Evaluating the Therapeutic Efficacy of PARP Inhibition in BRCA2-Mutated Ovarian Cancer

This paper concentrates on BRCA2 (BRCA2 DNA Repair Associated)-mutated ovarian cancer, PARP1 inhibition, and the therapeutic efficacy of PARP inhibitors. For the molecular mechanism, BRCA2 mutation leads to homologous recombination repair deficiency, which increases dependence of tumor cells on alternative DNA damage response pathways. This vulnerability, combined with PARP inhibition, creates synthetic lethality. Clinical trials such as SOLO1, SOLO2, and SOLO3 demonstrate clinical evidence showing benefit from olaparib in BRCA-mutated ovarian cancer. Despite significant initial efficacy, cancer cells can still develop resistance. Main resistance-associated mechanisms are BRCA2 reversion, HR restoration, replication fork protection, and drug efflux, which limit the durability of treatments. Findings of this review have multiple implications for clinical practices and future directions. BRCA2 is a valuable therapeutic biomarker: BRCA2 status can provide a basis for determining if patients are more likely to benefit from PARP inhibition treatment. Additionally, PARP inhibition is clinically effective, but initial effectiveness does not mean to be durable, so the clinical efficacy of PARP inhibition should also be evaluated by duration of benefit and development of resistance. Currently, many clinical trials studied pooled populations of BRCA1/2-mutated ovarian cancer patients, but more specific evidence related to BRCA2 is likely to be needed, because BRCA2-specific clinical efficacy cannot be separated in those trials. In the future, trials are expected to analyze BRCA2-mutated patients separate with whole BRCA-mutated groups; focus on better biomarker-based patient selection; and develop rational combination strategies to delay or reverse PARPi resistance.