A high-throughput pharmaceutical screen identifies compounds with specific toxicity against BRCA2-deficient tumors

Area of Science:

• Oncology
• Genetics
• Pharmacology

Background:

• Hereditary breast cancer is linked to BRCA1/BRCA2 mutations.
• Tumors with BRCA deficiency lose the remaining wild-type allele.
• Targeting BRCA deficiency is a key therapeutic strategy.

Purpose of the Study:

• Identify optimal compounds targeting BRCA deficiency.
• Test new combination therapies for BRCA-deficient breast cancer.
• Evaluate alternative compounds beyond current clinical trials.

Main Methods:

• High-throughput pharmaceutical screen on BRCA2-deficient mouse mammary tumor cells.
• In vitro and in vivo validation using mice with BRCA2-deficient mammary tumors.
• Drug combination experiments and tumor intervention studies.

Main Results:

• Three alkylators (chlorambucil, melphalan, nimustine) showed specific toxicity against BRCA2-deficient cells.
• Melphalan and nimustine demonstrated strong antitumor activity in vivo.
• Synergistic interactions observed between alkylators and olaparib in vitro.
• Combination of nimustine and olaparib led to recurrence-free survival exceeding 330 days in 3/5 animals.

Conclusions:

• A validated platform for identifying BRCA2-deficient cell-specific compounds was developed.
• Re-evaluation of alkylators like melphalan and nimustine is warranted.
• Combination therapy with poly-(ADP-ribose)-polymerase inhibitors may benefit BRCA-defective breast cancers.