What drives eligibility for PARP inhibitors in the described framework?

What drives eligibility for PARP inhibitors in the described framework?

• A. Somatic BRCA mutation
• B. Germline BRCA mutation
• C. PD-L1 expression
• D. EGFR mutation

Answer: (B)

The main idea is that PARP inhibitors target cancer cells with defective homologous recombination repair. BRCA1/2 are essential for this repair pathway. When a germline BRCA mutation is present, every cell carries one defective BRCA allele; tumor cells often lose the second allele, creating a state of homologous recombination deficiency. In this context, blocking PARP—the enzyme that helps fix single-strand breaks—leads to the accumulation of DNA damage that tumor cells cannot efficiently repair, resulting in selective cancer cell death through synthetic lethality. That’s why germline BRCA mutation status drives eligibility for PARP inhibitors in this framework. PD-L1 expression and EGFR mutation don’t directly determine PARP inhibitor effectiveness. PD-L1 is tied to immune checkpoint inhibitors, and EGFR mutations point to EGFR-targeted therapies, not PARP inhibition. Somatic BRCA mutations can indicate HRD in a tumor as well, but the described framework centers on germline BRCA status as the eligibility driver.

The main idea is that PARP inhibitors target cancer cells with defective homologous recombination repair. BRCA1/2 are essential for this repair pathway. When a germline BRCA mutation is present, every cell carries one defective BRCA allele; tumor cells often lose the second allele, creating a state of homologous recombination deficiency. In this context, blocking PARP—the enzyme that helps fix single-strand breaks—leads to the accumulation of DNA damage that tumor cells cannot efficiently repair, resulting in selective cancer cell death through synthetic lethality. That’s why germline BRCA mutation status drives eligibility for PARP inhibitors in this framework.

PD-L1 expression and EGFR mutation don’t directly determine PARP inhibitor effectiveness. PD-L1 is tied to immune checkpoint inhibitors, and EGFR mutations point to EGFR-targeted therapies, not PARP inhibition. Somatic BRCA mutations can indicate HRD in a tumor as well, but the described framework centers on germline BRCA status as the eligibility driver.