Brian Na

Background: Tumor invasion and malignant transformation are spatiotemporally coordinated processes that shape clinical behavior, diagnostic classification, and treatment response. Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive tumors that can arise sporadically or in people with neurofibromatosis type 1 (NF-1), yet how distinct spatial niches underlie MPNST intratumor heterogeneity, local invasion, or malignant transformation from benign precursors is not fully understood. Methods: We integrate spatial analysis of 50,896 transcriptomes from 15 human MPNSTs with deep learning image analysis to define the interplay between genetic alterations, the immune microenvironment, and epigenetic cell fate regulation in MPNST invasion and transformation. Results: Spatial transcriptomics reveal distinct infiltrating immune cells and immunomodulatory spatial clusters in sporadic compared to NF-1–associated MPNSTs. Local invasion is marked by spatially defined immunomodulatory and dedifferentiation programs. Analysis of 2 NF-1–associated MPNSTs with contiguous morphologically defined neurofibroma and MPNST components demonstrates that NF-1–associated tumors exhibit a similar malignant transformation process associated with dynamic immune infiltration, chromosome 9p loss, and dedifferentiation concomitant with increased cell proliferation. Finally, deep learning morphology encoders were trained on spatial transcriptomic data to predict spatial transcriptomic cluster identity and chromosome 9p loss from hematoxylin and eosin–stained images although the generalizability of such encoders remains a challenge. Conclusions: Our data provide a spatial framework for peripheral nerve sheath tumor transformation although the limited sample size of the present cohort will require additional validation of the proposed model.

Background and Objectives: Among CNS malignancies arising in infancy, ATRT stands out as the most frequently diagnosed in children younger than six months. Disruption of the SMARCB1 gene underlies the overwhelming majority of cases. Progress toward effective treatment has been hampered by two persistent challenges. Current mouse models, while informative, fall short of reproducing the full clinical and biological picture of human ATRT, and their ability to predict therapeutic outcomes in patients remains uncertain. Compounding this, the rarity of the disease makes it difficult to assemble patient cohorts of sufficient size for meaningful clinical trials. At the molecular level, germline loss of SMARCB1 exons 4 and 5 has emerged as a particularly penetrant predisposing event, with affected individuals presenting at an earlier age than those harboring other mutation types. The porcine SMARCB1 gene offers a compelling basis for translational modeling as its protein product is identical to the human ortholog at every amino acid position across isoforms, a degree of conservation that exceeds what is seen in the mouse. Methods: Thus, we hypothesized that germline deletion of exons 4 and 5 would predispose heterozygote swine to ATRT development. In this manuscript, we describe the creation of an ATRT porcine model through a CRISPR/Cas9 mediated gene-editing approach. Results: 15 piglets were produced, two of which had confirmed SMARCB1 targeted excisions. However, none developed tumors. To induce further tumorigenicity, one pig with confirmed exons 4 and 5 excision was crossed with a pig with TP53 exon 2 truncation. In total, 11 piglets were born, of which one contained the original excision without a TP53 mutation. This piglet developed a spinal mass at the T1 level. Conclusion: To our knowledge, this is the first ATRT porcine model ever developed and provides proof-of-concept feasibility for large animal modeling of SMARCB1-deficient rhabdoid tumors. These findings support the continued development of porcine RTPS-1 models toward preclinical application.

Although most primary central and peripheral nervous system (NS) tumors occur sporadically, there are a subset that may arise in the context of a cancer predisposition syndrome. These syndromes occur due to a pathogenic mutation in a gene that normally functions as a tumor suppressor. With increased understanding of the molecular pathogenesis of these tumors, more people have been identified with a cancer predisposition syndrome. Identification is crucial, as this informs surveillance, diagnosis, and treatment options. Moreover, relatives can also be identified through genetic testing. Although there are many cancer predisposition syndromes that increase the risk of NS tumors, in this review, we focus on three of the most common cancer predisposition syndromes, neurofibromatosis type 1, neurofibromatosis type 2, and tuberous sclerosis complex type 1 and type 2, emphasizing the clinical manifestations, surveillance guidelines, and treatment options.