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"Liu, Tracy"
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Over half of clinical practice guidelines use non-systematic methods to inform recommendations: A methods study
by
Ramasubbu, Cynthia
,
Puil, Lorri
,
Gerrish, Savannah
in
Anesthesiology
,
Bias
,
Clinical medicine
2021
Assessing the process used to synthesize the evidence in clinical practice guidelines enables users to determine the trustworthiness of the recommendations. Clinicians are increasingly dependent on guidelines to keep up with vast quantities of medical literature, and guidelines are followed to avoid malpractice suits. We aimed to assess whether systematic methods were used when synthesizing the evidence for guidelines; and to determine the type of review cited in support of recommendations.
Guidelines published in 2017 and 2018 were retrieved from the TRIP and Epistemonikos databases. We randomly sorted and sequentially screened clinical guidelines on all topics to select the first 50 that met our inclusion criteria. Our primary outcomes were the number of guidelines using either a systematic or non-systematic process to gather, assess, and synthesise evidence; and the numbers of recommendations within guidelines based on different types of evidence synthesis (systematic or non-systematic reviews). If a review was cited, we looked for evidence that it was critically appraised, and recorded which quality assessment tool was used. Finally, we examined the relation between the use of the GRADE approach, systematic review process, and type of funder.
Of the 50 guidelines, 17 (34%) systematically synthesised the evidence to inform recommendations. These 17 guidelines clearly reported their objectives and eligibility criteria, conducted comprehensive search strategies, and assessed the quality of the studies. Of the 29/50 guidelines that included reviews, 6 (21%) assessed the risk of bias of the review. The quality of primary studies was reported in 30/50 (60%) guidelines.
High quality, systematic review products provide the best available evidence to inform guideline recommendations. Using non-systematic methods compromises the validity and reliability of the evidence used to inform guideline recommendations, leading to potentially misleading and untrustworthy results.
Journal Article
Intratumoral administration of mRNA COVID-19 vaccine delays melanoma growth in mice
by
Damron, F. Heath
,
Kilic, Emel Sen
,
Liu, Tracy W.
in
631/250/590/2291
,
631/250/590/2293
,
631/67/1813/1634
2025
Immunotherapies are effective for cancer treatment but are limited in ‘cold’ tumor microenvironments due to a lack of infiltrating CD8
+
T cells, key players in the anti-cancer immune response. The onset of the COVID-19 pandemic sparked the widespread use of mRNA-formulated vaccines and is well documented that vaccination induces a Th1-skewed immune response. Here, we evaluated the effects of an intratumoral injection of the mRNA COVID-19 vaccine in subcutaneous melanoma tumor mouse models. Tumor growth and survival studies following a single intratumoral injection of the COVID-19 vaccine showed significant tumor suppression and prolonged survival in established B16F10 subcutaneous tumor-bearing mice. mRNA vaccine treatment resulted in a significant increase in CD8
+
T cell infiltration into the tumor microenvironment, as observed using intravital imaging and flow cytometry. Further tumor growth suppression was achieved using additional mRNA vaccine treatments. Combination administration of mRNA vaccine with immune checkpoint therapies demonstrated enhanced effects, further delaying tumor growth and improving the survival time of tumor-bearing mice. This study demonstrates that mRNA vaccines may be used as adjuvants for immunotherapies.
Journal Article
Peptide-based molecular beacons for cancer imaging and therapy
2011
Peptide-based molecular beacons are Förster resonance energy transfer-based target-activatable probes. They offer control of fluorescence emission in response to specific cancer targets and thus are useful tools for in vivo cancer imaging. With our increasing knowledge about human genome in health and disease, peptide-based “smart” probes are continually developed for in vivo optical imaging of specific molecular targets, biological pathways and cancer progression and diagnosis. A class of fluorescent photosensitizers further extends the application of peptide beacons to cancer therapeutics. This review highlights the applications of peptide beacons in cancer imaging, the simultaneous treatment and response monitoring and smart therapeutics with a focus on recent improvements in the design of these probes.
Journal Article
Inhibition of myeloperoxidase enhances immune checkpoint therapy for melanoma
2023
BackgroundThe presence of a highly immunosuppressive tumor microenvironment has limited the success of immune checkpoint therapy (ICT). Immune suppressing myeloid cells with increased production of reactive oxygen species are critical drivers of this immunosuppressive tumor microenvironment. Strategies to limit these immune suppressing myeloid cells are needed to enhance response to ICT.MethodsTo evaluate the contribution of myeloperoxidase (MPO), a myeloid lineage-restricted enzyme and a major source of reactive oxygen species, to mediating ICT response, we compared treatment outcome and immune composition in wild-type, MPO-deficient (MPO−/−), and MPO inhibitor-treated wild-type mice using established primary melanoma models.ResultsTumor growth and survival studies demonstrated that either host deficiency (MPO−/−) or pharmacological inhibition of MPO enhanced ICT response in two preclinical models of established primary melanoma in aged animals. The tumor microenvironment and systemic immune landscape underwent striking changes in infiltration of myeloid cells, T cells, B cells, and dendritic cells in MPO−/− mice; furthermore, a significant increase in myeloid cells was observed in ICT non-responders. The contribution of CD4+ T cells and NK cells during ICT response also changed in MPO−/− mice. Interestingly, MPO enzymatic activity, but not protein, was increased in CD11b+Ly6G+ myeloid cells isolated from marrow, spleen, and peritoneal cavities of mice bearing untreated melanoma, indicating systemic activation of innate immunity. Notably, repurposing MPO-specific inhibitors (verdiperstat, AZD5904) in combination with ICT pointedly enhanced response rates above ICT alone. Indeed, long-term survival was 100% in the YUMM3.3 melanoma model on treatment with verdiperstat plus ICT.ConclusionMPO contributes to ICT resistance in established melanoma. Repurposing MPO-specific inhibitors may provide a promising therapeutic strategy to enhance ICT response.
Journal Article
Targeting myeloperoxidase limits myeloid cell immunosuppression enhancing immune checkpoint therapy for pancreatic cancer
2024
Pancreatic ductal adenocarcinoma is a devastating disease characterized by an extreme resistance to current therapies, including immune checkpoint therapy. The limited success of immunotherapies can be attributed to a highly immunosuppressive pancreatic cancer microenvironment characterized by an extensive infiltration of immune suppressing myeloid cells. While there are several pathways through which myeloid cells contribute to immunosuppression, one important mechanism is the increased production of reactive oxygen species. Here, we evaluated the contribution of myeloperoxidase, a myeloid-lineage restricted enzyme and primary source of reactive oxygen species, to regulate immune checkpoint therapy response in preclinical pancreatic cancer models. We compared treatment outcome, immune composition and characterized myeloid cells using wild-type, myeloperoxidase-deficient, and myeloperoxidase inhibitor treated wild-type mice using established subcutaneous pancreatic cancer models. Loss of host myeloperoxidase and pharmacological inhibition of myeloperoxidase in combination with immune checkpoint therapy significantly delayed tumor growth. The tumor microenvironment and systemic immune landscape demonstrated significant decreases in myeloid cells, exhausted T cells and T regulatory cell subsets when myeloperoxidase was deficient. Loss of myeloperoxidase in isolated myeloid cell subsets from tumor-bearing mice resulted in decreased reactive oxygen species production and T cell suppression. These data suggest that myeloperoxidase contributes to an immunosuppressive microenvironment and immune checkpoint therapy resistance where myeloperoxidase inhibitors have the potential to enhance immunotherapy response. Repurposing myeloperoxidase specific inhibitors may provide a promising therapeutic strategy to expand therapeutic options for pancreatic cancer patients to include immunotherapies.
Journal Article
Using Theory-Based Frameworks to Identify Barriers and Enablers of Physicians’ Telemedicine Adoption and Develop Intervention Strategies in China: Multicenter Qualitative Study
2025
Telemedicine is developing rapidly, presenting new opportunities and challenges for physicians and patients. Limited research has examined physicians' behavior during the process of adopting telemedicine and related factors.
This study aimed to identify perceived barriers and enablers of physicians' adoption of telemedicine and to develop intervention strategies.
Three interlinked frameworks, the Theoretical Domains Framework (TDF), the Behavior Change Wheel (BCW), and behavior change techniques (BCTs), were used sequentially to identify the factors for physicians' telemedicine adoption and to develop intervention strategies. First, guided by the TDF, a questionnaire was developed and administered in interviews with 36 physicians from 29 different medical institutions in Beijing. Second, the content of the semistructured physician interviews was analyzed using the software NVivo 12.0 to extract themes under each domain. Each theme was then classified as either a barrier or an enabler based on the physicians' language and expression. Third, following the established relationships in the literature, we mapped each domain in the TDF to the corresponding intervention functions and policy categories within BCW. Fourth, for each identified intervention function, we further identified the associated BCTs using the standardized mappings reported in previous studies. The process of identifying intervention functions, policy categories, and techniques was guided by the APEASE (acceptability, practicability, effectiveness, affordability, spill-over effects, and equity) criteria. Last, potential implementation strategies were proposed via focus group discussion.
We identified 50 themes in relation to the adoption of telemedicine. These comprised 27 barriers and 23 enablers, ranging from administrative issues to specific clinical conditions. Of the 14 TDF domains, 11 domains were mentioned. The most frequently mentioned domains were environmental context and resources (10 themes), beliefs about consequences (9 themes), and emotion (7 themes). Major barriers comprised limited acceptance among senior physicians, inconsistent system performance, inadequate platform usability, and inadequate medical insurance coverage. Key enablers included sufficient communication skills and proficiency in system operations, together with the conviction that telemedicine may assist patients with resolving medical issues and prompt support from the IT department when challenges arise. Additionally, 7 of 9 intervention functions, 6 of 7 policy categories, and 26 of 93 BCTs were selected for each theme. Finally, we proposed several potential implementation strategies to enhance physician adoption of telemedicine.
This study identified a range of interventions and strategies that could improve telemedicine adoption in this context. Implementing these measures requires efforts from health administrative departments, medical institutions, and health care personnel.
Journal Article
Molecular probes of spike ectodomain and its subdomains for SARS-CoV-2 variants, Alpha through Omicron
2022
Since the outbreak of the COVID-19 pandemic, widespread infections have allowed SARS-CoV-2 to evolve in human, leading to the emergence of multiple circulating variants. Some of these variants show increased resistance to vaccine-elicited immunity, convalescent plasma, or monoclonal antibodies. In particular, mutations in the SARS-CoV-2 spike have drawn attention. To facilitate the isolation of neutralizing antibodies and the monitoring of vaccine effectiveness against these variants, we designed and produced biotin-labeled molecular probes of variant SARS-CoV-2 spikes and their subdomains, using a structure-based construct design that incorporated an N-terminal purification tag, a specific amino acid sequence for protease cleavage, the variant spike-based region of interest, and a C-terminal sequence targeted by biotin ligase. These probes could be produced by a single step using in-process biotinylation and purification. We characterized the physical properties and antigenicity of these probes, comprising the N-terminal domain (NTD), the receptor-binding domain (RBD), the RBD and subdomain 1 (RBD-SD1), and the prefusion-stabilized spike ectodomain (S2P) with sequences from SARS-CoV-2 variants of concern or of interest, including variants Alpha, Beta, Gamma, Epsilon, Iota, Kappa, Delta, Lambda, Mu, and Omicron. We functionally validated probes by using yeast expressing a panel of nine SARS-CoV-2 spike-binding antibodies and confirmed sorting capabilities of variant probes using yeast displaying libraries of plasma antibodies from COVID-19 convalescent donors. We deposited these constructs to Addgene to enable their dissemination. Overall, this study describes a matrix of SARS-CoV-2 variant molecular probes that allow for assessment of immune responses, identification of serum antibody specificity, and isolation and characterization of neutralizing antibodies.
Journal Article
Ceramide Transfer Protein (CERT): An Overlooked Molecular Player in Cancer
2021
Sphingolipids are a class of essential lipids implicated in constructing cellular membranes and regulating nearly all cellular functions. Sphingolipid metabolic network is centered with the ceramide–sphingomyelin axis. Ceramide is well-recognized as a pro-apoptotic signal; while sphingomyelin, as the most abundant type of sphingolipids, is required for cell growth. Therefore, the balance between these two sphingolipids can be critical for cancer cell survival and functioning. Ceramide transfer protein (CERT) dictates the ratio of ceramide to sphingomyelin within the cell. It is the only lipid transfer protein that specifically delivers ceramide from the endoplasmic reticulum to the Golgi apparatus, where ceramide serves as the substrate for sphingomyelin synthesis. In the past two decades, an increasing body of evidence has suggested a critical role of CERT in cancer, but much more intensive efforts are required to draw a definite conclusion. Herein, we review all research findings of CERT, focusing on its molecular structure, cellular functions and implications in cancer. This comprehensive review of CERT will help to better understand the molecular mechanism of cancer and inspire to identify novel druggable targets.
Journal Article
Hydroxychloroquine reduces metastatic tumor burden in pancreatic adenocarcinoma through myeloperoxidase inhibition
by
Geldenhuys, Werner
,
Hopen, Quinn
,
Liu, Tracy W.
in
Adenocarcinoma
,
Allergology
,
Biomedical and Life Sciences
2025
Background
Metastatic pancreatic adenocarcinoma has a 5-year survival of only 3%. Neutrophil extracellular traps are formed when neutrophils expel their intracellular contents and have been intricately linked to metastases. Hydroxychloroquine is an FDA-approved anti-malarial drug and neutrophil extracellular trap inhibitor with high potential for clinical translation. This study investigates the impact of hydroxychloroquine treatment on pancreatic metastases.
Results
Hydroxychloroquine reduced metastatic tumor burden via a neutrophil extracellular trap independent mechanism and resulted in prolonged survival. Hydroxychloroquine inhibited the function of myeloperoxidase in vitro via direct binding with a Kd of 9.74 mM. Myeloperoxidase inhibition via hydroxychloroquine in vivo was the direct result of suppressed activity. Hydroxychloroquine mediated myeloperoxidase inhibition was also demonstrated in metastatic pancreatic adenocarcinoma patients receiving neoadjuvant chemotherapy.
Conclusion
Hydroxychloroquine suppressed pancreatic metastases growth through myeloperoxidase inhibition, leading to a significant increase in survival. Corroborative data supports this mechanism in metastatic pancreatic adenocarcinoma patients treated with hydroxychloroquine. These data provide important insight into the role of myeloperoxidase in pancreatic metastases and the potential use of hydroxychloroquine in metastatic pancreatic adenocarcinoma treatment.
Journal Article
Group A streptococcal collagen-like protein 1 restricts tumor growth in murine pancreatic adenocarcinoma and inhibits cancer-promoting neutrophil extracellular traps
2024
Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer associated with an immunosuppressive environment. Neutrophil extracellular traps (NETs) were initially described in the context of infection but have more recently been implicated in contributing to the tolerogenic immune response in PDAC. Thus, NETs are an attractive target for new therapeutic strategies. Group A
(GAS) has developed defensive strategies to inhibit NETs.
In the present work, we propose utilizing intra-tumoral GAS injection to stimulate anti-tumor activity by inhibiting cancer-promoting NETs. Mice harboring Panc02 or KPC subcutaneous tumors injected with three different M-type GAS strains. Tumors and spleens were harvested at the endpoint of the experiments to assess bacterial colonization and systemic spread, while sera were analyzed for humoral responses toward the streptococcal antigens, especially the M1 and Scl1 proteins. Role of the streptococcal collagen-like protein 1 (Scl1) in anti-PDAC activity was assessed
after intratumoral injection with M1 GAS wild-type, an isogenic mutant strain devoid of Scl1, or a complemented mutant strain with restored scl1 expression. In addition, recombinant Scl1 proteins were tested for NET inhibition using
and
assays assessing NET production and myeloperoxidase activity.
Injection of three different M-type GAS strains reduced subcutaneous pancreatic tumor volume compared to control in two different murine PDAC models. Limitation of tumor growth was dependent on Scl1, as isogenic mutant strain devoid of Scl1 did not reduce tumor size. We further show that Scl1 plays a role in localizing GAS to the tumor site, thereby limiting the systemic spread of bacteria and off-target effects. While mice did elicit a humoral immune response to GAS antigens, tested sera were weakly immunogenic toward Scl1 antigen following intra-tumoral treatment with Scl1-expressing GAS. M1 GAS inhibited NET formation when co-cultured with neutrophils while Scl1-devoid mutant strain did not. Recombinant Scl1 protein inhibited NETs
in a dose-dependent manner by suppressing myeloperoxidase activity.
Altogether, we demonstrate that intra-tumoral GAS injections reduce PDAC growth, which is facilitated by Scl1, in part through inhibition of cancer promoting NETs. This work offers a novel strategy by which NETs can be targeted through Scl1 protein and potentiates its use as a cancer therapeutic.
Journal Article