Posted on Dec 08, 2023

A seminal study presented at the San Antonio Breast Cancer Symposium (SABCS) this week has shown that a validated, locally performed, RNA-based progesterone receptor (PGR) expression test could predict tumour gene expression results and independently identify tumours that are unlikely to be chemotherapy sensitive. This could screen out further genomic testing for up to 70% of patients.

Strong PgR expression predicts favourable outcomes for ER+ve HER2-ve breast cancer and has been proposed as a surrogate marker between IHC-defined luminal A and luminal B subtypes. The authors note that some validated, RNA-based PGR expression tests may also outperform IHC (Immunohistochemistry).

MammaTyper®, a RT-qPCR test that quantifies genes including PGR was included in the study and the results were very encouraging, aligning closely with Oncotype and outperforming other tests available on the market.

The research compared Oncotype DX RS with Oncotype DX reported PGR in 4 independent datasets, including 407 cases from the OPTIMA prelim trial. A further 251 OPTIMA prelim cases were analysed which had additional tumour gene expression data. The four Oncotype DX datasets consistently demonstrated that high Oncotype PGR expression was associated with a low Recurrence score (RS). 70.9% of tumours had a high PGR expression, of which 92.7% had an Oncotype RS of 25 or below.

The MammaTyper® and Oncotype PGR results were highly correlated in the OPTIMA prelim dataset, 93.2% of 176 MammaTyper® high PGR expression cases had a RS of 25 or below. At approximately 10% of the cost of more comprehensive genomic testing and performed locally, this could allow clinicians and medical facilities to screen patients and determine effective treatment paths early in their journey without further testing.

“This research demonstrates yet another use case for MammaTyper®; enabling reliable, quantitative measurement of PGR expression locally, so clinicians can factor it in and determine the best treatment for their patient. Being able to decide if further genomic testing is needed by conducting screening tests in-country or even on-site will help enormously,” said Richard Hughes, Director at Cerca Biotech. “We already know that MammaTyper® can detect tumour subtypes that IHC is not sensitive enough for, such as ER and HER2-low. Accurate measurement of PGR expression is another dimension that will give patients and their doctors the information with which to personalise treatment.”


About MammaTyper®

MammaTyper® is an innovative assay for the quantitative determination of the four key biomarkers used in the subtyping of breast cancer (Human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER), progesterone receptor (PR) and Ki-67). Applying 21st Century RT-qPCR techniques, it is the first real evolution in breast cancer diagnostics for over 50 years. It is a quick, accurate, reliable, and reproducible solution that enables medical professionals to accurately tailor treatment plans for the best chance of success. MammaTyper® is the only assay of its type on the market that is backed by extensive data and research.

About Cerca Biotech

MammaTyper® is manufactured by Cerca Biotech, a German-based diagnostic company focused on bringing innovative solutions to the oncology and women’s health market. Cerca Biotech strives to introduce the best tests to meet clinical needs at an affordable cost, with clinical accuracy and rapid results at the core. For more information, please visit or contact