Quantitative determination of HER2 levels predictive of better response to anti-HER2 therapy

Findings presented today at the 50th Annual Meeting of the American Society of Clinical Oncology (ASCO), May 30 – June 03, Chicago IL, USA, reveal that HER2+ breast cancer patients expressing high protein levels respond better to targeted therapy and survive longer.

Barcelona, June 02, 2014.– A collaborative study between the Vall d´Hebron Institute of Oncology´s (VHIO) Molecular Oncology and Breast Cancer & Melanoma Groups, the Memorial Sloan Kettering Cancer Center (MSKCC), and OncoplexDx, supported by the BBVA Foundation, establishes the importance of quantifying HER2 protein levels prior to initiating anti-HER2 therapy. Results of the study will be presented today by Paolo Nuciforo, Principal Investigator of VHIO´s Molecular Oncology Group, during the 2014 ASCO Annual Meeting, the largest of all oncology congresses worldwide.

HER2+ tumors account for 20% of all breast cancers, test positive for a protein called human epidermal growth factor receptor 2, HER2 (scored as 3+ by immunohistochemistry or amplified by in situ hybridization), and show higher proliferation rates. This type of breast cancer type is notoriously aggressive, carrying with it a higher risk of disease relapse and death. Over recent years however, current anti-HER2 therapies such as Trastuzumab and Lapatinib, have greatly improved outcomes for countless of patients suffering from this disease.

While immunohistochemistry (IHC) is the standard technique employed for detecting HER2 expression, it does not facilitate an absolute quantification of this receptor and is prone to false-positives. Thus, an important number of patients who are classified as HER2-positive, actually express low levels of the receptor.

Using a mass spectrometry-based assay, 60 HER2+ (IHC 3+) breast cancer patients treated with anti-HER therapy, were studied in order to quantify absolute levels of HER2. The research revealed high variability in HER2 expression within the patient population that had been homogenously classified as 3+ by IHC. Patients with high expression levels of the HER2 protein correlated with greater clinical benefit including prolonged survival rates than those patients with lower rates of expression.

While this data is preliminary, as Nuciforo explains, “If future studies enrolling a greater number of patients confirm these results, this would represent an important game changer in how we currently determine HER2 expression levels as well as provide oncologists with further insight to better tailor anti-HER2-based therapies according to HER2 protein levels.”


For more information please contact:

Amanda Wren, Director of Communication, Vall d´Hebron Institute of Oncology (VHIO): Tel.: +34 695207886, Email: awren@vhio.net.


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