Reports from Germany, Spain, France, the U.S., and elsewhere corroborate monitoring in over 10,000 breast cancer patients.