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The proto-oncogene MYCN is amplified in approximately half of patients with high-risk neuroblastoma. At relapse, tumors from high-risk patients typically activate a pathway called "MAP kinase signaling" through genetic mutations including loss of NF1, which normally dampens MAP kinase function. Since relapsed neuroblastoma is generally therapy resistant, these data suggest that MAP-kinase activation contributes to therapy resistance. Does MAP kinase signaling contribute to therapy resistance in MYCN-amplified neuroblastoma at diagnosis? Dr. Weiss proposes that dependence on increased MAP kinase signaling in MYCN-amplified neuroblastoma enables rare cells within this heterogeneous tumor to evade chemotherapy. This therapy-resistant population then undergoes selection for further activation of MAP-kinase signaling, reinforcing therapy resistance. How does MYCN drive MAP kinase? The NF1 tumor suppressor blocks MAP kinase signaling. Mis-splicing of the NF1 messenger RNA in neuroblastoma cells results in NF1-23a, a protein with decreased ability to block RAS. Inclusion of NF1 exon 23a is regulated by the RNA splicing proteins "T-cell intracellular antigen 1" (TIA1) and "TIA1 Like gene" TIAL1, both of which are MYCN target genes. If activation of TIAL and TIAL1 (TIA/L1) in MYCN-amplified neuroblastoma activates MAP-kinase signaling in primary tumors at diagnosis, does traditional treatment of these tumors select for further flux through MAP-kinase signaling, to enhance resistance at relapse? This is the issue that Dr. Weiss' proposal addresses. Successful completion clarifies the importance of MYCN-TIA/L1 axis as a driver of resistance in neuroblastoma, and suggests a a translational path to improve outcomes in neuroblastoma.

Dr. Weiss' grant is generously supported by the Arden Quinn Bucher Memorial Fund, a St. Baldrick's Hero Fund. Arden’s intelligence, empathy, and dynamic personality charmed everyone and is now her legacy. Before her neuroblastoma diagnosis on October 11, 2007 at age two, she happily played with boundless energy and imagination. Even throughout her difficult months of treatment, Arden bravely managed to keep smiling and learning. This fund supports St. Baldrick’s mission: funding the most promising research, wherever it takes place to provide kids fighting cancers less toxic, more effective treatments allowing them to live longer, healthier lives.

Half of neuroblastomas are high-risk neuroblastoma, with poor survival. Understanding abnormalities that drive high-risk neuroblastoma (drivers) enables development of therapies against specific drivers. Until 2015, we had identified drivers for half of high-risk neuroblastomas. Recently, most remaining high-risk neuroblastomas were shown to have high levels of TERT, a protein that helps chromosomes replicate. It is still not clear how a protein that helps chromosomes replicate could drive cancer. Perhaps TERT is needed for neuroblastoma tumors to grow, but is not driving the tumor. To distinguish these possibilities, Dr. Weiss is testing whether TERT can drive neuroblastoma in human stem-cell models. In Dr. Weiss' system, stem cells generated from normal human blood or skin cells, are differentiated to form a cell type called neural crest, from which neuroblastoma is derived. He is introducing known drivers into these cells to generate a model for neuroblastoma. Some known drivers (MYCN) lead to neuroblastoma, while others (ALK) do not. Dr. Weiss is using this model to test whether TERT is a driver, or is required for neuroblastoma in the context of other drivers (ALK). Successful completion will generate a model to evaluate whether therapy directed against TERT could help children with neuroblastoma.

This grant is generously supported by the Amanda Rozman Pediatric Cancer Research Fund created in memory of Amanda Rozman and honors her courageous battle with neuroblastoma by funding promising new to improve the efficacy and number of treatments available for relapsed and refractory neuroblastoma.

Targeted therapy works by attacking an abnormal gene product that is specific to the cancer type. Only a minority of neuroblastoma types show genetic drivers, which makes it difficult to develop targeted therapy. Most neuroblastomas show too many or too few copies of large chromosomal regions, called CNAs. Dr. Weiss is studying the connection between CNAs and neuroblastoma, to determine if it CNA is a possible candidate for targeted therapy. Dr. Weiss is engineering CNAs to create CNA-driven models of neuroblastoma, which he will then use to identify CNA-specific therapies to treat neuroblastoma.

Medulloblastoma is the most common malignant brain tumor in children. These tumors are caused by or associated with two proteins which cannot be directly attacked with drugs. However, these proteins rely on other proteins involved in the translation (the process of making more proteins) to cause cancer. Currently researchers can alter translation with drugs in clinical trials for adult cancers. Dr. Weiss's team is trying to determine how these two proteins rely on these translational proteins in medulloblastoma, and how to modulate them with currently available drugs, to halt tumor growth and destroy tumor cells.