Biology subjects

Schuerch, C. M.

Publications and source records attributed to Schuerch, C. M..

7 recordsLinked to original sources

bioRxiv2026

Genomic correlates of metastatic competence and progression in human melanoma

Genomic events and their timing that grant a primary tumour the competence to disseminate remain poorly defined. We performed sequencing of 247 stage I/II primary cutaneous melanomas (CMs) and 60 matched metastases without intervening therapy from a prospectively followed registry cohort with a median followup of 92 months, integrating copy-number, mutational, protein and spatial-transcriptomic analyses. Relapse was not distinguished by oncogenic point mutations, which were largely shared between primaries and metastases, but by somatic copy-number alterations (SCNAs) and global chromosomal instability. We defined OncoCycle, a six-gene copy-number signature (amplification of CDK4, MCL1 and CD276; biallelic loss of CDKN2A, CDKN2B and TP53BP1) that predicted relapse independently of established clinicopathological features in melanoma, and a pan-cancer analysis. In matched pairs, metastatic progression was driven by continued copy-number evolution and reduction in intra-tumoural heterogeneity, rather than by acquired point mutations, and OncoCycle alterations from primary tumours were preserved in metastasis seeding clones. Clonal reconstruction revealed both monoclonal and polyclonal metastasis seeding, and spatial transcriptomics resolved copy-number-defined metastatic subclones occupying and programming distinct immune and stromal niches. Thus, metastatic competence was primed early by focal SCNAs on a background of chromosomal instability, elaborated by continued copy-number evolution during dissemination and spatio-temporal interactions with the tumour-microenvironment.

genomics↗

bioRxiv2026

High immune receptor clonality in melanoma-draining lymph nodes associates with immune dysfunction and poor survival

Tumor-draining lymph nodes (tdLNs) are critical hubs of anti-tumor immunity but are also vulnerable to tumor-mediated immunosuppression. We analyzed T cell and B cell receptor (TCR/BCR) repertoires and transcriptomes from sentinel and non-sentinel lymph nodes of patients with melanoma from a historical pre-immune checkpoint inhibitor cohort (1994-2002) and an independent contemporary validation cohort (2022-2024). Melanoma-positive lymph nodes exhibited increased immune receptor clonality compared with tumor-free nodes. While average clonality showed no consistent association with outcome, the presence of extreme high-clonality outliers in individual lymph nodes was strongly associated with poor melanoma-specific survival. These outliers were characterized by a loss of lymphocyte-related genes and activation markers, an enrichment of melanocytic transcripts, and the suppression of immune signaling pathways, consistent with local immune dysfunction. Increased clonality was confined to lymph nodes and not observed in the peripheral blood. T cell responses to melanocyte differentiation antigens were infre-quently shared between lymph nodes and peripheral blood, highlighting immune compartmentalization.

immunology↗

bioRxiv2025

High-Dimensional Spatiotemporal Single-Cell and 3D Atlas of the Bone Marrow Microenvironment during Leukemic Progression

The bone marrow microenvironment (BMME) is essential for hematopoiesis and immunity, yet spatiotemporal single-cell analysis during leukemogenesis remains challenging. We characterized the BMME in femurs from wild-type and chronic myeloid leukemia (CML) mice at 7, 14 and 21 days post-induction by highly multiplexed and 3D microscopy. Using a 54-marker CODEX panel, we profiled 2,033,725 cells in 55 tissue regions of interest and identified 41 cell types through unsupervised clustering and supervised annotation. During leukemic progression, we observed an expansion of myeloid and progenitor cell populations, increased PD-L1+ leukemic cells, the upregulation of PD-1 on CD4+ and CD8+ T cells, and a profound loss of B cells, plasma cells and bone cells. Advanced CML exhibited a striking expansion of immature, pericyte-deficient vasculature that disrupted vascular niches and impaired hematopoietic stem/progenitor cell positioning. Spatial mapping revealed leukemia-specific cellular neighborhoods enriched in PD-1+CD8+ T cells, suggesting localized immune cell exhaustion. Early-stage CML showed increaseds between plasmacytoid dendritic cells and megakaryocytes, whereas advanced CML featured heightened megakaryocyte emperipolesis of non-leukemic granulocytes. Megakaryocytes were morphologically irregular in CML mice and BM trephine biopsies from CML patients. Laser-capture microdissected megakaryocytes from newly diagnosed CML patients had reduced expression of cytoskeleton genes, which was reversed in advanced cases treated with tyrosine kinase inhibitors. 3D imaging revealed vascular disorganization and depleted megakaryocytes in the diaphysis, underscoring region-specific pathology. Together, this study provides a spatiotemporal single-cell atlas of the BMME during leukemic progression, showing how leukemic cells reprogram the niche to support their expansion and immune evasion.

cancer biology↗

bioRxiv2023

S3-CIMA: Supervised spatial single-cell image analysis for the identification of disease-associated cell type compositions in tissue

The spatial organization of various cell types within the tissue microenvironment is a key element for the formation of physiological and pathological processes, including cancer and autoimmune diseases. Here, we present S3-CIMA, a weakly supervised convolutional neural network model that enables the detection of disease-specific microenvironment compositions from high-dimensional proteomic imaging data. We demonstrate the utility of this approach by determining cancer outcome- and cellular signaling-specific spatial cell state compositions in highly multiplexed fluorescence microscopy data of the tumor microenvironment in colorectal cancer. Moreover, we use S3-CIMA to identify disease onset-specific changes of the pancreatic tissue microenvironment in type 1 diabetes using imaging mass cytometry data. We evaluated S3-CIMA as a powerful tool to discover novel disease-associated spatial cellular interactions from currently available and future spatial biology datasets.

bioinformatics↗

bioRxiv2022

Multimodal and spatially resolved profiling identifies distinct patterns of T-cell infiltration in nodal B-cell lymphoma entities

T-cell-engaging immunotherapies have improved the treatment of nodal B-cell lymphoma, but responses vary highly. Future improvements of such therapies require better understanding of the variety of lymphoma-infiltrating T-cells. We employed single-cell RNA and T-cell receptor sequencing alongside quantification of surface proteins, flow cytometry and multiplexed immunofluorescence on 101 lymph nodes from healthy controls, and patients with diffuse large B-cell, mantle cell, follicular, or marginal zone lymphoma. This multimodal resource revealed entity-specific quantitative and spatial aberrations of the T-cell microenvironment. Clonal PD1+ TCF7- but not PD1+ TCF7+ cytotoxic T-cells converged into terminally exhausted T-cells, the proportions of which were variable across entities and linked to inferior prognosis. In follicular and marginal zone lymphoma, we observed expansion of follicular helper and IKZF3+ regulatory T-cells, which were clonally related and inversely associated with tumor grading. Overall, we portray lymphoma-infiltrating T-cells with unprecedented comprehensiveness and decipher both beneficial and adverse dimensions of T-cell response.

cancer biology↗

bioRxiv2022

Immunotherapy of glioblastoma explants induces interferon-γ responses and immune cell rearrangements in tumor center, but not periphery

Recent therapeutic strategies for glioblastoma (GBM) aim at targeting immune tumor microenvironment (iTME) components to induce antitumoral immunity. A patient-tailored, ex vivo drug testing and response analysis platform for GBM would facilitate personalized therapy planning, provide insights into treatment-induced immune mechanisms in the iTME, and enable the discovery of biomarkers of therapy response and resistance. We cultured 47 GBM explants from tumor center and periphery from 7 patients in perfusion bioreactors to assess iTME responses to immunotherapy. Explants were exposed to antibodies blocking the immune checkpoints CD47, PD-1 or or their combination, and were analyzed by highly multiplexed microscopy (CODEX, co-detection by indexing) using an immune-focused 55-marker panel. Culture media were examined for changes of soluble factors including cytokines, chemokines and metabolites. CODEX enabled the spatially resolved identification and quantification of >850,000 single cells in explants, which were classified into 10 cell types by clustering. Explants from center and periphery differed significantly in their cell type composition, their levels of soluble factors, and their responses to immunotherapy. In a subset of explants, culture media displayed increased interferon-{gamma} levels, which correlated with shifts in immune cell composition within specific tissue compartments, including the enrichment of CD4+ and CD8+ T cells within an adaptive immune compartment. Furthermore, significant differences in the expression levels of functional molecules in innate and adaptive immune cell types were found between explants responding or not to immunotherapy. In non-responder explants, T cells showed higher expression of PD-1, LAG-3, TIM-3 and VISTA, whereas in responders, macrophages and microglia showed higher cathepsin D levels. Our study demonstrates that ex vivo immunotherapy of GBM explants enables an active antitumoral immune response within the tumor center in a subset of patients, and provides a framework for multidimensional personalized assessment of tumor response to immunotherapy.

cancer biology↗

bioRxiv2019

Ion beam subcellular tomography

Multiplexed ion beam imaging (MIBI) has been previously used to profile multiple parameters in two dimensions in single cells within tissue slices. Here, a mathematical and technical framework for three-dimensional subcellular MIBI is presented. We term the approach ion beam tomography (IBT) wherein ion beam images are acquired iteratively across successive, multiple scans and later compiled into a 3D format. For IBT, cells were imaged at 0.2-4 pA ion current across 1,000 axial scans. Consecutive subsets of ion beam images were binned over 3 to 20 slices (above and below) to create a resolved image, wherein binning was incremented one slice at a time to yield an enhanced multi-depth data without loss of depth resolution. Algorithmic deconvolution, tailored for ion beams, was then applied to the transformed ion image series using a hybrid deblurring algorithm and an ion beam current-dependent point-spread function. Three-dimensional processing was implemented by segmentation, mesh, molecular neighborhoods, and association maps. In cultured cancer cells and tissues, IBT enabled accessible visualization of three-dimensional volumetric distributions of genomic regions, RNA transcripts, and protein factors with 65-nm lateral and 5-nm axial resolution. IBT also enabled label-free elemental mapping of cells, allowing "point of source" cellular component measurements not possible for most optical microscopy targets. Detailed multiparameter imaging of subcellular features at near macromolecular resolution should now be made possible by the IBT tools and reagents provided here to open novel venues for interrogating subcellular biology.

systems biology↗