Mediation of antitumor activity by AZD4820 oncolytic vaccinia virus encoding IL-12.

Oncolytic viruses are engineered to selectively kill tumor cells and have demonstrated promising results in early-phase clinical trials. To further modulate the innate and adaptive immune system, we generated AZD4820, a vaccinia virus engineered to express interleukin-12 (IL-12), a potent cytokine involved in the activation of natural killer (NK) and T cells and the reprogramming of the tumor immune microenvironment. Testing in cultured human tumor cell lines demonstrated broad in vitro oncolytic activity and IL-12 transgene expression. A surrogate virus expressing murine IL-12 demonstrated antitumor activity in both MC38 and CT26 mouse syngeneic tumor models that responded poorly to immune checkpoint inhibition. In both models, AZD4820 significantly upregulated interferon-gamma (IFN-γ) relative to control mice treated with oncolytic vaccinia virus (VACV)-luciferase. In the CT26 study, 6 of 10 mice had a complete response after treatment with AZD4820 murine surrogate, whereas control VACV-luciferase-treated mice had 0 of 10 complete responders. AZD4820 treatment combined with anti-PD-L1 blocking antibody augmented tumor-specific T cell immunity relative to monotherapies. These findings suggest that vaccinia virus delivery of IL-12, combined with immune checkpoint blockade, elicits antitumor immunity in tumors that respond poorly to immune checkpoint inhibitors.

Trajectory Inspection: A Method for Iterative Clinician-Driven Design of Reinforcement Learning Studies.

Reinforcement learning (RL) has the potential to significantly improve clinical decision making. However, treatment policies learned via RL from observational data are sensitive to subtle choices in study design. We highlight a simple approach, trajectory inspection, to bring clinicians into an iterative design process for model-based RL studies. We identify where the model recommends unexpectedly aggressive treatments or expects surprisingly positive outcomes from its recommendations. Then, we examine clinical trajectories simulated with the learned model and policy alongside the actual hospital course. Applying this approach to recent work on RL for sepsis management, we uncover a model bias towards discharge, a preference for high vasopressor doses that may be linked to small sample sizes, and clinically implausible expectations of discharge without weaning off vasopressors. We hope that iterations of detecting and addressing the issues unearthed by our method will result in RL policies that inspire more confidence in deployment.

Resistance to Durvalumab and Durvalumab plus Tremelimumab Is Associated with Functional STK11 Mutations in Patients with Non-Small Cell Lung Cancer and Is Reversed by STAT3 Knockdown.

Mutations in the STK11 (LKB1) gene regulate resistance to PD-1/PD-L1 blockade. This study evaluated this association in patients with nonsquamous non-small cell lung cancer (NSCLC) enrolled in three phase I/II trials. STK11 mutations were associated with resistance to the anti-PD-L1 antibody durvalumab (alone/with the anti-CTLA4 antibody tremelimumab) independently of KRAS mutational status, highlighting STK11 as a potential driver of resistance to checkpoint blockade. Retrospective assessments of tumor tissue, whole blood, and serum revealed a unique immune phenotype in patients with STK11 mutations, with increased expression of markers associated with neutrophils (i.e., CXCL2, IL6), Th17 contexture (i.e., IL17A), and immune checkpoints. Associated changes were observed in the periphery. Reduction of STAT3 in the tumor microenvironment using an antisense oligonucleotide reversed immunotherapy resistance in preclinical STK11 knockout models. These results suggest that STK11 mutations may hinder response to checkpoint blockade through mechanisms including suppressive myeloid cell biology, which could be reversed by STAT3-targeted therapy. SIGNIFICANCE: Patients with nonsquamous STK11-mutant (STK11mut) NSCLC are less likely than STK11 wild-type (STK11wt) patients to respond to anti-PD-L1 ± anti-CTLA4 immunotherapies, and their tumors show increased expression of genes and cytokines that activate STAT3 signaling. Preclinically, STAT3 modulation reverses this resistance, suggesting STAT3-targeted agents as potential combination partners for immunotherapies in STK11mut NSCLC.This article is highlighted in the In This Issue feature, p. 2659.

Distinct Biomarker Profiles and TCR Sequence Diversity Characterize the Response to PD-L1 Blockade in a Mouse Melanoma Model.

Only a subset of patients responds to immune checkpoint blockade (ICB) in melanoma. A preclinical model recapitulating the clinical activity of ICB would provide a valuable platform for mechanistic studies. We used melanoma tumors arising from an Hgftg;Cdk4R24C/R24C genetically engineered mouse (GEM) model to evaluate the efficacy of an anti-mouse PD-L1 antibody similar to the anti-human PD-L1 antibodies durvalumab and atezolizumab. Consistent with clinical observations for ICB in melanoma, anti-PD-L1 treatment elicited complete and durable response in a subset of melanoma-bearing mice. We also observed tumor growth delay or regression followed by recurrence. For early treatment assessment, we analyzed gene expression profiles, T-cell infiltration, and T-cell receptor (TCR) signatures in regressing tumors compared with tumors exhibiting no response to anti-PD-L1 treatment. We found that CD8+ T-cell tumor infiltration corresponded to response to treatment, and that anti-PD-L1 gene signature response indicated an increase in antigen processing and presentation, cytokine-cytokine receptor interaction, and natural killer cell-mediated cytotoxicity. TCR sequence data suggest that an anti-PD-L1-mediated melanoma regression response requires not only an expansion of the TCR repertoire that is unique to individual mice, but also tumor access to the appropriate TCRs. Thus, this melanoma model recapitulated the variable response to ICB observed in patients and exhibited biomarkers that differentiate between early response and resistance to treatment, providing a valuable platform for prediction of successful immunotherapy. IMPLICATIONS: Our melanoma model recapitulates the variable response to anti-PD-L1 observed in patients and exhibits biomarkers that characterize early antibody response, including expansion of the TCR repertoire.

HER2-targeted antibody-drug conjugate induces host immunity against cancer stem cells.

We previously tested HER2-targeted antibody-drug conjugates (ADCs) in immunocompromised (SCID) mice, precluding evaluation of host immunity, impact on cancer stem cells (CSCs), and potential benefit when combined with PD-L1 blockade. In this study, we tested HER2-targeted ADC in two immunocompetent mouse tumor models. HER2-targeted ADC specifically inhibited the growth of HER2-expressing tumors, prolonged animal survival, and reduced HER2+ and PD-L1+ cells. ADC + anti-PD-L1 antibody augmented therapeutic efficacy, modulated immune gene signatures, increased the number and function of CD3+ and CD19+ tumor-infiltrating lymphocytes (TILs), induced tumor antigen-specific immunological memory, stimulated B cell activation, differentiation, and IgG1 production both systemically and in the tumor microenvironment. In addition, ADC therapy modulated T cell subsets and their activation in TILs. Furthermore, HER2-targeted ADC reduced the number and tumorigenicity of ALDHhi CSCs. This study demonstrates that HER2-targeted ADC effectively targets ALDHhi CSCs and this effect is augmented by co-administration of anti-PD-L1 antibody.

[Effect of a mobile room air filter on the aerosol burden in surgical examination rooms against the background of the COVID-19 pandemic]. / Effekt eines mobilen Raumluftfilters auf die Aerosolbelastung in chirurgischen Untersuchungsräumen vor dem Hintergrund der COVID-19-Pandemie.

Due to the airborne transmission of the coronavirus disease 2019 (COVID 19) via aerosols or microdroplets, this study investigated the effect of a mobile air filter system in a surgical examination room. The use of the air filter system led to a significant reduction of aerosols in the room. Therefore the use of a high efficiency air filtration device, in examination rooms with poor ventilation, e.g. lack of windows or local exhaust, is mandatory.

Activity of murine surrogate antibodies for durvalumab and tremelimumab lacking effector function and the ability to deplete regulatory T cells in mouse models of cancer.

Preclinical studies of PD-L1 and CTLA-4 blockade have relied heavily on mouse syngeneic tumor models with intact immune systems, which facilitate dissection of immunosuppressive mechanisms in the tumor microenvironment. Commercially developed monoclonal antibodies (mAbs) targeting human PD-L1, PD-1, and CTLA-4 may not demonstrate cross-reactive binding to their mouse orthologs, and surrogate anti-mouse antibodies are often used in their place to inhibit these immune checkpoints. In each case, multiple choices exist for surrogate antibodies, which differ with respect to species of origin, affinity, and effector function. To develop relevant murine surrogate antibodies for the anti-human PD-L1 mAb durvalumab and the anti-human CTLA-4 mAb tremelimumab, rat/mouse chimeric or fully murine mAbs engineered for reduced effector function were developed and compared with durvalumab and tremelimumab. Characterization included determination of target affinity, in vivo effector function, pharmacokinetic profile, and anti-tumor efficacy in mouse syngeneic tumor models. Results showed that anti-PD-L1 and anti-CTLA-4 murine surrogates with pharmacologic properties similar to those of durvalumab and tremelimumab demonstrated anti-tumor activity in a subset of commonly used mouse syngeneic tumor models. This activity was not entirely dependent on antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis effector function, or regulatory T-cell depletion, as antibodies engineered to lack these features showed activity in models historically sensitive to checkpoint inhibition, albeit at a significantly lower level than antibodies with intact effector function.

A decision algorithm to promote outpatient antimicrobial stewardship for uncomplicated urinary tract infection.

Antibiotic resistance is a major cause of treatment failure and leads to increased use of broad-spectrum agents, which begets further resistance. This vicious cycle is epitomized by uncomplicated urinary tract infection (UTI), which affects one in two women during their life and is associated with increasing antibiotic resistance and high rates of prescription for broad-spectrum second-line agents. To address this, we developed machine learning models to predict antibiotic susceptibility using electronic health record data and built a decision algorithm for recommending the narrowest possible antibiotic to which a specimen is susceptible. When applied to a test cohort of 3629 patients presenting between 2014 and 2016, the algorithm achieved a 67% reduction in the use of second-line antibiotics relative to clinicians. At the same time, it reduced inappropriate antibiotic therapy, defined as the choice of a treatment to which a specimen is resistant, by 18% relative to clinicians. For specimens where clinicians chose a second-line drug but the algorithm chose a first-line drug, 92% (1066 of 1157) of decisions ended up being susceptible to the first-line drug. When clinicians chose an inappropriate first-line drug, the algorithm chose an appropriate first-line drug 47% (183 of 392) of the time. Our machine learning decision algorithm provides antibiotic stewardship for a common infectious syndrome by maximizing reductions in broad-spectrum antibiotic use while maintaining optimal treatment outcomes. Further work is necessary to improve generalizability by training models in more diverse populations.

Predicting human health from biofluid-based metabolomics using machine learning.

Biofluid-based metabolomics has the potential to provide highly accurate, minimally invasive diagnostics. Metabolomics studies using mass spectrometry typically reduce the high-dimensional data to only a small number of statistically significant features, that are often chemically identified-where each feature corresponds to a mass-to-charge ratio, retention time, and intensity. This practice may remove a substantial amount of predictive signal. To test the utility of the complete feature set, we train machine learning models for health state-prediction in 35 human metabolomics studies, representing 148 individual data sets. Models trained with all features outperform those using only significant features and frequently provide high predictive performance across nine health state categories, despite disparate experimental and disease contexts. Using only non-significant features it is still often possible to train models and achieve high predictive performance, suggesting useful predictive signal. This work highlights the potential for health state diagnostics using all metabolomics features with data-driven analysis.

Anti-PD-1 monoclonal antibody MEDI0680 in a phase I study of patients with advanced solid malignancies.

BACKGROUND: The safety, efficacy, pharmacokinetics, and pharmacodynamics of the anti-programmed cell death-1 antibody MEDI0680 were evaluated in a phase I, multicenter, dose-escalation study in advanced solid malignancies. METHODS: MEDI0680 was administered intravenously once every 2 weeks (Q2W) or once every 3 weeks at 0.1, 0.5, 2.5, 10 or 20 mg/kg. Two cohorts received 20 mg/kg once a week for 2 or 4 weeks, then 20 mg/kg Q2W. All were treated for 12 months or until progression. The primary endpoint was safety. Secondary endpoints were efficacy and pharmacokinetics. Exploratory endpoints included pharmacodynamics. RESULTS: Fifty-eight patients were treated. Median age was 62.5 years and 81% were male. Most had kidney cancer (n = 36) or melanoma (n = 9). There were no dose-limiting toxicities. Treatment-related adverse events occurred in 83% and were grade ≥ 3 in 21%. Objective clinical responses occurred in 8/58 patients (14%): 5 with kidney cancer, including 1 with a complete response, and 3 with melanoma. The relationship between dose and serum levels was predictable and linear, with apparent receptor saturation at 10 mg/kg Q2W and all 20 mg/kg cohorts. CONCLUSIONS: MEDI0680 induced peripheral T-cell proliferation and increased plasma IFNγ and associated chemokines regardless of clinical response. CD8+ T-cell tumor infiltration and tumoral gene expression of IFNG, CD8A, CXCL9, and granzyme K (GZMK) were also increased following MEDI0680 administration. TRIAL REGISTRATION: NCT02013804 ; date of registration December 12, 2013.

Potent Immune Modulation by MEDI6383, an Engineered Human OX40 Ligand IgG4P Fc Fusion Protein.

Ligation of OX40 (CD134, TNFRSF4) on activated T cells by its natural ligand (OX40L, CD252, TNFSF4) enhances cellular survival, proliferation, and effector functions such as cytokine release and cellular cytotoxicity. We engineered a recombinant human OX40L IgG4P Fc fusion protein termed MEDI6383 that assembles into a hexameric structure and exerts potent agonist activity following engagement of OX40. MEDI6383 displayed solution-phase agonist activity that was enhanced when the fusion protein was clustered by Fc gamma receptors (FcγRs) on the surface of adjacent cells. The resulting costimulation of OX40 on T cells induced NFκB promoter activity in OX40-expressing T cells and induced Th1-type cytokine production, proliferation, and resistance to regulatory T cell (Treg)-mediated suppression. MEDI6383 enhanced the cytolytic activity of tumor-reactive T cells and reduced tumor growth in the context of an alloreactive human T cell:tumor cell admix model in immunocompromised mice. Consistent with the role of OX40 costimulation in the expansion of memory T cells, MEDI6383 administered to healthy nonhuman primates elicited peripheral blood CD4 and CD8 central and effector memory T-cell proliferation as well as B-cell proliferation. Together, these results suggest that OX40 agonism has the potential to enhance antitumor immunity in human malignancies. Mol Cancer Ther; 17(5); 1024-38. ©2018 AACR.

MEDI1873, a potent, stabilized hexameric agonist of human GITR with regulatory T-cell targeting potential.

Glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) is part of a system of signals involved in controlling T-cell activation. Targeting and agonizing GITR in mice promotes antitumor immunity by enhancing the function of effector T cells and inhibiting regulatory T cells. Here, we describe MEDI1873, a novel hexameric human GITR agonist comprising an IgG1 Fc domain, a coronin 1A trimerization domain and the human GITRL extracellular domain (ECD). MEDI1873 was optimized through systematic testing of different trimerization domains, aglycosylation of the GITRL ECD and comparison of different Fc isotypes. MEDI1873 exhibits oligomeric heterogeneity and superiority to an anti-GITR antibody with respect to evoking robust GITR agonism, T-cell activation and clustering of Fc gamma receptors. Further, it recapitulates, in vitro, several aspects of GITR targeting described in mice, including modulation of regulatory T-cell suppression and the ability to increase the CD8+:CD4+ T-cell ratio via antibody-dependent T-cell cytotoxicity. To support translation into a therapeutic setting, we demonstrate that MEDI1873 is a potent T-cell agonist in vivo in non-human primates, inducing marked enhancement of humoral and T-cell proliferative responses against protein antigen, and demonstrate the presence of GITR- and FoxP3-expressing infiltrating lymphocytes in a range of human tumors. Overall our data provide compelling evidence that MEDI1873 is a novel, potent GITR agonist with the ability to modulate T-cell responses, and suggest that previously described GITR biology in mice may translate to the human setting, reinforcing the potential of targeting the GITR pathway as a therapeutic approach to cancer.

A Novel Murine GITR Ligand Fusion Protein Induces Antitumor Activity as a Monotherapy That Is Further Enhanced in Combination with an OX40 Agonist.

Purpose: To generate and characterize a murine GITR ligand fusion protein (mGITRL-FP) designed to maximize valency and the potential to agonize the GITR receptor for cancer immunotherapy.Experimental Design: The EC50 value of the mGITRL-FP was compared with an anti-GITR antibody in an in vitro agonistic cell-based reporter assay. We assessed the impact of dose, schedule, and Fc isotype on antitumor activity and T-cell modulation in the CT26 tumor model. The activity of the mGITRL-FP was compared with an agonistic murine OX40L-FP targeting OX40, in CT26 and B16F10-Luc2 tumor models. Combination of the mGITRL-FP with antibodies targeting PD-L1, PD-1, or CTLA-4 was analyzed in mice bearing CT26 tumors.Results: The mGITRL-FP had an almost 50-fold higher EC50 value compared with an anti-murine GITR antibody. Treatment of CT26 tumor-bearing mice with mGITRL-FP-mediated significant antitumor activity that was dependent on isotype, dose, and duration of exposure. The antitumor activity could be correlated with the increased proliferation of peripheral CD8+ and CD4+ T cells and a significant decrease in the frequency of intratumoral Tregs. The combination of mGITRL-FP with mOX40L-FP or checkpoint inhibitor antagonists enhanced antitumor immunity above that of monotherapy treatment.Conclusions: These results suggest that therapeutically targeting GITR represents a unique approach to cancer immunotherapy and suggests that a multimeric fusion protein may provide increased agonistic potential versus an antibody. In addition, these data provide, for the first time, early proof of concept for the potential combination of GITR targeting agents with OX40 agonists and PD-L1 antagonists. Clin Cancer Res; 23(13); 3416-27. ©2017 AACR.

DACT2 silencing by promoter CpG methylation disrupts its regulation of epithelial-to-mesenchymal transition and cytoskeleton reorganization in breast cancer cells.

Wnt signaling plays an important role in breast carcinogenesis. DAPPER2 (DACT2) functions as an inhibitor of canonical Wnt signaling and plays distinct roles in different cell contexts, with its role in breast tumorigenesis unclear. We investigated DACT2 expression in breast cancer cell lines and primary tumors, as well as its functions and molecular mechanisms. Results showed that DACT2 expression was silenced in 9/9 of cell lines. Promoter CpG methylation of DACT2 was detected in 89% (8/9) of cell lines, as well as in 73% (107/147) of primary tumors, but only in 20% (1/5) of surgical margin tissues and in none of normal breast tissues. Demethylation of BT549 and T47D cell lines with 5-aza-2'-deoxycytidine restored DACT2 expression along with promoter demethylation, suggesting that its downregulation in breast cancer is dependent on promoter methylation. Furthermore, ectopic expression of DACT2 induced breast cell apoptosis in vitro, and further inhibited breast tumor cell proliferation, migration and EMT, through antagonizing Wnt/ß-catenin and Akt/GSK-3 signaling. Thus, these results demonstrate that DACT2 functions as a tumor suppressor for breast cancer but was frequently disrupted epigenetically in this cancer.

CEA/CD3 bispecific antibody MEDI-565/AMG 211 activation of T cells and subsequent killing of human tumors is independent of mutations commonly found in colorectal adenocarcinomas.

Individual or combinations of somatic mutations found in genes from colorectal cancers can redirect the effects of chemotherapy and targeted agents on cancer cell survival and, consequently, on clinical outcome. Novel therapeutics with mechanisms of action that are independent of mutational status would therefore fulfill a current unmet clinical need. Here the CEA and CD3 bispecific single-chain antibody MEDI-565 (also known as MT111 and AMG 211) was evaluated for its ability to activate T cells both in vitro and in vivo and to kill human tumor cell lines harboring various somatic mutations commonly found in colorectal cancers. MEDI-565 specifically bound to normal and malignant tissues in a CEA-specific manner, and only killed CEA positive cells. The BiTE® antibody construct mediated T cell-directed killing of CEA positive tumor cells within 6 hours, at low effector-to-target ratios which were independent of high concentrations of soluble CEA. The potency of in vitro lysis was dependent on CEA antigen density but independent of the mutational status in cancer cell lines. Importantly, individual or combinations of mutated KRAS and BRAF oncogenes, activating PI3KCA mutations, loss of PTEN expression, and loss-of-function mutations in TP53 did not reduce the activity in vitro. MEDI-565 also prevented growth of human xenograft tumors which harbored various mutations. These findings suggest that MEDI-565 represents a potential treatment option for patients with CEA positive tumors of diverse origin, including those with individual or combinations of somatic mutations that may be less responsive to chemotherapy and other targeted agents.

Novel endoscopic sacroiliac screw removal technique: reduction of intraoperative radiation exposure.

OBJECTIVE: We report in the following on our technique of endoscopic sacroiliacal screw removal as a new extra-articular endoscopic method in soft tissue surgery, aimed at the reduction of radiation exposure for both the patient and the surgical teams. Patients who underwent endoscopic implant removal from the dorsal pelvic ring (Group A) were retrospectively compared with a control group, in which the screws were removed via the conventional approach (Group B). The parameters of interest were the extent of x-ray exposure in seconds and surgical duration in minutes as well as approach related peri- and postoperative complications. RESULTS: 34 screws were removed endoscopically from 28 patients in group A and 35 screws from 29 patients in group B. The mean skin-to-skin time in group A was 36.1 (15-111) min and 32.7 (12-114) min in group B. The difference was not statistically significant (p > 0.05). The average radiation time in group A was 5.7 ± 3.2 s (range, 0-101 s), while in group B the radiation time was significantly longer (52.6 ± 23 s (range, 0-239 s); p = 0.005). CONCLUSIONS: Endoscopic screw removal from the posterior pelvic ring reduces the intraoperative radiation time whereas the skin-to-skin times do not differ from the conventional procedure. LEVEL OF EVIDENCE: Case-control study, Level III.

Periprosthetic joint infection--effect on quality of life.

PURPOSE: Relatively little is known about the extent to which periprosthetic joint infections (PJI) affect the patient's long-term quality of life (QoL). Our study aim was to assess the effect of a periprosthetic infection on our patients' QoL. METHODS: We collected data retrospectively of patients who had undergone surgery in our institution between 2006 and 2011. To capture their overall QoL, we telephoned the patients who could be reached and asked them the questions on the SF-12 questionnaire. RESULTS: In 84 patients (53 male, 31 female, 43 TKA and 41 THA), 88 % of the hip infections and 62 % of the knee infections had been successfully treated. The hip infections' cure rate was significantly higher than that of the knee joint infections. The average SF-12 score was 36.2 points on the physical scale and 52 on the mental scale. The difference in QoL between patients with and without successful infection therapy was not significant, nor did the site of the infection (knee or hip) influence QoL significantly. Comparison of our patients' QoL data to that from the general population revealed a significant difference in the physical scale but not the mental scale. CONCLUSION: From these results QoL is substantially reduced after a prosthetic infection. We did however observe that post-Girdelstone procedure patients or those with an arthrodesis attained an acceptable QoL, and that those methods remain therapeutic alternatives as far as patient-perceived QoL is concerned.

Effect of 2 different thoracolumbar orthoses on the stability of the spine during various body movements.

STUDY DESIGN: Biomechanical volunteer study. OBJECTIVE: To quantify the stabilizing effect of 2 different semirigid thoracolumbar orthoses during various body movements. SUMMARY OF BACKGROUND DATA: Various spinal diseases need to be treated by immobilization. The literature shows, that the immobilizing effect of orthoses strongly depends on the orthosis design and on the loading direction. Few data are available for loading directions other than flexion and extension. METHODS: Ten young and healthy volunteers (22-44 yr, 5 male, 5 female) performed 4 different tasks: full active flexion/extension, lateral bending, and axial rotation as well as a full active everyday movement (flexion plus lateral bending plus axial rotation). These tasks were carried out without orthosis, with the DorsoFX (BORT GmbH, Weinstadt-Benzach, Germany) and with the SofTec Dorso orthosis (Bauerfeind AG, Zeulenroda-Triebes, Germany). The flexibility of the spine was measured using a 3-dimensional motion capturing system (Zebris Medical GmbH, Isny, Germany). Additionally, the pressure exerted by the orthoses on the subject's body surface was measured using a pressure sensor (Tekscan Inc., South Boston, MA). RESULTS: The range of motion significantly decreased in all loading planes by 42% to 69%. The movement with the largest decrease was axial rotation and the smallest decreases were observed in extension (DorsoFX), flexion and the everyday movement (SofTec Dorso), respectively. The differences between the 2 orthoses were small and not statistically significant. The pressure between orthosis and the body surface was similar for both orthoses but differed between the movements. CONCLUSION: Both orthoses had a similar stabilizing effect on the thoracolumbar spine. The stabilizing effect differed between the 4 movements, which indicates that all loading planes should be tested to understand the effect of an orthosis completely. Complete immobilization of the thoracolumbar spine was not possible with either of the 2 orthoses, but the stability increase was statistically significant. LEVEL OF EVIDENCE: N/A.

DACT1, an antagonist to Wnt/ß-catenin signaling, suppresses tumor cell growth and is frequently silenced in breast cancer.

INTRODUCTION: Aberrant activation of Wnt/ß-catenin signaling plays an important role in the pathogenesis of breast cancer. DACT1 (Dapper/Frodo) has been identified as involved in antagonizing Wnt/ß-catenin signaling through interacting with Dishevelled (Dvl), a central mediator of Wnt signaling, whereas its role in breast tumorigenesis remains unclear. METHODS: We examined DACT1 expression in breast cancer cell lines and primary tumors with semiquantitative or quantitative RT-PCR and immunochemistry, and further evaluated the promoter methylation of DACT1 with methylation-specific PCR (MSP). We also explored the tumor-suppressive functions of DACT1 in vivo and in vitro, and its related mechanism in breast cancer. RESULTS: We identified DACT1 as a methylated target in our breast cancer epigenome study. Here, we further investigated DACT1 expression in multiple breast cell lines and primary tumors, and further studied its function and molecular mechanisms. We found that DACT1 expression was silenced in eight (88.9%) of nine breast cancer cell lines, and its protein levels were obviously reduced in breast tumors compared with paired surgical-margin tissues. Promoter CpG methylation of DACT1 was detected in five (55.6%) of nine breast cancer cell lines and 40 (29.9%) of 134 primary tumors, but not in surgical-margin tissues and normal breast tissues. Demethylation treatment of breast cancer cell lines restored DACT1 expression along with promoter demethylation, suggesting that an epigenetic mechanism mediates DACT1 silencing in breast cancer. Functional assays showed that ectopic expression of DACT1 could inhibit breast tumor cell proliferation in vivo and in vitro through inducing apoptosis, and further suppress tumor cell migration through antagonizing the Wnt/ß-catenin signaling pathway. CONCLUSIONS: Our study demonstrates that DACT1 could function as a tumor suppressor but was frequently downregulated in breast cancer.

Effects of three-dimensional navigation on intraoperative management and early postoperative outcome after open reduction and internal fixation of displaced acetabular fractures.

BACKGROUND: This study was conducted to evaluate whether intraoperative procedure and/or early postoperative results after open reduction and internal fixation (ORIF) of displaced acetabulum fractures are influenced by the use of a three-dimensional (3D) image intensifier in combination with a navigation system. METHODS: From January 2004 until December 2008, all patients with acetabular fractures were followed prospectively. From January 2004 until October 2006, all operations were performed under fluoroscopic control using a conventional two-dimensional image intensifier. Since October 2006, we regularly operate acetabular fractures with the intraoperative use of a navigation system and a 3D image intensifier. Pre- and postoperative computed tomography scans of the affected hip were obtained in all patients as were standard anterior-posterior radiographs and ala- and obturator views. All data collection was performed according to the guidelines of the "German Pelvic fracture study group." RESULTS: In total, 68 patients with acetabular fractures were included in the study. A conventional image intensifier was used in 37 patients (group A) and a 3D image-based navigation was used in the remaining 31 patients (group B). In the navigated group, seven patients were assessed incapable of partial weight bearing. These patients underwent computer-assisted percutaneous screwing of their acetabular fracture. Using a navigation system in combination with a 3D image intensifier for ORIF of displaced acetabular fractures led to a significant increase in skin-to-skin time. Postoperative radiolographic analysis revealed an improvement in the quality of fracture reduction in the 3D navigation group. Navigation in combination with the 3D images of the ISO-C 3D limited the need for extended approaches. In addition, the complication rate in the navigated group was significantly lower. CONCLUSION: We support the use of navigation systems and a 3D image intensifier as helpful tools during ORIF of displaced acetabular fractures. LEVEL OF EVIDENCE: Therapeutic study, level III.