Friday, Bret B.

Importance The prognosis for patients with glioblastoma is poor following standard therapy with surgical resection, radiation, temozolomide, and tumor-treating fields. Objectives To evaluate the combination of veliparib and temozolomide in glioblastoma based on preclinical data demonstrating significant chemosensitizing effects of the polyadenosine diphosphate-ribose polymerase 1/2 inhibitor veliparib when combined with temozolomide. Design, Setting, and Participants Patients with newly diagnosed glioblastoma with MGMT promoter hypermethylation who had completed concomitant radiation and temozolomide were enrolled between December 15, 2014, and December 15, 2018, in this Alliance for Clinical Trials in Oncology trial. The data for this analysis were locked on April 21, 2023. Interventions Patients were randomized and treated with standard adjuvant temozolomide (150-200 mg/m 2 orally, days 1-5) combined with either placebo or veliparib (40 mg orally, twice daily, days 1-7) for 6 cycles. Main Outcomes and Measures The primary end point for the phase 3 portion of the trial was overall survival (OS). Results There were 322 patients randomized during the phase 2 accrual period and an additional 125 patients randomized to complete the phase 3 accrual, for a total of 447 patients in the final phase 3 analysis. The median (range) age for patients was 60 (20-85) years and 190 patients (42.5%) were female. The median OS was 24.8 months (90% CI, 22.6-27.7) for the placebo arm and 28.1 months (90% CI, 24.3-33.3) for the veliparib arm ( P = .17). The difference in survival did not meet the prespecified efficacy end point. However, there was a separation of the survival curves that favored the veliparib arm over 24 to 48 months of follow-up. The experimental combination was well tolerated with an acceptable elevation in grade 3 or 4 hematologic toxic effects. Conclusions and Relevance This trial found that adding veliparib to adjuvant temozolomide did not significantly extend OS in patients with newly diagnosed, MGMT -hypermethylated glioblastoma. Trial Registration ClinicalTrials.gov Identifier: NCT02152982

AbstractIntroductionNasal symptoms are frequently reported by patients undergoing chemotherapy.MethodsEligible patients planning to receive paclitaxel, docetaxel, nab‐paclitaxel, bevacizumab without a concomitant taxane, or “other” (non‐taxane, non‐bevacizumab) chemotherapy regimens were invited to participate in this prospective study. Patients reported nasal symptoms prior to each dose of chemotherapy.ResultsThe percentage of patients (95% CI) who reported nasal symptoms was the same for patients who received bevacizumab or nab‐paclitaxel, 82.6% (61.2%, 95.1%). There were no significant differences among the proportions of patients experiencing nasal symptoms within the paclitaxel, nab‐paclitaxel, and bevacizumab cohorts. Patients in the nab‐paclitaxel cohort were more likely to experience symptoms than those in the non‐taxane non‐bevacizumab cohort or docetaxel cohort (p = 0.001, p = 0.001). Patients in the bevacizumab cohort were more likely to experience nasal symptoms than those in the non‐taxane non‐bevacizumab cohort (p = 0.03).ConclusionNasal vestibulitis symptoms are common in patients receiving chemotherapy, especially those receiving paclitaxel, docetaxel, and bevacizumab. Further investigations into treatments of this symptom complex are warranted.

2038 The effects of combining histone deacetylase (HDAC) inhibitors and proteasome inhibitors were evaluated in both established glioblastoma multiforme (GBM) cell lines and short-term cultures derived from the Mayo Clinic xenograft GBM panel. Co-exposure of LBH589 (LBH) and botezomib (btzmb) results in a striking induction of apoptosis, at minimally toxic doses of either drug alone, in established U251, U87, and D37 GBM cell lines, as well as in GBM8 (G-8), GBM10 (G-10), GBM12 (G-12), GBM14 (G-14), and GBM56 (G-56) cells, which have been developed from the Mayo xenograft GBM panel and maintained in short-term cultures. Synergism of apoptosis induction was also observed in U251 cells when co-exposing other HDAC inhibitors, including LAQ824 (LAQ) and trichostatin A (TSA), with another proteasome inhibitor MG132, demonstarting a class effect. In U251 cells, btzmb alone or in combination with LBH decreased Raf-1 levels and inactivated Akt and Erk. Either LBH589 or bortezomib alone increased expression of the cell cycle regulators p21 and p27. Additionally, the combination, but not the individual agents, markedly increased JNK activation. In addition, cell death after exposure to LBH589 and bortezomib is associated with cytochrome c release, Bax translocation, as well as caspase and PARP cleavage. Bax translocation may contribute to the synergistic cytotoxicity of the combination of LBH and btzmb in glioma cells since Bax translocation to mitochondria is known to precede cytochrome c release and apoptosis, but other pathways are likely to be involved. This combination regimen warrants further preclinical and possible clinical study for glioma patients. No significant financial relationships to disclose.

Abstract AZD6244 (ARRY 142886) is a potent and selective mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor currently in early clinical trials. We examined the activity of AZD6244 in a panel of non–small cell lung cancer and a panel of cell lines representing many cancer types using in vitro growth assays. AZD6244 induced G0-G1 cell cycle arrest in sensitive cell lines that primarily included cells containing the BRAF V600E mutation. In these cells, G0-G1 arrest is accompanied by the up-regulation of the cell cycle inhibitors p21WAF1 and p27Kip1 and down-regulation of cyclin D1. In the majority of cell lines tested, including those with K-ras or non-V600E BRAF mutations, AZD6244 induced the accumulation of phospho-MEK, an effect not observed in the most sensitive BRAF V600E-containing cells. Accumulation of phospho-MEK in non–V600E-containing cell lines is due to abrogation of negative feedback pathways. BRAF V600E disrupts negative feedback signaling, which results in enhanced baseline phospho-MEK expression. Exogenous expression of BRAF V600E disrupts feedback inhibition but does not sensitize cells to AZD6244. Specific suppression of endogenous BRAF V600E does not confer resistance to AZD6244 but enhances sensitivity to AZD6244. Thus, our findings show that BRAF V600E marks cells with an in vitro requirement for MAPK signaling to support proliferation. These cells are exquisitely sensitive to AZD6244 (IC50, <100 nmol/L), have high baseline levels of phospho-MEK, and lack feedback inhibition between ERK and Raf. These data suggest an approach to identifying cells that may be sensitive to AZD6244 and other MEK inhibitors. [Cancer Res 2008;68(15):6145–53]

Abstract The identification of intracellular signaling cascades important for the growth and survival of cancer cells has led to the development of targeted cancer therapeutics aimed at blocking these signals. The mitogen-activated protein kinase (MAPK) pathway has a well-defined role in cancer biology and has been an important target in the development of targeted therapies. Recently, several small-molecule inhibitors of MAPK/extracellular signal–regulated kinase kinase (MEK), a key intermediary of MAPK signaling, have been developed and are currently being tested in clinical trials. Herein, we review the MAPK pathway, the development of small-molecule MEK inhibitors, and the results obtained to date with MEK inhibitors in human cancer trials.

Abstract Purpose: To evaluate the effects of combining the multiple receptor tyrosine kinase inhibitor AEE788 and histone deacetylase (HDAC) inhibitors on cytotoxicity in a broad spectrum of cancer cell lines, including cisplatin-resistant ovarian adenocarcinoma cells. Experimental Design: Multiple cancer cell lines were treated in vitro using AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A), either alone or in combination. Effects on cytotoxicity were determined by growth and morphologic assays. Effects of the combination on cell signaling pathways were determined by Western blotting, and the results were confirmed using pathway-specific inhibitors and transfection of constitutively active proteins. Results: Cell treatment with AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A) in combination resulted in synergistic induction of apoptosis in non–small cell lung cancer (MV522, A549), ovarian cancer (SKOV-3), and leukemia (K562, Jurkat, and ML-1) cells and in OV202hp cisplatin-resistant human ovarian cancer cells. AEE788 alone or in combination with LBH589 inactivated mitogen-activated protein kinase (MAPK) and Akt cascades. Inhibition of either MAPK and/or Akt enhanced LBH589-induced apoptosis. In contrast, constitutively active MAPK or Akt attenuated LBH589 or LBH589 + AEE788–induced apoptosis. Increased apoptosis was correlated with enhanced reactive oxygen species (ROS) generation. The free radical scavenger N-acetyl-l-cysteine not only substantially suppressed the ROS accumulation but also blocked the induction of apoptosis mediated by cotreatment with AEE788 and LBH589. Conclusion: Collectively, these results show that MAPK and Akt inactivation along with ROS generation contribute to the synergistic cytotoxicity of the combination of AEE788 and HDAC inhibitors in a variety of human cancer cell types. This combination regimen warrants further preclinical and possible clinical study for a broad spectrum of cancers.

Abstract This study was undertaken to characterize preclinical cytotoxic interactions for human malignancies between the multikinase inhibitor sorafenib (BAY 43-9006) and proteasome inhibitors bortezomib or MG132. Multiple tumor cell lines of varying histiotypes, including A549 (lung adenocarcinoma), 786-O (renal cell carcinoma), HeLa (cervical carcinoma), MDA-MB-231 (breast), K562 (chronic myelogenous leukemia), Jurkat (acute T-cell leukemia), MEC-2 (B-chronic lymphocytic leukemia), and U251 and D37 (glioma), as well as cells derived from primary human glioma tumors that are likely a more clinically relevant model were treated with sorafenib or bortezomib alone or in combination. Sorafenib and bortezomib synergistically induced a marked increase in mitochondrial injury and apoptosis, reflected by cytochrome c release, caspase-3 cleavage, and poly(ADP-ribose) polymerase degradation in a broad range of solid tumor and leukemia cell lines. These findings were accompanied by several biochemical changes, including decreased phosphorylation of vascular endothelial growth factor receptor-2, platelet-derived growth factor receptor-β, and Akt and increased phosphorylation of stress-related c-Jun NH2-terminal kinase (JNK). Inhibition of Akt was required for synergism, as a constitutively active Akt protected cells against apoptosis induced by the combination. Alternatively, the JNK inhibitor SP600125 could also protect cells from apoptosis induced by the combination, indicating that both inhibition of Akt and activation of JNK were required for the synergism. These findings show that sorafenib interacts synergistically with bortezomib to induce apoptosis in a broad spectrum of neoplastic cell lines and show an important role for the Akt and JNK pathways in mediating synergism. Further clinical development of this combination seems warranted. [Mol Cancer Ther 2006;5(9):2378–87]