TNBC is the most aggressive subtype of breast cancer, with high recurrence rates and limited treatment options1-3

What is triple-negative breast cancer (TNBC)?

TNBC refers to a subtype of breast cancer that is deemed ER–, PR–, and HER2– based on IHC. Other biomarkers, such as BRCA and PD-L1, may be present in TNBC and help inform treatment decisions.3-6

HER2 expression is heterogeneous and dynamic. Testing for IHC score can inform appropriate treatment options for mBC patients. The label HER2– comprises patients with a HER2 IHC score of 0, 1+, or 2+/ISH–.3,5-8

Female breast cancer types (%)1*
Pie chart showing Female breast cancer types  by percentage. From highest to least: HR-positive/HER2-negative 70%, triple-negative breast cancer (TNBC) 11%, HR-positive/HER2-positive 9%, unknown subtype 6%, and HR-negative/HER2-positive 4%. Pie chart showing Female breast cancer types  by percentage. From highest to least: HR-positive/HER2-negative 70%, triple-negative breast cancer (TNBC) 11%, HR-positive/HER2-positive 9%, unknown subtype 6%, and HR-negative/HER2-positive 4%.

TNBC makes up ~11% of all breast cancer cases

*According to SEER data from 2018-2022.

There is an unmet need in 1L mTNBC9

TNBC has the lowest 5-year survival rate of all mBC subtypes1

5-year overall survival by female mBC subtype1†
Bar chart showing 5-year overall survival by female mBC (metastatic breast cancer)  subtype by percentage. TNBC (triple-negative breast cancer) has the lowest 5-year overall survival of all metastatic breast cancer subtypes: TNBC 15%, HR-positive/HER2-negative 38%, HR-negative/HER2-positive 42%, and HR-positive/HER2-positive 49%. Bar chart showing 5-year overall survival by female mBC (metastatic breast cancer)  subtype by percentage. TNBC (triple-negative breast cancer) has the lowest 5-year overall survival of all metastatic breast cancer subtypes: TNBC 15%, HR-positive/HER2-negative 38%, HR-negative/HER2-positive 42%, and HR-positive/HER2-positive 49%.

†According to SEER data from 2015-2021.

While immunotherapy-based treatment is recommended in the 1L setting for eligible patients with mTNBC,

Up to 70%of patients with mTNBC are not candidates for immunotherapy-based treatment3,10,11


Chemotherapy remains the standard of care for mTNBC in 1L, despite limited patient benefit.9,12-14

Certain clinical characteristics may lead to a worse prognosis15-17:

  • Rapidly relapsed disease (DFI <12 months)
  • Visceral metastases, including brain metastases
  • ≥50 years of age
  • Multiple metastatic sites

Many patients with mTNBC do not receive treatment beyond 1L11,18

1L, first-line; BRCA, BReast CAncer gene; DFI, disease-free interval; ER–, estrogen receptor-negative; HER2, human epidermal growth factor receptor 2; HER2+, human epidermal growth factor receptor 2-positive; HER2–, human epidermal growth factor receptor 2-negative; HR+, hormone receptor-positive; HR–, hormone receptor-negative; IHC, immunohistochemistry; ISH, in situ hybridization; mBC, metastatic breast cancer; mTNBC, metastatic triple-negative breast cancer; PD-L1, programmed cell death-ligand 1; PR–, progesterone receptor-negative; SEER, The Surveillance, Epidemiology, and End Results Program; TNBC, triple-negative breast cancer.