Biology subjects

Mallory, P.

Publications and source records attributed to Mallory, P..

3 recordsLinked to original sources

bioRxiv2026

Spatially Organized Tertiary Lymphoid Structures Emerge in Small Cell Lung Cancer and Associate with Improved Survival

Tertiary lymphoid structures (TLS) are ectopic immune aggregates associated with improved prognosis and response to immunotherapy in multiple solid tumors. However, their presence, spatial organization, and functional relevance in small cell lung cancer (SCLC), a malignancy characterized by profound immune evasion, remain poorly understood. Using imaging mass cytometry (IMC) across 320 regions of interest spanning primary lung tumor, tumor-adjacent lung, liver and lymph node metastasis, complemented by Visium HD spatial transcriptomics, we characterized the cellular architecture and molecular programs of TLS-like niches in SCLC. TLS-like niches were identified in a subset of SCLC samples, predominantly primary lung tumor tissues and adjacent lung, spanning a continuum from loose lymphoid aggregates to compact follicle-like immune structures. Organized TLS-like niches contained CD20+ B-cell cores, closely associated with CD4+ and CD8A+ T cells, proliferating lymphocytes, HLA-DR+ antigen-presenting compartments, and SMA+ stromal scaffolds, and were enriched for canonical TLS organizer signals (CXCL13, LTB, FDCSP). Patients with TLS-positive tumors demonstrated improved overall survival, and core TLS-associated transcriptional programs were associated with favorable survival in an independent bulk RNA-seq cohort. To our knowledge, this represents one of the first spatially resolved analyses of TLS-like immune architecture in SCLC, demonstrating that organized lymphoid immunity can emerge in this classically immune-evasive disease and is associated with improved survival.

cancer biology↗

bioRxiv2025

Assessment of Imaging Mass Cytometry (IMC) as a Tool to Characterize Circulating Tumor Cells (CTCs) in Preclinical Mouse Models

Circulating tumor cells (CTCs), particularly multicellular clusters, are associated with poor prognosis and may provide insight into mechanisms of metastasis and therapy resistance. Unbiased approaches for functionally characterizing CTCs in liquid biopsies are therefore urgently needed. Here, we evaluate multiplex imaging mass cytometry (IMC) for CTC analysis in mice bearing human xenograft tumors. In a single-step workflow, IMC uses metal-conjugated antibodies to simultaneously detect numerous proteins and post-translational modifications in minimally processed, small-volume blood samples collected from the tail vein or heart. Using breast cancer cell lines and a patient-derived xenograft (PDX), we assessed a panel of antibodies, including human-specific markers such as Lamin B1 (LMNB1), to enable cross-species interpretation. Combined with manual review, HALO AI-based cell segmentation was used to identify CTCs and quantify marker expression. This approach enables studies of how genetic and pharmacologic interventions alter the properties of single CTCs and CTC clusters in tumor-bearing mice.

cancer biology↗

bioRxiv2025

Spatial profiling identifies regionally distinct microenvironments and targetable immunosuppressive mechanisms in pediatric osteosarcoma pulmonary metastases.

Osteosarcoma is the most common malignant bone tumor in young patients and remains a significant clinical challenge, particularly in the context of metastatic disease. Despite extensive documentation of genomic alterations in osteosarcoma, studies detailing the immunosuppressive mechanisms within the metastatic osteosarcoma microenvironment are lacking. Our objective was to characterize the spatial transcriptional landscape of metastatic osteosarcoma to reveal these immunosuppressive mechanisms and identify promising therapeutic targets. Here, we performed spatial transcriptional profiling on a cohort of osteosarcoma pulmonary metastases from pediatric patients. We reveal a conserved spatial gene expression pattern resembling a foreign body granuloma, characterized by peripheral inflammatory signaling, fibrocollagenous encapsulation, lymphocyte exclusion, and peritumoral macrophage accumulation. We also show that the intratumoral microenvironment of these lesions lack inflammatory signaling. Additionally, we identified CXCR4 as an actionable immunomodulatory target that bridges both the intratumoral and extratumoral microenvironments and highlights the spatial heterogeneity and complexity of this pathway. Collectively, this study reveals that metastatic osteosarcoma specimens are comprised of multiple regionally distinct immunosuppressive microenvironments.

cancer biology↗