Mayo Clinic Litta Children's Hospital Archives

2018

Quantum Grant

Richard Vile

Rochester, MN

Improving Treatment of Pediatric High Grade Gliomas

Pediatric high grade gliomas (pHGGs) including anaplastic astrocytoma, glioblastoma multiforme (GBM), and diffuse intrinsic pontine glioma (DIPG), manifest as aggressive diseases that represent a devastating and urgent unmet clinical need. Although the accumulation of mutations in the genome of tumor cells is a defining feature of cancer, some cancers, and in particular pHGGs, develop through the accumulation of relatively few mutations. Cancer immunotherapy drives the generation, or amplification, of an adaptive immune response to ‘non-self’ elements of cancer, such as the proteins that arise from mutated genes. Fewer mutations lead to fewer “non-self” targets, and often poor clinical responses to cancer immunotherapies. We have developed a therapeutic vaccination strategy to help overcome this barrier, and to mount a T cell response against overexpressed non-mutated genes in cancer. We have made use of the enzyme APOBEC3B to introduce mutations throughout the genome of tumor cells in vitro. These mutation rich tumor cells, once administered to mice as a vaccine, provide strong anti-cancer therapy. Our data has shown that when overexpressed in tumor cells, APOBEC3B generates a library of non-self peptides that prime CD4 and CD8 T cells which not only recognize the mutated sequence but also cross react on the corresponding unaltered self peptides expressed on the tumor cells. These mutations therefore generate a new set of T cell specificities which have the potential to recognize pre-existing antigens on the tumor cells where no such T cells existed before the vaccine. Our work will define the parameters in both mouse and in vitro human models to optimize this approach to translate this novel vaccination into a clinical dendritic cell vaccine trial for pHGG.

2017

Scholar Grant

Dr. Paul Galardy

Rochester, MN

USP44 as a biomarker and drug target in neuroblastoma

A combination of clinical and genetic features are currently used to stratify children with neuroblastoma (NBL) into very low, low, intermediate, and high-risk groups. Relapses still occur in non high-risk groups, and survival is still a challenge for those with advanced or recurrent disease. Next-generation sequencing has led to the identification of novel pathways and therapeutic targets for a number of cancers. Unfortunately, NBL has a very low rate of nucleotide mutations, posing a barrier for the identification of new treatments. A more detailed understanding of epigenetic signaling may improve risk stratification and point to new treatments, potentially reducing the therapeutic burden and adding precision to therapy. Deubiquitinating enzymes (DUBs) remove ubiquitin (Ub) from proteins and regulate myriad signaling pathways, including epigenetic marks. As most DUBs are cysteine proteases, they are eminently drugable with highly selective small molecule inhibitors under pharmacological development. Our central hypothesis is that the DUB USP44 regulates the epigenetic landscape in NBL and thereby alters disease aggression and therapeutic responses. This hypothesis is based on our preliminary data in which we found USP44, a known histone regulator, to be the most over-expressed DUB in high-risk NBL with its expression highly predictive of poor survival. The rationale for this proposal is that studying USP44 in NBL may lead to new mechanistic insight into disease development, progression, and its response to treatment. Our work may also improve our ability to identify patients with aggressive disease and may identify existing treatments that are more -or less -effective for them. Our work may also help identify patients that will most benefit from novel epigenetic modulators, thus enhancing therapeutic precision. We will address our hypothesis with the following specific aims: 1. Determine how high levels of USP44 affect disease aggression. 2. Determine the epigenetic impact of USP44 in aggressive neuroblastoma. We expect important outcomes from this work. In aim 1, we will learn the effect of USP44 on disease growth, metastasis, and the response to treatment. In aim 2 we will learn how USP44 affects the epigenetic landscape and how this leads to coordinated changes in tumor biology. The results from both aims will not only inform about the mechanistic contribution of USP44 in this disease but will directly point towards novel therapeutic avenues that may have unanticipated benefits for this subgroup of patients at high risk for relapse. Our work will also open new horizons for neuroblastoma research by highlighting the importance of histone ubiquitination on epigenetic regulation and its importance in the clinical behavior of this disease.

Overall Goals (Lay language):

Determine how high levels of the gene USP44 affects growth and spread of neuroblastoma
Determine the impact of USP44 on the effectiveness of treatment in neuroblastoma Identify how USP44 acts at the molecular level to explain its association with poor outcomes in neuroblastoma