BRCA1/2-negative hereditary triple-negative breast cancers exhibit BRCAness

Area of Science:

• Oncology
• Genetics
• Molecular Biology

Background:

• BRCA1/2-associated breast cancers show sensitivity to PARP inhibitors and platinum compounds due to impaired homologous recombination (HR) DNA repair.
• Triple-negative breast cancer (TNBC) is often not associated with BRCA1/2 mutations, limiting treatment options.
• BRCAness, a phenotype of HR deficiency in BRCA1/2-negative tumors, suggests potential sensitivity to these therapies.

Purpose of the Study:

• To investigate the hypothesis that hereditary BRCA1/2-negative TNBCs exhibit BRCAness.
• To identify a novel subset of hereditary TNBCs that may benefit from PARP inhibitors or platinum-based therapies.
• To assess the utility of family history in identifying patients for DNA repair-targeted therapies.

Main Methods:

• Analysis of family histories to identify hereditary TNBCs from a cohort of 360 patients.
• Germline BRCA1/2 mutation testing in the identified hereditary TNBC group.
• Real-time PCR arrays to compare expression of 120 HR-related genes and DNA damage repair genes between BRCA1/2-associated and BRCA1/2-negative subgroups.

Main Results:

• Approximately 73% of hereditary TNBCs were BRCA1/2-associated, while 27% were BRCA1/2-negative.
• No significant differences in the expression of analyzed DNA repair genes were observed between the BRCA1/2-associated and BRCA1/2-negative hereditary TNBC subgroups.
• This suggests that BRCA1/2-negative hereditary TNBCs exhibit BRCAness.

Conclusions:

• BRCA1/2-negative hereditary TNBCs represent a distinct subset with potential sensitivity to PARP inhibitors and platinum-based therapies.
• Family history is a valuable tool for selecting TNBC patients for DNA repair-targeted treatments.
• Identifying hereditary TNBCs can broaden the patient population eligible for these effective therapies.