Olaparib is an oral PARP inhibitor approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC) in patients with specific genetic mutations. It is used in men whose cancer has progressed after androgen receptor pathway inhibitors (like enzalutamide or abiraterone) and who have homologous recombination repair (HRR) gene mutations, such as BRCA1, BRCA2, or ATM.

Olaparib works by blocking the PARP enzyme, which cancer cells with defective DNA repair pathways rely on to survive. By inhibiting PARP, olaparib causes the accumulation of DNA damage, leading to cancer cell death. Clinical trials (e.g., PROfound study) have shown it improves radiographic progression-free survival and overall survival in eligible patients. Common side effects include anemia, nausea, fatigue, and low blood counts, so regular monitoring is required. Genetic testing is essential to determine eligibility for this