In silico assessment of histotripsy-induced changes in catheter-directed thrombolytic delivery

Introduction: For venous thrombosis patients, catheter-directed thrombolytic therapy is the standard-of-care to recanalize the occluded vessel. Limitations with thrombolytic drugs make the development of adjuvant treatments an active area of research. One potential adjuvant is histotripsy, a focused ultrasound therapy that lyses red blood cells within thrombus via the spontaneous generation of bubbles. Histotripsy has also been shown to improve the efficacy of thrombolytic drugs, though the precise mechanism of enhancement has not been elucidated. In this study, in silico calculations were performed to determine the contribution of histotripsy-induced changes in thrombus diffusivity to alter catheter-directed therapy.Methods: An established and validated Monte Carlo calculation was used to predict the extent of histotripsy bubble activity. The distribution of thrombolytic drug was computed with a finite-difference time domain (FDTD) solution of the perfusion-diffusion equation. The FDTD calculation included changes in thrombus diffusivity based on outcomes of the Monte Carlo calculation. Fibrin degradation was determined using the known reaction rate of thrombolytic drug.Results: In the absence of histotripsy, thrombolytic delivery was restricted in close proximity to the catheter. Thrombolytic perfused throughout the focal region for calculations that included the effects of histotripsy, resulting in an increased degree of fibrinolysis.Discussion: These results were consistent with the outcomes of in vitro studies, suggesting histotripsy-induced changes in the thrombus diffusivity are a primary mechanism for enhancement of thrombolytic drugs

Initial experience with an electron FLASH research extension (FLEX) for the Clinac system

Purpose: Radiotherapy delivered at ultra-high-dose-rates (≥40 Gy/s), that is, FLASH, has the potential to effectively widen the therapeutic window and considerably improve the care of cancer patients. The underlying mechanism of the FLASH effect is not well understood, and commercial systems capable of delivering such dose rates are scarce. The purpose of this study was to perform the initial acceptance and commissioning tests of an electron FLASH research product for preclinical studies. Methods: A linear accelerator (Clinac 23EX) was modified to include a nonclinical FLASH research extension (the Clinac-FLEX system) by Varian, a Siemens Healthineers company (Palo Alto, CA) capable of delivering a 16 MeV electron beam with FLASH and conventional dose rates. The acceptance, commissioning, and dosimetric characterization of the FLEX system was performed using radiochromic film, optically stimulated luminescent dosimeters, and a plane-parallel ionization chamber. A radiation survey was conducted for which the shielding of the pre-existing vault was deemed sufficient. Results: The Clinac-FLEX system is capable of delivering a 16 MeV electron FLASH beam of approximately 1 Gy/pulse at isocenter and reached amaximum dose rate \u3e3.8 Gy/pulse near the upper accessory mount on the linac gantry. The percent depth dose curves of the 16 MeV FLASH and conventional modes for the 10 × 10 cm2 applicator agreed within 0.5 mm at a range of 50% of the maximum dose. Their respective profiles agreed well in terms of flatness but deviated for field sizes \u3e10 × 10 cm2. The output stability of the FLASH system exhibited a dose deviation of \u3c1%.Preliminary cell studies showed that the FLASH dose rate (180 Gy/s) had much less impact on the cell morphology of 76N breast normal cells compared to the non-FLASH dose rate (18 Gy/s), which induced large-size cells. Conclusion: Our studies characterized the non-clinical Clinac-FLEX system as a viable solution to conduct FLASH research that could substantially increase access to ultra-high-dose-rate capabilities for scientists

Development and Validation of the Gene Expression Predictor of High-grade Serous Ovarian Carcinoma Molecular SubTYPE (PrOTYPE).

PURPOSE: Gene expression-based molecular subtypes of high-grade serous tubo-ovarian cancer (HGSOC), demonstrated across multiple studies, may provide improved stratification for molecularly targeted trials. However, evaluation of clinical utility has been hindered by nonstandardized methods, which are not applicable in a clinical setting. We sought to generate a clinical grade minimal gene set assay for classification of individual tumor specimens into HGSOC subtypes and confirm previously reported subtype-associated features. EXPERIMENTAL DESIGN: Adopting two independent approaches, we derived and internally validated algorithms for subtype prediction using published gene expression data from 1,650 tumors. We applied resulting models to NanoString data on 3,829 HGSOCs from the Ovarian Tumor Tissue Analysis consortium. We further developed, confirmed, and validated a reduced, minimal gene set predictor, with methods suitable for a single-patient setting. RESULTS: Gene expression data were used to derive the predictor of high-grade serous ovarian carcinoma molecular subtype (PrOTYPE) assay. We established a de facto standard as a consensus of two parallel approaches. PrOTYPE subtypes are significantly associated with age, stage, residual disease, tumor-infiltrating lymphocytes, and outcome. The locked-down clinical grade PrOTYPE test includes a model with 55 genes that predicted gene expression subtype with >95% accuracy that was maintained in all analytic and biological validations. CONCLUSIONS: We validated the PrOTYPE assay following the Institute of Medicine guidelines for the development of omics-based tests. This fully defined and locked-down clinical grade assay will enable trial design with molecular subtype stratification and allow for objective assessment of the predictive value of HGSOC molecular subtypes in precision medicine applications.See related commentary by McMullen et al., p. 5271.Core funding for this project was provided by the National Institutes of Health (R01-CA172404, PI: S.J. Ramus; and R01-CA168758, PIs: J.A. Doherty and M.A.Rossing), the Canadian Institutes for Health Research (Proof-of-Principle I program, PIs: D.G.Huntsman and M.S. Anglesio), the United States Department of Defense Ovarian Cancer Research Program (OC110433, PI: D.D. Bowtell). A. Talhouk is funded through a Michael Smith Foundation for Health Research Scholar Award. M.S. Anglesio is funded through a Michael Smith Foundation for Health Research Scholar Award and the Janet D. Cottrelle Foundation Scholars program managed by the BC Cancer Foundation. J. George was partially supported by the NIH/National Cancer Institute award number P30CA034196. C. Wang was a Career Enhancement Awardee of the Mayo Clinic SPORE in Ovarian Cancer (P50 CA136393). D.G. Huntsman receives support from the Dr. Chew Wei Memorial Professorship in Gynecologic Oncology, and the Canada Research Chairs program (Research Chair in Molecular and Genomic Pathology). M. Widschwendter receives funding from the European Union’s Horizon 2020 European Research Council Programme, H2020 BRCA-ERC under Grant Agreement No. 742432 as well as the charity, The Eve Appeal (https://eveappeal.org.uk/), and support of the National Institute for Health Research (NIHR) and the University College London Hospitals (UCLH) Biomedical Research Centre. G.E. Konecny is supported by the Miriam and Sheldon Adelson Medical Research Foundation. B.Y. Karlan is funded by the American Cancer Society Early Detection Professorship (SIOP-06-258-01-COUN) and the National Center for Advancing Translational Sciences (NCATS), Grant UL1TR000124. H.R. Harris is 20 supported by the NIH/National Cancer Institute award number K22 CA193860. OVCARE (including the VAN study) receives support through the BC Cancer Foundation and The VGH+UBC Hospital Foundation (authors AT, BG, DGH, and MSA). The AOV study is supported by the Canadian Institutes of Health Research (MOP86727). The Gynaecological Oncology Biobank at Westmead, a member of the Australasian Biospecimen Network-Oncology group, was funded by the National Health and Medical Research Council Enabling Grants ID 310670 & ID 628903 and the Cancer Institute NSW Grants ID 12/RIG/1-17 & 15/RIG/1-16. The Australian Ovarian Cancer Study Group was supported by the U.S. Army Medical Research and Materiel Command under DAMD17-01-1-0729, The Cancer Council Victoria, Queensland Cancer Fund, The Cancer Council New South Wales, The Cancer Council South Australia, The Cancer Council Tasmania and The Cancer Foundation of Western Australia (Multi-State Applications 191, 211 and 182) and the National Health and Medical Research Council of Australia (NHMRC; ID199600; ID400413 and ID400281). BriTROC-1 was funded by Ovarian Cancer Action (to IAM and JDB, grant number 006) and supported by Cancer Research UK (grant numbers A15973, A15601, A18072, A17197, A19274 and A19694) and the National Institute for Health Research Cambridge and Imperial Biomedical Research Centres. Samples from the Mayo Clinic were collected and provided with support of P50 CA136393 (E.L.G., G.L.K, S.H.K, M.E.S.)

Data for clot degradation under the action of histotripsy bubble activity and a lytic drug

Venous thromboembolism is a major source of morbidity worldwide, and the degree of intervention depends on the likelihood of sequalae. Iliofemoral thrombi can migrate to the pulmonary circulation, which has a high associated risk of mortality. The frontline treatment for deep vein thrombosis is recanalization with a catheter-directed fibrinolytic administered over the course of several hours. Prolonged exposure to fibrinolytic carries an increased risk of undue bleeding. Further, mature venous thrombi contain components that are resistant to thrombolysis. Ultrasound has been investigated as both a direct means of achieving recanalization via mechanical ablation of thrombi or as an adjuvant therapy that enhances the efficacy of a lytic. Sonothrombolysis relies on bubble oscillations caused by an ultrasound pressure wave to diffuse lytic into the thrombus and to promote fibrinolysis. Histotripsy relies on ultrasound-induced nucleation of bubble clouds to liquefy tissue in situ. Because bubble activity is common to histotripsy and sonothrombolysis, histotripsy combined with a lytic is hypothesized to reduce the overall clot burden by erythrocyte fractionation (hemolysis) and increased lytic activity (fibrinolysis). In vitro studies were performed in a venous flow phantom to gauge the degree of hemolysis and fibrinolysis for clots exposed to histotripsy and lytic. Overall treatment efficacy was assessed via clot mass loss. Studies here indicated hemolysis and fibrinolysis contributed equally to thrombolytic efficacy for this combination therapy. Secondary analyses demonstrated the bubble cloud acts equally to promote hemolysis and fibrinolysis. These results show that histotripsy adjuvant to lytic therapy can reduce clot burden through multiple mechanisms

Histotripsy as an Adjuvant Therapy for Deep Vein Thrombosis

Deep vein thrombosis encompasses a wide range of morphologies, and a subset of cases require clinical intervention. The current treatment for vessel recanalization, catheter-directed thrombolytics, is effective for acute cases but has a diminished response for chronic disease. An adjuvant approach that is effective for intractable thrombi should therefore improve clinical outcomes. Histotripsy is a focused ultrasound therapy which has been demonstrated to enhance lytic efficacy via the nucleation of bubble clouds in pre-clinical studies. Translating histotripsy from benchtop studies into the clinic is predicated upon three points: 1). The basic mechanism of action should be well characterized, 2) There must be image guidance capable of monitoring the strength and location of the treatment in situ, and 3) Outcomes should be improved compared to current treatment methods. To bridge the gaps identified above, the following aims were executed in this dissertation. In the first aim, the structure and thrombolytic response of ex vivo human venous thrombi were examined to understand the differences between acute and chronic thrombi. Imaging techniques were also tested to gauge sample response to lytic therapy. We found thrombi older than 7 days have substantial changes in the extracellular structure compared younger thrombi (< 7 days old). A positive trend was observed between MR imaging metrics and sample response to thrombolysis. The second aim of this dissertation tested how medium stiffness, a consideration for heterogeneous thrombi, affects the energy of histotripsy bubble activity necessary to cause ablation. Material stiffness induced minimal changes in bubble dynamics as tracked with acoustic emissions mapped with passive cavitation imaging. Further, a fixed minimal acoustic power was associated with histotripsy liquefaction for media with E < 142 kPa. The third aim of this dissertation examined the mechanisms of clot degradation under the action of histotripsy and systemic administration of thrombolytic. These studies revealed histotripsy bubble activity contributes equally to hemolysis and fibrinolysis. Further, hemolysis and fibrinolysis contribute equally to overall treatment efficacy when employing histotripsy. Finally, the objective of the fourth aim was to determine how the dose of lytic administration affects the synergy of histotripsy bubble activity. The results of this aim suggest that histotripsy can reduce the lytic dose by tenfold and still cause the same degree of mass loss and fibrinolysis as compared to the current clinical standard. Overall, the work in this thesis shows that histotripsy is an effective adjuvant therapy for deep vein thrombosis. It is my sincere hope that this work will one day help bring this exciting treatment paradigm to the clinic

(More than) doubling down: Effective fibrinolysis at a reduced rt-PA dose for catheter-directed thrombolysis combined with histotripsy

Deep vein thrombosis is a major source of morbidity and mortality worldwide. For acute proximal deep vein thrombosis, catheter-directed thrombolytic therapy is an accepted method for vessel recanalization. Thrombolytic therapy is not without risk, including the potential for hemorrhagic bleeding that increases with lytic dose. Histotripsy is a focused ultrasound therapy that generates bubble clouds spontaneously in tissue at depth. The mechanical activity of histotripsy increases the efficacy of thrombolytic therapy at doses consistent with current pharmacomechanical treatments for venous thrombosis. The objective of this study was to determine the influence of lytic dose on histotripsy-enhanced fibrinolysis. Human whole blood clots formed in vitro were exposed to histotripsy and a thrombolytic agent (recombinant tissue plasminogen activator, rt-PA) in a venous flow model perfused with plasma. Lytic was administered into the clot via an infusion catheter at concentrations ranging from 0 (control) to 4.54 μg/mL (a common clinical dose for catheter-directed thrombolysis). Following treatment, perfusate samples were assayed for markers of fibrinolysis, hemolysis, and intact red blood cells and platelets. Fibrinolysis was equivalent between the common clinical dose of rt-PA (4.54 μg/mL) and rt-PA at a reduction to one-twentieth of the common clinical dose (0.23 μg/mL) when combined with histotripsy. Minimal changes were observed in hemolysis for treatment arms with or without histotripsy, potentially due to clot damage from insertion of the infusion catheter. Likewise, histotripsy did not increase the concentration of red blood cells or platelets in the perfusate following treatment compared to rt-PA alone. At the highest lytic dose, a refined histotripsy exposure scheme was implemented to cover larger areas of the clot. The updated exposure scheme improved clot mass loss and fibrinolysis relative to administration of lytic alone. Overall, the data collected in this study indicate the rt-PA dose can be reduced by more than a factor of ten and still promote fibrinolysis when combined with histotripsy

The Russian detour : real transition in a virtual economy?

Illustrates the creation of a market economy by showing that no easy procedures automatically lead to that goal; the Russian forest sector is used as a model for all Russian industries. The major obstacle for the forest sector is the existing institutional framework consisting of both formal & informal rules. In Russia, the institutional system adversely affects the new & more market-oriented institutions. Indeed, multiple problems undermine the Russian forest industry. Laws are often ignored, property rights are ill defined, the market does not always determine value, & authorities often fail to prosecute violations of laws. Through a comparative study of the Russian & Swedish forest industries the authors reveal that Russian firms lack funding & bank support, they are more burdened by taxes, & trading is marred by contract violations. Further complicating the issue is Russia's overlapping jurisdictions; the forest sector is regulated by three levels of rules. Consequently, the problems must be solved at three different levelsValiderad; 2001; 20070207 (keni

p120 catenin suppresses basal epithelial cell extrusion in invasive pancreatic neoplasia

©2016 AACR. Aberrant regulation of cellular extrusion can promote invasion and metastasis. Here, we identify molecular requirements for early cellular invasion using a premalignant mouse model of pancreatic cancer with conditional knockout of p120 catenin (Ctnnd1). Mice with biallelic loss of p120 catenin progressively develop high-grade pancreatic intraepithelial neoplasia (PanIN) lesions and neoplasia accompanied by prominent acute and chronic inflammatory processes, which is mediated, in part, through NF-κB signaling. Loss of p120 catenin in the context of oncogenic Kras also promotes remarkable apical and basal epithelial cell extrusion. Abundant single epithelial cells exit PanIN epithelium basally, retain epithelial morphology, survive, and display features of malignancy. Similar extrusion defects are observed following p120 catenin knockdown in vitro, and these effects are completely abrogated by the activation of S1P/S1pr2 signaling. In the context of oncogenic Kras, p120 catenin loss significantly reduces expression of genes mediating S1P/S1pr2 signaling in vivo and in vitro, and this effect is mediated at least, in part, through activation of NF-κB. These results provide insight into mechanisms controlling early events in the metastatic process and suggest that p120 catenin and S1P/S1pr2 signaling enhance cancer progression by regulating epithelial cell invasion