Abstract B76: Characterizing vascular invasion in hepatoblastoma

Hepatoblastoma (HB) is the most common pediatric liver malignancy, and patients with high-risk, metastatic disease have a five-year overall survival (OS) of only about 40%. Of note, HB patients with vascular invasion (VI) have a much worse OS. Our hypothesis is that HB tumors with VI possess unique clones that invade the vasculature, resulting in dissemination of disease. We injected the aggressive HepT1 cell line with confirmed CTNNB1 and NFE2L2 mutations in the livers of immunocompromised NSG mice to generate intrahepatic tumors. After 4 weeks, we had 100% take of tumors in animals. Serum human α-fetoprotein (AFP) increased with the growth of tumors. At time of death, we saw clear presence of intrahepatic VI, vena caval tumor thrombus, extrahepatic disease including within periportal lymph nodes, and lung metastasis in animals with tumors. We grew adherent and nonadherent cell lines from tumor samples, including one cell line from intrahepatic VI and one from vena caval tumor thrombus. Cells derived from VI areas had obvious differences in phenotype from cells from the primary tumor (PT). To further pursue these provocative changes between PT and VI areas, we generated two unique patient-derived xenograft (PDX) models of HB with intrahepatic implantation of PT and VI tumor samples from a nonmetastatic pretreatment extent of disease (PRETEXT) stage 4 patient. Mice harboring the VI PDX showed serum elevation of human AFP and obvious tumor with MRI. PT and VI PDX tissues expressed established HB markers nuclear Beta-catenin, Glypican-3, and AFP, resembling the primary patient sample. We also developed a novel cell line with growth of cells from a VI tumor in vitro. With both the HepT1 and PDX models, gene set enrichment transcriptomic analyses of RNA sequencing data showed clear changes in expression in aggressive tissues that invaded vessels, including significant (p Citation Format: Sarah E. Woodfield, Roma H. Patel, Aryana M. Ibarra, Barry Zorman, Andrew Badachhape, Ketan B. Ghaghada, Dolores Lopez-Terrada, Pavel Sumazin, Sanjeev A. Vasudevan. Characterizing vascular invasion in hepatoblastoma [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B76.