Publications by authors named "Ungar D"

Article Synopsis
  • Glycosylation significantly influences the pharmacological properties of biologics, leading to variability in their glycan structures and posing challenges for consistent therapeutic development.
  • The study uses omics technologies, specifically RNA-sequencing, to predict optimal cell lines for producing specific glycosylation profiles in monoclonal antibodies (mAbs), identifying Alg5 and UDP-Gal transporter levels as key predictive markers.
  • While transcriptomic data is useful in forecasting glycosylation trends, it fails to capture important factors like enzyme localization and cellular dynamics that are crucial for the actual outcomes of glycosylation.
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Cholera toxoid is an established tool for use in cellular tracing in neuroscience and cell biology. We use a sortase labeling approach to generate site-specific N-terminally modified variants of both the A2-B heterohexamer and B pentamer forms of the toxoid. Both forms of the toxoid are endocytosed by GM1-positive mammalian cells, and while the heterohexameric toxoid was principally localized in the ER, the B pentamer showed an unexpectedly specific localization in the medial/trans-Golgi.

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Iron oxide nanoparticles (IONPs) surface functionalised with thermo-responsive polymers can encapsulate therapeutic proteins and release them upon heating with an alternating magnetic field above the lower critical solution temperature (LCST). In order to make this delivery system clinically-relevant, we prepared IONPs coated with poly--isopropylmethacrylamide (PNIPMAM), a polymer with LCST above human body temperature. The optimal polymer chain length and nanoparticle size to achieve LCST of 45 °C were 19 kDa PNIPMAM and 16 nm IONPs.

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Chinese hamster ovary (CHO) cells are widely used for production of biologics including therapeutic monoclonal antibodies. Cell death in CHO cells is a significant factor in biopharmaceutical production, impacting both product yield and quality. Apoptosis has previously been described as the major form of cell death occurring in CHO cells in bioreactors.

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Article Synopsis
  • Understanding Golgi-resident protein organization is key to sorting molecules and regulating modifications, but studying these changes is often complex and requires detailed experiments.
  • This study suggests using a systems biology approach that focuses on cellular N-glycan profiles to infer changes in Golgi organization and protein localization, making the process simpler.
  • By simulating N-glycan biosynthesis and applying Bayesian analysis, the researchers can reveal how alterations in enzyme amounts and positions affect Golgi organization, demonstrating a new way to integrate math and biology for deeper insights.
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We developed an integrated population pharmacokinetic model to investigate loncastuximab tesirine pharmacokinetics (PK) and exposure-response relationships for relapsed/refractory B cell non-Hodgkin lymphoma, including diffuse large B cell lymphoma (DLBCL). The model, based on the recommended dosing schedule (150 µg/kg every 3 weeks [Q3W] for 2 cycles; 75 µg/kg Q3W thereafter) and drug concentrations in phase 1 and 2 studies (DLBCL [n = 284], non-DLBCL [n = 44]), was used to characterize loncastuximab tesirine PK and evaluate exposure covariates. Relationships between exposure (pyrrolobenzodiazepine-conjugated antibody [cAb] cycle 1 average concentration) and (1) efficacy (including overall response rate [ORR; primary endpoint] and overall survival [OS]) and (2) grade ≥ 2 treatment-emergent adverse events were explored.

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Background: Loncastuximab tesirine has shown antitumor activity with an acceptable toxicity profile in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) who were relapsed or refractory after ≥2 prior therapies, including activity in patients with high-risk disease characteristics. This analysis examined health-related quality of life (HRQoL), symptoms, and tolerability in patients receiving loncastuximab tesirine for relapsed or refractory DLBCL.

Patients And Methods: The single-arm, open-label phase II LOTIS-2 study (ADCT-402-201; NCT03589469) enrolled 145 patients aged ≥18 years.

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Modeling glycan biosynthesis is becoming increasingly important due to the far-reaching implications that glycosylation can exhibit, from pathologies to biopharmaceutical manufacturing. Here we describe a stochastic simulation approach, to overcome the deterministic nature of previous models, that aims to simulate the action of glycan modifying enzymes to produce a glycan profile. This is then coupled with an approximate Bayesian computation methodology to systematically fit to empirical data in order to determine which set of parameters adequately describes the organization of enzymes within the Golgi.

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Background: Patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) who do not respond to or who have progressive disease after salvage therapies have a poor prognosis. Loncastuximab tesirine is a CD19-directed antibody-drug conjugate with encouraging phase 1 single-agent antitumour activity and acceptable safety in non-Hodgkin lymphoma. We aimed to evaluate the antitumour activity and safety of loncastuximab tesirine in patients with relapsed or refractory DLBCL.

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The prognosis for patients with relapsed or refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL) remains poor, with a need for alternatives to current salvage therapies. Loncastuximab tesirine (ADCT-402) is an antibody-drug conjugate comprising a humanized anti-CD19 monoclonal antibody conjugated to a pyrrolobenzodiazepine dimer toxin. Presented here are final results of a phase 1 dose-escalation and dose-expansion study in patients with R/R B-NHL.

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Introduction: Congenital disorders of glycosylation (CDG) are inborn errors of glycan metabolism with high clinical variability. Only a few antenatal cases have been described with CDG. Due to a lack of reliable biomarker, prenatal CDG diagnostics relies primarily on molecular studies.

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Article Synopsis
  • Glycans in glycoproteins are complex and varied, creating challenges for common structural biology techniques like X-ray crystallography and cryo-electron microscopy.
  • Advancements in mass spectrometry have enhanced our understanding of glycan composition, including specific details about their chemical linkages, facilitating the development of glycomics.
  • This work discusses the extension of the Privateer software to utilize glycomics data, improving the validation process of 3D glycoprotein structures significantly.
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Nanoparticles could conceal bioactive proteins during therapeutic delivery, avoiding side effects. Superparamagnetic iron oxide nanoparticles (SPIONs) coated with a temperature-sensitive polymer were tested for protein release. We show that coated SPIONs can entrap test proteins and release them in a temperature-controlled manner in a biological system.

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Relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) remains a therapeutic challenge. Loncastuximab tesirine is an antibody-drug conjugate against CD19, an antigen expressed in many B-cell malignancies. This open-label, single-arm, dose-escalation, dose-expansion study assessed the safety, tolerability, pharmacokinetics (PKs), immunogenicity, and preliminary clinical activity of loncastuximab tesirine in adults with R/R B-ALL.

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Purpose: ADCT-402 (loncastuximab tesirine) is an antibody-drug conjugate comprising a CD19-targeting antibody and pyrrolobenzodiazepine dimers. A first-in-human study evaluated the safety and preliminary clinical activity of loncastuximab tesirine in patients with B-cell non-Hodgkin lymphoma (NHL).

Patients And Methods: A multicenter, phase I, dose-escalation and dose-expansion study enrolled patients ages ≥18 years with relapsed/refractory (R/R) B-cell NHL.

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Heterogeneity is an inherent feature of the glycosylation process. Mammalian cells often produce a variety of glycan structures on separate molecules of the same protein, known as glycoforms. This heterogeneity is not random but is controlled by the organization of the glycosylation machinery in the Golgi cisternae.

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The decoration of proteins by carbohydrates is essential for eukaryotic life yet heterogeneous due to a lack of biosynthetic templates. This complex carbohydrate mixture-the glycan profile-is generated in the compartmentalized Golgi, in which level and localization of glycosylation enzymes are key determinants. Here, we develop and validate a computational model for glycan biosynthesis to probe how the biosynthetic machinery creates different glycan profiles.

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Article Synopsis
  • - COPI is essential for protein transport in cells, mainly recruited by Arf GTPases to form transport intermediates for proteins like Golgi enzymes.
  • - The study identifies GORAB, a protein linked to gerodermia osteodysplastica, as a key player in the COPI machinery, aiding in its recruitment to the trans-Golgi network through interactions with Scyl1.
  • - Mutations in GORAB disrupt its function and disrupt the retrieval process for Golgi enzymes, leading to issues in glycosylation, which contributes to the disease's development.
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Glycans are inherently heterogeneous, yet glycosylation is essential in eukaryotes, and glycans show characteristic cell type-dependent distributions. By using an immortalized human mesenchymal stromal cell (MSC) line model, we show that both - and O-glycan processing in the Golgi functionally modulates early steps of osteogenic differentiation. We found that inhibiting O-glycan processing in the Golgi prior to the start of osteogenesis inhibited the mineralization capacity of the formed osteoblasts 3 weeks later.

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Intra-Golgi retrograde vesicle transport is used to traffic and sort resident Golgi enzymes to their appropriate cisternal locations. An assay was established to investigate the molecular details of vesicle targeting in a cell-free system. Stable cell lines were generated in which the -Golgi enzyme galactosyltransferase (GalT) was tagged with either CFP or YFP.

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Obesity affects more than 35% of Americans, increasing the risk of more than 200 comorbid conditions, impaired quality of life and premature mortality. This review aimed to summarize literature published over the past 15 years regarding the prevalence and impact of obesity in people with haemophilia (PWH) and to discuss implementing general guidelines for weight management in the context of the haemophilia comprehensive care team. Although few studies have assessed the effects of obesity on haemophilia-specific outcomes, existing evidence indicates an important impact of weight status on lower extremity joint range of motion and functional disability, with potentially important effects on overall quality of life.

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A method has been developed for release/isolation of O-glycans from glycoproteins in whole cell lysates for mass spectrometric analysis. Cells are lysed in SDS, which is then exchanged for urea and ammonium bicarbonate in a centrifugal filter, before treating with NHOH to release O-glycans. Following centrifugation, O-glycans are recovered in the filtrate.

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Tumor cells gain metastatic capacity through a Golgi phosphoprotein 3-dependent (GOLPH3-dependent) Golgi membrane dispersal process that drives the budding and transport of secretory vesicles. Whether Golgi dispersal underlies the pro-metastatic vesicular trafficking that is associated with epithelial-to-mesenchymal transition (EMT) remains unclear. Here, we have shown that, rather than causing Golgi dispersal, EMT led to the formation of compact Golgi organelles with improved ribbon linking and cisternal stacking.

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