Triple negative breast cancer

Triple-Negative Breast Cancer (TNBC) is a heterogeneous and aggressive disease which, compared to other breast cancer subtypes, has faster growing, less differentiated and higher histologic grade tumors that tend to be larger at diagnosis^1,3,4.

TNBC is defined by the lack of expression of estrogen receptor (ER) and progesterone receptor (PR) and absence of HER2 overexpression and/or gene amplification, key drivers that are characteristic for other breast cancer subtypes³. They represent a heterogeneous breast cancer subtype with poor prognosis and patients are typically diagnosed at younger age compared to other breast cancer subtypes^1,3,4,5.

According to data from the Belgian Cancer Registry, approximately 1.216 patients will be diagnosed each year with TNBC, representing 9-11% of all new breast cancer diagnosis⁷.

Furthermore, a significant proportion of patients having received past diagnosis of breast cancer will experience during their lifetime a relapse of disease with a new and different histologic profile, a dismal diagnosis suggestive of a more aggressive disease, with high metastatic potential and poor response to therapy⁸.

Until recently, treatment for metastatic TNBC patients has relied almost exclusively on non-selective cytotoxic agents, with modest success as overall survival by year of metastatic diagnosis has not improved over time from 2008 till 2016¹¹. Furthermore, treatment with conventional chemotherapy, has a limited median survival of 12 to 18 months and an estimated 5-year overall survival of 12%^12,13, underscoring the very high unmet medical need of these patients lacking innovative therapeutic options for the treatment of these heterogeneous and aggressive tumors.

Recent advances in the use of PARP inhibitors and immune checkpoint blockade offer more targeted solutions for some of these patients in the metastatic setting. However, a prominent unmet medical need remains for patients relapsing or not eligible to receive immunotherapy such as anti PD-(L)1 agents or targeted therapies, such as PARP inhibitors^3,5.