BioNTech Diagnostics GmbH is announcing new results from two studies on the MammaTyper® test which were presented at the Breast Cancer Symposium in San Antonio in December.

The results of these studies again demonstrate the benefits of breast cancer subtyping using MammaTyper® to predict the course of the disease and to aid in the selection of effective, tailored therapy. MammaTyper® allows precise, quantitative measurement of the mRNA expression of the ERBB2 (HER2), ESR1 (ER), PGR (PR) and  MKI67 (proliferation marker Ki-67) biomarkers, which in turn facilitates molecular subtyping of tumor tissue according to St. Gallen guidelines. MammaTyper® thus provides accurate molecular stratification of breast cancer, information which is required for the selection of effective therapy tailored to each patient.(3) "Quantitative measurement of the expression levels of the four St. Gallen biomarkers was a much better predictor of Oncotype DX® Recurrence Score (RS) results than using traditional IHC methods" according to Dr. Mark Laible, Head of Molecular Pathology at BioNTech Diagnostics. "An additional study could show that the MammaTyper® test also helps physicians avoid overtreating certain patient groups, thus sparing patients from additional rounds of debilitating chemotherapy" added Dr. Sierk Pötting, CFO BioNTech Diagnostics GmbH.

The study results in detail:

Study on the ability of MammaTyper® to predict Oncotype DX®-type results by measuring local gene expression

This retrospective study conducted in Germany and Switzerland was a collaboration between the Institute of Pathology at the Bodensee Medical Campus in Friedrichshafen, the OptiPath Pathology Health Center in Frankfurt am Main, and BioNTech Diagnostics GmbH in Mainz in Germany, and the Institute for Surgical Pathology at the University Hospital of Zürich, Switzerland. The study analyzed the power of standardized measurement of the expression levels of HER2, ER, PR, and Ki67 using MammaTyper® to predict a low risk of distant metastasis on the Oncotype Recurrence Score compared with immunohistochemical detection of these biomarkers. A total of 198 FFPE breast cancer tissue samples were analyzed retrospectively using MammaTyper®, of which 38% (n=76) were typed as luminal A-like. The Recurrence Score (RS) was <25 for 99% of samples, and <18 for 70%. MammaTyper® thus allows the identification of patients with a low risk for distant metastasis, who do not benefit from adjuvant chemotherapy versus endocrine therapy alone (RS<25). The study could clearly demonstrate that analyzing mRNA expression using MammaTyper® was superior to IHC-based methods at predicting RS. It is not possible to fully standardize measurement of the proliferation marker Ki67 using semi-quantitative ICH. In contrast, due to its high degree of standardization, local measurement of gene expression may represent a more reliable method to identify patients with a low risk of relapse according to Oncotype DX® criteria.

Study on the ability of MammaTyper® to predict distant metastasis in low-risk breast cancer patients using RT-qPCR-based subtyping

This retrospective analysis investigated the predictive power of molecular subtyping of archived samples from low-risk breast cancer patients using MammaTyper®. It was conducted by BioNTech Diagnostics and the PATH Biobank with its network of six breast cancer centers in Germany. The tissue samples were collected between 2005 and 2011 from patients who had received only adjuvant endocrine therapy. The inclusion criteria were (1) FFPE samples from female invasive breast cancer which (2) had been typed as ER-positive and HER-negative by IHC/ISH at the initial diagnosis. Patients could not have (3) distant metastases at the time of diagnosis, and (4) could not have received any treatment other than endocrine therapy.

Distant metastases were later identified in 8.5% of the 319 patients providing samples after a mean follow-up of 7.8 years. MammaTyper® identified 60% (n=192) of the samples as luminal A-like; 4.7% (n=9) of these later exhibited distant metastases. According to the test, 37% (n=119) of the samples were of the luminal B-like subtype (HER2-negative), of which 13.4% (n=16) later exhibited distant metastases. 1.3% (n=4) of samples were classified as triple negative (ductal), 25% (n=1) of which later exhibited distant metastases. 0.6% (n=2) samples were classified as not conforming to St. Gallen criteria, of which 50% (n=1) later exhibited distant metastases. There were no distant metastases for luminal B-like (HER2-positive) samples (0.6%, n=2). In contrast, patients with samples classified as luminal A-likeexperienced significantly longer disease-free survival regardless of the number of involved lymph nodes.

Measurement of the mRNA levels of HER2, ER, PR, and Ki67 facilitates molecular subtyping according to the St. Gallen classification. A low risk of distant metastasis could be confirmed for samples classified by MammaTyper as luminal A-like. The high degree of standardization for mRNA measurement by MammaTyper may promote the use of the proliferation biomarker Ki67/MKI67 in the routine pathology of breast cancer.

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