control vs PARPi PEO4 at 1uM). (C)To investigate thein vivoimpact of prolonged PARPi, tumor [from a patient with a BRCA2MUT(8945delAA); WO-2-1] was transplanted to the fallopian tube/ovary of 10 NSG mice. colony formation and suppressed but did not eliminate tumor growth at the maximum-tolerated dose in a BRCAMUTPDX. PARPi treatment increased pATR and pCHK1 indicating activation from the ATR-CHK1 fork protection pathway is relied upon for genome stability under PARPi. Indeed, combination of ATRi or CHK1i with PARPi synergistically decreased survival and colony formation compared to single agent remedies in BRCAMUTcells. Notably, PARPi led to G2 phase build up, and the addition of ATRi or CHK1i released cells from G2 causing premature mitotic access with increased chromosomal aberrations and apoptosis. Moreover, the combinations of PARPi with ATRi or CHK1i were synergistic in causing tumor suppression in a BRCAMUTPDX with the PARPi-ATRi combination inducing tumor regression and in most cases, complete remission.



== Findings == PARPi causes increased reliance on ATR/CHK1 intended for genome stability and combination PARPi with ATR/CHK1i is more effective than PARPi alone in reducing tumor burden in BRCAMUTmodels. Keywords: ATR/CHK1, PARP inhibition, ovarian cancer == INTRODUCTION == Ovarian cancer survival offers improved minimally over the last decade(1) despite the unprecedented progress in understanding the genetics of ovarian cancer(2). There is a critical need to develop better therapeutic strategies that exploit the biology and genetics of high grade serous ovarian cancer (HGSOC). Approximately 50% of HGSOCs have defects in genes involved in homologous recombination (HR) repair(2, 3)BRCA 1and2(Breast Cancer Susceptibility Gene 1 and 2) mutant HGSOCs possess a deficiency in the repair of double strand DNA breaks (DSB) by HR(4). Poly (ADP-ribose) polymerase inhibitors (PARPi) impair the repair of single-stranded DNA breaks leading to DNA DSB which cannot be repair

📌 control vs PARPiat 1uM) (Anupgarh)
🏢 CareerPeer
📍 Anupgarh