Oncolytic DNX-2401 Virus for Pediatric Diffuse Intrinsic Pontine Glioma

BACKGROUND

Pediatric patients with diffuse intrinsic pontine glioma (DIPG) have a poor prognosis, with a median survival of less than 1 year. Oncolytic viral therapy has been evaluated in patients with pediatric gliomas elsewhere in the brain, but data regarding oncolytic viral therapy in patients with DIPG are lacking.

METHODS

We conducted a single-center, dose-escalation study of DNX-2401, an oncolytic adenovirus that selectively replicates in tumor cells, in patients with newly diagnosed DIPG. The patients received a single virus infusion through a catheter placed in the cerebellar peduncle, followed by radiotherapy. The primary objective was to assess the safety and adverse-event profile of DNX-2401. The secondary objectives were to evaluate the effect of DNX-2401 on overall survival and quality of life, to determine the percentage of patients who have an objective response, and to collect tumor-biopsy and peripheral-blood samples for correlative studies of the molecular features of DIPG and antitumor immune responses.

RESULTS

A total of 12 patients, 3 to 18 years of age, with newly diagnosed DIPG received 1×1010 (the first 4 patients) or 5×1010 (the subsequent 8 patients) viral particles of DNX-2401, and 11 received subsequent radiotherapy. Adverse events among the patients included headache, nausea, vomiting, and fatigue. Hemiparesis and tetraparesis developed in 1 patient each. Over a median follow-up of 17.8 months (range, 5.9 to 33.5), a reduction in tumor size, as assessed on magnetic resonance imaging, was reported in 9 patients, a partial response in 3 patients, and stable disease in 8 patients. The median survival was 17.8 months. Two patients were alive at the time of preparation of the current report, 1 of whom was free of tumor progression at 38 months. Examination of a tumor sample obtained during autopsy from 1 patient and peripheral-blood studies revealed alteration of the tumor microenvironment and T-cell repertoire.

CONCLUSIONS

Intratumoral infusion of oncolytic virus DNX-2401 followed by radiotherapy in pediatric patients with DIPG resulted in changes in T-cell activity and a reduction in or stabilization of tumor size in some patients but was associated with adverse events. (Funded by the European Research Council under the European Union's Horizon 2020 Research and Innovation Program and others; EudraCT number, 2016-001577-33; ClinicalTrials.gov number, NCT03178032.).

CTIM-08. SAFETY, EFFICACY, AND SURVIVAL RESULTS FROM A PHASE 1 STUDY OF THE ONCOLYTIC ADENOVIRUS DNX-2401 FOLLOWED BY STANDARD OF CARE RADIOTHERAPY FOR NEWLY DIAGNOSED DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is the most lethal pediatric brain tumor. Median overall survival (OS) with standard of care radiation therapy (RT) is approximately 8-10 months and 2-year survival is < 10%. A Phase 1 single-center study was conducted to evaluate the oncolytic adenovirus, DNX-2401 (tasadenoturev), followed by RT for DIPG.

METHODS

Newly-diagnosed DIPG patients 1-18 years old received a tumor biopsy through the cerebellar peduncle followed by intratumoral injection of 1e10 – 5e10 vp DNX-2401 and conventional RT 1-3 weeks later.

RESULTS

Subjects were enrolled (n=12) from December 2017 to January 2020 and had a median age of 9 years (range 3-18) and Lansky/Karnofsky performance scores of 90-100 (n=4; 33%) or 70-80 (n=8; 67%). Genetic assessment was completed for 11 subjects (92%) and histone 3 K27M mutations were identified in 10 subjects, including H3F3A (n=8), HIST2H3C (n=1), and HIST1H3B (n=1); 1 subject was H3 wildtype (n=1). TP53 mutations were identified in 5 subjects (42%). DNX-2401 was administered followed by RT (n=11; 92%). No dose-limiting toxicities were observed and the treatment regimen was well-tolerated. The most commonly reported adverse events (≥ 5 subjects), regardless of study drug relationship, include asthenia, headache, vomiting, pyrexia, and neurological deterioration. Three serious adverse events were reported including grade 3 abdominal pain, grade 3 lymphopenia, and grade 3 clinical deterioration. Tumor reductions were reported for 9 subjects (75%), including 2 confirmed (17%) and 2 unconfirmed (17%) responses per RAPNO criteria. As of the data cutoff, median OS is 19.7 months and OS-24 is 32% with follow-up ongoing for 3 subjects (26.9, 25.6, 13.7 months).

CONCLUSIONS

DNX-2401 followed by RT can be safely administered to DIPG. Survival outcomes are encouraging, thus warranting further evaluation in a Phase 2 study.

Abstract 6713: Oncolytic adenoviruses expressing immune modulators enhance tumor cell killing in human cancer 3D microtumor models

A series of investigational oncolytic immunotherapies based on DNX-2401 (tasadenoturev) are under development for the treatment of advanced cancers. Viruses “armed” with cell surface or secreted immune modulatory molecules inserted in the DNX-2401 backbone were evaluated using human cell derived 3D microtumor/ T cell models to elucidate specific anti-tumor properties and determine differences in immune activation.

Background: DNX-2401 is a conditionally replicative adenovirus serotype 5 containing: 1) a 24 bp deletion from the E1A gene (Rb-binding domain) to confer cancer cell selectivity, and 2) insertion of an integrin-binding motif (RGD-4C) in the fiber to enhance infectivity across a broad range of cancers. DNX-2401 selectively replicates in cancer cells, causes tumor destruction, and triggers the recruitment of lymphocytes, leading to anti-tumor response. Phase 1 and 2 studies of DNX-2401 are ongoing in patients with glioblastoma and diffuse intrinsic pontine glioma. The first immune modified virus in the series, DNX-2440, engineered to express OX40L, is being evaluated in a Phase 1 study in patients with glioblastoma.

Results: Immune modulator coding sequences inserted in place of E3 in the DNX-2401 backbone expressed properly localized and biologically active transgenes. DNX-2440 infected tumor cells expressed OX40L localized to the cell surface capable of stimulating OX40-expressing T cells. Tumor cells infected with a second virus, which was engineered to express a cytokine, secreted high levels of active protein. Both armed viruses showed infection, replication, and oncolytic activity in a panel of cancer cell lines under standard culture conditions. 3D microtumors composed of melanoma or lung cancer cells and normal human dermal fibroblasts were utilized to assess immune activation following virus infection. Unstimlated or pre-stimulated human immune cells were co-cultured for 12 days with the 3D microtumors infected with DNX-2401 or each armed virus. Infection with DNX-2440 increased T cell-mediated killing of tumor cells that was dependent on OX40/OX40L engagement, as the effect was abrogated in the presence of an OX40L blocking antibody. The kinetics of oncolytic activity, immune cell activation, and tumor infiltration were dependent on the immune modulator expressed from the oncolytic virus, resulting in differences in tumor clearance. These results demonstrate how oncolytic viruses can be customized to have unique properties by inserting different immune modulators into the virus genome, thus providing a customized approach for treating different cancers.

Citation Format: Laura K. Springgay, Amy M. Strauwald, Brett Ewald, Joan M. Robbins, Winnie M. Chan. Oncolytic adenoviruses expressing immune modulators enhance tumor cell killing in human cancer 3D microtumor models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6713.

Phase I Study of DNX-2401 (Delta-24-RGD) Oncolytic Adenovirus: Replication and Immunotherapeutic Effects in Recurrent Malignant Glioma

Purpose DNX-2401 (Delta-24-RGD; tasadenoturev) is a tumor-selective, replication-competent oncolytic adenovirus. Preclinical studies demonstrated antiglioma efficacy, but the effects and mechanisms of action have not been evaluated in patients. Methods A phase I, dose-escalation, biologic-end-point clinical trial of DNX-2401 was conducted in 37 patients with recurrent malignant glioma. Patients received a single intratumoral injection of DNX-2401 into biopsy-confirmed recurrent tumor to evaluate safety and response across eight dose levels (group A). To investigate the mechanism of action, a second group of patients (group B) underwent intratumoral injection through a permanently implanted catheter, followed 14 days later by en bloc resection to acquire post-treatment specimens. Results In group A (n = 25), 20% of patients survived > 3 years from treatment, and three patients had a ≥ 95% reduction in the enhancing tumor (12%), with all three of these dramatic responses resulting in > 3 years of progression-free survival from the time of treatment. Analyses of post-treatment surgical specimens (group B, n = 12) showed that DNX-2401 replicates and spreads within the tumor, documenting direct virus-induced oncolysis in patients. In addition to radiographic signs of inflammation, histopathologic examination of immune markers in post-treatment specimens showed tumor infiltration by CD8+ and T-bet+ cells, and transmembrane immunoglobulin mucin-3 downregulation after treatment. Analyses of patient-derived cell lines for damage-associated molecular patterns revealed induction of immunogenic cell death in tumor cells after DNX-2401 administration. Conclusion Treatment with DNX-2401 resulted in dramatic responses with long-term survival in recurrent high-grade gliomas that are probably due to direct oncolytic effects of the virus followed by elicitation of an immune-mediated antiglioma response.

Abstract LB-235: Delta-24-RGD oncolytic adenovirus treatment downmodulates the key regulator of T-cell exhaustion TIM3 in malignant gliomas

T cell exhaustion is a key mechanism of tumor immune suppression and is commonly observed in several cancers. The exhausted T cells in the tumor microenvironment overexpress inhibitory receptors, show decreased effector cytokine production, and exhibit diminished cytolytic capabilities, resulting in the failure to eliminate cancer cells. Restoring the activity of exhausted T cells is a desirable strategy to improve immune-based anti-cancer therapies, and has yielded encouraging results. Exhausted T cells are characterized by the expression of high levels of PD-1 and TIM3, which cooperate to induce T-cell hyporesponsiveness. In this study, we sought to determine whether the infection of human gliomas with oncolytic viruses modifies the expression of T cell markers. As part of a phase 1, dose-escalation, biological-endpoint clinical study (NCT00805376) of Delta-24-RGD, a Rb-targeted, tumor-selective, replication-competent oncolytic adenovirus, conducted in 37 patients with recurrent malignant glioma, 12 patients received an intratumoral injection through an implanted catheter, followed 14-days later by en bloc resection and Delta-24-RGD injections into the post-resection tumor bed. 10 surgical post-treatment specimens and 5 pre-treated tumors were examined for markers of immune response. From all selected cases, formalin fixed, paraffin embedded tissue blocks were examined. IHC was performed using a Leica Bond Max automated stainer as previously described. The slides were scanned in an Aperio AT2 scanner (Leica Biosystems). The IHC scores for CD3, CD4, CD8, CD45Ro, FOXP3, TIM3, LAG-3, VISTA, CD20, CD57, CD68, and OX40 were expressed as cell density in the inflammatory cell population (number of positive cells per mm square of tumor area), except PD-L1, PD-L2, B7-H3, B7-H4, IDO-1, which were expressed using percentage of positive tumor cells, and also as H-Score of the tumor cells (which integrates percentage of tumor cells and intensity of staining, with a final H-score ranging from 0 to 300). Correlations between immunostaining marker values and survival and dose level were assessed using Spearman rank correlation analysis. Differences in immunostaining marker values before and after treatment were assessed using the Wilcoxon rank sum test. These analyses demonstrated that all the target proteins are expressed in gliomas in different patterns and tumor regions. Although, we did not observe significant treatment-related changes in the expression of PD-1 in lymphocytes and PD-L1 in glioma cells, TIM3, a marker for T cell exhaustion, was downregulated after Delta-24-RGD treatment. In addition, expression of B7-H3, a marker of poor prognosis in other tumors, correlated with poorer survival. Because PD-1 and TIM3 cooperate to maintain T-cell exhaustion our data provide a rationale for the combination of Delta-24-RGD and anti-PD-1 antibodies for the treatment of malignant gliomas. Importantly, a multicenter clinical trial to test this strategy has already been open (NCT02798406).

Citation Format: Juan Fueyo, Candelaria Gomez-Manzano, Pamela Villalobos, Jaime Rodriguez-Canales, Barbara Mino, Ignacio Wistuba, Kenneth Hess, Marta Alonso, Sonia Tejada, Ricardo Diez-Valle, Brett Ewald, Frank Tufaro, Frederick Lang. Delta-24-RGD oncolytic adenovirus treatment downmodulates the key regulator of T-cell exhaustion TIM3 in malignant gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-235. doi:10.1158/1538-7445.AM2017-LB-235

HDAC Inhibition Induces MicroRNA-182, which Targets RAD51 and Impairs HR Repair to Sensitize Cells to Sapacitabine in Acute Myelogenous Leukemia

PURPOSE

The double-strand breaks elicited by sapacitabine, a clinically active nucleoside analogue prodrug, are repaired by RAD51 and the homologous recombination repair (HR) pathway, which could potentially limit its toxicity. We investigated the mechanism by which histone deacetylase (HDAC) inhibitors targeted RAD51 and HR to sensitize acute myelogenous leukemia (AML) cells to sapacitabine.

EXPERIMENTAL DESIGN

Chromatin immunoprecipitation identified the role of HDACs in silencing miR-182 in AML. Immunoblotting, gene expression, overexpression, or inhibition of miR-182 and luciferase assays established that miR-182 directly targeted RAD51. HR reporter assays, apoptotic assays, and colony-forming assays established that the miR-182, as well as the HDAC inhibition-mediated decreases in RAD51 inhibited HR repair and sensitized cells to sapacitabine.

RESULTS

The gene repressors, HDAC1 and HDAC2, became recruited to the promoter of miR-182 to silence its expression in AML. HDAC inhibition induced miR-182 in AML cell lines and primary AML blasts. miR-182 targeted RAD51 protein both in luciferase assays and in AML cells. Overexpression of miR-182, as well as HDAC inhibition-mediated induction of miR-182 were linked to time- and dose-dependent decreases in the levels of RAD51, an inhibition of HR, increased levels of residual damage, and decreased survival after exposure to double-strand damage-inducing agents.

CONCLUSIONS

Our findings define the mechanism by which HDAC inhibition induces miR-182 to target RAD51 and highlights a novel pharmacologic strategy that compromises the ability of AML cells to conduct HR, thereby sensitizing AML cells to DNA-damaging agents that activate HR as a repair and potential resistance mechanism. Clin Cancer Res; 22(14); 3537-49. ©2016 AACR.

Determinants of the knowledge of and attitude towards tuberculosis in Nigeria

Globally, Nigeria had the fourth highest incidence of tuberculosis (TB) cases in 2009. Datasets of the 2008 Nigeria Demographic and Health Survey (NDHS) were used for examining factors associated with respondents' knowledge of and attitude towards TB in Nigeria. With the same age-group of males and females, the sample included 47,193 respondents aged 15-49 years. Factors associated with the knowledge of and attitude towards TB were examined against a set of individual-, household- and community-level variables, using multiple binary logistic regression analyses. Respondents who reported having ever heard of TB was 74.7%. Of those who ever heard of TB, 76.9% believed that TB can be cured, and 19.6% would want a family member's TB to be kept secret. Of those who ever heard of TB, 63.1% believed that TB was spread from person to person through the air by coughing or sneezing. Multivariate analysis indicated that the probability of having poor knowledge of and negative attitude towards TB was consistently significant among the poorest household (lowest wealth quintile), geopolitical regions (North Central), respondents with no schooling, non-working respondents, youngest age-group (15-19 years), and rural areas [adjusted odds ratios (AOR)=0.76, 95% CI 0.66-0.86 for respondents who had ever heard of TB; AOR=0.89, 95% CI 0.80-0.99 for respondents who had ever heard of TB and believed that TB can be cured; AOR=0.83, 95% CI 0.73-0.94 for those who had ever heard of TB and concealed the fact that a family member had TB; and AOR=0.88, 95% CI 0.78-0.99 for those who had ever heard of TB and believed TB was spread from person to person through the air by coughing or sneezing]. Efforts to improve the knowledge of and attitude towards TB in Nigeria should focus on the youngest age-group (15-19 years), the poorest households, and respondents with no schooling. Improving the knowledge and attitude of these groups of individuals may result in an increase in the number of people who will seek early treatment.

Phase IA/II, multicentre, open-label study of the CD40 antagonistic monoclonal antibody lucatumumab in adult patients with advanced non-Hodgkin or Hodgkin lymphoma

Despite advancements in the treatment of non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL), patients continue to relapse and thus a need for new targeted therapies remains. The CD40 receptor is highly expressed on neoplastic B cells and activation leads to enhanced proliferation and survival. Lucatumumab (HCD122) is a fully human antagonistic CD40 monoclonal antibody. A phase IA/II study was designed to determine the maximum tolerated dose (MTD) and activity of lucatumumab in patients with relapsed/refractory lymphoma. Determination of the MTD was the primary objective of the phase IA dose escalation portion and clinical response was the primary objective of the phase II dose expansion portion. Patients received escalating doses of lucatumumab administered intravenously once weekly for 4 weeks of an 8-week cycle. MTD was determined at 4 mg/kg of lucatumumab. A total of 111 patients with NHL (n = 74) and HL (n = 37) were enrolled. Responses were observed across various lymphoma subtypes. The overall response rate by computed tomography among patients with follicular lymphoma (FL) and marginal zone lymphoma of mucosa-associated lymphatic tissue (MZL/MALT) was 33·3% and 42·9%, respectively. Lucatumumab demonstrates modest activity in relapsed/refractory patients with advanced lymphoma, suggesting that targeting of CD40 warrants further investigation.

A phase 1 study of lucatumumab, a fully human anti-CD40 antagonist monoclonal antibody administered intravenously to patients with relapsed or refractory multiple myeloma

In this open-label, multicentre, phase 1 study a fully human anti-CD40 antagonist monoclonal antibody, lucatumumab, was evaluated in patients with relapsed/refractory multiple myeloma (MM). The primary objective was to determine the maximum tolerated dose (MTD) based on dose-limiting toxicities (DLTs). Secondary objectives included safety, pharmacokinetics, pharmacodynamics and antimyeloma activity. Twenty-eight patients, enrolled using a standard '3 + 3' dose escalation, received one or two (n = 3) cycles of lucatumumab 1·0, 3·0, 4·5 or 6·0 mg/kg once weekly for 4 weeks. Common lucatumumab-related adverse events were reversible, mild-to-moderate infusion reactions. Severe adverse events were anaemia, chills, hypercalcaemia and pyrexia (7% each). DLTs included grade 4 thrombocytopenia, grade 3 increased alanine aminotransferase and grade 4 increased lipase (n = 1 each). The MTD was 4·5 mg/kg. At doses ≥3·0 mg/kg, sustained receptor occupancy (≥87%), observed throughout weekly infusions up to 5 weeks after the last infusion, correlated with an estimated half-life of 4-19 d. Twelve patients (43%) had stable disease, and one patient (4%) maintained a partial response for ≥8 months. These findings indicate that single-agent lucatumumab was well tolerated up to 4·5 mg/kg with modest clinical activity in relapsed/refractory MM, warranting further study as a combination therapy.

Killing of chronic lymphocytic leukemia by the combination of fludarabine and oxaliplatin is dependent on the activity of XPF endonuclease

PURPOSE

Chronic lymphocytic leukemia (CLL) resistant to fludarabine-containing treatments responds to oxaliplatin-based therapy that contains fludarabine. We postulated that a mechanism for this activity is the incorporation of fludarabine into DNA during nucleotide excision repair (NER) stimulated by oxaliplatin adducts.

EXPERIMENTAL DESIGN

We analyzed CLL cell viability, DNA damage, and signaling pathways in response to treatment by fludarabine, oxaliplatin, or the combination. The dependency of the combination on oxaliplatin-induced DNA repair was investigated using siRNA in CLL cells or cell line models of NER deficiency.

RESULTS

Synergistic apoptotic killing was observed in CLL cells after exposure to the combination in vitro. Oxaliplatin induced DNA synthesis in CLL cells, which was inhibited by fludarabine and was eliminated by knockdown of XPF, the NER 5'-endonuclease. Wild-type Chinese hamster ovarian cells showed synergistic killing after combination treatment, whereas only additive killing was observed in cells lacking XPF. Inhibition of repair by fludarabine in CLL cells was accompanied by DNA single-strand break formation. CLL cells initiated both intrinsic and extrinsic apoptotic pathways as evidenced by the loss of mitochondrial outer membrane potential and partial inhibition of cell death upon incubation with FasL antibody.

CONCLUSIONS

The synergistic cell killing is caused by a mechanistic interaction that requires the initiation of XPF-dependent excision repair in response to oxaliplatin adducts, and the inhibition of that process by fludarabine incorporation into the repair patch. This combination strategy may be useful against other malignancies.

Abstract 5379: Mechanism of fludarabine and oxaliplatin combined activity depends on the activity of XPF endonuclease

We set out to determine the mechanism by which fludarabine and oxaliplatin exert more than additive cell killing in chronic lymphocytic leukemia (CLL). We postulate that enhanced activity of oxaliplatin and fludarabine combination is based on termination by fludarabine of DNA re-synthesis associated with nucleotide excision repair (NER) following removal of oxaliplatin adducts. The blocked repair would result in single-strand and double-strand DNA breaks which would activate cell DNA damage signaling and apoptosis. More than additive apoptotic killing was observed in 49% (±22) of CLL cells after exposure to oxaliplatin and fludarabine in vitro, although single agents showed minimal increase in cell death (3% ±9 for oxaliplatin, 13% ±14 for fludarabine), as demonstrated by Annexin V and PI staining at 24 hr (expected vs. observed p=0.0003; n=10). Oxaliplatin induced a 2-fold increase in DNA synthesis in CLL cells, which was inhibited by fludarabine, as determined by thymidine incorporation (n=5). Knockdown of XPF, the NER 5′ endonuclease, in CLL patient samples (n=3) eliminated oxaliplatin induced DNA synthesis (3-fold increase in thymidine incorporation with scramble siRNA compared to 1.4-fold increase with XPF siRNA). Wild type CHO (AA8) cells showed more than additive killing after combination treatment similar to the observation with CLL patient samples (predicted survival 50%; observed 21%). In contrast, only additive killing was observed in CHO cells lacking XPF (UV41) with equitoxic doses of oxaliplatin and fludarabine (predicted survival 56%; observed 54%) suggesting that XPF function is essential for the cooperative interaction of the combination. Alkaline assays demonstrated that inhibition of repair by fludarabine was accompanied by DNA strand break formation within 12 hr (n=4) in CLL patients samples. The increase in Olive tail moment ranged from 2- to 5-fold, confirming induction of single-strand breaks. The double-strand break repair proteins ATM, SMC1, H2AX and DNA-PKcs were phosphorylated as early as 2 hr post-treatment with the combination and persisted up to 24 hr (3-fold, 24-fold, 10-fold and 10-fold increase, respectively; n=4). This response suggests that DNA damage generated by fludarabine and oxaliplatin exposure was processed to double-strand DNA breaks in CLL cells. Our work provides evidence that the combination of oxaliplatin and fludarabine results in the formation of toxic DNA damage and that their combined activity depends on a functional NER pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5379.

ATM and the Mre11-Rad50-Nbs1 complex respond to nucleoside analogue-induced stalled replication forks and contribute to drug resistance

The Mre11-Rad50-Nbs1 complex and autophosphorylated Ser(1981)-ATM are involved in recognizing and repairing DNA damage, such as double-strand breaks (DSB). However, the role of these factors in response to stalled replication forks is not clear. Nucleoside analogues are agents that are incorporated into DNA during replication, which cause stalling of replication forks. The molecular mechanisms that sense these events may signal for DNA repair and contribute to survival but are poorly understood. Cellular responses to both DSBs and stalled replication forks are marked by H2AX phosphorylation on Ser(139) (gamma-H2AX), which forms nuclear foci at sites of DNA damage. Here, concentrations of the nucleoside analogues 1-beta-d-arabinofuranosylcytosine (cytarabine; ara-C), gemcitabine, and troxacitabine, which inhibited DNA synthesis by 90% within 2 hours, were determined for each agent. Using gamma-H2AX as a marker for changes in chromatin structure, we show that Mre11, Rad50, Nbs1, and phosphorylated ATM respond to nucleoside analogue-induced stalled replication forks by forming nuclear foci that colocalize with gamma-H2AX within 2 hours. Because neither DSBs nor single-strand breaks were detectable after nucleoside analogue exposure, we conclude that this molecular response is not due to the presence of DNA breaks. Deficiencies in ATM, Mre11, or Rad50 led to a 2- to 5-fold increase in clonogenic sensitization to gemcitabine, whereas Nbs1 and H2AX deficiency did not affect reproductive growth. Taken together, these results suggest that ATM, Mre11, and Rad50 are required for survival after replication fork stalling, whereas Nbs1 and H2AX are inconsequential.

Pedometer counts superior to physical activity scale for identifying health markers in older adults

OBJECTIVE

Measuring physical activity is a key part of studying its health effects. Questionnaires and pedometers each have weaknesses but are the cheapest and easiest to use measurement methods for large-scale studies. We examined their capacity to detect expected associations between physical activity and a range of surrogate health measures.

DESIGN

Cross-sectional analysis of 669 community-dwelling participants (mean age 63.3 (7.7) years) who completed the Physical Activity Scale for the Elderly (PASE) questionnaire and who, within 2 weeks, wore a pedometer for 7 days.

RESULTS

PASE score and step count were only poorly correlated (r = 0.37 in women, r = 0.30 in men). Of 12 expected associations examined between activity and surrogate markers of health, 10 were detected as statistically significant by step counts but only 3 by PASE scores. Significant associations in the expected direction were found between step counts and high-density lipoprotein, body mass index, waist circumference, waist-to-hip ratio, blood glucose level, white cell count and fibrinogen. There was no association with either systolic or diastolic blood pressure. The association between PASE score and these markers was detected as significant only for body mass index and waist circumference in women and waist-to-hip ratio in both sexes. Associations were stronger for steps multiplied by stride length than for raw step count.

CONCLUSIONS

Pedometer-derived step counts are a more valid measurement of overall physical activity in this sample than PASE score. Researchers should use objective measures of physical activity whenever possible.

H2AX phosphorylation marks gemcitabine-induced stalled replication forks and their collapse upon S-phase checkpoint abrogation

Gemcitabine is a nucleoside analogue that is incorporated into replicating DNA, resulting in partial chain termination and stalling of replication forks. The histone variant H2AX is phosphorylated on Ser(139) (gamma-H2AX) and forms nuclear foci at sites of DNA damage. Here, we characterize the concentration- and time-dependent phosphorylation of H2AX in response to gemcitabine-induced stalled replication forks. The number of gamma-H2AX foci increased with time up to 2 to 6 h after exposure to gemcitabine, whereas longer exposures did not cause greater phosphorylation or increase cell death. The percentage of gamma-H2AX-positive cells increased with concentrations of gemcitabine up to 0.1 micromol/L, and gamma-H2AX was most evident in the S-phase fraction. Phosphorylation of ataxia-telangiectasia mutated (ATM) on Ser(1981) was also associated with S-phase cells and colocalized in the nucleus with phosphorylated H2AX foci after gemcitabine exposure. Chemical inhibition of ATM, ATM- and Rad3-related, and DNA-dependent protein kinase blocked H2AX phosphorylation. H2AX and ATM phosphorylation were associated with inhibition of DNA synthesis, S-phase accumulation, and activation of the S-phase checkpoint pathway (Chk1/Cdc25A/cyclin-dependent kinase 2). Exposure of previously gemcitabine-treated cultures to the Chk1 inhibitor 7-hydroxystaurosporine (UCN-01) caused a 10-fold increase in H2AX phosphorylation, which was displayed as an even pan-nuclear staining. This increased phosphorylation was not due to apoptosis-induced DNA fragmentation and was associated with the S-phase fraction and decreased reproductive viability. Thus, H2AX becomes phosphorylated and forms nuclear foci in response to gemcitabine-induced stalled replication forks, and this is greatly increased upon checkpoint abrogation.

Incidence of surgical site infections and accompanying risk factors in Vietnamese orthopaedic patients

A cohort study of surgical site infections (SSIs) was conducted in 582 orthopaedic surgical patients at Cho Ray Hospital, a reference hospital in Ho Chi Minh City, Vietnam, in order to determine the incidence and analyse risk factors for SSIs in this population. The SSI incidence rate was 12.5% (73 of 582); 3.6% incisional SSIs, 6.8% deep incisional SSIs and 2.1% organ/space SSIs. The incidence increased from 2% in clean wounds to 44.6% in dirty wounds, or 1.3% in patients with a National Nosocomial Infections Surveillance (NNIS) risk index of 0 to 75% in patients with an NNIS risk ratio of 3. In multi-variate analysis, having a dirty wound [odds ratio (OR) 8.7; 95% confidence intervals (CI) 4.6--16.4], American Society of Anesthesiologists' score >2 (OR 3.9; 95%CI 1.8-8.8), procedures with external fixation (OR 2.9; 95%CI 1.4-5.9), emergency surgery with motor-vehicle-related trauma (OR 2.1; 95%CI 1.2-3.9), or duration of procedure >2h (OR 2.1; 95%CI 1.1-4.2) were independent risk factors for SSI. Lack of appropriate prophylaxis was of borderline significance (OR 3.2; 95%CI 0.9-11.1, P=0.06). Among 76 patients with SSIs, 22 patients were discovered during postdischarge follow-up. These late SSIs had age as an additional risk factor (OR 2.8; 95%CI 1.1-7.2). Our data show that SSIs were frequent and differed widely by wound class. The NNIS risk index was predictive of SSI for this population. With a high number of motor vehicle accidents in Vietnam, the majority of orthopaedic operations are trauma related. Emergency surgery for injuries sustained in these accidents, and procedures with external fixation were especially prone to infections.

Refinement of the crystal structure of diniobium trisoxydisulfate hydrate, Nb2O3(SO4)2 · 0.25H2O

H0.5Nb2O11.25S2, trigonal, R3̅ (no. 148), a = 10.378(2) Å, c = 26.540(5) Å, V = 2475.7 Å3, Z = 24, Rgt(F) = 0.031, wRref(F2) = 0.072, T = 295 K.

Crystal structure of discandium tris-monohydrogenphosphate(III), Sc2(HPO3)3

H3O9P3Sc2, hexagonal, P63/m (No. 176), a = 8.3055(7) Å, c = 7.697(1) Å, V = 459.8 Å3, Z = 2, Rgt(F) = 0.028, wRref(F2) = 0.061, T = 293 K.

Genotypes of the vitamin-D-receptor gene and bone mineral density in Caucasoid postmenopausal females

OBJECTIVE

To evaluate the relation of bone mineral density (BMD) to inherited polymorphisms within the gene coding for the vitamin D receptor (VDR) in postmenopausal women.

METHODS

DNA samples from 163 post-menopausal women and from 112 controls were genotyped for common allelic determinants within the VDR gene as defined by the restriction enzyme sites for BsmI, ApaI, and TaqI. BMD was evaluated at the lumbar spine (L2-L4) by dual energy X-ray absorptiometry. Single restriction enzyme site polymorphisms as well as their joint genotypes were evaluated for their association with BMD in postmenopausal women.

RESULTS

The three restriction site polymorphisms showed a close association indicating linkage disequilibrium (P < 0.0001). There was no relationship between any of the single restriction site polymorphisms and BMD. The distribution of the five most common joint genotypes among postmenopausal women and controls was similar. There was no relation of BMD and any of the five most common VDR genotype groups. Females more than 5 years after menopause had a significantly lower BMD than those less than 5 years after menopause (P < 0.001). This age-related decrease of BMD was also decernible within genotype groups.

CONCLUSION

In our population, the postmenopausal period has a major influence on BMD, but BMD is not controlled significantly by any of the common allelic variations within the VDR gene.