Grant: 5445-16 | Career Development Program (CDP):
Location:University of California, San Francisco, San Francisco, California 94143
Project Title: Identifying Ubiquitin Ligase Substrates Important For Progression Of Multiple MyelomaProject Summary:
In recent years, patient survival of multiple myeloma has been greatly enhanced by the introduction of two classes of pharmaceuticals, bortezomib and the IMiDs, including pomalidomide and lenalidomide. Both of these drug classes inhibit a cellular pathway called the ubiquitin-proteasome system (UPS). The Toczyski laboratory has developed a technology that can be used to explore the function of components of this pathway. In this proposal, I plan to use this technology on two groups of enzymes. First, I will use it on a protein (called CRBN) already known to be important for multiple myeloma progression and which is the target of the IMiDs. This will allow us to better understand how this protein works and will inform our ability to generate new drugs against it. Second, I will use it to explore the function of related proteins in multiple myeloma cells. Together, these studies will provide valuable information for combating this disease.
Grant: 6482-16 | Translational Research Program (TRP):
Location:Brigham and Women’s Hospital, Boston, Massachusetts 02241-3149
Project Title: Development Of SALL4 Inhibitory Drug(s) In Treating AMLProject Summary:
A total of 18,860 new cases and 10,460 deaths from acute myeloid leukemia (AML) are estimated in the United States in 2014. This is a disease in which standard chemotherapy has not changed in over 25 years, and survival remains extremely poor.
Our proposal is to treat leukemia by targeting a transcription factor SALL4. SALL4 is a gene that is expressed in embryonic stem cells, down-regulated during development, and absent in most adult tissues. Importantly, SALL4 is aberrantly re-expressed in various cancer cells, including most AML. We have recently reported that the transcription factor SALL4 plays a key role in promoting self-renewal of leukemic stem cells (LSC). We have identified a peptide that can block SALL4 function in leukemogenesis. We further propose that with the design of small molecules that mimic the peptide to inhibit SALL4, we can better target leukemia.
To pursue this direction, Leukemia and Lymphoma Society (LLS) has recently funded us a 320K-compound screen project under the screen to lead (SLP) program. We have successfully identified and validated several small molecule chemical scaffolds that could be potential SALL4 inhibitors. These compounds represent novel non-peptide/peptoid scaffolds. We further propose to collaborate with chemists and to use these hits we identified through the SLP program as starting points for medicinal modifications and development of more potent, selective, and efficacious lead small molecules as novel therapies against leukemias.
Over all, accomplishment of our proposed project will help us to identify new lead compounds for therapeutic use in a disease in which survival remains extremely poor. In addition, our ground-breaking novel approach in targeting SALL4 in AML will serve as a paradigm for targeting SALL4 in other tumors since SALL4 is also aberrantly expressed in various solid tumors, thus, provide a new direction in targeted cancer therapy.
Grant: 6489-16 | Translational Research Program (TRP):
Location:Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024
Project Title: Optimizing Bispecific Antibody Therapy For Acute LeukemiaProject Summary:
Acute leukemias are difficult-to-treat cancers of white blood cells from which many patients will eventually die despite aggressive treatments. There is thus a critical need for new drugs to treat these tumors. For more than 30 years, proteins (so-called “antibodies”) that specifically recognize and grip on to leukemic cells have been developed with the hope of providing an effective yet relatively non-toxic treatment option for these diseases. So far, however, antibodies have shown relatively limited activity in the clinic against acute leukemias. One strategy that is pursued to make antibodies more effective is to modify them in a manner that they become “bispecific”, that is they recognize leukemia cells and the patient’s own immune cells (typically T-cells, a type of lymphocyte) at the same time, thereby bringing these 2 cell types in close contact to one another. The T-cell can then selectively kill the attached cancer cell. Highly promising results were recently reported with a small bispecific antibody called “blinatumomab” in some patients with acute lymphoblastic leukemia (ALL) who failed conventional chemotherapy. However, because of the small size of this antibody, it is eliminated efficiently by the kidneys; therefore, continuous intravenous administration via infusion pump is required for several weeks to maintain adequate blood levels. Also, about half of the patients do not experience good benefit from this antibody. The reasons why some but not all patients respond to these small bispecific antibodies are currently not fully understood, but our preliminary indicate that stimuli sent via T-cell co-receptors might play a role. Recognizing the limitations of presently exploited bispecific antibodies, the goal of our collaborative research project is to develop novel, highly active bispecific antibodies for the treatment of acute myeloid leukemia (AML) and ALL that have longer half-lives and can thus be given in a simpler fashion than current antibodies. We hope that our studies will identify lead candidate molecules that could be brought to the clinic toward the end of the 3-year award period. We will also study in detail how exactly small bispecific antibodies lead to the killing of acute leukemia cells, and study potential resistance mechanisms that may limit the usefulness of bispecific antibody. By understanding the factors that predict response, our research will then allow us to identify the most appropriate patients to be treated with these antibodies. Our findings will also lead to the development of combination treatments that may overcome resistance, thereby expanding the patient subsets that could benefit from these agents. Together, by optimizing bispecific antibodies, we anticipate that our investigations may significantly improve the treatment options for patients with acute leukemia.
Grant: 6485-16 | Translational Research Program (TRP):
Location:Regents of the University of Michigan, Pittsburgh, Pennsylvania 15251-2131
Project Title: Therapeutic Targeting Of Ash1L Histone Methyltransferase In Acute LeukemiasProject Summary:
Acute Myeloid Leukemia (AML) is a highly incurable disease and there is an urgent need for development of novel therapies. AML patients with high expression level of HOX genes have particularly unfavorable prognosis. Likewise, high level of HOXA9 was also shown to be implicated in T-cell acute lymphoblastic leukemia (ALL) cases. Therefore, regulation of HOX genes expression, in particular HOXA cluster genes, should represent an attractive target for drug discovery. Small molecule inhibitors that reduce HOXA gene expression might represent a potential treatment strategy for acute leukemia patients. Ash1L (Absent, small or homeotic 1-like) is a histone methyltransferase that belongs to a Trithorax group proteins involved in regulation of HOX genes. We have recently discovered that silencing of Ash1L expression results in a strong downregulation of HoxA genes in vivo.
In this project, we propose to target histone methyltransferase activity of Ash1L with small molecules as a potential therapeutic strategy for acute leukemias with high expression level of HOXA genes. We have already developed small molecule inhibitors of the Ash1L histone-methyltransferase activity, which directly bind to the SET domain of Ash1L and inhibit its enzymatic activity. These molecules represent very attractive lead compounds for further drug discovery efforts to develop potent Ash1L inhibitors with favorable drug-like properties. To achieve this goal, we propose three specific aims. Aim 1 will be focused on medicinal chemistry efforts combined with structural biology to improve potency and drug-like properties of our lead compounds, with the overall goal to develop Ash1L inhibitors suitable for in vivo efficacy studies in animal models of acute leukemias. In Aim 2 we will perform extensive characterization of Ash1L inhibitors in a panel of acute leukemia cells with various levels of HOXA9 and MEIS1 expression to assess their cellular effect and specificity. In addition, the most potent compounds will be evaluated in vivo in mice models of acute leukemias. In Aim 3 we will put efforts to assess whether small molecule inhibition of Ash1L affects the self-renewal potential of leukemic stem cells. We expect these studies will result in development of promising candidate compounds as novel therapeutic agents for acute leukemias with high expression level of HOX genes.
Grant: 1329-16 | Career Development Program (CDP):
Location:The Trustees of Columbia University in the City of New York, Columbia University Medical Center, New York, New York 10027
Project Title: Transcriptional Regulation Of Non-coding RNA Promotes AID Targeting And Chromosomal Alterations In The B Cell GenomeProject Summary:
B-lymphocytes are known for their ability to generate antibodies of the highest affinity to neutralize various antigens we encounter. In the process of generating high-affinity antibodies, B cells mutate the immunoglobulin loci (antibody encoding genes) and other regions of the B cell genome. These mutations are catalyzed by the enzyme activation induced deaminase (AID). Sometimes AID, in its effort to generate genetic diversity, mutagenizes other (inappropriate) regions of the B cell genome which eventually act as genetic lesions responsible for chromosomal translocations, causing cancer. Recent advances in biology have lead to the paradigm-shifting discovery that close to 90% of mammalian genomes express non-protein coding (nc) RNAs that may have some unidentified biological function. We aim to investigate how AID utilizes the non-coding RNA transcriptome of B cells to identify and mutate its target DNA sequences. We have identified a subset of large non-coding RNAs (lncRNAs) that are expressed from AID target DNA sequences in B cells; some of these lncRNAs have homologs in mammalian cells and that are mutated in B cell lymphomas. Using mouse genetics, genomics, and biochemistry we aim to investigate the role of these novel lncRNAs in B cell development and tumorigenesis. We realize that the expression of some of the identified ncRNAs may directly correlate with oncogenesis; we plan to evaluate the potential of these RNAs as cancer biomarkers.
Grant: 6486-16 | Translational Research Program (TRP):
Location:The University of Texas MD Anderson Cancer Center, Houston, Texas 77210-4266
Project Title: Targeting Apoptosis In ALL With Venetoclax And Cytotoxic ChemotherapyProject Summary:
While well over 90% of children diagnosed with acute lymphoblastic leukemia can now expect to be cured of their disease, the prognosis in adults is not as good. Roughly half of adult patients diagnosed with ALL will succumb to the disease. Thus, there is an important unmet need to improve therapy in adult ALL. We propose to perform initial clinical testing of the safety and effectiveness of an exciting new drug, venetoclax (ABT-199, AbbVie), that has the potential to cause malignant ALL cells to essentially commit suicide.
Inside each of our cells is a cell suicide program called apoptosis. If a cell sustains enough damage, it senses this and commits suicide by apoptosis. In most cells in our bodies, the program of apoptosis is relatively dormant, so that it requires a lot to make normal cells commit suicide. However, in certain cancers like ALL, the apoptosis program is quite active and agents that activate apoptosis can very effectively induce the malignant cells to commit suicide. In some cases of ALL, there is a protein, called BCL-2, which opposes apoptosis, and keeps the ALL cells from committing to apoptosis. In such cells, a selective inhibitor of BCL-2 is likely to be effective.
Venetoclax is an oral drug from AbbVie Pharmaceuticals that selectively inhibits BCL-2. It has shown excellent efficacy in clinical trials of chronic lymphocytic leukemia, a disease of abnormal white blood cells similar, but not identical, to ALL. In clinical trials of venetoclax, over 80% of patients who were resistant to prior therapies had a good response to the drug. 25% had a complete response, so that no remaining disease was detectable by conventional means. Moreover, there were few toxicities. In addition, venetoclax has showed activity in different types of lymphoma as well as acute myelogenous leukemia.
Several laboratories, including those of Drs. Konopleva and Letai, have shown that ALL is dependent on BCL-2 and sensitive to venetoclax. Similar results provoked the clinical trials in CLL and AML where venetoclax has shown such promising activity. The purpose of this proposal is to test our ability to extend the benefits of venetoclax to ALL. We propose to perform initial clinical testing of the effectiveness of an exciting new drug, venetoclax (ABT-199, AbbVie). We propose to use this agent in elderly patients in combination with a conventional low intensity chemotherapy regimen to test the safety of the combination but also to get preliminary estimates of its effectiveness. In addition, Dr. Letai has developed an exciting biomarker that has previously demonstrated the ability to predict which cases of leukemia are most sensitive to venetoclax in other clinical trials. We will be using BH3 profiling in parallel with this study to see if we can predict which patients get most benefit. If successful we will be able to use BH3 profiling to direct venetoclax therapy to those who will benefit most in future clinical trials.
Grant: 5447-16 | Career Development Program (CDP):
Location:Board of Trustees of the Leland Stanford Junior University, San Francisco, California 94144-4253
Project Title: SINGLE CELL RNA IMAGE SEQUENCING FOR SPATIO-TEMPORAL ANALYSIS OF T-CELL DEVELOPMENT FROM STEM CELLSProject Summary:
Grant: R6503-16 | Translational Research Program (TRP):
Location:Regents of the University of Michigan, Pittsburgh, Pennsylvania 15251-2131
Project Title: Peripheral T-cell Lymphoma, Not Otherwise Specified: The Cell Of Origin As A Predictive Biomarker And Therapeutic Target.Project Summary:
T-cell cancers, collectively referred to as T-cell lymphomas (TCLs), are relatively rare, difficult to classify, and poorly understood. Most TCLs are clinically aggressive and resistant to standard chemotherapy regimens. Therefore, these lymphomas are rarely curable with existing therapies. We believe that the biology of normal (noncancerous) human T cells can provide clues about TCL classification that may lead to the development of improved treatment strategies. For example, different subsets of normal T cells are tightly controlled by a group of regulatory proteins. One of these proteins, called GATA-3, regulates the growth and survival of a particular T-cell subset. We speculated that expression of GATA-3 and other related proteins might determine important aspects of TCL biology and aid in TCL classification. We found that the majority of patients with the most common TCL express either GATA-3 or an alternative regulatory protein, T-bet. These patients were previously thought to have the same TCL. However, our findings demonstrate that this TCL comprises two clinically and molecularly distinct subsets: one characterized by GATA-3 expression and the other by T-bet expression. These findings have significant implications for the classification of this TCL and for its treatment. For example, one of these TCL subsets may respond better than the other to standard chemotherapeutic agents. We will conduct a multicenter clinical trial to address this possibility. Patients with relapsed or refractory TCL will be classified as having either “GATA-3” or “T-bet” TCL prior to treatment with one of four standard chemotherapy agents (selected by their physician), and the response to treatment will be subsequently evaluated. We anticipate that the results of this study will help physicians select the “right therapy” for the “right patient”. Part of this effort will require development of reliable, accurate, and clinically accessible assays to identify these TCL subsets. We will examine two complementary assays in a large cohort of well-characterized TCL patients. While optimization of currently available therapies is important, an equally important goal is the development of improved therapeutic strategies. For the second proposed study, we will test a new therapeutic strategy based on our work demonstrating that GATA-3 confers resistance to chemotherapy. Since GATA-3 expression is controlled by a cell surface protein called the T-cell receptor (TCR), inhibition of TCR signals by the oral chemotherapeutic agent Ixazomib should inhibit GATA-3 expression in TCL. This novel therapeutic strategy will be examined in a single center, phase II study. We hope that the knowledge gained from this body of work will ultimately improve outcomes for patients afflicted with these aggressive lymphomas.
Grant: 6488-16 | Translational Research Program (TRP):
Location:Albert Einstein College of Medicine, Inc., Bronx, New York 10461
Project Title: STAT3 Inhibition As A Therapeutic Strategy Against MDS And AML Stem CellsProject Summary:
Myelodysplastic syndromes and acute myeloid leukemia are blood cancers that are increasing in incidence and can result from exposure to harmful chemicals and ionizing radiation. These diseases are caused by genetic changes in the blood stem cells that lead to a disruption of their functionality. Blood stem cells are capable of differentiating in all different types of blood cells and rely on certain networks of genes that have to be switched on or off in a coordinated manner. We have shown that stem cells in MDS and AML patients have genetic alterations. We have also shown that these abnormal stem cells are not killed by drugs such as azacytidine and are a cause of disease relapse. Thus, identification of targets against these abnormal stem cells is important in the development of future curative therapeutic strategies. In this proposal we aim to target MDS stem cells with a drugs against the protein STAT3. We have shown that abnormal stem cells from MDS and AML patients have higher levels of STAT3 and that patients with higher STAT3 levels have a shorter lifespan. Our work has shown that inhibiting this protein can lead to death of MDS/AML stem cells and potentially prevent disease relapses. We propose to test a novel protein based drug called STAT3-ISIS-Rx in human samples and animal models of MDS and AML. This agent is also a selective inhibitor of the STAT3 protein and is being tested in clinical trials in lymphoma We also propose to test an approved drug, Pyrimethamine, that is being used in another leukemia (CLL) based on its ability to inhibit the STAT3 protein. We will test whether inhibition of STAT3 by these drugs can inhibit genetically abnormal MDS stem cells in patients. Our studies will lead to its development of these agents in future clinical trials in MDS and AML patients.
Grant: R6501-16 | Translational Research Program (TRP):
Location:Mayo Clinic Rochester, Minneapolis, Minnesota 55486-0334
Project Title: Overcoming T-cell Exhaustion In Follicular B-cell LymphomaProject Summary:
Immune cells within the tumor play a critical role in follicular non-Hodgkin lymphoma (NHL). Although lymphoma B-cells predominate, other cells are commonly present in malignant lymph nodes. These cells include T lymphocytes that appear to target lymphoma B-cells, and while increased numbers of intratumoral T-cells are associated with an improved outcome, intratumoral T-cells seem unable to eradicate the malignant cells.
In work done during the initial funding period, we have shown that intratumoral T-cells in follicular lymphoma are functionally exhausted due to chronic cytokine stimulation. Specifically, we have found that immunostimulatory proteins including interleukin-12 (IL-12), transforming growth factor beta (TGF-β) and monokine induced by gamma interferon (MIG/CXCL9) cause T-cell exhaustion. Exhausted T-cells are characterized by expression of TIM-3 and PD-1 on the cell surface. Exhausted cells are unable to grow, produce cytokines or respond to activation, and signaling through PD-1 perpetuates the exhausted T-cell phenotype. Increased numbers of intratumoral TIM-3+PD-1+ T-cells are associated with a poor prognosis and an increased likelihood of transformation to a more aggressive lymphoma.
We therefore hypothesize that blocking PD-1 signaling will reverse T-cell exhaustion and result in clinical benefit for lymphoma patients. Initial clinical trials have reported responses in low-grade lymphoma patients treated with anti-PD-1 antibodies, but not all patients treated benefited from this therapy. In this grant renewal, we propose to test the safety and efficacy of an anti-PD-1 antibody, pembrolizumab, in patients with relapsed low-grade lymphoma and to identify the immune cell composition that is associated with clinical responses. We will then determine whether reversal of T-cell exhaustion is the dominant mechanism responsible for clinical benefit.
Successful completion of the aims of this proposal will result not only in confirmation of a novel therapy to improve tumor immunity in patients with follicular lymphoma, but also in the identification of an immune signature that identifies patients most likely to benefit from this treatment approach.