Grant: 5469-18 | Career Development Program (CDP):
Location:Joan & Sanford I. Weill Medical College of Cornell University, New York, New York 10022
Project Title: Mutations Disrupting Gene Enhancer Epigenetic Complexes As Drivers Of Lymphomagenesis.Project Summary:
Lymphoma is a form of cancer that affects immune cells called lymphocytes, a type of white blood cell. There are many subtypes and maturation stages of lymphocytes and, therefore, many kinds of lymphomas. Follicular lymphomas (FL) develop from B lymphocytes (B-cells) and are the second most common subtype of non-Hodgkin lymphoma. Clinically, FL is an indolent lymphoma, characterized by slow progression and relatively high overall survival rate. However, FL is generally considered incurable and roughly half of all FL patients eventually progress into a more aggressive lymphoma with very poor prognoses.
During the normal immune response, B-cells undergo a stage where they grow much faster than usual and tolerate changes in their genetic material, allowing them to develop into fine-tuned functional immune effectors. Three proteins, called BCL6, SMRT and NCoR, work together to drive this process of terminal differentiation in a tightly controlled manner. Any alterations, such as those occurring in FL, can cause cells to become unresponsive to signals cueing exit from this program. B-cells thus become “frozen” at this stage of development; they are unable to complete their normal program and fail to die when instructed to, collecting in the lymph nodes and forming tumors.
Recently, through analyzing the genomes of FL patients, our laboratory has identified several mutations in a gene called TBL1XR1. Our preliminary data suggest that mutations in TBL1XR1 may result in increased stability of SMRT and NCoR. In this study, we plan to investigate whether the increased stability of SMRT and NCoR proteins by TBL1XR1 mutants can cause enhanced BCL6 activity and in turn lead to the development of FL. Unveiling the mechanisms by which B-cells cease to respond to their normal regulatory signals will profoundly contribute to our understanding of FL. In addition, our study will explore whether TBL1XR1 mutations can predict which FL patients have a BCL6-dependent disease and thereby help identify patients who could benefit from existing drugs targeting this protein.
Grant: 5463-18 | Career Development Program (CDP):
Location:La Jolla Institute for Allergy and Immunology, La Jolla, California 92037
Project Title: TET Proteins In B Cell Function And Malignancy.Project Summary:
DNA methylation is a fundamental biological process that controls the activation state of genes, which represent basic modules of biological systems. TET proteins were recently identified as enzymes that mediate the removal of DNA methylation and have been shown to play vital roles in normal development of organisms. Moreover, the activity of TET enzymes is often deregulated during the pathogenesis of various hematological and non-hematological cancers. Consistent with these observations, recent studies have identified loss of TET protein functions in B-cell-derived malignancies, which are the most common hematological malignancies among adults in Western countries. However, the precise role of TET proteins in the regulation of normal B-cell functions and the mechanisms by which loss of TET activity contributes to development of B-cell-derived malignancies remains unclear. Interestingly, my preliminary studies suggest that TET protein shave important roles in the normal functions of B-cells and that loss of TET expression and activity in B-cells is associated with increased instability of the genetic material, which may cause a predisposition to cancer. I am currently investigating the mechanisms by which TET proteins control the physiological functions of B-cells as important components of the immune system. I will further extend these findings to understand mechanisms by which loss of TET proteins contributes to the development of B-cell lymphoma. Because TET protein functions are frequently deregulated in various cancers, the insights gained from these studies may be important in deciphering the origins of not just B-cell malignancies but also other kinds of cancers associated with deregulation of TET protein functions. This knowledge can be further applied in future designing of specific therapies that may potentially be efficacious across a broad spectrum of hematological and non-hematological malignancies.
Grant: 5470-18 | Career Development Program (CDP):
Location:Board of Trustees of the Leland Stanford Junior University, San Francisco, California 94144-4253
Project Title: Dissecting The Topological Consequences Of Mutations In The Cohesin Complex And Their Contribution To Human Leukemia Initiation And Progression.Project Summary:
The human genome is exquisitely organized, packing five feet of DNA into a microscopic nucleus. This level of compaction requires an equally impressive level of organization. Not only does the DNA have to fit into such a tiny space; the genes required for the cell’s function must be properly expressed with high fidelity. To accomplish this seemingly insurmountable task, the genome is organized into a cascading series of loops whose formation is mediated by a multi-protein complex called the cohesin complex. This complex forms a ring-like structure that holds the ends of each loop together much like the clasp of a necklace. Recently, mutations in the cohesin complex have been identified as major drivers of acute myeloid leukemia initiation and progression. With such an important basic cellular function as the organization of DNA, it remains of vital importance to understand how mutations in the cohesin complex mechanistically cause leukemia and to identify avenues for therapeutic intervention.
Of the core components of the cohesin complex, the STAG2 gene is the most frequently mutated and is often lost altogether. Using state-of-the-art technologies, we will study how the composition and function of the cohesin complex changes in the context of a loss of the STAG2 protein. These technologies include the ability to map the three-dimensional organization of the genome, enabling us to study how the DNA loops that are orchestrated by the cohesin complex are disrupted in AML. These molecular and mechanistic studies will be accompanied by genetic and pharmacologic screening to identify putative therapeutic targets. Ultimately, this research will bring us closer to understanding how acute myeloid leukemia develops and how dysregulation of genome organization contributes to this process. We hope that our work will identify promising drug targets and facilitate the treatment of this otherwise deadly disease.
Grant: R6509-18 | Translational Research Program (TRP):
Location:University Health Network, Toronto, Ontario M5G 1Z5
Project Title: Phase I Study Of Allogeneic Double Negative T Cells In Patients With High Risk AMLProject Summary:
Acute Myeloid Leukemia (AML) is a cancer affecting the bone marrow that requires intensive chemotherapy for disease control. This may be associated with significant toxicity. Treatment for AML aims to destroy the leukemia cells and allow the bone marrow to work normally again. Chemotherapies help most AML patients to achieve a state of remission in which the leukemic cells have fallen to a very low level and normal blood cell production has returned. However, despite decades of using chemotherapy to treat AML patients, there continues to be a very high chance of the disease coming back as the cancer cells develop resistance to chemotherapies. Once the disease comes back, few treatment options are available to patients. Consequently, overall survival is about 40% for those <50 years of age and is significantly worse for older patients. Thus, new treatments that are effective at targeting chemotherapy-resistant AML with low toxicity are needed for this unmet challenge.
Double negative T cells (DNTs) are a type of white blood cell in the blood that has the ability to selectively kill cancer cells while sparing normal cells and tissues. In peripheral blood, DNTs are quite rare. To be of value in the treatment of cancer it is necessary to have large numbers of these cells. We have developed methods in the laboratory to grow DNTs from healthy volunteers to large numbers and have shown that these DNTs have potent anti-leukemia effect without detectable toxicity on normal cells and tissues in animal models. In this first-in-man clinical trial, DNTs will be obtained from healthy donors and expanded (increased in numbers) in the laboratory, in order to enhance their tumor destroying potential. In addition, the most potent DNT donor will be selected for each patient by screening before his/her DNT treatment. DNTs will be administered at 3 different dose levels (different numbers of DNT cells) into 3 different groups of patients. After infusion of the first (lowest cell number) dose level, patients will be monitored to make sure they do not experience any severe adverse side effects. Only after the confirmation of the safety of the previous dose, the next group of patients will be given the next dose (higher cell number). In addition to determining the safety of DNT treatment, we will take blood samples from the treated patients at several time points after infusion to assess how long the DNT cells are detectable in the patients, which will provide guidance on the optimal number of injections and the time between each injection required to achieve the best results. In addition, we will determine if infusion of DNT cells changed the amount of time for the patients’ immune cells to recover from chemotherapy. Furthermore, whether DNT treatment will decrease AML cells and reduce the rate of the disease returning will be monitored. The results from this study will indicate whether DNTs can be safely used as a new treatment for AML to save patient lives.
Grant: 6555-18 | Translational Research Program (TRP):
Location:The University of Texas MD Anderson Cancer Center, Houston, Texas 77210-4266
Project Title: Immunotherapy For Multiple Myeloma Using Off-the-Shelf Cord Blood Derived Natural Killer CellsProject Summary:
Multiple myeloma (MM) is caused by the malignant transformation of plasma cells. High dose chemotherapy followed by stem cell transplantation from a matched healthy donor (allogeneic stem cell transplantation) offers a potentially curative treatment for advanced cases of this disease. Unfortunately, only about 25% of MM patients can expect to benefit from this approach, mainly because of the high risk of infection and other toxicities associated with allogeneic stem cell transplantation, as well as the high relapse hazard that defines resistant MM. We propose to take advantage of an exciting new weapon, cancer immunotherapy, to combat high-risk MM without the risks associated with allogeneic stem cell transplantation. Natural killer (NK) cells, isolated either from the patients themselves or from normal adult donors, are being used increasingly because of their potent anti-cancer effects. We have identified umbilical cord blood as an ideal source of NK cells, as the cells are already frozen and ready for use, without the need for collection from an adult donor. The aim of this research is to harness NK cells to destroy MM cells. Recent progress in our laboratories has shown that NK cells can be isolated from cord blood and expanded outside the body to large enough numbers to be used in adult patients, where they are expected to kill MM cells efficiently without introducing major toxic effects. This NK cell activity, when combined with high dose chemotherapy, a novel drug called lenalidomide (which promotes the anti-myeloma effects of NK cells), and elotuzumab (an antibody that targets a protein on the surface of myeloma cells) could establish an entirely new strategy of effective immunotherapy for MM that may eliminate the need for allogeneic stem cell transplantation in this disease. Finally, we propose to boost the anti-myeloma potential of NK cells by engineering them to increase their ability to recognize and kill MM cells using a mouse model of the disease. If our attempt at specific targeting is successful in the laboratory, we will move this strategy into clinical testing as rapidly as possible.
Grant: 6544-18 | Translational Research Program (TRP):
Location:Mayo Clinic, Rochester, Minneapolis, Minnesota 55486-0334
Project Title: Modulating Immune Function In Peripheral T-cell Lymphoma (PTCL)Project Summary:
Patients with peripheral T- cell lymphoma (PTCL) constitute approximately 12-15% of all lymphoma cases and PTCL patients typically have a poor outcome. Patients with PTCL typically respond to initial combination chemotherapy, but most patients subsequently progress and require additional therapy. Treatments such as romidepsin and belinostat have been approved for patients with PTCL, but their efficacy has been limited. There is therefore clearly a need for additional new therapies to treat patients with PTCL.
Multiple mechanisms account for the lack of durable benefit with current treatment, but the inability of tumor-specific immune cells to eradicate the lymphoma is a central issue. A novel mechanism used by cancer cells to inhibit the immune response, however, is overexpression of programmed death ligand 1 or 2 (PD-L1 or PD-L2). These proteins interact with the programmed death-1 (PD-1) receptor expressed on intratumoral T-cells and provide an inhibitory signal thereby suppressing anti-tumor immunity. In previous work, we have shown that PD-1/PD-1 ligand interactions are critically important in PTCL and have found that PD-1 is expressed both on malignant cells and in the tumor microenvironment. Similarly, we have found that PD-L1 is highly expressed by malignant T-cells and intratumoral monocytes, and have shown that tumor-associated PD-L1 suppresses T-cell immunity.
Monoclonal antibodies that block PD-1 signaling can prevent T-cell suppression and promote an anti-lymphoma immune response. Antibodies, directed against PD-1 or PD-L1, are currently being tested in clinical trials and have shown remarkable efficacy in some hematologic malignancies. Despite broad clinical use of PD-1 directed therapy, very little is known about the immunology of PD-1 signaling in hematological malignancies. In PTCL in particular, PD-1/PD-L1/2 signaling is complicated by the fact that the receptor and ligands can both be expressed on the cancer cell. Furthermore, initial clinical trials have included very few patients with PTCL; however, in 5 patients receiving nivolumab, an antibody that blocks PD-1 signaling, 2 patients had an objective response, suggesting possible efficacy of PD-1 blockade in PTCL.
In this application, therefore, we propose to 1) measure the immune consequences of inhibiting PD-1/PD-1 ligand signaling, 2) determine the clinical efficacy of PD-1 blockade alone, and in combination with romidepsin, in patients with relapsed and refractory PTCL, and 3) determine the immunological predictors of clinical response to PD-1 therapy in patients with PTCL. In the proposed aims, we will determine how well PD-1 blockade works in PTCL, the specific mechanism of action of PD-1 blockade in PTCL, and in which subgroup of PTCL patients PD-1 blockade is predicted to have clinical benefit. Successful completion of this project is likely to have a major impact on clinical practice by potentially leading to an effective new therapy for patients with PTCL.
Grant: 6539-18 | Translational Research Program (TRP):
Location:Board of Trustees of the Leland Stanford Junior University, San Francisco, California 94144-4253
Project Title: Applying An Innovative Microscopy Platform To Study Lymphoma In The Context Of A New Clinical TrialProject Summary:
For decades, cancer treatment has relied on toxic chemotherapy to kill cancer cells, which also kills normal cells in the body and causes severe side effects. We have entered a new era of cancer therapies in which we harness the precision of the body’s immune system to seek and destroy each cancer cell, akin to how it rids the body of infections. However, this result currently remains out of reach for the vast majority of cancer patients. There are two main hurdles to overcome. First, we need better strategies that work in a larger proportion of patients. Second, and related, we need a better understanding of the ingredients necessary to produce a powerful immune response against the cancer.
To address the first challenge, our group has focused on a strategy called in situ vaccination, which involves injecting immune stimulants directly into a tumor to activate the body’s immune cells, which can then recognize and kill tumor cells anywhere in the body. These cells will also persist as memory cells to prevent the cancer from returning, similar to how a vaccine can prevent an infectious disease from taking root. The trick is to find the right combination of immune stimulants to make this work. In multiple mouse models of cancer, a small molecule called SD-101 and an antibody drug that recognizes the OX40 protein on immune cells combine to produce this exact result. SD-101 is a synthetic molecule that mimics bacterial DNA, thus acting as a danger signal that activates the immune system. We have found that this activation increases the amount of OX40 protein on T cells in the tumor, the immune cells responsible for recognizing and killing tumor cells. The anti-OX40 antibody boosts the activation of these T cells while also suppressing regulatory cells that dampen the immune response. In mice growing two tumors under their skin, injecting these two agents directly into just one tumor results in both tumors disappearing. We now propose to study this novel approach in patients with lymphoma in a clinical trial.
With regard to the second challenge, we have struggled to understand how cancer cells and immune cells interact because we lack techniques to study these processes broadly in small patient samples. Thus, we are collaborating to pilot a novel microscopy platform that simultaneously identifies a diverse array of cell types and proteins in a patient’s cancer, while preserving the tissue architecture, something that has not previously been possible. We propose to use this technique to study samples from patients as they undergo our combination treatment, to provide an unprecedented look at the precise interactions between the immune system and cancers. Armed with this knowledge, we hope to one day bring the power of immunotherapy to all cancer patients.
Grant: 5473-18 | Career Development Program (CDP):
Location:Broad Institute, Inc., Cambridge, Massachusetts 02142
Project Title: Probing The Translatome For Neoantigens In Chronic Lymphocytic LeukemiaProject Summary:
Our cells display on their surface a snapshot of their protein repertoire processed and presented in the form of antigens. Antigens are recognized by the immune cells, which assess whether the antigens are known or foreign and mount an immune response against cells with foreign antigens. DNA mutations in cancer cells produce mutant proteins, presented as neoantigens on the cancer cell surface. The immune cells recognize neoantigens as foreign and attempt to mount an immune response against these cancer cells. Recently approved immunotherapy drugs boost this immune response and show great promise in the clinic, but the response is often non-specific and may affect healthy tissues, resulting in autoimmunity. Thus, directing the immune cells to defend against specific neoantigens will further boost the immune response and minimize autoimmunity. However, identifying and selecting neoantigens to target remains challenging.
Putative neoantigens are commonly predicted by sequencing and identifying mutations in the exons (molecules which mostly contain information coding for amino acids) of a given genome. This approach is generally sufficient for cancers characterized by many DNA mutations. However, some cancers, such as chronic lymphocytic leukemia (CLL) accumulate fewer DNA mutations, resulting in fewer predicted neoantigens. Since exons represent about 1% of our genome and mutations can be found anywhere in the genome, we have the opportunity to identify previously unknown neoantigens that are generated from mutations outside of the exons. Using next generation sequencing technologies and computational tools, we will expand the neoantigen search beyond currently known genes, maximizing our chances at identifying neoantigens to target. The expanded search for neoantigens will broaden potential targets for therapy for CLL. Importantly, the computational approaches we are developing may be useful beyond CLL and may be used to identify novel neoantigens in any cancer, particularly those with low mutation load.
Grant: 5467-18 | Career Development Program (CDP):
Location:Walter & Eliza Hall Institute of Medical Research, Parkville 3050, Victoria
Project Title: The Key To Cancer Cell Death; Regulation Of The Pro-apoptotic Protein BIMProject Summary:
Treating blood cancer patients with conventional approaches remains unsatisfactory because the cancer often recurs and because of the undesirable side effects caused by many of the treatments currently offered. By improving our understanding of the genetic basis of hematopoietic malignancies, we can develop targeted agents that are more selective in their action against tumor cells.
In healthy organisms, many cells have a finite lifespan. These cells undergo a normal, programmed cell death process called “apoptosis” and are then replaced with new cells. Apoptosis is regulated by a number of proteins, including pro-apoptotic proteins, such as BIM and anti-apoptotic proteins, such as BCL2. A prominent hallmark of many leukemias and lymphomas is their inability to undergo apoptosis, allowing them to survive indefinitely. Research at my host institution contributed to the development of venetoclax, an inhibitor of the pro-survival protein BCL2, which treats cancers by restoring their ability to undergo cell death. In chronic lymphocytic leukemia (CLL), a leukemia where BCL2 is overactive, remarkable results have been achieved in clinical trials, recently leading to FDA approval of the drug for treatment of patients with high-risk CLL. Since different tumor types may express different apoptotic regulators, the results with venetoclax suggest that targeting apoptotic regulators specific to a tumor type may lead to better patient outcomes in a number of different cancers.
In mantle cell lymphoma (MCL), a disease related to CLL, expression of the pro-death molecule BIM is suppressed in 20% of patients. Thus, restoring BIM expression should sensitize these cells to undergo cell death, which may be particularly beneficial in combination with standard-of-care chemotherapeutic agents or the BCL2 inhibitor. This combination therapy may result in greater cell death and thus an enhanced therapeutic benefit. Though the role of BIM in regulating cell death is well-described, it is less clear how levels of BIM are regulated in normal cells or how BIM is suppressed in MCL. The focus of my research is to unravel the molecular mechanisms by which the expression of pro-death molecules, such as BIM, is controlled. I anticipate that the results I obtain could help explain how hematopoietic cancer cells can evade cell death and potentially lead to the development of novel approaches to treat these malignancies more effectively.
Grant: 3373-18 | Career Development Program (CDP):
Location:Emory University, Atlanta, Georgia 30322-4250
Project Title: Tetrameric Acetyltransferase ACAT1 Is A Novel Therapeutic Target In Treatment Of Human LeukemiaProject Summary:
Tyrosine kinases (TKs) are a group of proteins that serve as "on/off" switches to control various cellular functions. When TKs are continuously turned on (“activated”) in blood cells leukemia may result. Anti-leukemia drugs that are designed to target TKs in leukemia cells are widely used in clinics. However, many patients develop resistance to these drugs over time, making them less effective or not effective at all. Thus, it is critical to find alternative therapies to battle drug resistance and improve clinical outcome. Cancer cells, including leukemia cells, consume more sugar compared to normal cells. However, unlike normal cells that use glucose primarily for energy, cancer cells use glucose primarily to generate the “building blocks” of proteins and lipids, enabling the cancer cells’ rapid division rate. A protein complex called pyruvate dehydrogenase complex (PDC) functions as a “gatekeeper” to control the flow of sugar toward either energy generation or building block production. When the PDC is “closed,” such as in leukemia cells, most glucose will go towards the production of building blocks. Thus, finding out how PDC activity is inhibited in leukemia cells may uncover a new vulnerability of human leukemias.
Our previous research showed that a protein called acetyl-CoA acetyltransferase 1 (ACAT1) can significantly inhibit PDC activity. Our current studies show that ACAT1 can be highly activated in leukemia cells by TKs through a chemical modification called tyrosine phosphorylation, resulting in a more stabilized and activated form of ACAT1. Most importantly, we found that ACAT1 is more activated in leukemia patients than in healthy people, resulting in further PDC inhibition. Thus, we think ACAT1 is a promising anti-leukemia drug target. By screening FDA-approved compounds, we successfully identified a novel ACAT1 inhibitor called Arecoline Hydrobromide (AH). Our results showed that AH can effectively inhibit leukemia cell growth. We will perform further studies to gain a detailed understanding of how AH inhibits PDC, and we will test AH potency in various leukemia cell lines, animal models, and leukemia patient samples. We will also work with expert chemists to develop new ACAT1 inhibitors, related to AH, but with improved potency. Altogether, this research will provide new insight into anti-leukemia drug design, help identify new novel drug targets, and ultimately uncover novel therapeutic approaches in blood cancers.