Clinical BRCA1/2 Reversion Analysis Identifies Hotspot Mutations and Predicted Neoantigens Associated with Therapy...

Area of Science:

• Genetics
• Oncology
• Molecular Biology

Background:

• Reversion mutations in BRCA1 or BRCA2 genes are a primary mechanism of resistance to PARP inhibitors and platinum-based chemotherapy in cancer patients.
• Understanding the characteristics and patterns of these reversion mutations is crucial for managing treatment resistance.

Purpose of the Study:

• To collate, codify, and analyze over 300 reported clinical reversion mutations in BRCA1 and BRCA2.
• To identify mutation hotspots and deserts within BRCA2, and to characterize the types of mutations and their repair mechanisms.
• To explore the potential of reversion mutations to encode immunogenic neopeptides for therapeutic targeting.

Main Methods:

• Systematic collation and analysis of over 300 clinical reversion mutations in BRCA1/2.
• Identification of mutation hotspots and deserts in specific BRCA2 regions.
• Classification of mutation types (e.g., deletions, missense, splice-site) and assessment of microhomology.
• In silico prediction of neopeptide generation from reversion sequences.

Main Results:

• Identified distinct "hotspots" and "deserts" in BRCA2, indicating variable reversion risk based on mutation location.
• Found that missense and splice-site mutations are less likely to revert than truncating mutations.
• Determined that most reversions are small deletions (<100 bp), often with microhomology, suggesting diverse DNA repair pathways.
• Predicted that many reversions encode immunogenic neopeptides, offering potential therapeutic targets.

Conclusions:

• The location of BRCA2 mutations influences the risk of reversion, impacting drug resistance.
• Multiple DNA repair mechanisms contribute to the formation of reversion mutations.
• Reverted cancers may be susceptible to immunotherapies targeting neoantigens, providing a novel treatment strategy.