The company discussed the diagnostic test’s effectiveness at the Breast Cancer Symposium in San Antonio in December 2017.
MammaTyper measures levels of several breast cancer biomarkers in messenger RNA, a molecule that is an intermediary between a gene and a protein. The biomarkers are estrogen receptor, or ER; progesterone receptor, or PR; human epidermal growth factor receptor 2, or HER2; and a cell multiplication signpost known as Ki-67.
The levels of these proteins determine which one of five types of cancer a patient has. The categories are luminal A-like; luminal B-like HER2 negative; luminal B-like HER2 positive; HER2 positive non-luminal; and triple negative ductal.
These categories help doctors predict the course of the disease and select treatments.
A clinical trial (NCT02244580) looked at whether MammaTyper could do a better job than standard analysis of predicting which patients were at low risk of their breast cancer progressing or recurring. Standard analysis involves using an online tool to assess levels of protein markers in tissue samples. The yardstick that doctors use to predict cancer returning is patients’ Oncotype DX Recurrence Scores.
Researchers titled the study they generated from the findings “Prediction of Oncotype DX results based on local gene expression measurements by MammaTyper.”
Oncotype DX Recurrence Score is the risk barometer that experts recommend for patients with ER+/HER2- early-stage breast cancer. Patients with a score lower than 25 are deemed as being at low risk of the cancer spreading to other parts of the body. The typical determination is that these patients will not benefit from chemotherapy plus endocrine therapy, compared with endocrine therapy alone.
The study covered 198 breast cancer tissue samples. MammaTyper generated a recurrence score below 25 in 99 percent of the samples, and below 18 in 70 percent of them. With standard methods, 61 percent of patients were deemed at being at low risk, and 74 percent had a score below 18.
When the team developed a model to identify patients at low risk of having their cancer spread, they found that the MammaTyper-based forecasts were more accurate than the standard ones.
“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 [immunohistochemistry] methods,” Dr. Mark Laible, head of molecular pathology at BioNTech Diagnostics, said in a press release.
In a second trial, researchers tested MammaTyper’s ability to predict cancer’s return in patients with low-risk breast cancer. The study was titled “Prediction of distant recurrence in low risk early breast cancer by RT-qPCR based subtyping using MammaTyper.”
The team examined tissue samples from 319 ER+/HER2- breast cancer patients. When they were diagnosed, none of the patients’ cancer had spread to other areas of the body. All were treated only with hormone therapy.
After a mean follow-up of 7.8 years, 27 patients’ cancer had spread.
A key finding was that patients with luminal A-like tumors lived significantly longer without their disease progressing than patients with other types, whether or not their cancer had spread to their lymph nodes. Another finding was that the cancer of patients with luminal B-like tumors had not spread.
The results indicated that the MammaTyper is able to use mRNA levels of HER2, ER, PR, and Ki67 to determine the categories of breast cancer that patients have and predict with accuracy which patients with luminal A-like tumors are at low risk of having their cancer spread.
“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,” said Dr. Sierk Pötting, BioNTech Diagnostics’ CFO.