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HERmark Presents Assay Results In Metastatic Breast Cancer

Armen Hareyan's picture

Monogram Biosciences presented the results of a study detailing the HERmark Assay's ability to identify metastatic breast cancer patients who are most likely to respond to Herceptin.

The study results were presented this week at the San Antonio Breast Cancer Symposium. Also this week, Monogram received confirmation from the College of Pathologists (CAP) that the HERmark assays are approved for routine patient testing in Monogram's CLIA certified clinical reference laboratory.

"The results presented today are an important step along the way to clinical validation of HERmark, the first product based on the VeraTag technology platform," said William Young, Monogram chief executive officer. "In addition to the presentation of important clinical data, I am pleased to report today that the HERmark assays have completed their validation process in Monogram's CLIA-certified clinical reference laboratory. The establishment of solid technical validation data and the ability to perform the assays under high-throughput, well controlled conditions will provide a strong basis for commercialization of HERmark after completion of our ongoing clinical studies."

In the study reported today, Monogram analyzed tissue samples from patients with metastatic breast cancer who were treated with Herceptin, having been selected for such treatment by centralized IHC testing. While current testing methods identified all these patients as being appropriate for Herceptin treatment, Monogram's HERmark Assay was able to distinguish separate sub-populations of patients with different clinical outcomes.

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Study details: Those patients with higher HER2 expression levels (i.e. in the upper half of the distribution for the study cohort) experienced a 59% objective response rate while those with lower levels of HER2 expression (i.e. in the lower half of the distribution) had a response rate of only 18%. Additional analyses revealed that patients with higher HER2 expression values had a median time-to-progression of 12.8 months while those in the lower half of the distribution had a median time-to-progression of only 4 months. This result was statistically significant (p = 0.01). Finally, multivariate Cox proportional hazards models identified HER2 expression (HR = 0.16, p < 0.001) and HER2:HER2 dimer levels (HR = 0.32, p < 0.001) as measured by HERmark as being statistically significant predictors of time-to-progression.

"Current testing technologies do not provide an accurate or precise view of HER2 biology in breast cancer, classifying patients as either HER2 'positive' or HER2 'negative'," continued Young. "At best, conventional technologies provide a semi-quantitative analysis. However, only about half of metastatic patients selected by current technologies for Herceptin treatment respond to the drug. Data are now emerging to suggest that patients who could benefit from Herceptin may be missed by currently used assays. Our HERmark studies have provided data which consistently indicate that HERmark can precisely measure HER2 expression and HER2:HER2 dimer levels in clinical FFPE samples, and that those patients with higher levels of expression have significantly better clinical outcomes than those with lower levels. These data strongly suggest that HERmark can identify patients who are likely to respond to Herceptin better than the assays currently in use."

HERmark Assay in Metastatic Breast Cancer

At ASCO in June 2007, Monogram reported results of studies of HERmark in two patient cohorts. In the first of these studies, it was demonstrated that within a population of patients that were stringently selected by FISH testing, the HERmark assay was able to measure a gradient of HER2 expression and HER2 homodimer levels that was significantly correlated with time-to- progression and overall survival on Herceptin.

In the second metastatic patient cohort presented at ASCO, selected by IHC in a clinic-based setting, the HERmark assay was also able to demonstrate that patients who were confirmed HER2 positive by IHC on repeat testing showed a gradient of response, and that those with higher levels of HER2 expression and HER2 homodimer levels as measured by HERmark lived longer than those who had lower levels. The results of these two previously reported cohorts, along with the third cohort presented today, provide the basis for Monogram's ongoing work in metastatic breast cancer. There are approximately 60,000 women annually in the U.S. who are newly diagnosed with Stage IV breast cancer or who have progressed from earlier stages of disease. These are patients for whom the cancer has spread beyond the breast, and in many cases multiple treatments may have already been provided.