Targeting RNA Condensates in Pediatric Myeloid Leukemia

Acute myeloid leukemia (AML), the second most common childhood leukemia, is an aggressive blood cancer driven by uncontrolled proliferation of immature white blood cells. Only 65% of children achieve long-term remission, despite intensive chemotherapy that results in harsh side effects and even death. We aim to discover alternative therapies by understanding what makes pediatric AML cells survive. Here, we found P-bodies to be crucial for pediatric AML cell survival. P-bodies are small particles within the cell that serve as reservoirs to store mRNAs and prevent them from guiding protein production. We discovered that a gene called DDX6, responsible for assembling P-bodies, is overexpressed in pediatric AML patients. Moreover, AML cells have more P-bodies compared to healthy blood cells. We further show that P-bodies are crucial for progression of pediatric AML. By isolating intact P-bodies from pediatric AML cells, we found that pediatric AML cells use them to hide mRNAs encoding key tumor suppressors, preventing them from exerting an anti-cancer effect. Therefore, targeting P-bodies could be a potential therapeutic approach for treating pediatric AML. Through our research, we aim to gain insights into how dysregulation of DDX6 and P-body assembly sustains pediatric AML. By understanding these mechanisms, we hope to develop more effective and targeted treatments, improving the lives of young patients and reducing the severe side effects associated with current therapies.

The Role of S100A8/A9-IL6R in B-ALL Chemoresistance

In spite of dramatic improvements in outcome for B acute lymphoblastic leukemia (B-ALL) it remains a leading cause of cancer associated death in children and treatment is associated with short and long-term side effects. In an effort to understand how B-ALL cells evade therapy and result in relapse, we have studied genetic and epigenetic differences between blasts at diagnosis (sensitive) and relapse (resistant). Our work and results from others have identified key pathways that leukemia cells use to overcome treatment. Targeting these pathways will lead to more effective and potentially less toxic forms of treatment. We now have significant preliminary data showing that a majority of relapsed B-ALL cells express an inflammatory signature with overexpression of S100A8/A9 and IL6R that results in a protective niche within the bone marrow. The availability of agents already in clinical trials that block these pathways highlights the immediate clinical significance of this work.

Epitranscriptomic mechanisms of therapy resistance in high-risk neuroblastoma

Neuroblastoma is a fatal childhood cancer with approximately 50% chance of recurrence despite multiple lines of aggressive therapies. Therefore, new therapies are urgently required to fight this devastating cancer. Our group has recently identified and characterized the malignant cells that survive chemotherapy in neuroblastoma patients. We found that neuroblastoma cancer cells may alter the levels of proteins which allow them to resist chemotherapy. They do so by chemically changing certain RNA molecules, which are derivatives of the DNA. The altered RNA molecules lead to changes of the these important proteins, which result in drug resistance. In this project, we ask: "how does chemotherapy change the chemical structure of RNA molecules in a way that allow neuroblastoma cells to survive instead of dying?". Together with our collaborators, who are world experts in RNA chemical modifications, we will use advanced technologies to study the differences in RNA chemistry before and after chemotherapy and identify the proteins that allow neuroblastoma cells to escape chemotherapy. If successful, our results may lead to the discovery of new therapies that prevent the RNA molecules from being chemically changed and kill the remaining neuroblastoma cells. Thus, our project has the potential of changing the way we currently treat children with neuroblastoma and improve their chances of surviving.

A PHASE 1 STUDY OF REVUMENIB, AZACITIDINE, AND VENETOCLAX AND IN PEDIATRIC AND YOUNG ADULT PATIENTS WITH REFRACTORY OR RELAPSED ACUTE MYELOID LEUKEMIA

Although survival rates for children with AML are greater than 60%, the outcome for patients with relapsed or refractory disease remains poor, with less than 40% of these patients becoming long term survivors. Therefore, novel approaches are urgently needed, both for the treatment of patients who have relapsed and for incorporation into treatment regimens for newly diagnosed patients. Because AML is a genetically and biologically diverse group of diseases, a rational approach is to develop and test novel therapies in patients who are predicted to respond to those agents. Exciting and extensive preclinical data strongly suggest that menin inhibitors will be active in patients with specific genetic alterations. Preclinical data also demonstrate that the combination of a menin inhibitor with a BCL2 inhibitor is synergistic, as is the combination of a BCL2 inhibitor with a hypomethylating agent. Our proposed RAVAML trial will be the first pediatric trial to test the combination of all three classes of agents, including revumenib (a menin inhibitor), azacitidine (a hypomethylating agent), and venetoclax (a BCL2 inhibitor). We strongly believe that this trial will facilitate the development of menin inhibitor therapy for children with AML and will help move this novel and effective therapy into the frontline setting, ultimately changing the treatment paradigm for children with AML.

Validating PRL2 as a New Therapeutic Target in T-ALL

Acute lymphoblastic leukemia (ALL) is the most common form of cancer in children and T-cell ALL (T-ALL) is a high risk subtype of this disease that accounts for 10-15% of pediatric cases. Changes in the PI3K/PTEN/AKT signaling pathway are often seen in T-ALL and this is associated with reduced disease free and overall survival. PTEN is a tumor suppressor gene that inhibits PI3K/AKT signaling, but its expression is often decreased in cancer. PRL2, in contrast, is a gene that is highly expressed in T-ALL cells. This gene can inhibit PTEN, thus promoting increased cell proliferation and survival. We hypothesize that PRL2 promotes T-ALL development by inhibiting the PTEN tumor suppressor pathway. In Aim 1, we will assess how PRL2 loss alone or in combination with PTEN loss affects overall survival in mouse models of T-ALL. We will also evaluate how increased or decreased PRL2 expression affects T-ALL cell growth and signaling through the PI3K/PTEN/AKT pathway. In Aim 2, we will assess the effectiveness of a PRL2 inhibitor against primary T-ALL patient samples and in mouse models of T-ALL. We will evaluate how chemical inhibition can affect T-ALL cell growth and signaling and determine whether treatment with a PRL2 inhibitor can prolong overall survival in human T-ALL cells grown in mice. Through this work, we hope to learn more about how PRL2 and PTEN contribute to T-ALL development and validate PRL2 as a new therapeutic target in T-ALL.

Developing Human Cerebellar Organoid Models of Group 4 Medulloblastoma to Identify the Cell of Origin and Mechanisms that Support Oncogenesis

Our research will study the mysteries behind Group 4 Medulloblastoma (MB), a form of brain cancer commonly found in children. MB tumor cells originate from a specific set of cells in the developing brain that rely on interactions with other early normal brain cells to fuel their growth. To unravel the mysteries of Group 4 MB, we aim to 1) pinpoint the exact source of the tumor cells using miniature brain models known as organoids and 2) investigate which normal brain cells play a role in supporting the growth of these tumor cells. We will create a scenario where the tumor and normal brain cells interact and observe the outcomes closely. By successfully addressing these two aspects, we expect to gain crucial insights into the nature of Group 4 MB, potentially discovering novel avenues for therapeutic interventions. Our efforts are ultimately geared towards enhancing the prognosis and treatment strategies for children affected by Group 4 MB.

Preclinical evaluation of omacetaxine as a novel therapeutic for ATRT

Children with atypical teratoid/rhabdoid tumor (ATRT), an aggressive brain cancer mainly afflicting infants and toddlers, frequently relapse and die from disease, despite receiving intensive treatment. As such, developing rational and effective therapeutic approaches for ATRT is a pressing clinical need. Unfortunately, extensive efforts to study ATRT have not shown genetic alterations that are readily targetable with therapeutic agents. Therefore, to achieve better treatments for children with ATRT, new therapeutic approaches based on the biology of this disease are needed. We have found that ATRT cells exhibit an exaggerated reliance on the cellular process of protein translation, which is how cancer cells convert genetic material (DNA and RNA) into functional proteins that perform cellular jobs. Moreover, protein translation is targetable, and one drug, named omacetaxine, is already used in adult cancer patients with leukemia. We have found that omacetaxine is highly effective at killing ATRT cells. The purpose of this grant is to evaluate this omacetaxine for the treatment of mouse models of ATRT. We hypothesize that treatment with omacetaxine will result in increased survival for mouse models of ATRT. Thus, successful completion of this proposal will provide the pre-clinical data necessary to support a clinical trial testing omacetaxine in children. Our overall goal is to translate the findings of this research into a clinical trial within the next 3-4 years.

Targeting apoptosis to prevent cancer therapy-induced cardiovascular dysfunction in pediatric patients

Cancers commonly arising in children including leukemias, lymphomas and solid tumors of the nervous system are a leading cause of death and long-term disability. These cancers are typically treated with radiation and chemotherapies, which can control or even eradicate tumors in pediatric patients. However, these treatments can also severely damage cells within the developing heart and vascular system, causing life-long cardiovascular dysfunction including chronic heart failure and stroke. We recently discovered that cell death is regulated differently in our varying healthy tissues during development and early childhood. In fact, cells within the developing heart and vasculature are highly prone to dying via apoptosis, which may explain why many childhood cancer survivors experience cardiovascular disease. However, it is unclear which cells within the developing heart and vasculature are particularly at risk of dying in response to cancer therapies and how the loss of each cell type contributes to long-term dysfunction. Our proposal will build our understanding of how the regulation of apoptosis in young heart and vasculature affects both short-term therapy induced toxicity as well as long-term dysfunction. In addition, our studies will test the extent to which blocking cell death in healthy tissue will prevent therapy-induced dysfunction to enable the development of treatments that will reduce cardiovascular toxicity and improve the lives of pediatric cancer patients.

Dietary valine modulation to enhance therapies for high-risk T-ALL

Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer with more than 3000 children/adolescents under the age of 20 diagnosed with ALL each year in the United States. ALL is a disease that affects a type of white blood cells called lymphocytes that help the body fight infection and disease. ALL can be broadly divided into either B-ALL or T-ALL. B-ALL affects a type of lymphocytes called B-lymphocytes whereas T-ALL affects T lymphocytes. Historically children with T-ALL have worse prognosis than B-ALL. B-ALL also have better therapeutic options available including targeted and immunotherapies, whereas children with T-ALL are limited to therapies with well-documented long-term negative effects like chemotherapy, radiation therapy. Hence, better therapies that kill leukemic cells without harming normal cells is the need of the hour in T-ALL. In this proposal, we aim to evaluate a new therapeutic approach of nutrient deprivation to treat T-ALL grounded on our strong preliminary finding that T-ALL cells need high levels of the nutrient valine for their growth and survival. Our project investigates plausible different avenues of using this approach in combination with currently used chemotherapy and with new drugs in T-ALL treatment. The goal of our project is to identify therapy combinations that willm increase the efficiency of current treatments in killing the leukemia cells to prevent relapse and to provide new options for treatment of high-risk disease.

CAR gamma delta T cell-based multi-pronged immunotherapy for AML

Acute myeloid leukemia (AML) is the second most common type of leukemia in children and remains very deadly in patients with treatment-resistant disease. In other blood cancers, immunotherapy with patients’ immune cells (called T cells) that are genetically modified to express cancer-finding proteins called CARs has been very effective. However, extending this approach to AML is very difficult because cancerous cells frequently lose CAR targets thus becoming invisible to therapeutic cells. We will overcome this problem by utilizing a special subset of T cells, called gamma delta T cells. These cells can recognize and kill AML without a CAR, and therefore can be used to track down and eradicate cancer cells that lost the CAR target. Another advantage is that gamma delta T cells do not attack patients’ healthy tissue, and therefore can be generated from healthy individuals and infused into multiple patients. Here, we will establish a safe and effective CAR gamma delta T cell platform that we will manufacture from healthy donors and equip these cells with receptors to avoid immune rejection in AML patients. If successful, this will lead to a new therapeutic option available off-the-shelf for patients with difficult-to-treat AML.