Hotspot DNA Methyltransferase 3A (DNMT3A) and Isocitrate Dehydrogenase 1 and 2 (IDH1/2) Mutations in Acute Myeloid Leukemia and Their Relevance as Targets for Immunotherapy.

DNA methyltransferase 3A (DNMT3A) and isocitrate dehydrogenase 1 and 2 (IDH1/2) are genes involved in epigenetic regulation, each mutated in 7-23% of patients with acute myeloid leukemia. Here, we investigated whether hotspot mutations in these genes encode neoantigens that can be targeted by immunotherapy. Five human B-lymphoblastoid cell lines expressing common HLA class I alleles were transduced with a minigene construct containing mutations that often occur in DNMT3A or IDH1/2. From these minigene-transduced cell lines, peptides were eluted from HLA class I alleles and analyzed using tandem mass spectrometry. The resulting data are available via ProteomeXchange under the identifier PXD050560. Mass spectrometry revealed an HLA-A*01:01-binding DNMT3AR882H peptide and an HLA-B*07:02-binding IDH2R140Q peptide as potential neoantigens. For these neopeptides, peptide-HLA tetramers were produced to search for specific T-cells in healthy individuals. Various T-cell clones were isolated showing specific reactivity against cell lines transduced with full-length DNMT3AR882H or IDH2R140Q genes, while cell lines transduced with wildtype genes were not recognized. One T-cell clone for DNMT3AR882H also reacted against patient-derived acute myeloid leukemia cells with the mutation, while patient samples without the mutation were not recognized, thereby validating the surface presentation of a DNMT3AR882H neoantigen that can potentially be targeted in acute myeloid leukemia via immunotherapy.

Raman spectroscopy to discriminate laryngeal squamous cell carcinoma from non-cancerous surrounding tissue.

As for many solid cancers, laryngeal cancer is treated surgically, and adequate resection margins are critical for survival. Raman spectroscopy has the capacity to accurately differentiate between cancer and non-cancerous tissue based on their molecular composition, which has been proven in previous work. The aim of this study is to investigate whether Raman spectroscopy can be used to discriminate laryngeal cancer from surrounding non-cancerous tissue. Patients surgically treated for laryngeal cancer were included. Raman mapping experiments were performed ex vivo on resection specimens and correlated to histopathology. Water concentration analysis and CH-stretching region analysis were performed in the high wavenumber range of 2500-4000 cm-1. Thirty-four mapping experiments on 22 resection specimens were used for analysis. Both laryngeal cancer and all non-cancerous tissue structures showed high water concentrations of around 75%. Discriminative information was only found to be present in the CH-stretching region of the Raman spectra of the larynx (discriminative power of 0.87). High wavenumber region Raman spectroscopy can discriminate laryngeal cancer from non-cancerous tissue structures. Contrary to the findings for oral cavity cancer, water concentration is not a discriminating factor for laryngeal cancer.

The course of health-related quality of life in the first 2 years after a diagnosis of head and neck cancer: the role of personal, clinical, psychological, physical, social, lifestyle, disease-related, and biological factors.

PURPOSE: The aim of this prospective cohort study was to estimate the relationship between the course of HRQOL in the first 2 years after diagnosis and treatment of head and neck cancer (HNC) and personal, clinical, psychological, physical, social, lifestyle, HNC-related, and biological factors. METHODS: Data were used from 638 HNC patients of the NETherlands QUality of life and BIomedical Cohort study (NET-QUBIC). Linear mixed models were used to investigate factors associated with the course of HRQOL (EORTC QLQ-C30 global quality of life (QL) and summary score (SumSc)) from baseline to 3, 6, 12, and 24 months after treatment. RESULTS: Baseline depressive symptoms, social contacts, and oral pain were significantly associated with the course of QL from baseline to 24 months. Tumor subsite and baseline social eating, stress (hyperarousal), coughing, feeling ill, and IL-10 were associated with the course of SumSc. Post-treatment social contacts and stress (avoidance) were significantly associated with the course of QL from 6 to 24 months, and social contacts and weight loss with the course of SumSc. The course of SumSc from 6 to 24 months was also significantly associated with a change in financial problems, speech problems, weight loss, and shoulder problems between baseline and 6 months. CONCLUSION: Baseline clinical, psychological, social, lifestyle, HNC-related, and biological factors are associated with the course of HRQOL from baseline to 24 months after treatment. Post-treatment social, lifestyle, and HNC-related factors are associated with the course of HRQOL from 6 to 24 months after treatment.

Intraoperative assessment of resection margins by Raman spectroscopy to guide oral cancer surgery.

Patients with oral cavity cancer are almost always treated with surgery. The goal is to remove the tumor with a margin of more than 5 mm of surrounding healthy tissue. Unfortunately, this is only achieved in about 15% to 26% of cases. Intraoperative assessment of tumor resection margins (IOARM) can dramatically improve surgical results. However, current methods are laborious, subjective, and logistically demanding. This hinders broad adoption of IOARM, to the detriment of patients. Here we present the development and validation of a high-wavenumber Raman spectroscopic technology, for quick and objective intraoperative measurement of resection margins on fresh specimens. It employs a thin fiber-optic needle probe, which is inserted into the tissue, to measure the distance between a resection surface and the tumor. A tissue classification model was developed to discriminate oral cavity squamous cell carcinoma (OCSCC) from healthy oral tissue, with a sensitivity of 0.85 and a specificity of 0.92. The tissue classification model was then used to develop a margin length prediction model, showing a mean difference between margin length predicted by Raman spectroscopy and histopathology of -0.17 mm.

Frailty in Non-geriatric Patients With Head and Neck cancer.

OBJECTIVE: Patients with head and neck cancer (HNC) are characterized by a poor lifestyle and comorbidity. The Geriatric 8 (G8) is an established screening tool to identify frail older patients with cancer. However, studies evaluating frailty in younger HNC patients are lacking. The aim of this study is to evaluate if the G8 can identify frailty and if it is related to mortality in younger HNC patients. STUDY DESIGN: Case-control study design. SETTING: Tertiary cancer center. METHODS: We studied patients <70 years with HNC. Patients with G8 ≤ 14 were considered frail. Patients were matched to nonfrail (G8 > 14) control patients. Patients were matched according to sex, age, smoking, tumor location, and period of first consultation. Baseline health characteristics were compared between frail patients and nonfrail controls. Second, the treatment plan and adverse outcomes were compared. RESULTS: Forty-five patients with G8 ≤ 14 were included and matched to 90 nonfrail controls. The median follow-up time was 357 days. Frail patients had a significantly lower body mass index and level of education, a worse World Health Organization performance status, and reported lower experienced overall health. 28.9% of the frail patients died after 1 year versus 10% of the nonfrail control patients (hazard ratio: 3.87 [95% confidence interval: 1.32-11.36], p = 0.014). CONCLUSION: The G8 is a valid screening tool to identify frail patients in younger HNC patients.

Minimizing population health loss due to scarcity in OR capacity: validation of quality of life input.

OBJECTIVES: A previously developed decision model to prioritize surgical procedures in times of scarce surgical capacity used quality of life (QoL) primarily derived from experts in one center. These estimates are key input of the model, and might be more context-dependent than the other input parameters (age, survival). The aim of this study was to validate our model by replicating these QoL estimates. METHODS: The original study estimated QoL of patients in need of commonly performed procedures in live expert-panel meetings. This study replicated this procedure using a web-based Delphi approach in a different hospital. The new QoL scores were compared with the original scores using mixed effects linear regression. The ranking of surgical procedures based on combined QoL values from the validation and original study was compared to the ranking based solely on the original QoL values. RESULTS: The overall mean difference in QoL estimates between the validation study and the original study was - 0.11 (95% CI: -0.12 - -0.10). The model output (DALY/month delay) based on QoL data from both studies was similar to the model output based on the original data only: The Spearman's correlation coefficient between the ranking of all procedures before and after including the new QoL estimates was 0.988. DISCUSSION: Even though the new QoL estimates were systematically lower than the values from the original study, the ranking for urgency based on health loss per unit of time delay of procedures was consistent. This underscores the robustness and generalizability of the decision model for prioritization of surgical procedures.

Risk Factors For Hearing Decline From Childhood To Early Adolescence.

OBJECTIVE: To identify risk factors of hearing decline between 9 and 13 years of age. The risk factors examined included sociodemographic, health, and lifestyle-related factors. METHODS: This study was embedded within a population-based prospective cohort study from fetal life onwards in the Netherlands. Pure-tone audiometry and tympanometry were performed at the age of 9 and 13 years. The hearing decline was defined as an increase in low-frequency or high-frequency pure-tone average of at least 5 dB in one of both ears. Multivariable logistic regression was performed to examine the association of possible risk factors with hearing decline. The study was conducted from April 2012 to October 2015, and from April 2016 to September 2019. RESULTS: Of the 3,508 participants included, 7.8% demonstrated a hearing decline in the low frequencies, and 11.3% in the high frequencies. Participants who reported alcohol consumption were more likely to have a hearing decline in the low frequencies (OR 1.5, 95% CI 1.1; 2.0). Moreover, a lower educational level was associated with an increased odds of having a hearing decline in the high frequencies (OR 1.4, 95% CI 1.0; 1.8). Age, sex, household income, personal music player use, and body mass index were not associated with hearing decline. CONCLUSION: Educational level and risky behavior were significantly associated with hearing decline from childhood to early adolescence. The findings of the present study can help in the design of public health interventions to prevent hearing loss at a young age. LEVEL OF EVIDENCE: 2 (prospective cohort study) Laryngoscope, 133:389-395, 2023.

Phosphorylcholine Monoclonal Antibody Therapy Decreases Intraplaque Angiogenesis and Intraplaque Hemorrhage in Murine Vein Grafts.

Phosphorylcholine (PC) is one of the main oxLDL epitopes playing a central role in atherosclerosis, due to its atherogenic and proinflammatory effects. PC can be cleared by natural IgM antibodies and low levels of these antibodies have been associated with human vein graft (VG) failure. Although PC antibodies are recognized for their anti-inflammatory properties, their effect on intraplaque angiogenesis (IPA) and intraplaque hemorrhage (IPH)-interdependent processes contributing to plaque rupture-are unknown. We hypothesized that new IgG phosphorylcholine antibodies (PC-mAb) could decrease vulnerable lesions in murine VGs.Therefore, hypercholesterolemic male ApoE3*Leiden mice received a (donor) caval vein interposition in the carotid artery and weekly IP injections of (5 mg/kg) PCmAb (n = 11) or vehicle (n = 12) until sacrifice at day 28. We found that PCmAb significantly decreased vein graft media (13%), intima lesion (25%), and increased lumen with 32% compared to controls. PCmAb increased collagen content (18%) and decreased macrophages presence (31%). PCmAb resulted in 23% decreased CD163+ macrophages content in vein grafts whereas CD163 expression was decreased in Hb:Hp macrophages. PCmAb significantly lowered neovessel density (34%), EC proliferation and migration with/out oxLDL stimulation. Moreover, PCmAb enhanced intraplaque angiogenic vessels maturation by increasing neovessel pericyte coverage in vivo (31%). Together, this resulted in a 62% decrease in IPH. PCmAb effectively inhibits murine atherosclerotic lesion formation in vein grafts by reducing IPA and IPH via decreased neovessel density and macrophages influx and increased neovessel maturation. PC-mAb therefore holds promise as a new therapeutic approach to prevent vein graft disease.

Logic-gated antibody pairs that selectively act on cells co-expressing two antigens.

The use of therapeutic monoclonal antibodies is constrained because single antigen targets often do not provide sufficient selectivity to distinguish diseased from healthy tissues. We present HexElect®, an approach to enhance the functional selectivity of therapeutic antibodies by making their activity dependent on clustering after binding to two different antigens expressed on the same target cell. lmmunoglobulin G (lgG)-mediated clustering of membrane receptors naturally occurs on cell surfaces to trigger complement- or cell-mediated effector functions or to initiate intracellular signaling. We engineer the Fc domains of two different lgG antibodies to suppress their individual homo-oligomerization while promoting their pairwise hetero-oligomerization after binding co-expressed antigens. We show that recruitment of complement component C1q to these hetero-oligomers leads to clustering-dependent activation of effector functions such as complement mediated killing of target cells or activation of cell surface receptors. HexElect allows selective antibody activity on target cells expressing unique, potentially unexplored combinations of surface antigens.

Distortion Product Otoacoustic Emissions in Screening for Early Stages of High-frequency Hearing Loss in Adolescents.

Objective: Adolescents may be at risk of noise-induced hearing loss due to recreational sound. The aim of this study was to examine the role of distortion product otoacoustic emissions (DPOAEs) in screening for early stages of high-frequency loss such as can be observed in noise-induced hearing loss. Setting and design: This cross-sectional study was embedded within Generation R, an ongoing prospective birth cohort study in Rotterdam, The Netherlands. Data were collected from April 2016 to September 2019. Methods: A total of 3456 adolescents with a mean age of 13 years and 8 months old (standard deviation ± 5 months) were included. Pure-tone thresholds were measured in a sound-treated booth. DPOAEs were recorded using an ILO V6 analyzer with primary levels of 65/55 dB SPL and frequency ratio f2/f1 of 1.22. Subjects had normal middle ear function at the time of assessment, based on tympanometry results. Results: Measurements in 6065 ears showed that DPOAE levels tend to decrease with increasing pure-tone thresholds. However, the intersubject variability of DPOAE levels in ears with the same threshold was large. DPOAE levels could reasonably identify early stages of high-frequency hearing loss. Conclusion: The findings of present study indicate that DPOAE measurements can potentially be used for adolescents hearing screening in the high frequencies. Future research is needed to optimize test performance.

Psychological Problems among Head and Neck Cancer Patients in Relation to Utilization of Healthcare and Informal Care and Costs in the First Two Years after Diagnosis.

BACKGROUND: To investigate associations between psychological problems and the use of healthcare and informal care and total costs among head and neck cancer (HNC) patients. METHOD: Data were used of the NETherlands QUality of Life and Biomedical Cohort study. Anxiety and depression disorder (diagnostic interview), distress, symptoms of anxiety and depression (HADS), and fear of cancer recurrence (FCR) and cancer worry scale (CWS) were measured at baseline and at 12-month follow-up. Care use and costs (questionnaire) were measured at baseline, 3-, 6-, 12-, and 24-month follow-up. Associations between psychological problems and care use/costs were investigated using logistic and multiple regression analyses. RESULTS: Data of 558 patients were used. Distress, symptoms of anxiety or depression, FCR, and/or anxiety disorder at baseline were significantly associated with higher use of primary care, supportive care, and/or informal care (odds ratios (ORs) between 1.55 and 4.76). Symptoms of anxiety, FCR, and/or depression disorder at 12-month follow-up were significantly associated with use of primary care, supportive care, and/or informal care (ORs between 1.74 and 6.42). Distress, symptoms of anxiety, and FCR at baseline were associated with higher total costs. DISCUSSION: HNC patients with psychological problems make more use of healthcare and informal care and have higher costs. This is not the result of worse clinical outcomes.

Biophysical Characterization and Stability of Modified IgG1 Antibodies with Different Hexamerization Propensities.

The hexamerization of natural, human IgG antibodies after cell surface antigen binding can induce activation of the classical complement pathway. Mutations stimulating Fc domain-mediated hexamerization can potentiate complement activation and induce the clustering of cell surface receptors, a finding that was applied to different clinically investigated antibody therapeutics. Here, we biophysically characterized how increased self-association of IgG1 antibody variants with different hexamerization propensity may impact their developability, rather than functional properties. Self-Interaction Chromatography, Dynamic Light Scattering and PEG-induced precipitation showed that IgG variant self-association at neutral pH increased in the order wild type (WT) < E430G < E345K < E345R < E430G-E345R-S440Y, consistent with functional activity. Self-association was strongly pH-dependent, and single point mutants were fully monomeric at pH 5. Differential Scanning Calorimetry and Fluorimetry showed that mutation E430G decreased conformational stability. Interestingly, heat-induced unfolding facilitated by mutation E430G was reversible at 60°C, while a solvent-exposed hydrophobic mutation caused irreversible aggregation. Remarkably, neither increased dynamic self-association propensity at neutral pH nor decreased conformational stability substantially affected the stability of concentrated variants E430G or E345K during storage for two years at 2-8°C. We discuss how these findings may inform the design and development of IgG-based therapeutics.

Health outcome priorities in older patients with head and neck cancer.

OBJECTIVES: Older patients with head and neck cancer often have comorbidity, have reduced life-expectancy and await intensive treatment. For the decision-making process, knowledge of a patient's health outcome prioritization is of paramount importance. We aim to study the health outcome priorities of older patients with head and neck cancer, and to evaluate whether general health, markers of physical, cognitive, and social functioning, and quality of life are associated with health outcome prioritization. MATERIALS AND METHODS: Patients aged ≥70 years with head and neck cancer received a Comprehensive Geriatric Assessment and their priorities were assessed using the Outcome Prioritization Tool (OPT). Distribution of first priority, and associations with general health, markers of physical, cognitive, and social functioning, and quality of life were evaluated using ANOVA or chi-square. RESULTS: Of the 201 included patients, the OPT was available in 170 patients. The majority prioritized maintaining independence (n = 91, 53.3%), followed by extending life (n = 58, 34.1%), reducing pain (n = 14, 8.2%), and reducing other symptoms (n = 7, 4.1%). Housing situation, Body Mass Index, presence of musculoskeletal diseases, and quality of life were significantly related to prioritization of health outcomes. Reducing pain or other symptoms was more often prioritized by patients who lived alone, had a history of musculoskeletal problems, or had poor perceived quality of life. Age, sex, comorbidity, and markers of physical and cognitive functioning were not associated with health prioritization. CONCLUSION: Maintaining independence is most often prioritized by older patients with head and neck cancer. In addition, we found that health outcome priorities of older patients are only limited based on general and specific health characteristics. We suggest to systematically discuss patients' priorities in order to facilitate complex treatment decisions in older patients with cancer.

Study retention and attrition in a longitudinal cohort study including patient-reported outcomes, fieldwork and biobank samples: results of the Netherlands quality of life and Biomedical cohort study (NET-QUBIC) among 739 head and neck cancer patients and 262 informal caregivers.

BACKGROUND: Longitudinal observational cohort studies in cancer patients are important to move research and clinical practice forward. Continued study participation (study retention) is of importance to maintain the statistical power of research and facilitate representativeness of study findings. This study aimed to investigate study retention and attrition (drop-out) and its associated sociodemographic and clinical factors among head and neck cancer (HNC) patients and informal caregivers included in the Netherlands Quality of Life and Biomedical Cohort Study (NET-QUBIC). METHODS: NET-QUBIC is a longitudinal cohort study among 739 HNC patients and 262 informal caregivers with collection of patient-reported outcome measures (PROMs), fieldwork data (interview, objective tests and medical examination) and biobank materials. Study retention and attrition was described from baseline (before treatment) up to 2-years follow-up (after treatment). Sociodemographic and clinical characteristics associated with retention in NET-QUBIC components at baseline (PROMs, fieldwork and biobank samples) and retention in general (participation in at least one component) were investigated using Chi-square, Fisher exact or independent t-tests (p< 0.05). RESULTS: Study retention at 2-years follow-up was 80% among patients alive (66% among all patients) and 70% among caregivers of patients who were alive and participating (52% among all caregivers). Attrition was most often caused by mortality, and logistic, physical, or psychological-related reasons. Tumor stage I/II, better physical performance and better (lower) comorbidity score were associated with participation in the PROMs component among patients. No factors associated with participation in the fieldwork component (patients), overall sample collection (patients and caregivers) or PROMs component (caregivers) were identified. A better performance and comorbidity score (among patients) and higher age (among caregivers) were associated with study retention at 2-years follow-up. CONCLUSIONS: Retention rates were high at two years follow-up (i.e. 80% among HNC patients alive and 70% among informal caregivers with an active patient). Nevertheless, some selection was shown in terms of tumor stage, physical performance, comorbidity and age, which might limit representativeness of NET-QUBIC data and samples. To facilitate representativeness of study findings future cohort studies might benefit from oversampling specific subgroups, such as patients with poor clinical outcomes or higher comorbidity and younger caregivers.

Identification of Functional HLA-A*01:01-Restricted Epstein-Barr Latent Membrane Protein 2-Specific T-Cell Receptors.

BACKGROUND: Adoptive transfer of genetically engineered T cells expressing antigen-specific T-cell receptors (TCRs) is an appealing therapeutic approach for Epstein-Barr virus (EBV)-associated malignancies of latency type II/III that express EBV antigens (LMP1/2). Patients who are HLA-A*01:01 positive could benefit from such products, since no T cells recognizing any EBV-derived peptide in this common HLA allele have been found thus far. METHODS: HLA-A*01:01-restricted EBV-LMP2-specific T cells were isolated using peptide major histocompatibility complex (pMHC) tetramers. Functionality was assessed by production of interferon gamma (IFN-γ) and cytotoxicity when stimulated with EBV-LMP2-expressing cell lines. Functionality of primary T cells transduced with HLA-A*01:01-restricted EBV-LMP2-specific TCRs was optimized by knocking out the endogenous TCRs of primary T cells (∆TCR) using CRISPR-Cas9 technology. RESULTS: EBV-LMP2-specific T cells were successfully isolated and their TCRs were characterized. TCR gene transfer in primary T cells resulted in specific pMHC tetramer binding and reactivity against EBV-LMP2-expressing cell lines. The mean fluorescence intensity of pMHC-tetramer binding was increased 1.5-2 fold when the endogenous TCRs of CD8+ T cells was knocked out. CD8+/∆TCR T cells modified to express EBV-LMP2-specific TCRs showed IFN-γ secretion and cytotoxicity toward EBV-LMP2-expressing malignant cell lines. CONCLUSIONS: We isolated the first functional HLA-A*01:01-restricted EBV-LMP2-specific T-cell populations and TCRs, which can potentially be used in future TCR gene therapy to treat EBV-associated latency type II/III malignancies.

An HLA-A*11:01-Binding Neoantigen from Mutated NPM1 as Target for TCR Gene Therapy in AML.

Acute myeloid leukemia (AML) is a hematological malignancy caused by clonal expansion of myeloid progenitor cells. Most patients with AML respond to chemotherapy, but relapses often occur and infer a very poor prognosis. Thirty to thirty-five percent of AMLs carry a four base pair insertion in the nucleophosmin 1 gene (NPM1) with a C-terminal alternative reading frame of 11 amino acids. We previously identified various neopeptides from the alternative reading frame of mutant NPM1 (dNPM1) on primary AML and isolated an HLA-A*02:01-restricted T-cell receptor (TCR) that enables human T-cells to kill AML cells upon retroviral gene transfer. Here, we isolated T-cells recognizing the dNPM1 peptide AVEEVSLRK presented in HLA-A*11:01. The TCR cloned from a T-cell clone recognizing HLA-A*11:01+ primary AML cells conferred in vitro recognition and lysis of AML upon transfer to CD8 cells, but failed to induce an anti-tumor effect in immunodeficient NSG mice engrafted with dNPM1 OCI-AML3 cells. In conclusion, our data show that AVEEVSLRK is a dNPM1 neoantigen on HLA-A*11:01+ primary AMLs. CD8 cells transduced with an HLA-A*11:01-restricted TCR for dNPM1 were reactive against AML in vitro. The absence of reactivity in a preclinical mouse model requires further preclinical testing to predict the potential efficacy of this TCR in clinical development.

Phosphorylcholine antibodies restrict infarct size and left ventricular remodelling by attenuating the unreperfused post-ischaemic inflammatory response.

Phosphorylcholine is a pro-inflammatory epitope exposed on apoptotic cells, and phosphorylcholine monoclonal immunoglobulin (Ig)G antibodies (PC-mAb) have anti-inflammatory properties. In this study, we hypothesize that PC-mAb treatment reduces adverse cardiac remodelling and infarct size (IS) following unreperfused transmural myocardial infarction (MI). Unreperfused MI was induced by permanent ligation of the left anterior descending (LAD) coronary artery in hypercholesterolaemic APOE*3-Leiden mice. Three weeks following MI, cardiac magnetic resonance (CMR) imaging showed a reduced LV end-diastolic volume (EDV) by 21% and IS by 31% upon PC-mAb treatment as compared to the vehicle control group. In addition, the LV fibrous content was decreased by 27% and LV wall thickness was better preserved by 47% as determined by histological analysis. Two days following MI, CCL2 concentrations, assessed by use of ELISA, were decreased by 81% and circulating monocytes by 64% as assessed by use of FACS analysis. Additionally, local leucocyte infiltration determined by immunohistological analysis showed a 62% decrease after three weeks. In conclusion, the local and systemic inflammatory responses are limited by PC-mAb treatment resulting in restricted adverse cardiac remodelling and IS following unreperfused MI. This indicates that PC-mAb holds promise as a therapeutic agent following MI limiting adverse cardiac remodelling.

Minimizing Population Health Loss in Times of Scarce Surgical Capacity During the Coronavirus Disease 2019 Crisis and Beyond: A Modeling Study.

OBJECTIVES: Coronavirus disease 2019 has put unprecedented pressure on healthcare systems worldwide, leading to a reduction of the available healthcare capacity. Our objective was to develop a decision model to estimate the impact of postponing semielective surgical procedures on health, to support prioritization of care from a utilitarian perspective. METHODS: A cohort state-transition model was developed and applied to 43 semielective nonpediatric surgical procedures commonly performed in academic hospitals. Scenarios of delaying surgery from 2 weeks were compared with delaying up to 1 year and no surgery at all. Model parameters were based on registries, scientific literature, and the World Health Organization Global Burden of Disease study. For each surgical procedure, the model estimated the average expected disability-adjusted life-years (DALYs) per month of delay. RESULTS: Given the best available evidence, the 2 surgical procedures associated with most DALYs owing to delay were bypass surgery for Fontaine III/IV peripheral arterial disease (0.23 DALY/month, 95% confidence interval [CI]: 0.13-0.36) and transaortic valve implantation (0.15 DALY/month, 95% CI: 0.09-0.24). The 2 surgical procedures with the least DALYs were placing a shunt for dialysis (0.01, 95% CI: 0.005-0.01) and thyroid carcinoma resection (0.01, 95% CI: 0.01-0.02). CONCLUSION: Expected health loss owing to surgical delay can be objectively calculated with our decision model based on best available evidence, which can guide prioritization of surgical procedures to minimize population health loss in times of scarcity. The model results should be placed in the context of different ethical perspectives and combined with capacity management tools to facilitate large-scale implementation.

Staphylococcal protein A inhibits complement activation by interfering with IgG hexamer formation.

Immunoglobulin (Ig) G molecules are essential players in the human immune response against bacterial infections. An important effector of IgG-dependent immunity is the induction of complement activation, a reaction that triggers a variety of responses that help kill bacteria. Antibody-dependent complement activation is promoted by the organization of target-bound IgGs into hexamers that are held together via noncovalent Fc-Fc interactions. Here we show that staphylococcal protein A (SpA), an important virulence factor and vaccine candidate of Staphylococcus aureus, effectively blocks IgG hexamerization and subsequent complement activation. Using native mass spectrometry and high-speed atomic force microscopy, we demonstrate that SpA blocks IgG hexamerization through competitive binding to the Fc-Fc interaction interface on IgG monomers. In concordance, we show that SpA interferes with the formation of (IgG)6:C1q complexes and prevents downstream complement activation on the surface of S. aureus. Finally, we demonstrate that IgG3 antibodies against S. aureus can potently induce complement activation and opsonophagocytic killing even in the presence of SpA. Together, our findings identify SpA as an immune evasion protein that specifically blocks IgG hexamerization.