Grant: 5472-18 | Career Development Program (CDP):
Location:British Columbia Cancer Agency Branch, Vancouver, British Columbia V5Z 1L3
Project Title: Roles Of MicroRNA MiR-146a In Hematopoietic Stem Cell FunctionProject Summary:
Myelodysplastic syndrome (MDS) is a cancer of blood stem cells, the blood-forming cells in the bone marrow. In MDS, cancerous blood stem cells lose the ability to make blood cells, and can also block the function of the remaining normal blood cells. Aging and environmental factors are associated with developing MDS, but how these processes affect the function of both cancerous and coexisting normal blood stem cells in MDS remains poorly understood. Few treatments are available for MDS, and treatment resistance develops in most patients; therefore, understanding the molecular mechanisms that disrupt blood stem cell function in MDS is critical for improving patient outcomes.
I aim to study the molecular mechanisms affecting the function of coexisting cancerous and normal blood stem cells in a mouse model of MDS. I will focus in particular on a subtype of MDS that lacks the gene miR-146a, as we have found that miR-146a deletion in a mouse model causes aggressive MDS symptoms with severe defects in blood stem cell function. To better recreate the bone marrow of MDS patients in which normal and mutant cells coexist, I will co-transplant equal amounts of normal bone marrow with miR-146a-deleted bone marrow, and study the function of both cancerous (miR-146a deleted) and normal (miR-146a intact) blood stem cells. Our data suggest that miR-146a deletion activates inflammation, increases cellular aging, and disrupts energy metabolism in blood stem cells. I will use chemical and genetic strategies to manipulate inflammation, aging pathways, and energy metabolism, with the hope of reversing the dysfunctions of cancerous and normal blood stem cells in this mouse model.
This research will provide the first evidence as to whether drugs targeting inflammation, aging pathways, or energy metabolism may be useful additions to current treatment regimens for MDS. As few effective long-term treatments are available for MDS, my research may one day improve the prognosis for patients with MDS.
Grant: 2317-18 | Career Development Program (CDP):
Location:Washington University in St. Louis, St. Louis , Missouri 63130
Project Title: Targeting Leukemia Stromal Interactions In T-ALLProject Summary:
T-cell acute lymphoblastic leukemia (T-ALL) is a subtype which comprises about 20% of all cases of acute lymphoblastic leukemia. T-ALL is a particularly rare disease in adults, with only about 600 new cases per year in the United States. Furthermore, the prognosis of adults is poor; only 40% of adults with T-ALL are cured with current treatments.
Our laboratory work has demonstrated that T-ALL cells interact with normal cells present in their local environment (called the “microenvironment”), which provides key signals that regulate tumor growth and survival. Our research has focused on a specific protein, CXCR4, which is present in T-ALL cells. In T-ALL, the tumor microenvironment provides a potent growth and survival signal, which is mediated by CXCR4, to T-ALL.
We hypothesize that it is possible to disrupt this tumor-microenvironmental interaction as a means to treat T-ALL patients. We will disrupt the key survival signal to T-ALL cells using a novel inhibitor of CXCR4 known as BL-8040. We are currently conducting a multicenter study to combine BL-8040 treatment with chemotherapy in patients with T-ALL that has relapsed or is refractory to standard treatments. As part of this study, we will test blood and bone marrow samples from patients after treatment to determine the effects of BL-8040 on leukemia cells. We will also conduct additional preclinical studies to test the effects of new combinations of drugs to improve the effectiveness of BL-8040. The overall goal of this project is to target tumor-microenvironment interactions to improve the outcomes of patients with T-ALL.
Grant: 5464-18 | Career Development Program (CDP):
Location:Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037
Project Title: The Impact Of Immunoglobulin Isotype (IgM Vs IgG) On B Cell Lymphomagenesis And Progression.Project Summary:
B-cell lymphomas continuously multiply because growth regulation signaling is altered to stay ‘on’ all the time. This signaling is normally triggered by activation of proteins called receptors on the cell surface. Most lymphomas require signaling from a group of receptors called the B-cell receptor (BCR). Normal B-cells produce a type of BCR, called immunoglobulin (Ig), in a process called the germinal center (GC) reaction. There are several types of Ig subtypes – IgM, IgG, and IgA isotypes—which are produced during the GC in response to stimuli generated by agents foreign to the body. B-cells with different Ig isotypes behave and function differently. Diffuse large B-cell Lymphoma (DLBCL) frequently arises during the GC reaction and express either IgM, IgG or IgA types of BCR. However, the signaling potential and role of Ig isotypes in B-cell lymphoma is poorly understood.
DLBCL can be further sub-categorized into two subgroups: the Germinal Center B-cell type (GCB) DLBCL and Activated B-cell type (ABC) DLBCL. While ABC-DLBCL is a more aggressive disease with a poorer clinical outcome, the GCB-DLBCL is a less aggressive disease with better patient outcomes. Importantly, both subgroups of DLBCL depend on B-cell receptor (BCR) signaling for their survival and proliferation. Interestingly, GCB-DLBCL cells primarily express the IgG isotype of BCR, whereas the majority of ABC-DLBCL cells express IgM. Consistent with these findings, the two subgroups of DLBCL respond differently to BCR signaling inhibition by ibrutinib. In a recent study, there was only a 5% response rate among GCB-DLBCL patients treated with ibrutinib, whereas there was a 38% response rate among ABC-DLBCL patients. These findings, along with the expression of different Ig isotypes, are suggestive of the involvement of differential BCR signaling cascades in the pathogenesis of GCB- versus ABC-DLBCL. To address this idea, we analyzed changes in protein activation between IgM and IgG positive cells in normal B-cells from mice. Remarkably, we observed differential activation of common signaling components among the different Ig isotypes. We are currently seeking to elucidate the molecular mechanisms by which different Ig isotypes impact the survival and proliferation of lymphoma cells. We will also study the effect that these differences may have on regulating the sensitivity of lymphoma cells to approved therapies. Lastly, during these studies we hope to uncover novel therapeutic targets, which may eventually lead to better treatments for DLBCL.
Grant: 1352-18 | Career Development Program (CDP):
Location:New York University School of Medicine, Boston, Massachusetts 02241-415026
Project Title: MicroRNA Regulation Of Leukemia Stem CellsProject Summary:
Acute myeloid leukemia (AML) is composed of two populations of cells with differing characteristics. The bulk population directly gives rise to the disease symptoms. The second population is very small and is composed of leukemia stem cells (LSCs), whose role is to initiate disease and generate the AML bulk population. These self-renewing LSCs are therapy resistant and mediate disease relapse; therefore, it is critical to understand the mechanisms that regulate LSCs in order to develop strategies designed with the intent to cure.
The characteristics of all cells are determined by DNA contained in the nucleus of the cell. The information DNA provides is converted to RNA, which is exported out of the nucleus into the cytoplasm of the cell, where the cell’s proteins are produced. Small RNA molecules, called microRNAs (miRNAs) regulate the expression of protein-encoding genes in cells.
My laboratory has shown that miRNAs can regulate normal blood stem cell function, promote the development of AML, and regulate LSCs. We have shown that two nearly identical microRNAs are frequently overexpressed in LSCs, but it is unclear what their relative contributions are to regulating leukemia cell survival and LSC function. We hypothesize that these two microRNAs can serve overlapping but non-redundant functions due to differences in their location within the cell. Indeed, while most miRNAs are thought to function in the cytoplasm of the cell, some microRNAs enter the nucleus, and we predict that such a nuclear distribution will affect their ability to regulate genes critical for LSC function. Leveraging our expertise in LSC biology, as well as novel technologies that we have either developed or optimized, we seek to better understand the role of these critical miRNAs in AML disease initiation and maintenance. Thus, we propose to: 1) Determine whether structurally similar microRNAs play similar or unique roles in LSCs; 2) Determine whether the subcellular location of microRNAs dictates their ability to regulate LSC function; and 3) Identify the genes that these microRNAs regulate, specifically in LSCs. Overall, we expect to not only reveal how microRNAs regulate LSCs but also to provide general insights into how microRNAs can differentially regulate gene expression based on their position within a cell. These investigations may lead to a better understanding of AML and may provide avenues for novel therapeutic approaches.
Grant: 6543-18 | Translational Research Program (TRP):
Location:Children's Research Institute, Washington, District of Columbia 20010
Project Title: Novel Combination Immunotherapies For High Risk Hodgkin's LymphomaProject Summary:
Hodgkin’s lymphoma (HL), a type of blood cancer is largely curable but with significant long-term side effects. Moreover 10-20% of patients are resistant to treatment and difficult to cure. HL is unique that the tumor cells are surrounded by an inhibitory environment that makes the immune system dysfunctional and allows evasion from an effective anti-tumor response. Understanding this environment may provide insight into how we can spur the immune system to attack HL cells effectively. Like many cancer cells, HL cells escape the immune attack by expressing a protein called PD1 or PDL-1, which is is normally expressed by healthy T cells to prevent them from attacking healthy cells. PD1-inhbitors are drugs that can bind to the PD-1/PDL-1 on lymphoma cells thereby releasing the “brakes” on the immune system to mount a strong attack on the HL cells. The lymphoma cells also secrete certain chemicals like TGFβ which incapacitates the immune cells to kill the lymphoma cells effectively. The goal of this project is to understand how we can change the tumor microenvironment sufficiently to unleash pre-existing anti-tumor immune responses and allow more successful incorporation of killer- T cells. We will determine if PD1 inhibitors when given in combination with the administration of a novel cancer killing T-cell therapy will produce long-lasting cures in patients with high risk HL with less side effects than conventional chemotherapy. Finally, we will continue to improve the efficacy of our combination immunotherapy approach by also engineering the cancer killing T cells to become resistant to the inhibitory chemical TGFβ which is released by the HL tumor cells and has devastating effects on T cell function in vivo. In the laboratory we will determine if these engineered T cells have enhanced killing ability compared to the non engineered T cells.
Grant: 6549-18 | Translational Research Program (TRP):
Location:The University of Iowa, Iowa City, Iowa 52242
Project Title: Clinical Investigation Of CD38+/ Light Chain+/CD24+ As Putative Multiple Myeloma Stem Cell MarkersProject Summary:
Treatment failure in cancers, including, multiple myeloma (MM), is due to persistence of a minor population of cancer stem cells (CSCs), which are mainly non-cycling and very drug-resistant tumor cells. One major clinical observation supporting the existence of MMSCs is that we have shown that gene expression profiles (GEP) remain abnormal in many MM patients with long-lasting complete remission (CR) (> 10 years), suggesting the persistence of a cancer cell population with very low proliferative capacity and very limited sensitivity to our most intensive therapies. Different groups have reported on the presumed identity of MMSCs; however, a unique MMSC phenotype has not yet been established. To further identify phenotypic markers of MMSC, gene expression profiles were analyzed using primary MM cells of both MM stem cells and the bulk MM cells. The cell surface protein CD24 was found to be significantly upregulated in the MMSCs compared to the bulk MM cells. We have confirmed that CD24+ MM cells showed stem cell features, such as increased clonogenic potential, drug resistance and tumor formation capacity with as little as 10 cells. Importantly, we also confirmed that CD24+ MM cells exist in clinical MM samples, which are CD38+/CD24+/k+ or λ+ . Therefore, we have designed two Specific Aims to accomplish this project: (1) We will characterize the role of CD24 in maintaining stem cell features and investigate its clinical relevance in MM; and (2) We will determine whether CD38+/CD24+/k+ or λ+ primary MM cells have cancer stem cell features. Improved understanding of MMSCs biology will likely lead to the development of novel therapeutic targets that can be tested in the laboratory and in the clinic. Evidence from clinical trials and correlative studies should provide proof that that inhibition of MMSCs leads to improvement in long-term clinical outcomes. Such critical studies can only be conducted if we are able to determine and analyze if CD38+/CD24+/k+ or λ+ are indeed consistent MMSC markers. Eventually, we hope this work can define MMSC markers in clinical samples and to use this knowledge to develop a novel therapy to prevent MM relapse.
Grant: 6542-18 | Translational Research Program (TRP):
Location:Oregon Health & Science University, Portland, Oregon 97239
Project Title: Novel Approach To Thwart MYC In B-cell Neoplasia By Selective Targeting Cyclin-dependent Kinase 9Project Summary:
Diffuse large B-cell lymphoma (DLBCL), a disease of the lymph nodes, is the most common subtype of non-Hodgkin lymphoma accounting for >10,000 deaths in the United States annually. While “targeted therapy” has made significant progress in treatment of blood cancers, we continue to treat DLBCL with standard chemotherapy regimens, which are associated with significant side effects and high rate of failure. When DLBCL recurs after initial therapy, it often becomes incurable with chemotherapy. The novel class of agents called inhibitors of cyclin-dependent kinases (or “CDK inhibitors”) has shown promise in therapy of cancer. Cyclin-dependent kinases are proteins which exist in cells under normal conditions. A whole range of them exist and ensure that cells can make all the necessary components for their survival, as well as reproduce. Cancer cells co-opt CDKs in their unlimited growth, and thus CDKs are attractive targets in cancer therapy. However, drugs which inhibit multiple CDKs are toxic, probably because they inhibit he function of multiple CDKs in normal (non-cancerous) cells. By contrast, emergent selective CDKs which target only one-two specific proteins hold promise to be more efficacious and have fewer adverse events. Here we propose to study how selective CDK inhibitors work in cancer, specifically focusing on inhibition of CDK9. Our preliminary experiments suggest that selective CDK9 inhibition stems lymphoma growth by disrupting the function of another protein, called MYC. MYC regulates synthesis of many cellular constituents which ultimately ensure tumor survival and growth. MYC levels are high in DLBCL and it contributes to therapy resistance. Here we will study the effect of CDK inhibitors on MYC function. We will determine how MYC function is affected, and whether MYC disruption is the dominant mechanism of how cells die in response to CDK inhibitors. We will also search for drug partners which will make CDK inhibitors more toxic specifically to tumor cells. Together, this study will help develop novel targeted therapies with the goal of eradicating DLBCL.
Grant: 6550-18 | Translational Research Program (TRP):
Location:Dana-Farber Cancer Institute, Boston, Massachusetts 02215
Project Title: Prioritizing The In Vivo Therapeutic Relevance Of "myeloma-selective" Essential GenesProject Summary:
Multiple myeloma (MM) remains incurable because its malignant cells manage to eventually escape from even the most potent combinations of new therapies for this disease. Despite years of extensive research, the MM field has not yet comprehensively characterized which genes are essential for MM cells to survive and grow within the supportive microenvironmental niche of the bone marrow (BM). We applied, in our lab, the exciting recent technology of CRISPR/Cas9 genome editing to simultaneously investigate the function of thousands of genes. We identified in our studies a select set of genes that are considerably more important for survival and growth of MM cells in the laboratory, compared to tumor cells from other blood cancers or from solid tumors. Some of these "MM-selective" essential genes have known roles in the biology of MM pathophysiology, but several others have not been previously considered major therapeutic targets. This project will validate the therapeutic relevance of these "MM-selective" essential genes using a model in which biocompatible scaffolds are implanted into mice and are engineered, with the use of human stromal cells from the BM, to resemble the properties and local conditions of the BM in patients with MM. Building on our experience with the CRISPR/Cas9 system both in the lab and in mouse studies, we will examine in this "humanized" BM-like scaffold model which of our candidate genes remain essential for MM cells in this context and therefore represent promising therapeutic targets. Investigational drug-like small molecules are available for only a few of these "MM-selective" essential genes, while most of the latter are deemed currently "undruggable". We observed though that specific small molecule inhibitors against other targets involved in distinct components of the regulation of gene expression can significantly down-regulate the transcript levels of several of the most prominent "currently undruggable" MM-selective essential genes in MM cells, and indirectly can disrupt the molecular network of these genes. We will therefore examine if small-molecule inhibitors targeting MM-essential genes, directly or indirectly, exhibit activity against MM cells in the "humanized" BM-like scaffold-based model. By combining the powerful CRISPR technology with in vivo models simulating the human BM, and pharmacological agents with direct or indirect activity against individual or multiple candidate MM-selective essential genes, we hope to determine the therapeutic relevance of these gene and provide a framework to guide the translation of inhibitors for these targets towards the clinic for MM patients.
Grant: 1349-18 | Career Development Program (CDP):
Location:Washington University School of Medicine in St. Louis, St. Louis, Missouri 63112-1408
Project Title: Protection Of Proliferating B Lymphocytes From Transformation By A C-MYC-induced Tumor Suppressive ProgramProject Summary:
Lymphomas and leukemias are caused by uncontrolled proliferation of lymphocytes due to accumulating errors in the genome. However, cell proliferation is also an important biological activity across many different tissues and cell types. Specifically, proliferation of lymphocytes is essential for the immune responses that protect individuals from invading pathogens. Normal lymphocytes are able to proliferate even quicker than cancer cells in response to infection for extended periods of time. In the course of normal immune system development, lymphocytes also mutate their own genome to establish better immunity to infection. However, it is unknown how lymphocytes undergo normal proliferation and mutation events without increasing the risk of cancers. We hypothesize that lymphocytes engage an unidentified, unique mechanism to minimize the risk of cancers while facing the demand to proliferate and mutate their genome during their normal functional activities. To explore this hypothesis, we have studied sets of genes that are activated by a protein named c-Myc, which has been causally linked to many cancers in humans and other organisms. Since c-Myc is also essential for lymphocyte proliferation in response to infection, c-Myc may activate an unidentified pathway that is required to protect normally proliferating lymphocytes from becoming cancerous. Accordingly, mutations of genes in the pathway may increase the risk of lymphomas or leukemias. Indeed, we have identified a gene that is activated by c-Myc in proliferating lymphocytes and is necessary to suppress blood cancer development in an animal model.Moreover, a few mutations of this gene have been found in leukemic cells from human patients.Starting with these discoveries, we will define the molecular mechanisms by which this c-Myc initiated regulatory pathway suppresses leukemia and lymphoma. The knowledge from this study will contribute to the development of improved strategies for the risk assessment and diagnosis of leukemias and lymphomas and also to inventing new therapeutic approaches.
Grant: 3378-18 | Career Development Program (CDP):
Location:Sloan Kettering Institute for Cancer Research, New York, New York 10087
Project Title: Optimizing CAR T Cell Therapy For Multiple MyelomaProject Summary:
While advances have recently been made in the management of multiple myeloma (MM), MM is still considered incurable, with most patients dying from their disease. Thus, there is a critical need to identify and evaluate new therapeutic modalities that may induce durable remissions or cures.
T-cells keep the body healthy by killing cells infected with bacteria or viruses. Chimeric antigen receptor (CAR) T-cell therapy involves collecting a patient’s T-cells and genetically reprogramming them in the lab to recognize and kill cancer cells instead of infected cells. The cells are then infused back to the same patient where they serve as a living drug. In relapsed or refractory acute lymphoblastic leukemia (ALL) this strategy led to dramatic complete responses in approximately 80% of patients treated.
To extend the effectiveness of this therapy to MM, we and others developed MM-specific CARs. Specifically, we screened tens of billions of human antibody fragments and identified a handful that bound to a specific protein target unique to MM cells. We then used the DNA encoding these ‘hits’ to make CARs. Subsequently, we compared how T-cells modified to contain these different CARs preformed in a variety of tests in cell cultures and in mice. We found one CAR, which conveyed very favorable properties on T-cells, to test in patients. We recently began treating MM patients on the clinical trial to test this novel CAR T-cell therapy.
Based on our experience with CAR T-cell therapy for ALL, we hypothesize that patients may develop resistance to our therapeutic approach. Potential sources of resistance may include loss of our target protein on the MM cells and/or suppression by other cells in the environment in which the MM cells reside. We will evaluate the effectiveness, including resistance mechanisms, of our CAR T-cell therapy by analyzing samples obtained through clinical trial. We are also developing “armored CARs,” which express a second protein that may alter the environment in a way that enhances anti-tumor immunity. Additionally, we will study patient samples in a unique mouse model that can support both MM tumor cells and cells found in the environment in which MM cells normally reside in patients. This model will be used to investigate whether our next generation CAR vectors, including CAR T-cells targeting MM-specific proteins (our armored CAR) may enhance long term anti-MM immunity.