Veliparib (ABT-888) (ABT-888) is an orally bioavailable inhibitor of PARP (Kis: 5.2/2.9 nM for PARP1/2). It enhances apoptosis and autophagy.

PARP2:2.9 nM (cell free), PARP1:5.2 nM (cell free)

Veliparib (ABT-888) 是一种针对PARP-1和PARP-2的高效抑制剂，其K(i)分别为5.2和2.9 nmol/L [1]。在HaCaT细胞模型中，ABT-888能减少SM诱导的NAD(+)/ATP耗竭以及凋亡/坏死[2]。ABT-888减少了H460肺癌细胞的集落形成能力，并通过DNA链断裂标志物组蛋白γ-H2AX表达的增强，抑制了DNA修复[3]。

PARP抑制剂显著提高了以Veliparib剂量低至3.1 mg/kg/d时的temozolomide效能，并在25 mg/kg/d时达到最大效能。在MX-1乳腺异种移植模型（BRCA1缺失和BRCA2突变）中，Veliparib增强了cisplatin、carboplatin和cyclophosphamide的效果，导致已建立肿瘤的缩小；而与单独相当剂量的细胞毒性化合物相比，只展现出适度的肿瘤抑制作用[1]。在小鼠模型中，Veliparib在耐受剂量下增加了肿瘤生长延迟。对于肿瘤体积增加5倍，Veliparib单独使用的肿瘤生长延迟为1天，仅辐射治疗为7天，而联合治疗为13.5天。体外Veliparib/辐射联合治疗减少了内皮管腔形成，而体内通过von Willebrand因子染色的肿瘤切片显示出血管形成的减少[3]。

PARP assays were conducted in a buffer containing 50 mmol/L Tris (pH 8.0), 1 mmol/L DTT, 1.5 μmol/L [3H]NAD+ (1.6 μCi/mmol), 200 nmol/L biotinylated histone H1, 200 nmol/L slDNA, and 1 nmol/L PARP-1 or 4 nmol/L PARP-2 enzyme. Reactions were terminated with 1.5 mmol/L benzamide, transferred to streptavidin Flash plates, and counted using a TopCount microplate scintillation counter [1].

Cell viability was quantified using the Cell Counting Kit-8 (CCK-8). This assay is based on Dojindo's highly water-soluble tetrazolium salt. WST-8 is reduced by dehydrogenases in cells to give an orange, water-soluble formazan dye. The amount of formazan dye generated by dehydrogenases in cells is directly proportional to the number of living cells. Briefly, exponentially growing HaCaT cells were seeded in 96-well plates at a density of 10,000 cells/well. 6 h or 24 h after exposure to SM and the administration of ABT-888, the CCK-8 reagent was added as recommended by the supplier [2].

For oral pharmacokinetic studies, ABT-888 was separated from plasma and brain homogenate using liquid-liquid extraction with a mixture of ethyl acetate and hexane at alkaline pH. ABT-888 and the internal standard were separated from each other and coextracted contaminants on a 50 × 3 mm Keystone Betasil Cyano 5 μm C18 column with acetonitrile: 0.1% trifluoroacetic acid mobile phase (40:60, by volume) at a flow rate of 0.3 mL/min. Analysis was done on a Sciex API3000 Biomolecular Mass Analyzer with a turbo-ionspray interface using Sciex MacQuan software. The analysis of plasma pharmacokinetics from osmotic minipump (OMP) studies was conducted using acidified methanol precipitated plasma. Samples were injected onto a Phenomenex Synergi 4μ Polar RP column and ABT-888 eluted with a mixture of acetonitrile and 0.1% acetic acid in water at a flow rate of 0.4 mL/min. Mass analysis was done with a ThermoFinnigan LCQ Duo using Xcalibur software [1].