New York University School of Medicine Archives

2019

Scholar Grant

William Carroll

New York City, NY

Title: THE ROLE OF LOSS-OF-FUNCTION MUTATIONS OF SETD2 IN RELAPSED PEDIATRIC ACUTE LYMPHOBLASTIC LEUKEMIA

Executive Summary:
While the outcomes for childhood acute lymphoblastic leukemia (ALL) have improved dramatically, the prognosis for those children who relapse remains poor. The underlying factor leading to relapse is the development of chemotherapy resistance. Therefore, in an effort to improve survival for these patients, our lab has focused on discovering relapse-specific genetic and epigenetic alterations that could be responsible for disease recurrence and drug resistance. Interestingly, alterations that effect epigenetic regulatory pathways are among the most frequently observed, including loss of function mutations (LOF) in SETD2. SETD2 has been shown to be involved in disease progression in AML and many solid tumors. However, the mechanistic role of SETD2 mutations has not been elucidated and has not been studied in ALL. Our preliminary data supports the hypothesis that SETD2 mutations operate collaboratively with other genetic alterations to drive clonal fitness. The overarching objectives of this application are to discover the mechanisms by which alterations in SETD2 confer treatment resistance and to translate these findings into novel therapies to prevent and treat relapsed disease. We have developed a panel of isogenic leukemia cell lines with and without SETD2 mutation and will examine changes in proliferation, clonal growth and drug sensitivity to determine the impact of SETD2 LOF mutations in a range of genetic backgrounds. Furthermore, we plan to identify the impact of SETD2 on the 3D genome and the downstream pathways controlled by SETD2 through next generation sequencing approaches allowing us to dissect the mechanism of SETD2 in altering leukemia cell phenotypes. The genes and pathways discovered will be validated in experimental models and patient samples with the immediate goal of developing novel, targeted therapy to prevent the emergence of resistant clones and to restore chemosensitivity in relapsed blasts.
• Epigenetic regulators are among the most commonly mutated genes observed in relapsed pediatric ALL, including SETD2
• The aim of this work is to determine the role of SETD2 mutations in pediatric ALL with the overarching goal of developing novel
targeted therapy to prevent or treat relapse.

2018

Scholar Grant

Christopher Park

New York, NY

Therapeutic Targeting of CD99 in Pediatric Acute Lymphoblastic Leukemia/Lymphoma

Acute lymphoblastic leukemia/lymphoma (ALL) is the most common pediatric cancer and the most frequent cause of death from cancer before 20 years of age. The development of multi-agent chemotherapy has increased the survival rate among ALL patients from less than 10% in the 1960s to 90% at present, but it is clear that improved therapies will be required to cure all patients as well as to spare patients from the toxic effects of chronic chemotherapy.

CD99 is a cell surface protein present in nearly all cases of pediatric T-ALL and B-ALL. Given CD99’s broad expression in ALL, others have investigated the potential of therapeutically targeting CD99, showing that CD99 monoclonal Abs (mAbs) can induce cell death directly as well as promote cell death mediated by NK cells. Despite this finding, however, therapeutic antibodies against CD99 have not been developed and brought forward to the clinic for the treatment of pediatric ALL.

We became interested in CD99 following our observation that CD99 is overexpressed on disease stem cells in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) –diseases that primarily affect adults, but which also affect children. We showed that specific mAb clones directed against CD99 can induce the death of both AML and MDS stem cells and that novel CD99 mAbs developed by our group can effectively deplete leukemia stem cells (LSCs) in mice bearing human AML. We recently expanded the scope of our studies to include pediatric ALL and have shown that CD99 mAbs can directly induce death of pediatric ALL cell lines and primary blasts in vitro. We will investigate the utility of CD99 mAbs as ALL therapy using both in vitro and xenotransplantation models utilizing ALL cell lines and pediatric patent ALL samples. Thus, our specific aims are as follows:

AIM 1. Test the ability of novel CD99 mAbs to therapeutically target pediatric ALL blasts.
a. Determine the sensitivity of pediatric ALL cell lines and primary samples to CD99 mAbs in vitro.
b. Determine whether CD99 mAbs target ALL LSCs by performing limiting dilution and serial transplants following treatment of ALL xenografts.

AIM 2. Identify the molecular requirements for CD99 mAb induced cell death in ALL.
a. Determine if inhibition of protein synthesis is required for CD99 mAb induced cell death.
b. Determine if SFK dependent signaling pathways are required for CD99 mAb induced cell death.

We expect these studies to credential our novel CD99 mAbs for the treatment of pediatric ALL as well as investigate the mechanisms by which they induce cell death. Furthermore, these studies may promote novel strategies to inhibit translation as a therapeutic approach in ALL, for which such strategies have not yet been brought forward to the clinic.