RB loss sensitizes triple-negative breast cancer to apoptosis induced by cellular stress

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Loss of the RB1 gene is frequent in triple-negative breast cancer (TNBC).
• RB1 loss correlates with poor response to therapies like CDK4/6 inhibitors.
• RB deficiency leads to replication stress and mitotic dysregulation.

Purpose of the Study:

• To identify therapeutic strategies targeting RB-deficient TNBC.
• To investigate synthetic lethality in RB-deficient models.
• To explore the role of apoptosis in RB-deficient TNBC response to therapy.

Main Methods:

• Unbiased drug screening to identify effective drug combinations.
• Co-targeting cell cycle processes (DNA repair, mitosis) and apoptosis pathways.
• Utilizing birinapant (XIAP inhibitor) with CHK1 or AURKA inhibitors.
• In vivo studies in RB-deficient TNBC models.

Main Results:

• Co-targeting cell cycle and apoptosis induces synthetic lethality in RB-deficient models.
• RB-deficient cells exhibit increased apoptosis upon cell cycle inhibition.
• Birinapant combined with CHK1 or AURKA inhibitors selectively kills RB-deficient TNBC cells.
• Combination therapy demonstrated durable disease control in vivo.

Conclusions:

• RB loss in TNBC sensitizes cells to apoptosis.
• Targeting XIAP in combination with cell cycle inhibitors is a promising strategy for RB-deficient TNBC.
• This approach offers a new avenue for targeted therapeutic interventions in TNBC.