Citations

Abstract Purpose/Background: The first-line chemotherapeutic temozolomide (TMZ) does not offer any therapeutic benefit in some cases of glioblastoma (GBM) and emergence of resistance leads to tumor progression in almost all patients. While the expression of O-6-methylguanine-DNA-methyltransferase (MGMT) correlates well with TMZ resistance, its expression varies among GBM tumors. The goal of this study is to identify additional genes with potential roles in TMZ resistance. Materials and Methods: Five primary GBM xenografts were generated from patient samples, and subsequent secondary models for resistance were developed by subjecting tumor-bearing mice to escalating doses of TMZ. Triplicate samples from parental and TMZ-resistant xenografts were analyzed for gene expression using the Illumina BeadChip microarray platform. The top 100 differentially expressed genes for each line were considered candidates. Genes were selected for qRT-PCR validation after ontological and pathway analysis. A lentivirus-mediated shRNA knockdown was performed to validate the role of several candidate genes in TMZ resistance in U87 and primary GBM12 cell lines. Knockdown was confirmed with qRT-PCR and western blots. TMZ responsiveness was assessed using CyQUANT and Neurosphere assays. Results: Upregulated MGMT expression was found in 3 of the 5 xenografts (GBM12TMZ, GBM14TMZ and GBM28TMZ) and was mechanistically linked with TMZ resistance in these lines using O6-benzylguanine to reverse the resistance phenotype. Differential expression of other DNA damage response genes included CCND2, CDKN1A, GADD45B, UBB as well as apoptosis regulators NFKB2 and BIRC3. In lines with unchanged MGMT expression (GBM22TMZ and GBM39TMZ), changes in anti-apoptosis genes NFKB2 and MAP3K1, transcription factor SRF and signal transduction gene PRKCDBP were validated by qRT-PCR. In GBM12TMZ, in addition to MGMT upregulation, expression of Ubiquitin B (UBB) was found to be the most significantly down-regulated gene both on microarray (Log2FC = −4.55, Fold change = 0.043) and qRT-PCR (Log2RQ =-4.04, RQ = 0.061). To test a possible role of UBB in TMZ resistance, knockdown was achieved in U87 (knockdown efficiency=91.2%) and in primary xenograft line GBM12 (knockdown efficiency=84.4%). The CyQUANT assay for U87UBB-KD and U87NT treated with escalating doses of TMZ revealed no significant difference in cell survival (10 M TMZ relative survival= 89.7% for U87UBB-KD and 79.2% for U87NT; p-value=0.53). Similarly, a neurosphere assay for GBM12UBB-KD and GBM12NT also yielded no significant difference in cell survival (10 M TMZ relative survival= 25.13% for GBM12UBB-KD and 23.35% for GBM12NT; p-value=0.83). Conclusions: We have used a TMZ resistance xenograft model to identify candidate TMZ resistance genes. The current data provides evidence on the role of MGMT in the development of acquired TMZ resistance while ruling out UBB as potential TMZ resistance gene in GBM. Additional studies are underway to assess the functional significance of other candidate genes, particularly those with differential expression in the setting of constant MGMT expression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B68.

Abstract Glioblastoma multiforme (GBM) is the most common and highly malignant primary brain tumor in adults with a median survival just over 1 year, and novel therapies are urgently needed. Deregulation of the p16 (INK4A)-CDK4/6-pRb pathway are commonly found in human GBM patients and selective inhibitors of CDK4/6 may be specifically useful to suppress proliferation associated with these alterations. PD0332991 is an orally active small molecule that specifically inhibits CDK4 and CDK6. Therefore, the efficacy of PD0332991 was evaluated in the Mayo panel of primary GBM xenograft lines using short-term explant cultures. We hypothesized that expression of p15 and/or p16, endogenous inhibitors of CDK4/6 activity, would suppress the response of GBM tumors to PD0332991 treatment. To test this hypothesis, 2 GBM xenograft cell lines with wild-type p16/p15 levels (GBM5 and 28) and 2 lines without detectable p16/p15 levels (GBM22 and 43) were selected for further analysis. Tumor cells were treated with graded concentrations (10 nanoM to1 microM) of PD0332991 for 5 days and subjected to CyQUANT cell proliferation assays. Consistent with our hypothesis, treatment with 1 microM PD0332991 effectively inhibited cell proliferation to 56.6±3.5% (P<0.001) and 44.3±3.4% (P<0.001) of control in GBM22 and GBM43 cells respectively, but did not affect cell proliferation in GBM5 and GBM28 cells (98.7±15.6% and 101.8±12.0% of control, respectively). In addition, 1 microM PD0332991 induced G1-phase cell cycle arrest in GBM22 (treated 79.7±0.8% vs. control 63.4±0.5% of cells in G1 phase, P<0.001) and GBM43 (treated 70.6±1.1% vs. control 48.9±4.6% of cells in G1 phase, P<0.001) but not in GBM5 and GBM28 (treated 52.3±2.7% vs. control 54.0±5.1%, treated 52.4±4.7% vs. control 54.6±2.6%, respectively). The status of p15 and p16 was confirmed by RT-PCR, which demonstrated readily detectable expression of p15 and p16 in GBM5 and GBM28, but not in GBM22 and GBM43 cells. Additional comparative genomic hybridization (CGH) data showed that CDKN2A and 2B (genes encode for p16 and p15 respectively) are homozygously deleted in GBM22 and 43, hemizygously deleted in GBM5 and normal in GBM28. We also examined the status of CDK4, CDK6, pRb and other molecules in the p16-CDK4/6-pRb pathway by Western, RT-PCR and CGH in these GBM lines and the data will be presented. We are now testing whether shRNA knockdown and/or re-expression of p15/p16 in the relevant cell lines alters their responsiveness to PD0332991. In conclusion, CDK4/6 inhibitor PD0332991 inhibits cell proliferation and induces G1 cell cycle arrest in p15/p16- null GBM tumors, but is less effective in p15/p16 expressing tumors. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C191.

Abstract It is now widely accepted that a spectrum of somatic alterations occur in human cancer and that particular alterations are associated with response or lack of response to anti-cancer therapies. Here, we undertook a systematic correlation analysis of somatic mutations, copy number aberrations and drug response across 300+ human cancer cell lines. We studied the RAF and VEGFR inhibitor, sorafenib, evaluating associations between sorafenib response and somatic mutations in 35 common cancer genes and high-level amplifications and homozygous deletions in more than 100 minimal common regions of gain and loss, which include many known oncogenes and tumor suppressor genes. Notably, we found that NRAS mutations, among other alterations, were significantly associated with sensitivity to sorafenib (odds ratio = 7, p-value = 0.003), whereas activating BRAF mutations were strongly associated with a lack of response (odds ratio = 4.9, p-value = 0.012). Specifically, 64% (7 of 11) of NRAS mutant cell lines were sensitive to sorafenib, while only 20% (34 of 170) of NRAS wild-type lines were sensitive. On the contrary, just 6.7% (2 of 30) of BRAF mutant lines were sensitive to sorafenib. Because NRAS mutations occur frequently in leukemia and no leukemia cell lines were included in the original analysis, we selected 5 NRAS mutant and 5 NRAS wild-type leukemia cell lines for further evaluation. Consistent with our previous observation, the four most sensitive leukemia cell lines were all NRAS mutant, each line exhibiting greater than 50% growth inhibition after 72 hours of exposure to 4uM sorafenib. These results confirm the original association and suggest that across both solid tumors and hematologic malignancies, NRAS mutations may identify a subset of cancers that are likely to respond sorafenib. In addition, this work demonstrates that systematic analysis of somatic alterations and drug response across a large collection of cancer cell lines is capable of discovering novel predictive biomarkers. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A47.

Providing personalized treatments designed to maximize benefits and minimizing harms is of tremendous current medical interest. One problem in this area is the evaluation of the interaction between the treatment and other predictor variables. Treatment effects in subgroups having the same direction but different magnitudes are called quantitative interactions, whereas those having opposite directions in subgroups are called qualitative interactions (QIs). Identifying QIs is challenging because they are rare and usually unknown among many potential biomarkers. Meanwhile, subgroup analysis reduces the power of hypothesis testing and multiple subgroup analyses inflate the type I error rate. We propose a new Bayesian approach to search for QI in a multiple regression setting with adaptive decision rules. We consider various regression models for the outcome. We illustrate this method in two examples of phase III clinical trials. The algorithm is straightforward and easy to implement using existing software packages. We provide a sample code in Appendix A. Copyright © 2012 John Wiley & Sons, Ltd.

Described for the first time in 1971, Schimke immuno-osseous dysplasia (SIOD) is an autosomal-recessive multisystem disorder that is caused by bi-allelic mutations of SMARCAL1, which encodes a DNA annealing helicase. To define better the dental anomalies of SIOD, we reviewed the records from SIOD patients with identified bi-allelic SMARCAL1 mutations, and we found that 66.0% had microdontia, hypodontia, or malformed deciduous and permanent molars. Immunohistochemical analyses showed expression of SMARCAL1 in all developing teeth, raising the possibility that the malformations are cell-autonomous consequences of SMARCAL1 deficiency. We also found that stimulation of cultured skin fibroblasts from SIOD patients with the tooth morphogens WNT3A, BMP4, and TGFβ1 identified altered transcriptional responses, raising the hypothesis that the dental malformations arise in part from altered responses to developmental morphogens. To the best of our knowledge, this is the first systematic study of the dental anomalies associated with SIOD.

Background Cardiac mortality and myocardial infarction (MI) rates are used to evaluate the efficacy of coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). We compared 5-year cardiac mortality and MI rates in 1829 patients with multivessel disease randomized to CABG or PTCA. Methods and Results The 5-year cardiac mortality rate was 8.0% in patients assigned to PTCA compared with 4.9% in those assigned to CABG (relative risk [RR] of 1.55 with a 95% confidence interval [CI] of 1.07 to 2.23; P =.022). In a subgroup of 1476 nondiabetic patients, there were no significant differences between treatment groups in cardiac mortality either overall (4.6% versus 4.2%; RR=1.04, 95% CI, 0.65 to 1.66; P =.908) or in subgroups based on symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery. The two treatment groups had similar event rates for the combined end point of cardiac death or MI. The RR for cardiac mortality in 264 patients who sustained an MI compared with those who did not was 5.9 ( P <.001). MIs were more common after CABG during index hospitalization ( P =.004), but in the PTCA group, they were more common after discharge ( P <.001). Conclusions The Bypass Angioplasty Revascularization Investigation (BARI) trial indicates 5-year cardiac mortality in patients with multivessel disease was significantly greater after initial treatment with PTCA than with CABG. The difference was manifest in diabetic patients on drug therapy. There were no significant differences overall for the composite end point of cardiac mortality or MI between treatment groups or for cardiac mortality in nondiabetic patients regardless of symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery.

Background The NHLBI Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry followed 1345 consecutive patients with first PTCA between 1977 and 1981 (registry 1) and 2136 consecutive patients with PTCA between 1985 and 1986 (registry 2). Changes in patient selection and in immediate and 1-year outcome are presented. This report extends to 5 years the comparison of the effects of early and more recent management with PTCA. Methods and Results Sixteen participating centers entered consecutive patients who had angioplasty for the first time between 1977 and 1981 and between 1985 and 1986. Patients with recent myocardial infarction (MI) were excluded. Vessel disease was defined according to the Coronary Artery Surgery Study. Successful dilatation required ≥20% reduction in luminal narrowing and <50% lumen diameter stenosis after intervention. Routine annual follow-up was conducted by telephone interview. The product-limit method was used to estimate freedom from untoward events, Cox regression analysis to model relative risk and adjusted relative risk of events between the two registries, and logistic regression when the exact time of outcome (such as recurrence of symptoms) was not known. Long-term event rates were computed by vessel disease for all patients and for the cohort of patients with initially successful PTCA. After adjustment for extent of disease, diabetes, prior bypass surgery (CABG), hypertension, age, and sex, the 5-year risk of death was similar in the two registry cohorts. However, rates of MI, CABG, and a combined outcome measure of death, MI, and/or CABG were significantly lower in the registry 2 cohort both for all patients and for patients who were initially treated successfully. Use of repeated PTCA was higher, and freedom from symptoms without adverse events was significantly better in the latter cohort. Conclusions Compared with registry 1, the management of the registry 2 cohort resulted in lower 5-year morbid event rates and reduced CABG operations. Mortality rates remained similar. When symptomatic status was considered in combination with events, a significantly better outcome was seen overall and in the initially successful cohort. In registry 2, repeated PTCA was used with much greater frequency early after the initial procedure.

Background There are few data comparing clinical outcome and potential indications for routine post–myocardial infarction cardiac catheterization and revascularization of patients who sustain a non–Q-wave versus Q-wave infarct after thrombolytic therapy. Methods and Results A secondary analysis of 2634 patients enrolled in the TIMI II trial with a first myocardial infarction was performed to determine 6-week and 1-year cardiac event rates and identify clinical and angiographic differences between the 1867 patients (70.9%) who evolved a Q-wave infarct and the 767 patients (29.1%) who sustained a non–Q-wave infarct after treatment with intravenous thrombolytic therapy. Male sex (85.3% versus 75.6%; P <.001) and anterior wall infarcts (53.8% versus 43.7%; P <.001) were more frequent in the Q-wave versus the non–Q-wave group. During recombinant tissue-type plasminogen activator (rTPA) infusion, a greater percentage of non–Q-wave patients (37.3% versus 23.5%; P =.001) had normalization of initial ST-segment elevation. Infarct-related artery patency (TIMI flow grade 2 or 3) ( P =.02), complete infarct-related artery reperfusion (TIMI 3 flow grade) ( P <.001), and the percentage of patients with a predischarge resting left ventricular ejection fraction >55% ( P <.001) were greater in the non–Q-wave group. New congestive heart failure during hospitalization developed more frequently in Q-wave patients (18.9% versus 11.6%; P <.001). After 42 days, the occurrences of reinfarction ( P =.76), death ( P =.76), and combined death or reinfarction ( P =.43) were similar in patients assigned to the invasive or conservative postlytic management strategy, regardless of infarct type. One-year mortality was 3.4% versus 4.4% for non–Q-wave versus Q-wave infarct type, respectively ( P =.25). Conclusions Angiographic and clinical differences were observed between patients who present with initial ST-segment elevation and evolve early non–Q-wave versus Q-wave myocardial infarcts after treatment with rTPA, heparin, and aspirin. Early mortality and adverse clinical cardiac events in these patients are not significantly different after a conservative compared with an invasive treatment strategy, regardless of whether the infarct type is non–Q wave or Q wave.

BACKGROUND Coronary revascularization with bypass has been shown to improve survival in patients with coronary artery disease and left ventricular dysfunction. In these patients, use of nonsurgical revascularization with percutaneous transluminal coronary angioplasty (PTCA) is increasing, although their long-term outcome has not been well delineated. The purpose of this investigation was to characterize the outcome of angioplasty in patients with decreased left ventricular function and contrast it with the results in patients with normal left ventricular function. METHODS AND RESULTS In the 1985-1986 National Heart, Lung, and Blood Institute's PTCA Registry, of 1,802 patients undergoing PTCA, 244 patients (13.5%) had an ejection fraction of < or = 45% (mean, 39.6 +/- 6.8%). These patients had a higher incidence of prior infarction, a longer and worse history of manifestations of coronary disease, and more extensive coronary artery disease than patients with well-preserved function; 88% and 91%, respectively, had successful dilation of at least one lesion (nonsignificant difference). However, patients with decreased left ventricular function had a decreased frequency of successful dilation of all lesions in which PTCA was attempted (76% versus 84%, p < 0.01). There were no statistically significant differences in in-hospital complications--death occurred in 0.8% and 0.7%, nonfatal myocardial infarction occurred in 4.9% and 4.5%, and emergency surgical revascularization was performed in 4.5% and 3.2%, respectively. Patients were followed for a mean of 4.1 years; during this time, patients with decreased left ventricular function had significantly worse survival and combined event-free survival. Despite this, at 4 years, 87% of the patients with a mean ejection fraction of 39.6% remained alive, and 77% were alive and had not experienced infarction or required bypass. CONCLUSIONS PTCA is effective in selected patients with depressed left ventricular function. Initial outcome and risk-benefit ratio are excellent. Successful dilation of at least one vessel was achieved in 88% of patients with depressed left ventricular function and in 91% of patients with more normal left ventricular function. The former group, however, had a decreased incidence of successful dilation in all lesions in which dilation was attempted (76% versus 84%, p < 0.01). There was no significant difference in in-hospital complications between the two groups. During follow-up, patients with decreased left ventricular function had worse event-free survival, although 77% were alive without infarction or bypass grafting at 4 years.

Background —Patients with treated diabetes in the randomized-trial segment of the Bypass Angioplasty Revascularization Investigation (BARI) who were randomized to initial revascularization with PTCA had significantly worse 5-year survival than patients assigned to CABG. This treatment difference was not seen among diabetic patients eligible for BARI who opted to select their mode of revascularization. We hypothesized that differences in patient characteristics, assessed and unmeasured, together with the treatment selection in the registry, at least partially account for this discrepancy. Methods and Results —Among diabetics taking insulin or oral hypoglycemic drugs at entry, angiographic and clinical presentations were comparable between randomized and registry patients. However, more registry patients were white, and registry diabetics tended to be more educated and more physically active and to report better quality of life. Procedural characteristics and in-hospital complications were comparable. The 5-year all-cause mortality rate was 34.5% in randomized diabetic patients assigned to PTCA versus 19.4% in CABG patients ( P =0.0024; relative risk [RR]=1.87); corresponding cardiac mortality rates were 23.4% and 8.2%, respectively ( P =0.0002; RR=3.10). The CABG benefit was more apparent among patients requiring insulin. In the registry, all-cause mortality was 14.4% for PTCA versus 14.9% for CABG ( P =0.86, RR=1.10), with corresponding cardiac mortality rates of 7.5% and 6.0%, respectively ( P =0.73; RR=1.07). These RRs in the registry increased to 1.29 and 1.41, respectively, after adjustment for all known differences between treatment groups. Conclusions —BARI registry results are not inconsistent with the finding in the randomized trial that initial CABG is associated with better long-term survival than PTCA in treated diabetic patients with multivessel coronary disease suitable for either surgical or catheter-based revascularization.