Showing papers by "Anat Levin published in 2021"

CAR T cells: Building on the CD19 paradigm.

Abstract: Spearheaded by the therapeutic use of chimeric antigen receptors (CARs) targeting CD19, synthetic immunology has entered the clinical arena. CARs are recombinant receptors for antigen that engage cell surface molecules through the variable region of an antibody and signal through arrayed T cell activating and costimulatory domains. CARs allow redirection of T cell cytotoxicity against any antigen of choice, independent of MHC expression. Patient T cells engineered to express CARs specific for CD19 have yielded remarkable outcomes in subjects with relapsed/refractory B cell malignancies, setting off unprecedented interest in T cell engineering and cell-based cancer immunotherapy. In this review, we present the challenges to extend the use of CAR T cells to solid tumors and other pathologies. We further highlight progress in CAR design, cell manufacturing and genome editing, which in aggregate hold the promise of generating safer and more effective genetically instructed immunity. Novel engineered cell types, including innate T cell types, natural killer (NK) cells, macrophages and induced pluripotent stem (iPS) cell-derived immune cells, are on the horizon, as are applications of CAR T cells to treat autoimmunity, severe infections and senescence-associated pathologies. This article is protected by copyright. All rights reserved.

Imaging with Local Speckle Intensity Correlations: Theory and Practice

Abstract: Recent advances in computational imaging have significantly expanded our ability to image through scattering layers such as biological tissues by exploiting the auto-correlation properties of captured speckle intensity patterns. However, most experimental demonstrations of this capability focus on the far-field imaging setting, where obscured light sources are very far from the scattering layer. By contrast, medical imaging applications such as fluorescent imaging operate in the near-field imaging setting, where sources are inside the scattering layer. We provide a theoretical and experimental study of the similarities and differences between the two settings, highlighting the increased challenges posed by the near-fieldsetting. We then draw insights from this analysis to develop a new algorithm for imaging through scattering that is tailored to the near-field setting by taking advantage of unique properties of speckle patterns formed under this setting, such as their local support. We present a theoretical analysis of the advantages of our algorithm and perform real experiments in both far-field and near-field configurations, showing an order-of magnitude expansion in both the range and the density of the obscured patterns that can be recovered.

Shaping Functional Avidity of CAR T Cells: Affinity, Avidity, and Antigen Density That Regulate Response.

Abstract: Chimeric antigen receptors (CARs) are immunoreceptors that redirect T cells to selectively kill tumor cells. Given their clinical successes in hematologic malignancies, there is a strong aspiration to advance this immunotherapy for solid cancers; hence, molecular CAR design and careful target choice are crucial for their function. To evaluate the functional significance of the biophysical properties of CAR binding (i.e., affinity, avidity, and antigen density), we generated an experimental system in which these properties are controllable. We constructed and characterized a series of CARs, which target the melanoma tumor-associated antigen Tyr/HLA-A2, and in which the affinity of the single-chain Fv binding domains ranged in KD from 4 to 400 nmol/L. These CARs were transduced into T cells, and each CAR T-cell population was sorted by the level of receptor expression. Finally, the various CAR T cells were encountered with target cells that present different levels of the target antigen. We detected nonmonotonic behaviors of affinity and antigen density, and an interrelation between avidity and antigen density. Antitumor activity measurements in vitro and in vivo corroborated these observations. Our study contributes to the understanding of CAR T-cell function and regulation, having the potential to improve therapies by the rational design of CAR T cells.See related article on p. 946.

P32-specific CAR T cells with dual antitumor and antiangiogenic therapeutic potential in gliomas.

Abstract: Glioblastoma is considered one of the most aggressive malignancies in adult and pediatric patients. Despite decades of research no curative treatment is available and it thus remains associated with a very dismal prognosis. Although recent pre-clinical and clinical studies have demonstrated the feasibility of chimeric antigen receptors (CAR) T cell immunotherapeutic approach in glioblastoma, tumor heterogeneity and antigen loss remain among one of the most important challenges to be addressed. In this study, we identify p32/gC1qR/HABP/C1qBP to be specifically expressed on the surface of glioma cells, making it a suitable tumor associated antigen for redirected CAR T cell therapy. We generate p32 CAR T cells and find them to recognize and specifically eliminate p32 expressing glioma cells and tumor derived endothelial cells in vitro and to control tumor growth in orthotopic syngeneic and xenograft mouse models. Thus, p32 CAR T cells may serve as a therapeutic option for glioblastoma patients.

Extracellular Vesicles Derived from Chimeric Antigen Receptor-T Cells: A Potential Therapy for Cancer

Abstract: Chimeric antigen receptor (CAR)-T cells are genetically engineered T cells, directed against a tumor-associated antigen. Extracellular vesicles (EVs) derived from CAR-T cells (CAR-T EVs) may preser...

Single scattering modeling of speckle correlation

Abstract: Coherent images of scattering materials, such as biological tissue, typically exhibit high-frequency intensity fluctuations known as speckle. These seemingly noise-like speckle patterns have strong statistical correlation properties that have been successfully utilized by computational imaging systems in different application areas. Unfortunately, these properties are not well-understood, in part due to the difficulty of simulating physically-accurate speckle patterns. In this work, we propose a new model for speckle statistics based on a single scattering approximation, that is, the assumption that all light contributing to speckle correlation has scattered only once. Even though single-scattering models have been used in computer vision and graphics to approximate intensity images due to scattering, such models usually hold only for very optically thin materials, where light indeed does not scatter more than once. In contrast, we show that the single-scattering model for speckle correlation remains accurate for much thicker materials. We evaluate the accuracy of the single-scattering correlation model through exhaustive comparisons against an exact speckle correlation simulator. We additionally demonstrate the model's accuracy through comparisons with real lab measurements. We show, that for many practical application settings, predictions from the single-scattering model are more accurate than those from other approximate models popular in optics, such as the diffusion and Fokker-Planck models. We show how to use the single-scattering model to derive closed-form expressions for speckle correlation, and how these expressions can facilitate the study of statistical speckle properties. In particular, we demonstrate that these expressions provide simple explanations for previously reported speckle properties, and lead to the discovery of new ones. Finally, we discuss potential applications for future computational imaging systems.

Proteolysis Targeting Chimeras for BTK Efficiently Inhibit B-Cell Receptor Signaling and Can Overcome Ibrutinib Resistance in CLL Cells.

Abstract: Proteolysis targeting chimeras (PROTACs) are small molecules that form ternary complexes between their target and E3 ligase, resulting in ubiquitination and proteasomal degradation of the target protein. Using our own designed Bruton's tyrosine kinase (BTK) PROTAC compounds, we show herein efficient BTK degradation in chronic lymphocytic leukemia (CLL) cells. The reversible non-covalent compound (NC-1) was the most potent and therefore we focused on this PROTAC to investigate its subsequent effects on the BCR pathway. NC-1 decreased baseline BTK phosphorylation as well as activation of BTK and other signaling molecules downstream of the BCR pathway, following IgM engagement. These effects were also obtained in samples from CLL patients with clinical resistance to ibrutinib and mutations at C481. NC-1 treatment further decreased baseline CD69 surface levels, completely abrogated its upregulation following IgM activation, decreased CLL cells migration toward SDF-1 and overcame stromal anti-apoptotic protection. In conclusion, our results indicate that targeting BTK using the PROTAC strategy could be a potential novel therapeutic approach for CLL.

Reference Wave Design for Wavefront Sensing

Abstract: One of the classical results in wavefront sensing is phase-shifting point diffraction interferometry (PS-PDI), where the phase of a wavefront is measured by interfering it with a planar reference created from the incident wave itself. The limiting drawback of this approach is that the planar reference, often created by passing light through a narrow pinhole, is dim and noise sensitive. We address this limitation with a novel approach called ReWave that uses a non-planar reference that is designed to be brighter. The reference wave is designed in a specific way that would still allow for analytic phase recovery, exploiting ideas of sparse phase retrieval algorithms. ReWave requires only four image intensity measurements and is significantly more robust to noise compared to PS-PDI. We validate the robustness and applicability of our approach using a suite of simulated and real results.

A Single scattering analysis of speckle correlation

Abstract: We propose a closed-form expression for memory effect speckle correla- tions, enriching our understanding of their unique properties. The model considers only the single-scattering component of light, yet offers a good approximation even in thicker volumes.

Near-field imaging inside scattering layers

Abstract: We use speckle intensity correlations to image incoherent illuminators inside scattering samples. Our approach uses correlation properties specific t o s peckle patterns created by near-field illuminators. Compared to previous far-field approaches, our approach achieves order-of-magnitude expansion in both the range and density of illuminators it can recover.