MK-4827

MK-4827 (Niraparib, MK4827) is a highly potent PARP inhibitor with IC50 of 3.8 nM/2.1 nM for PARP1/PARP2; inhibits PARP activity with EC50=4 nM in a whole cell assay, and inhibits proliferation of cancer cells with mutant BRCA-1 and BRCA-2 with CC50 in the 10 100 nM range; well tolerated in vivo and demonstrates efficacy as a single agent in a xenograft model of BRCA-1 deficient cancer.Ovarian Cancer Approved (In Vitro) :Niraparib (MK-4827) inhibits PARP activity with EC50=4 nM and EC90=45 nM in a whole cell assay. MK-4827 inhibits proliferation of cancer cells with mutant BRCA-1 and BRCA-2 with CC50 in the 10-100 nM range. MK-4827 displays excellent PARP 1 and 2 inhibition with IC50=3.8 and 2.1 nM, respectively, and in a whole cell assay. To validate that Niraparib (MK-4827) inhibits PARP in these cell lines, A549 and H1299 cells are treated with 1 μM MK-4827 for various times and measured PARP enzymatic activity using a chemiluminescent assay. The results show that Niraparib (MK-4827) inhibits PARP within 15 minutes of treatment reaching about 85% inhibition in the A549 cells at 1 h and about 55% inhibition at 1 h for the H1299 cells. (In Vivo) :Niraparib (MK-4827) is well tolerated and demonstrates efficacy as a single agent in a xenograft model of BRCA-1 deficient cancer. Niraparib (MK-4827) is well tolerated in vivo and demonstrates efficacy as a single agent in a xenograft model of BRCA-1 deficient cancer. Niraparib (MK-4827) is characterized by acceptable pharmacokinetics in rats with plasma clearance of 28 (mL/min) /kg, very high volume of distribution (Vdss=6.9 L/kg), long terminal half-life (t1/2=3.4 h), and excellent bioavailability, F=65%. Niraparib (MK-4827) enhances radiation response of p53 mutant Calu-6 tumor in both cases, with the single daily dose of 50 mg/kg being more effective than 25 mg/kg given twice daily.