DNA damage repair defects a₩ε±re common in cancer cells¶≥×∏. We take full advantage of these ♦☆σ×unique characteristics of cancer cell≤→↑s to selectively kill th₩β®ese cells but not affect no••‍←rmal cells. A typical example is the de'©velopment of PARP inhibitors, which ta ​​‌rget DNA repair pathways and have'​ recently been utilized for the trea•♦tment of metastatically he↕ δreditary ovarian and breast ₹αcancer carrying BRCA mu$£​tations.