A randomized phase II trial of veliparib,radiotherapy, and temozolomide in patients with unmethylated MGMT glioblastoma: the VERTU study

BackgroundTemozolomide offers minimal benefit in patients with glioblastoma with unmethylated O⁶-methylguanine-DNA methyltransferase (MGMT) promoter status, hence, the need for novel therapies. This study evaluated whether veliparib, a brain-penetrant poly(ADP-ribose) polymerase (PARP) inhibitor, acts synergistically with radiation and temozolomide.MethodsVERTU was a multicenter 2:1 randomized phase II trial in patients with newly diagnosed glioblastoma and MGMT-unmethylated promotor status. The experimental arm consisted of veliparib and radiotherapy, followed by adjuvant veliparib and temozolomide. The standard arm consisted of concurrent temozolomide and radiotherapy, followed by adjuvant temozolomide. The primary objective was to extend the progression-free survival rate at six months (PFS-6m) in the experimental arm.ResultsA total of 125 participants were enrolled, with 84 in the experimental arm and 41 in the standard arm. The median age was 61 years, 70% were male, 59% had Eastern Cooperative Oncology Group (ECOG) performance status of 0, and 87% underwent macroscopic resection. PFS-6m was 46% (95% confidence interval [CI]: 36%-57%) in the experimental arm and 31% (95% CI: 18%-46%) in the standard arm. Median overall survival was 12.7 months (95% CI: 11.4-14.5 months) in the experimental arm and 12.8 months (95% CI: 9.5-15.8 months) in the standard arm. The most common grade 3-4 adverse events were thrombocytopenia and neutropenia, with no new safety signals.ConclusionThe veliparib-containing regimen was feasible and well tolerated. However, there was insufficient evidence of clinical benefit in this population. Further information from correlative translational work and other trials of PARP inhibitors in glioblastoma are still awaited.     

Blocking PARP activity with the inhibitor veliparib enhances radiotherapy sensitivity in endometrial carcinoma

ObjectiveOur study aimed to investigate the potential clinical utility of a poly(ADP‐ribose) polymerase (PARP) inhibitor, veliparib (ABT‐888), as a radiosensitizer in the medication of endometrial carcinoma (EC).MethodsHuman Ishikawa endometrial adenocarcinoma cells were treated with veliparib, radiotherapy (RT), or combination treatment. The viabilities, radiosensitivity enhancement ratio (sensitizer enhancement ratio (SER), and apoptosis of Ishikawa cells were, respectively, evaluated by Cell Counting Kit‐8 (CCK‐8), colony formation experiment, and flow cytometry. The tumor growth was assessed by xenograft mice models. Western blot assay investigated the expression of DNA damage and apoptosis‐related proteins in vivo and in vitro.ResultsCell Counting Kit‐8 revealed that the 10% inhibition concentration (IC₁₀) and 50% inhibition concentration (IC₅₀) values of veliparib‐treated Ishikawa cells were 1.7 and 133.5 µM, respectively. The SER of veliparib combined with RT was 1.229 in vitro. Flow cytometry analysis results indicated that the apoptosis rate of the veliparib + RT group was markedly higher than that of the RT group in vitro (p < 0.05). Furthermore, in vivo data revealed that veliparib + RT treatment significantly decreased tumor growth compared with single treatments of veliparib or RT and with the control group (p < 0.05). Then western blot confirmed the levels of anti‐phospho‐histone (γH2AX), caspase‐3, and B‐cell lymphoma 2 (Bcl‐2) associated protein X (Bax) were significantly higher in the veliparib + RT group, while the level of Bcl‐2 was lower compared with that of the RT group (p < 0.05), both in vivo and in vitro.ConclusionOur results indicate that veliparib in combination with RT markedly improved the therapeutic efficiency in human endometrial carcinoma.     

A phase I trial of veliparib (ABT-888) and temozolomide in children with recurrent CNS tumors: a Pediatric Brain Tumor Consortium report

Background

A phase I trial of veliparib (ABT-888), an oral poly(ADP-ribose) polymerase (PARP) inhibitor, and temozolomide (TMZ) was conducted in children with recurrent brain tumors to (i) estimate the maximum tolerated doses (MTDs) or recommended phase II doses (RP2Ds) of veliparib and TMZ; (ii) describe the toxicities of this regimen; and (iii) evaluate the plasma pharmacokinetic parameters and extent of PARP inhibition in peripheral blood mononuclear cells (PBMCs) following veliparib.

Methods

TMZ was given once daily and veliparib twice daily for 5 days every 28 days. Veliparib concentrations and poly(ADP-ribose) (PAR) levels in PBMCs were measured on days 1 and 4. Analysis of pharmacokinetic and PBMC PAR levels were performed twice during study conduct to rationally guide dose modifications and to determine biologically optimal MTD/RP2D.

Results

Twenty-nine evaluable patients were enrolled. Myelosuppression (grade 4 neutropenia and thrombocytopenia) were dose limiting. The RP2Ds are veliparib 25 mg/m² b.i.d. and TMZ 135 mg/m²/d. Only 2 out of 12 patients treated at RP2Ds experienced dose-limiting toxicities. Although no objective response was observed, 4 patients had stable disease >6 months in duration, including 1 with glioblastoma multiforme and 1 with ependymoma. At the RP2D of veliparib, pediatric pharmacokinetic parameters were similar to those in adults.

Conclusions

Veliparib and TMZ at the RP2D were well tolerated in children with recurrent brain tumors. A phase I/II trial to evaluate the tolerability and efficacy of veliparib, TMZ, and radiation in children with newly diagnosed brainstem gliomas is in progress.     

Microglial activation induced by the alarmin S100B is regulated by poly(ADP‐ribose) polymerase‐1

Brain injury resulting from stroke or trauma can be exacerbated by the release of proinflammatory cytokines, proteases, and reactive oxygen species by activated microglia. The microglial activation resulting from brain injury is mediated in part by alarmins, which are signaling molecules released from damaged cells. The nuclear enzyme poly(ADP‐ribose) polymerase‐1 (PARP‐1) has been shown to regulate microglial activation after brain injury, and here we show that signaling effects of the alarmin S100B are regulated by PARP‐1. S100B is a protein localized predominantly to astrocytes. Exogenous S100B added to primary microglial cultures induced a rapid change in microglial morphology, upregulation of IL‐1β, TNFα, and iNOS gene expression, and release of matrix metalloproteinase 9 and nitric oxide. Most, though not all of these effects were attenuated in PARP‐1^‐/‐ microglia and in wild‐type microglia treated with the PARP inhibitor, veliparib. Microglial activation and gene expression changes induced by S100B injected directly into brain were likewise attenuated by PARP‐1 inhibition. The anti‐inflammatory effects of PARP‐1 inhibitors in acutely injured brain may thus be mediated in part through effects on S100B signaling pathways. GLIA 2016;64:1869–1878     

新型PARP抑制剂veliparib

肿瘤细胞能够激活自身DNA的损伤修复机制进行修复,从而导致其对抗肿瘤药物和放疗产生耐药性,而聚腺苷酸二磷酸核糖转移酶(poly ADP-ribose polymerase,PARP)是一种DNA修复酶,在DNA修复通路中起关键作用.veliparib 是一种新型高选择抑制PARP的苯并咪唑类化合物,体内外实验表明本品具有显著的抑制PARP活性的作用.在治疗转移性乳腺癌、结肠癌、转移性黑色素瘤和脑肿瘤方面已取得显著的效果,其与替莫唑胺联用治疗乳腺癌的研究即将进入Ⅲ期临床.