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HERmark Breast Cancer Assay

Wednesday 7 December 2011

The availability of drugs targeting the EGFR/HER/erbB signaling pathway has created a need for diagnostics that accurately predict treatment responses.

HERmark Breast Cancer Assay precisely quantifies HER2 total protein and HER2 homodimer levels in Formalin Fixed Parrafin Embedded Tissue (FFPE).

The assay performance characteristics are validated according to CLIA standards. HERmark results provide healthcare professionals with additional information for managing breast cancer patients.

ASCO/CAP guidelines recommend that HER2 status be determined for all invasive breast cancer patients. These guidelines caution that current HER2 testing methods (central IHC and FISH) may be inaccurate in up to 20% of cases.

HERmark Breast Cancer Assay precisely quantifies HER2 total protein and HER2 homodimer levels in FFPE. HERmark reclassified up to 25% of samples from a cohort of the FinHer Adjuvant Breast Cancer Study

Links

- HERmark Breast Cancer Assay by Monogram BioSciences
- VeraTag assay by Monogram BioSciences

It has been developed and characterized a novel assay to provide sensitive and quantitative measures of HER proteins and homodimers in formalin-fixed, paraffin-embedded (FFPE) cell lines and breast tumor tissues, to test these variables.

In the VeraTag assay, HER proteins and homodimers are detected through the release of fluorescent tags conjugated to specific HER antibodies, requiring proximity to a second HER antibody.

HER2 protein quantification was normalized to tumor area, and compared to receptor numbers in 12 human tumor cell lines determined by fluorescence-activated cell sorting (FACS), and with HER immunohistochemistry (IHC) test categories and histoscores in cell lines and 170 breast tumors.

HER1 and HER2 expression levels determined by the VeraTag assay are proportional to receptor number over more than a 2 log10 range, and HER homodimer levels are consistent with crosslinking and immunoprecipitation results.

VeraTag HER2 measurements of breast tumor tissue and cell lines correlate with standard IHC test categories (P<0.001).

VeraTag HER2 levels also agree with IHC histoscores at lower HER2 protein levels, but are continuous and overlapping between IHC test categories, extending the dynamic range 5-fold to 10-fold at higher HER2 levels.

The VeraTag assay specifically and reproducibly measures HER1 and HER2 protein and homodimers in FFPE tissues.

The continuous measure of HER2 protein levels over a broad dynamic range, and the novel HER2 homodimer measure, are presently being assessed as predictive markers for responses to targeted HER2 therapy.

Data suggest that more quantitative or functional measurements of HER2 status may facilitate the development of more personalized treatment strategies for patients with metastatic breast cancer. (#19214112#)

HER2 Assays

- qRT-PCR
- quantitation of HER1 and HER2 total protein expression and homodimerization (#19214113#)
- immunochemistry

References

- College of American Pathologists. HER2 Testing Guidelines. Accessed February 23, 2009.

- Monogram data on file.

- Joensuu H, Weidler J, Lie Y, et al. Quantitative measurements of HER2 expression and HER2 homodimers using a novel proximity based assay: comparison with HER2 status by immunohistochemistry and chromogenic in situ hybridization in the FinHer study. Poster presented at: 31st Annual San Antonio Breast Cancer Symposium; December 10-14, 2008; San Antonio, TX.

- A novel proximity assay for the detection of proteins and protein complexes: quantitation of HER1 and HER2 total protein expression and homodimerization in formalin-fixed, paraffin-embedded cell lines and breast cancer tissue. Shi Y, Huang W, Tan Y, Jin X, Dua R, Penuel E, Mukherjee A, Sperinde J, Pannu H, Chenna A, DeFazio-Eli L, Pidaparthi S, Badal Y, Wallweber G, Chen L, Williams S, Tahir H, Larson J, Goodman L, Whitcomb J, Petropoulos C, Winslow J. Diagn Mol Pathol. 2009 Mar;18(1):11-21. PMID: #19214113#

- Quantitation of HER2 expression or HER2:HER2 dimers and differential survival in a cohort of metastatic breast cancer patients carefully selected for trastuzumab treatment primarily by FISH. Desmedt C, Sperinde J, Piette F, Huang W, Jin X, Tan Y, Durbecq V, Larsimont D, Giuliani R, Chappey C, Buyse M, Winslow J, Piccart M, Sotiriou C, Petropoulos C, Bates M. Diagn Mol Pathol. 2009 Mar;18(1):22-9. PMID: #19214112#