Precise Quantitative Biomarker Detection for Molecular Breast Cancer Subtyping

BioNTech Diagnostics GmbH announces the publication of new study data that prove the significant advantages of the in vitro diagnostic test kit MammaTyper^® (CE / IVD marked) over the currently established methods of detection used in breast cancer subtyping.

In the prospective-retrospective study, MammaTyper^® achieved ground-breaking results with precise quantitative detection of the biomarkers ERBB2 (HER2), ESR1 (ER), PGR (PR) and MKI67 (proliferation marker Ki-67). It must be emphasized particularly that MammaTyper^® was superior to immunohistochemistry with regard to the prognosis when measuring MKI67 (Ki-67). Thus the study shows that MammaTyper^® ensures patient stratification as recommended by the St Gallen criteria, including reliable measurement of proliferation by MKI67. "The positive study data for MammaTyper^® underline our commitment to making personalized medicine broadly available for treating cancer", added Dr Sierk Poetting, Managing Director at BioNTech Diagnostics.

Over the past few years, the IHC method has been discussed time and again by expert groups with regard to its reproducibility, objectivity and comparability. Differences do arise, particularly when measuring the proliferation marker Ki-67 which is used, for example, to differentiate between luminal A and luminal B tumors, among other things.

Previous studies have already shown that molecular detection of mRNA expression of the markers by RT-qPCR (reverse transcription quantitative real time polymerase chain reaction), on which the in vitro diagnostic test kit MammaTyper^® is also based, have significant advantages over IHC.

The recently published prospective-retrospective randomized MammaTyper^® clinical study enrolled a total of 769 patients from the FinHer study. It was the first to compare quantitative measurements of tumor ESR1-, PGR-, ERBB2- and MKI67-mRNA using MammaTyper^® with the results of ER-, PR-, and Ki-67 protein expression by IHC or of HER2 by chromogenic in situ hybridization (CISH). The results were correlated with disease-free survival and the overall survival period. The data show that quantitative measurement of ESR1- and PGR- and ERBB2-mRNA by MammaTyper^® correlates with the results from IHC and in situ hybridization in pathology laboratories [ER/ESR1: 92 %, p < 0.0001; PR/PGR: 83 %, p < 0.0001 and HER2/ERBB2: 92 %, p < 0.0001, OPA*].

Measurements of MKI67 mRNA expression with MammaTyper^® showed that patients who express a low level of MKI67 have a significantly better prognosis with regard to disease-free survival and overall survival than patients with a high MKI67 expression. In contrast, measurement of Ki-67 protein expression by IHC showed no significant difference between these two groups for the prognosis of the two parameters.

The study also showed that the patients identified as luminal B by MammaTyper^® who were treated with docetaxel FEC had a more favorable prognosis for disease-free survival and overall survival than those who were treated with vinorelbin FEC. The IHC results were not able to show this relation between subtype and response to the medication. This means that, compared to IHC, breast cancer subtyping by MammaTyper^® opens up new opportunities of providing predictive information about the benefits of adjuvant taxane treatment.

In summary, the study clearly shows that, in comparison to established methods, MammaTyper^® allows a precise biomarker measurement method that can be standardized and, due to the reliable detection of Ki-67, provides better indications of the need for and benefits of chemotherapy.

*OPA: Overall percent agreement