PARP inhibitor

PARP inhibitors are a group of pharmacological inhibitors of the enzyme poly ADP ribose polymerase (PARP). They are developed for multiple indications, including the treatment of . Several forms of cancer are more dependent on PARP than regular cells, making PARP (PARP1, PARP2 etc) an attractive target for cancer therapy. PARP inhibitors appear to improve progression-free survival in women with recurrent platinum-sensitive ovarian cancer, as evidenced mainly by olaparib added to conventional treatment. In addition to their use in cancer therapy, PARP inhibitors are considered a potential treatment for acute life-threatening diseases, such as stroke and myocardial infarction, as well as for long-term neurodegenerative diseases. Olaparib: In December, 2014, the EMA and US FDA approved olaparib as monotherapy (at 400 mg taken twice per day) for patients with germline BRCA mutated (gBRCAm) advanced ovarian cancer who have been treated with three or more prior lines of chemotherapy. Rucaparib: On December 19, 2016 the US FDA granted accelerated approval for previously treated BRCA-mutant ovarian cancer. In April 2018 it was granted FDA approval. Niraparib: In March 2017 approved by US FDA for epithelial ovarian, fallopian tube, and primary peritoneal cancer. Inhibitor of PARP1 and PARP2. Talazoparib was approved in 2018 by US FDA for breast cancer with germline BRCA mutations. The main function of radiotherapy is to produce DNA strand breaks, causing severe DNA damage and leading to cell death. Radiotherapy has the potential to kill 100% of any targeted cells, but the dose required to do so would cause unacceptable side effects to healthy tissue. Radiotherapy therefore can only be given up to a certain level of radiation exposure. Combining radiation therapy with PARP inhibitors offers promise, since the inhibitors would lead to formation of double strand breaks from the single-strand breaks generated by the radiotherapy in tumor tissue with BRCA1/BRCA2 mutations.