Horbinski, Craig

Abstract Background Oligodendrogliomas were previously defined by histology, but since 2016, the WHO has integrated molecular signatures to create the entity of IDH-mutant 1p/19q-codeleted oligodendroglioma. These tumors harbor recurrent genetic alterations—including IDH mutations, CIC and FUBP1 loss-of-function mutations, and PI3K-activating mutations—that collectively define a genetic profile distinct from IDH-mutant astrocytoma and IDH wild-type glioblastoma. The paucity of faithful model systems has impeded progress in advancing mechanistic insights and therapeutic development for oligodendroglioma. Results To test whether recurrent mutations found in oligodendroglioma patients would drive tumor formation in mice, we utilized in utero electroporation to introduce combinations of gain- and loss-of-function mutations into the developing cortex. Initial tests that included expression of IDH-and PIK3CA-mutants with Cic and Fubp1 loss (termed Oligo) were non-tumorigenic but biased cells towards glial lineages. Introducing Cdkn2a-loss, which is normally suppressed by IDH-associated epigenetic changes in human tumors, to the Oligo combination (termed Oligo-Cdkn2a) resulted in fully penetrant tumor formation. Histopathological review showed the Oligo Cdkn2a-loss mouse model resembled grade II/III oligodendroglioma with rounded nuclei and open chromatin. If Trp53-loss is used (termed Oligo-Trp53) in place of Cdkn2a-loss, tumor histology shifts to a more astrocytic phenotype with angulated nuclei with denser chromatin, demonstrating a direct impact of Trp53-loss on histological features. Bulk RNA-sequencing verifies metabolic alterations driven by the presence of IDH-mutations in Oligo-Cdkn2a mouse models compared to an IDH wild-type GBM model. Single-cell transcriptional profiling shows that Oligo-Cdkn2a tumors contain an increased population of tumor cells that resemble more differentiated oligodendrocytes. Examination of the tumor immune microenvironment within Oligo-Cdkn2a and IDHWT GBM mouse models is being performed to determine changes in immune cell infiltration and transcriptional programs. Conclusion We have created, to our knowledge, the first murine model of IDH-mutant 1p/19q-codeleted oligodendroglioma that incorporates Cic loss. This immune-competent mouse model of IDH-mutant 1p/19q-codeleted oligodendroglioma offers a powerful new tool for interrogating tumor biology and evaluating preclinical therapeutic strategies.

Foundation models are reshaping computational pathology by enabling scalable task-agnostic representations of histopathological whole-slide images (WSIs). Unlike earlier task-specific deep learning systems, pathology foundation models (PFMs) leverage massive whole-slide image repositories and self-supervised Vision Transformer architectures to achieve broad generalization and few-shot adaptability. Their evolution reflects a shift from weakly supervised approaches such as Clustering-Constrained Attention Multiple Instance Learning (CLAM) and hierarchical architectures such as Hierarchical Image Pyramid Transformer (HIPT) to large-scale efforts including foundation models, UNI, Virchow, Phikon, CONtrastive learning from Captions for Histopathology (CONCH), GigaPath, H-Optimus, Transformer-Based Pathology Image and Text Alignment Network (TITAN), and the Mayo Clinic Atlas. These models demonstrate impressive performance across diagnostic and prognostic benchmarks while also opening pathways for multimodal integration with genomics and clinical data. Yet significant barriers remain including inconsistent generalization across institutions, interpretability lagging behind clinical needs, and slow integration into routine laboratory workflows. Certain domains of anatomic pathology such as cytopathology, transplant pathology, frozen sections, and rare tumor subtypes remain particularly resistant to current models. Here, we review the development of PFMs, critically evaluate their strengths and limitations, and outline priorities for their safe and effective clinical translation. We argue that the next phase of PFM development will depend on rigorous benchmarking, pathologist-in-the-loop deployment, and multimodal fusion ensuring these models evolve from research tools into clinically robust systems.

ABSTRACT Bispecific T cell engagers (BTEs) induce MHC‐independent cytotoxicity by bridging T cells to tumor cells via binding a T cell–activating receptor and a tumor‐associated antigen. BTEs have proven effective in hematologic malignancies and some solid tumors, yet their potential in glioblastoma (GBM) is largely unexplored. We developed a fully humanized BTE (hBTE) targeting interleukin‐13 receptor alpha 2 (IL13RA2), a tumor‐associated antigen widely expressed in GBM and associated with poor prognosis. In vitro, hBTE activated T cells and induced antigen‐dependent cytokine release and cytotoxicity against IL13RA2‐positive GBM cells. In vivo, hBTE showed robust target‐specific activity and markedly prolonged survival in primary and recurrent GBM xenograft models, without detectable off‐target local or systemic toxicity. Beyond GBM, hBTE also exhibited antitumor activity in IL13RA2‐expressing solid tumors, demonstrating selective tumor accumulation and therapeutic efficacy in models of breast cancer brain metastases and extracranial lung cancer. This work highlights the therapeutic potential of BTEs in IL13RA2‐expressing tumors and establishes a strong preclinical rationale for advancing hBTE therapy toward clinical translation in GBM and other tumors.