TMOD-09. HUMAN PLURIPOTENT STEM CELL-BASED MODELS OF NEUROBLASTOMA

Abstract

Neuroblastoma (NB) is a malignant tumor that accounts for ~15% of all pediatric cancer mortality. Nearly half of patients present with high-risk disease that has poor outcome, and the proto-oncogene MYCN is amplified in 45% of high-risk cases. Further, relapsed neuroblastoma demonstrates frequent activation of mitogen activated protein kinase (MAPK) signaling, including mutations in tumor suppressor NF1 and epigenetic silencing of the gene. Human induced pluripotent stem cells (iPSCs) represent a valuable tool by which to further dissect the genetic requirements of high-risk NB. Human iPSCs are superior to genetically engineered mouse models (GEMMs) at capturing the telomere biology and chromosomal landscape of primary human neuroblastoma. Further, they can be genetically manipulated to determine the genetic drivers of the disease. As proof of principle, we first differentiated normal human iPSCs toward trunk neural crest cells (NCC), the putative cells of origin for NB. We subsequently introduced established genetic drivers of NB (MYCN, ALK) and orthotopically implanted the resulting trunk NCCs into the renal capsules of immunocompromised mice. Three months post injection, tumors developed in 60% of MYCN/ALK mice, 10% in MYCN alone, and no tumors developed in ALK alone or empty vector. Tumors were transplantable and expressed markers typically found in NB, while lacking markers of other tumors such as rhabdomyosarcoma, Ewing sarcoma, and lymphoma. To show we can use our model to evaluate candidate drivers of NB, we knocked out NF1 in MYCN trunk NCCs using CRISPR/Cas9 and implanted these cells orthotopically in mice. 80% of mice with MYCN/NF1 modified cells developed tumors while NF1 knockout alone did not. Thus, we have generated the first human iPSC model of NB driven by MYCN and have shown the utility of our model in validating cooperating mutations. MH and TZ contributed equally to this work.