Cancer

Coding Dimension ID: 
280
Coding Dimension path name: 
Cancer
Funding Type: 
Disease Team Therapy Planning I
Grant Number: 
DR2-05352
Investigator: 
Type: 
PI
ICOC Funds Committed: 
$65 120
Disease Focus: 
Cancer
oldStatus: 
Closed
Public Abstract: 

A important benefit of the tremendous progress in stem cell research has been the recognition that stem cell pathways are frequently re-activated in cancer cells conferring stem cell-like properties on a subset of tumor cells. This understanding is the basis for the emerging field of cancer stem cell (CSC) research.
The cancer stem cell paradigm is a new approach in cancer research that has profound implications for new anti-cancer drug development. It is now widely understood that tumors are comprised of different cell types. Experimental evidence has accumulated from many laboratories indicating that different tumor cells vary dramatically in their ability to grow a new tumor. The tumor cells capable of re-growing a new tumor are the CSCs, whereas the bulk of the tumor cells lack this capacity. This property of seeding new tumor growth is analogous to the growth of distant metastases that is a major cause of mortality in cancer patients. The highly tumorigenic cells CSCs share certain properties with normal stem cells, but have accumulated cancer causing mutations clearly making them abnormal. It is now widely appreciated that may current therapies fail to effectively target the CSC population, and thus the CSCs mediate recurrence of disease after treatment. New drugs that target CSCs to kill them or cause them to differentiate into less dangerous, non-tumorigenic cells have the potential to provide significant benefit to patients and to dramatically improve cancer treatment.
This project is focused on developing a new anti-cancer drug that has been shown to effectively block CSC self renewal in a variety of common types of cancer. New therapeutic agents that are effective in targeting cancer stem cells may reduce metastases and relapse after treatment thus providing a chance for improved long term survival of cancer patients. In the first phase of the project, we will complete the manufacturing of the drug for subsequent use in clinical trial and also execute safety studies that are necessary before initiating clinical trials. Next, we will test the safety of the drug in patients in Phase 1 clinical trials. Lastly, we will determine the efficacy in breast cancer patients in Phase 2 trials. This project will utilize innovative clinical trial designs to identify the patient populations most likely to benefit from treatment with this new treatment. We intend to focus our clinical testing on an important subset of women with breast cancer for whom effective therapies are currently lacking. Our project is a unique partnership of industry and academic researchers and clinicians dedicated to bringing new medicines to patients most in need of effective therapy.

Statement of Benefit to California: 

This project will benefit the state of California and its citizens in several significant ways. The goal of the work funded by this grant is to develop a new cancer treatment. This agent attacks cancer stem cells - the most dangerous type of tumor cells because they have the unique ability to resist many current therapies and re-grow and metastasize to distant sites in the body. The funds from this study will be used to support innovative drug development and clinical testing in women with advanced breast cancer. Thus, this therapy will benefit cancer patients with a critical need for new treatment options. We have observed that agents that reduce cancer stem cells in tumors also inhibit the spread of metastatic disease. Patients with advanced cancers which have disseminated to distant organs typically require high cost hospital stays. Our new treatment is intended to ameliorate the incidence and relapse of metastatic cancer, thus reducing the requirement for hospitalization and associated specialized care for this class of advanced cancer patients.

In addition to the medical benefits of this project, funds from this grant will create and maintain high quality jobs in the state of California. California has been a recognized leader in biomedical research over the past several decades because of its excellent academic institutions and innovative companies attracting researchers from all over the country and the world. Many companies have made significant investments in establishing research facilities in California. Thus, biomedical research generates significant economic activity in the state. Continued leadership in the life sciences field relies on being at the forefront of cutting edge fields that are focal points of research interest and investment. Novel anti-cancer therapeutics, in general, and cancer stem cell-based therapeutic approaches, in particular, are excellent examples of important and innovative directions in drug development. CIRM will provide an important source of funding to support cancer stem cell therapeutics which hold the promise of becoming breakthrough medications in cancer treatment.

Progress Report: 
  • Our project is focused on developing a new anti-cancer drug that has been shown to effectively block cancer stem cell (CSC) self renewal in a variety of major tumor types. During the reporting period our group made significant advances on several fronts in advancing our novel stem cell directed therapy toward clinical development. In particular, we have associated cancer causing mutations in breast cancer in the molecular target of our therapeutic and shown that tumors bearing this type of mutation are exquisitely sensitive to our treatment. Based on this discovery, we have developed methodologies and reagents to identify patients who are most likely to benefit from treatment with our agent. Thus, this project is an excellent example of how "personalized medicine" is becoming a reality in cancer drug development. Furthermore, our results highlight the promise of targeting inappropriate activation of stem cell pathways as new strategy in cancer treatment.
  • During the reporting period we have assembled an experienced team of scientists and clinicians at our institution and also at collaborating institutions to execute the pre-clinical and clinical development of our new anti-cancer treatment. We have developed a detailed clinical strategy which involves a close collaboration between academic medical centers and the biotech industry. We have planned a series of clinical trials which will test the safety and efficacy of our anti-cancer drug and also test our hypothesis regarding selecting patients most likely to respond to treatment. This trials will take place at multiple sites including several in California.
  • In addition, we have made tremendous and tangible progress in advancing our therapeutic toward clinical testing. These steps include the completion of GMP manufacture of the drug for IND-enabling safety studies and for use in subsequent Phase 1 clinical trials and the initiation of IND-enabling safety studies.
Funding Type: 
Basic Biology III
Grant Number: 
RB3-05217
Investigator: 
Name: 
Type: 
PI
ICOC Funds Committed: 
$1 375 983
Disease Focus: 
Blood Cancer
Cancer
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 

The clinical potential of pluripotent stem cells for use in regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and controlled than is currently the case. Fundamental questions remain about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The overall goal of this research proposal is to discover if the cell types produced during differentiation of PSC produce the microenvironment needed for specialized tissue stem cells to develop.

To approach this question we will use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation pathways and offers a range of unique technical tools with which to rigorously study questions of differentiation. Adult hematopoietic stem cells survive and grow in the bone marrow only if they are physically close to specialized cell types, the so-called hematopoietic stem cell “niche”. We hypothesize that hematopoietic stem cells are not produced from pluripotent cells because the cells that form the niche and provide the necessary signals are not present during this early stage of differentiation.

Our research proposal has three specific aims. The first aim is to determine if a single cell type derived from pluripotent cells can generate both blood cells and the cells of the hematopoietic niche. The second aim is to identify the types of niche cells produced from pluripotent cells and define how each of them affect the growth of adult stem cells. In the third aim, the cell types that are found in aim 2 to best support adult hematopoiesis, will then be tested for their ability to promote the production of hematopoietic stem cells from pluripotent stem cells.

The findings from these studies will have broad applicability to the production of other types of tissues from pluripotent stem cells, all of which have stem cells that require interaction with a specialized niche. In addition to the biological questions explored in this proposal, our focus on the blood system has direct clinical relevance to the field of bone marrow and cord blood transplantation. The development of a human hematopoietic niche from pluripotent stem cells could potentially be used to expand hematopoietic stem cells from adult tissues like cord blood. Most importantly, the ability to control differentiation from pluripotent stem cells into the blood lineage could provide an unlimited source of matched cells for transplantation for patients with leukemia and other diseases of the bone marrow and the immune system who currently lack suitable donors.

Statement of Benefit to California: 

The unique combination of pluripotentiality and unlimited capacity for proliferation has raised the hope that pluripotent stem cells will one day provide an inexhaustible source of tissue for transplantation and regeneration. Diseases that might be treated from such tissues affect millions of Californians and their families. However, much is still to be learned about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The clinical potential of pluripotent stem cells for regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and better controlled than is currently the case.

The research proposed in this application has broad potential benefits for Californians both through the biological questions it will answer and the relevance of these studies for clinical translation. Our goal is to understand the way the microenvironment influences tissue production from pluripotent stem cells, a critical issue for the field of stem cell biology. Specifically we will explore the question- Do the cell types produced during differentiation of pluripotent stem cells produce an adequate microenvironment for the differentiation of tissue or are some cells inhibitory to tissue production? Our approach to these questions will be to use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation and offers a range of unique technical tools with which to study these questions rigorously. However, the fundamental concepts formed from these studies will have great relevance for the clinical production of other types of tissues from pluripotent stem cells, such as islets, neural cells and cardiac muscle.

In addition to the broad biological questions explored in this proposal, our focus on the blood system has direct clinical relevance to the field of bone marrow and cord blood transplantation. One goal in the proposal is to generate a cellular platform from pluripotent stem cells that will create an environment in which adult blood stem cells can grow and be expanded. Cell numbers collected from cord blood at birth are often insufficient for transplantation in adult patients and older children. The development of a human cell culture system that could expand the number of cord blood stem cells would provide new opportunities for transplantation for patients with leukemia and other diseases of the bone marrow and the immune system who currently lack suitable donors. All scientific findings and technical tools developed in this proposal will be made available to researchers throughout California, under the guidelines from the California Institute of Regenerative Medicine.

Progress Report: 
  • The clinical potential of pluripotent stem cells for use in regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and controlled than is currently the case. Fundamental questions remain about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The overall goal of this research proposal is to discover if the cell types produced during differentiation of PSC produce the microenvironment needed for specialized tissue stem cells to develop.
  • To approach this question we use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation pathways and offers a range of unique technical tools with which to rigorously study questions of differentiation. Adult hematopoietic stem cells survive and grow in the bone marrow only if they are physically close to specialized cell types, the so-called hematopoietic stem cell “niche”. We hypothesize that hematopoietic stem cells are not produced from pluripotent cells because the cells that form the niche and provide the necessary signals are not present during this early stage of differentiation.
  • Our research proposal has three specific aims. The first aim is to determine if a single cell type derived from pluripotent cells can generate both blood cells and the cells of the hematopoietic niche. The second aim is to identify the types of niche cells produced from pluripotent cells and define how each of them affect the growth of adult stem cells. In the third aim, the cell types that are found in aim 2 to best support adult hematopoiesis, will then be tested for their ability to promote the production of hematopoietic stem cells from pluripotent stem cells.
  • During the first year of support, we have made significant progress in the first two specific aims. We have developed a method that allows us to track the common origin of the blood forming cells and their microenvironment. We also have identified subsets of cells generated from pluripotent cells that have distinct functions in blood formation. Our plan during the next year is to fully characterize these subsets to understand how they function, and to improve our methods to expand them in culture.
  • The clinical potential of pluripotent stem cells for use in regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and controlled than is currently the case. Fundamental questions remain about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The overall goal of this research proposal is to discover if the cell types produced during differentiation of PSC produce the microenvironment needed for specialized tissue stem cells to develop.
  • To approach this question we use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation pathways and offers a range of unique technical tools with which to rigorously study questions of differentiation. Adult hematopoietic stem cells (HSC) survive and grow in the bone marrow only if they are physically close to specialized cell types, the so-called hematopoietic stem cell “niche”. We hypothesize that hematopoietic stem cells are not produced from pluripotent cells because the cells that form the niche and provide the necessary signals are not present during this early stage of differentiation.
  • Our research proposal has three specific aims. The first aim is to determine if a single cell type derived from pluripotent cells can generate both blood cells and the cells of the hematopoietic niche. The second aim is to identify the types of niche cells produced from pluripotent cells and define how each of them affect the growth of adult stem cells. In the third aim, the cell types that are found in aim 2 to best support adult hematopoiesis, will then be tested for their ability to promote the production of hematopoietic stem cells from pluripotent stem cells.
  • During the second year of support, we have made significant progress in all three specific aims. We continue to refine our method that allows us to track the common origin of the blood forming cells and their microenvironment during development. We have identified subsets of cells generated from pluripotent cells that can support cord blood HSC and now we are determining the mechanisms by which these cells act and how they can be best used to support HSC that develop from PSC.
  • The clinical potential of pluripotent stem cells for use in regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and controlled than is currently the case. Fundamental questions remain about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The overall goal of this research proposal is to discover if the cell types produced during differentiation of PSC produce the microenvironment needed for specialized tissue stem cells to develop.
  • To approach this question we use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation pathways and offers a range of unique technical tools with which to rigorously study questions of differentiation. Adult hematopoietic stem cells (HSC) survive and grow in the bone marrow only if they are physically close to specialized cell types, the so-called hematopoietic stem cell “niche”. We hypothesize that hematopoietic stem cells are not produced from pluripotent cells because the cells that form the niche and provide the necessary signals are not present during this early stage of differentiation.
  • Our research proposal has three specific aims. The first aim is to determine if a single cell type derived from pluripotent cells can generate both blood cells and the cells of the hematopoietic niche. The second aim is to identify the types of niche cells produced from pluripotent cells and define how each of them affect the growth of adult stem cells. In the third aim, the cell types that are found in aim 2 to best support adult hematopoiesis, will then be tested for their ability to promote the production of hematopoietic stem cells from pluripotent stem cells.
  • During the third year of support, we have made significant progress in all three specific aims. We have now completed our studies that track the common origin of the blood forming cells and their microenvironment. We have performed functional studies to identify which of the cell types that we generate from pluripotent cells support HSC when grown in culture, and which do not. Finally we have performed gene expression analyses on these different cell types to understand the molecular pathways that they use to support HSC in culture.
  • The clinical potential of pluripotent stem cells for use in regenerative medicine will be realized only when the process by which tissues are generated from these cells is significantly more efficient and controlled than is currently the case. Fundamental questions remain about the mechanisms by which pluripotent stem cells differentiate into mature tissue. The overall goal of this research proposal is to discover if the cell types produced during differentiation of PSC produce the microenvironment needed for specialized tissue stem cells to develop.
  • To approach this question we use the hematopoietic (“blood-forming”) system as our model, as it is the best characterized tissue in terms of differentiation pathways and offers a range of unique technical tools with which to rigorously study questions of differentiation. Adult hematopoietic stem cells (HSC) survive and grow in the bone marrow only if they are physically close to specialized cell types, the so-called hematopoietic stem cell “niche”. We hypothesize that HSC are not produced from pluripotent cells because the cells that form the niche and provide the necessary signals are not present during this early stage of differentiation.
  • Our research proposal has three specific aims. The first aim is to determine if a single cell type derived from pluripotent cells can generate both blood cells and the cells of the hematopoietic niche. The second aim is to identify the types of niche cells produced from pluripotent cells and define how each of them affect the growth of adult stem cells. In the third aim, the cell types that are found in aim 2 to best support adult hematopoiesis, will then be tested for their ability to promote the production of hematopoietic stem cells from PSC.
  • In previous years we found that two types of mesenchyme (niche cells) can be produced from PSC, one of which is significantly better than the other at supporting the growth and maintenance of adult HSC. We have performed gene expression analyses on these different types of mesenchyme to uncover which molecular pathways are important for the support HSC in culture. During the fourth and final year of support, we have focused most of our attention on experiments to functionally test two of these pathways to determine if they are key to how mesenchyme sustains adult HSC. These studies are ongoing. In addition we have now completed our studies that track the common origin of the blood forming cells and their microenvironment and submitted them for publication.
Funding Type: 
Early Translational II
Grant Number: 
TR2-01816-A
Investigator: 
Type: 
PI
ICOC Funds Committed: 
$3 607 305
Disease Focus: 
Blood Cancer
Cancer
Stem Cell Use: 
Cancer Stem Cell
Cell Line Generation: 
Adult Stem Cell
Cancer Stem Cell
Public Abstract: 

Leukemia is the most frequent form of cancer in children and teenagers, but is also common in adults. Chemotherapy has vastly improved the outcome of leukemia over the past four decades. However, many patients still die because of recurrence of the disease and development of drug-resistance in leukemia cells.
In preliminary studies for this proposal we discovered that in most if not all leukemia subtypes, the malignant cells can switch between an “proliferation phase” and a “quiescence phase”. The “proliferation phase” is often driven by oncogenic tyrosine kinases (e. g. FLT3, JAK2, PDGFR, BCR-ABL1, SRC kinases) and is characterized by vigorous proliferation of leukemia cells. In this phase, leukemia cells not only rapidly divide, they are also highly susceptible to undergo programmed cell death and to age prematurely. In contrast, leukemia cells in “quiescence phase” divide only rarely. At the same time, however, leukemia cells in "quiescence phase" are highly drug-resistant. These cells are also called 'leukemia stem cells' because they exhibit a high degree of self-renewal capacity and hence, the ability to initiate leukemia. We discovered that the BCL6 factor is required to maintain leukemia stem cells in this well-protected safe haven. Our findings demonstrate that the "quiescence phase" is strictly dependent on BCL6, which allows them to evade cell death during chemotherapy treatment. Once chemotherapy treatment has ceased, persisting leukemia stem cells give rise to leukemia clones that reenter "proliferation phase" and hence initiate recurrence of the disease. Pharmacological inhibition of BCL6 using inhibitory peptides or blocking molecules leads to selective loss of leukemia stem cells, which can no longer persist in a "quiescence phase".
In this proposal, we test a novel therapeutic concept eradicate leukemia stem cells: We propose that dual targeting of oncogenic tyrosine kinases (“proliferation”) and BCL6 (“quiescence”) represents a powerful strategy to eradicate drug-resistant leukemia stem cells and prevent the acquisition of drug-resistance and recurrence of the disease. Targeting of BCL6-dependent leukemia stem cells may reduce the risk of leukemia relapse and may limit the duration of tyrosine kinase inhibitor treatment in some leukemias, which is currently life-long.

Statement of Benefit to California: 

Leukemia represents the most frequent malignancy in children and teenagers and is common in adults as well. Over the past four decades, the development of therapeutic options has greatly improved the prognosis of patients with leukemia reaching 5 year disease-free survival rates of ~70% for children and ~45% for adults. Despite its relatively favorable overall prognosis, leukemia remains one of the leading causes of person-years of life lost in the US (362,000 years in 2006; National Center of Health Statistics), which is attributed to the high incidence of leukemia in children.
In 2008, the California Cancer Registry expected 3,655 patients with newly diagnosed leukemia and at total of 2,185 death resulting from fatal leukemia. In addition, ~23,300 Californians lived with leukemia in 2008, which highlights that leukemia remains a frequent and life-threatening disease in the State of California despite substantial clinical progress. Here we propose the development of a fundamentally novel treatment approach for leukemia that is directed at leukemia stem cells. While current treatment approaches effectively diminish the bulk of proliferating leukemia cells, they fail to eradicate the rare leukemia stem cells, which give rise to drug-resistance and recurrence of the disease. We propose a dual targeting approach which combines targeted therapy of the leukemia-causing oncogene and the newly discovered leukemia stem cell survival factor BCL6. The power of this new therapy approach will be tested in clinical trials to be started in the State of California.

Progress Report: 
  • Leukemia is the most frequent form of cancer in children and teenagers, but is also common in adults. Chemotherapy has vastly improved the outcome of leukemia over the past four decades. However, many patients still die because of recurrence of the disease and development of drug-resistance in leukemia cells. In preliminary studies for this proposal we discovered that in most if not all leukemia subtypes, the malignant cells can switch between an "expansion phase" and a "dormancy phase". The "expansion phase" is often driven by oncogenic tyrosine kinases (e. g. FLT3, JAK2, PDGFR, BCR-ABL1, SRC kinases) and is characterized by vigorous proliferation of leukemia cells. In this phase, leukemia cells not only rapidly divide, they are also highly susceptible to undergo programmed cell death and to age prematurely. In contrast, leukemia cells in "quiescence phase" divide only rarely. At the same time, however, leukemia cells in "domancy phase" are highly drug-resistant. These cells are also called 'leukemia stem cells' because they exhibit a high degree of self-renewal capacity and hence, the ability to initiate leukemia.
  • Progress during Year 1: During the first year of this project, we discovered that the BCL6 factor is required to maintain leukemia stem cells in this well-protected safe haven. Our findings during year 1 demonstrate that the "dormancy phase" is strictly dependent on BCL6, which allows them to evade cell death during chemotherapy treatment. Once chemotherapy treatment has ceased, persisting leukemia stem cells give rise to leukemia clones that reenter "proliferation phase" and hence initiate recurrence of the disease. Pharmacological inhibition of BCL6 using inhibitory peptides or blocking molecules leads to selective loss of leukemia stem cells, which can no longer persist in a "dormancy phase" .
  • In year 1, we have performed screening procedures to identify novel therapeutic BCL6 inhibitors to eradicate leukemia stem cells: We have found that dual targeting of oncogenic tyrosine kinases ("expansion phase" ) and BCL6 ("dormancy phase") represents a powerful strategy to eradicate drug-resistant leukemia stem cells and prevent the acquisition of drug-resistance and recurrence of the disease.
  • Goal for years 2-3: Targeting of BCL6-dependent leukemia stem cells may reduce the risk of leukemia relapse and may limit the duration of tyrosine kinase inhibitor treatment in some leukemias, which is currently life-long.
Funding Type: 
Early Translational II
Grant Number: 
TR2-01816-B
Investigator: 
Institution: 
Type: 
Partner-PI
ICOC Funds Committed: 
$3 607 305
Disease Focus: 
Blood Cancer
Cancer
Collaborative Funder: 
Germany
Stem Cell Use: 
Cancer Stem Cell
Cell Line Generation: 
Adult Stem Cell
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Leukemia is the most frequent form of cancer in children and teenagers, but is also common in adults. Chemotherapy has vastly improved the outcome of leukemia over the past four decades. However, many patients still die because of recurrence of the disease and development of drug-resistance in leukemia cells.
In preliminary studies for this proposal we discovered that in most if not all leukemia subtypes, the malignant cells can switch between an “proliferation phase” and a “quiescence phase”. The “proliferation phase” is often driven by oncogenic tyrosine kinases (e. g. FLT3, JAK2, PDGFR, BCR-ABL1, SRC kinases) and is characterized by vigorous proliferation of leukemia cells. In this phase, leukemia cells not only rapidly divide, they are also highly susceptible to undergo programmed cell death and to age prematurely. In contrast, leukemia cells in “quiescence phase” divide only rarely. At the same time, however, leukemia cells in "quiescence phase" are highly drug-resistant. These cells are also called 'leukemia stem cells' because they exhibit a high degree of self-renewal capacity and hence, the ability to initiate leukemia. We discovered that the BCL6 factor is required to maintain leukemia stem cells in this well-protected safe haven. Our findings demonstrate that the "quiescence phase" is strictly dependent on BCL6, which allows them to evade cell death during chemotherapy treatment. Once chemotherapy treatment has ceased, persisting leukemia stem cells give rise to leukemia clones that reenter "proliferation phase" and hence initiate recurrence of the disease. Pharmacological inhibition of BCL6 using inhibitory peptides or blocking molecules leads to selective loss of leukemia stem cells, which can no longer persist in a "quiescence phase".
In this proposal, we test a novel therapeutic concept eradicate leukemia stem cells: We propose that dual targeting of oncogenic tyrosine kinases (“proliferation”) and BCL6 (“quiescence”) represents a powerful strategy to eradicate drug-resistant leukemia stem cells and prevent the acquisition of drug-resistance and recurrence of the disease. Targeting of BCL6-dependent leukemia stem cells may reduce the risk of leukemia relapse and may limit the duration of tyrosine kinase inhibitor treatment in some leukemias, which is currently life-long.

Statement of Benefit to California: 

Leukemia represents the most frequent malignancy in children and teenagers and is common in adults as well. Over the past four decades, the development of therapeutic options has greatly improved the prognosis of patients with leukemia reaching 5 year disease-free survival rates of ~70% for children and ~45% for adults. Despite its relatively favorable overall prognosis, leukemia remains one of the leading causes of person-years of life lost in the US (362,000 years in 2006; National Center of Health Statistics), which is attributed to the high incidence of leukemia in children.
In 2008, the California Cancer Registry expected 3,655 patients with newly diagnosed leukemia and at total of 2,185 death resulting from fatal leukemia. In addition, ~23,300 Californians lived with leukemia in 2008, which highlights that leukemia remains a frequent and life-threatening disease in the State of California despite substantial clinical progress. Here we propose the development of a fundamentally novel treatment approach for leukemia that is directed at leukemia stem cells. While current treatment approaches effectively diminish the bulk of proliferating leukemia cells, they fail to eradicate the rare leukemia stem cells, which give rise to drug-resistance and recurrence of the disease. We propose a dual targeting approach which combines targeted therapy of the leukemia-causing oncogene and the newly discovered leukemia stem cell survival factor BCL6. The power of this new therapy approach will be tested in clinical trials to be started in the State of California.

Progress Report: 
  • During the past reporting period (months 18-24 of this grant), we have made progress towards all three milestones. Major progress in Milestone 1 was made by identifying 391 compounds in 10 lead classes that will be developed further in a secondary fragment-based screen. While the goal of identifying lead class compounds with BCL6 inhibitory activity has already been met, we propose to run a secondary, fragment-based screen to refine the existing lead compounds and prioritize a small number for cell-based validation in Milestone 2. The success in Milestone 1 was based on computational modeling, HTS of 200,000 compounds and Fragment-based drug discovery (FBDD).
  • For Milestone 2, we have successfully established POC analysis tools for validation of the ability of compounds to bind the BCL6 lateral groove and already produced 300 mg of BCL6-BTB domain protein needed for biochemical binding assays. Progress in Milestone 2 is based on surface plasmon resonance (SPR) and nuclear magnetic resonance (NMR) assays. In the coming months, we will use crystallographic fragment screening using a subset of our fragment library in addition to SPR and NMR, since crystallographic fragment screens have been shown to yield complimentary hits. For Milestone 3, we have now set up a reliable method to measure disease-modifying activity of BCL6-inhibitory compounds based on a newly generated knockin BCL6 reporter mouse model, in which transcriptional activation of the endogenous BCL6 promoter drives expression of mCherry. This addresses a main caveat of these measurements was that they were strongly influenced by the copy number of lentivector integrations. The BCL6fl/+-mCherry knockin BCL6 reporter system will provide a stable platform to study BCL6-expressing leukemia cells and effects of BCL6 small molecule inhibitors on survival and proliferation on BCL6-dependent leukemia cell populations. This will be a key requirement to measure disease-modifying activity of inhibitory compounds in large-scale assays in Milestone 3. Other requirements (e.g. leukemia xenografts) are already in place. 
  • During the past two years of this grant, we have generated compounds that have the ability to block the function of BCL6. In previous work, we had identified BCL6 as a key requirement for persistence of leukemia stem cells, which are the root cause of leukemia relapse and drug-resistance in patients. Over the past six months, we have focused on validating the new compounds based on functional tests that allow us to measure the depth and durability of BCL6 blockade in cell-based assay. To this end, we designed a large-scale petri-dish system in which we measured the efficacy of 11 lead compounds and their derivatives to abrogate the ability of leukemia cells to form colonies, a capability that reflects the activity of leukemia stem cells. This assay allowed us to prioritize 4 compounds for further testing. In parallel, we developed a biological assay to verify that the compounds are actually hitting their target, i.e. BCL6, by measuring the activity of genes that are typically regualted by BCL6. These genes include tumor suppressors like p53 and Arf and we measured the ability of our compounds to re-instate p53 and Arf expression. We found that p53 and Arf were reinstated only by 2 of our 4 lead candidates, so current trouble-shooting efforts will attempt to clarify why this is the case and whether we can modify these two compounds to improve their on-target efficacy. The other two compounds will move forward in the next derivative screen, in which we perform a fragment-based, screen, i.e. test multiple derivative based on addition and removal of small structural changes (fragments). Other caveats to address in the next year will be stability (half-life) of the lead compounds, bioavailability (how much and how long the compound will be available in the blood stream) and toxicity (how much of the compound will be tolerated by mice, is there indication of damage to tissues upon long-term treatment?).The goal of these studies will be to make a strong case for IND-enabling studies, i.e. to enter a formal, government-regulated process to convert the strongest of our compound into an FDA-approved drug for potential clinical testing in patients with drug-refractory AML and ALL.
  • For Milestone 1, we have successfully completed aa second focused screen of derivative compounds based on 6 leads in the first round. The fragment-based screen is currently in validation for structure-activity relationships (SAR; collaboration with Dr. Paul Workman, ICR, London). The proof-of-concept analysis for Milestone 2, and demonstration of specific interaction in the BCL6 lateral grove has been completed at the end of month 36 of this grant. Using computer-aided drug design (CADD), Dr. Melnick’s group and collaborators had previously identified a small molecule, 79-6, that bound to the BCL6-BTB domain. Thereby, 79-6 targeted the interaction of BCL6 and its co-repressors NCOR, BCOR and SMRT, and restored expression of BCL6 targets in leukemia cells, including Arf and p53. One caveat of the 79-6 compound that was identified by validation studies in Dr. Workman’s laboratory included the low degree of cell penetration and short half-life of the compound. To address these caveats, Dr. Cardenas applied a novel, CADD-based methodology based on “site identification by ligand competitive saturation” (SILCS). SILCS is a method for identifying a molecule’s binding site by simulating its physical movement. In this case, SILCS simulated the physical movement of 79-6 tool compound in solution to map the exact interaction interface between 79-6 and the BCL6 lateral groove. Thereby, SILCS produced a 3-dimensional map of the 79-6 molecule’s probable binding sites, which was then used to design 35 compounds to test in vitro. The new lead compound emerging from Dr. Melnick’s SILCS screen, FX-1085, is approximately 30-fold more effective than 79-6 and is now being validated in our studies on AML and ALL samples (Milestone 3). Results from this collaboration indicates that FX-1085 robustly prevents the formation of complexes between BCL6 and its co-repressors NCOR, BCOR and SMRT and, hence, re-activates BCL6 target genes, including Arf and p53. In the past six months (6-12 of the NCE), we have performed experiments to validate activity of BCL6 inhibition in vivo for the treatment of xenografted Ph+ ALL cells, MLL-rearranged ALL and RAS-driven acute leukemias.
Funding Type: 
Early Translational II
Grant Number: 
TR2-01791
Investigator: 
ICOC Funds Committed: 
$3 370 607
Disease Focus: 
Brain Cancer
Cancer
Stem Cell Use: 
Adult Stem Cell
Cell Line Generation: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 

Modified viruses can be used to infect tumor cells and alter the tumor cell to make anti-tumor proteins. Most researchers use virus that can infect and modify the tumor cell it enters, but can not make more of itself to infect additional cells surrounding the original infected cell. This type of virus is called replication-incompetent virus. Use of replication-incompetent virus is considered safe because no additional virus, which potentially could get out of control, is generated inside of the tumor. However such therapies have been shown to have only limited beneficial effects, presumably because too many tumor cells never get infected.

Newer approaches investigate the use of replication-competent viruses to achieve highly efficient gene transfer to tumors. A successfully transduced tumor cell itself becomes a virus-producing cell, sustaining further transduction events even after initial administration. We propose here to use a type of replication-competent virus that only infects dividing cells and therefore will infect the rapidly dividing cancer cells but not normal brain cells.

The use of replication-competent virus is potentially more risky but is well justified in clinical scenarios involving highly aggressive and rapidly progressing metastatic tumor growth in the brain. To administer therapeutic virus into the brain, the virus is injected right into the center of the tumor. Yet, human brain tumors are often found as diffusely spreading foci in the brain and may be difficult to eliminate by locally-administered replication-competent retrovirus (RCR) vectors alone.

In this study we propose to use a type of adult stem cell called a "mesenchymal stem cell" (MSC) as a delivery system for the RCR vectors. Mesenchymal stem cells (MSCs) have been shown to have natural tumor-homing abilities, and can migrate to tumor foci and penetrate through into the interior of tumor masses. We propose to engineer them into "aircraft carriers" that release tumor-selective viruses, which can then efficiently spread suicide genes from one cancer cell to another in multiple tumor foci in the brain.

Statement of Benefit to California: 

This research is based on a solid foundation that combines two innovative technologies for the treatment of primary brain tumors, particularly glioblastoma multiforme (GBM) the most malignant form of brain tumor, which afflicts men, women, and children in California and elsewhere. Each of these technologies has been approved separately by FDA for clinical testing in humans: human mesenchymal stem cells (MSCs), and replication-competent retrovirus (RCR) vectors.

MSCs have been reported to exhibit a natural ability to migrate to solid tumors and penetrate into the tissue mass. Once inside a tumor, RCR vectors can spread selectively in the cancer cells and their replication can keep up with their uncontrolled proliferation, and their ability to integrate themselves into the cancer cell genome allows them to permanently "seed" tumor cells with therapeutic genes.

Here we propose to utilize the natural tumor homing ability of MSCs to deliver RCR vectors into brain tumors. This "virus vs. cancer" strategy takes advantage of the amplification process inherent in the spread of virus from cell to cell, and by using MSCs to initiate the virus infection efficiently in brain tumors, represents an approach that will have the potential to effectively treat this poor prognosis disease.

If successful, clinical application of this strategy can be implemented by an "off-the-shelf" mesenchymal stem cell (MSC) primary cell lines that have been pre-characterized for their tumor homing ability and virus production capability, and can be offered to patients without requiring an invasive procedure to harvest their own stem cells. Furthermore, this represents a treatment that could potentially be administered through a needle, thus making it unnecessary for patients to undergo major neurosurgical procedures entailing craniotomy at an advanced medical center. Hence this research could lead to a novel treatment approach that would particularly address the needs of brain tumor patients in California who are underserved due to socioeconomic and geographic constraints, as well as the elderly who are poor-risk for surgical interventions.

Progress Report: 
  • The goal of this project is to develop clinically translatable methods for engineering human mesenchymal stem cells (hMSC) to serve as tumor-homing cellular carriers that will deliver a replication-competent retrovirus (RCR) vector throughout primary brain tumors (gliomas). RCR vectors expressing a prodrug activator (also known as a "suicide gene"), which converts a non-toxic "pro-drug" compound into a potent chemotherapy drug directly generated within the infected tumor cells, have recently initiated testing in Phase I/II clinical trials for suicide gene therapy of recurrent high-grade gliomas. We are examining whether MSCs can serve as producer cells for this RCR vector, and whether the tumor transduction efficiency and therapeutic efficacy of this vector can be significantly enhanced, without compromising its safety profile, hMSC-based RCR producer cells (MSC-RCR) are used as a tumor-homing mobile carrier system that releases the virus as the cells migrate toward and within tumor masses in the brain. In particular, we are comparing this MSC-RCR cell-based carrier method against conventional delivery methods by direct intratumoral injection of 'naked' virus, in subcutaneous and intracranial brain tumor models.
  • To date, we have accomplished our milestone tasks for Year 1, by:
  • - successfully developing efficient methods to transduce hMSCs with RCR vectors and thereby convert them into vector producer cells
  • - developing and comparing in vitro and in vivo assays to evaluate the tumor-homing migratory activity of hMSCs
  • - applying these assays to screen and evaluate commercially available hMSC isolates
  • - demonstrating that the MSC-RCR delivery system can achieve significantly more efficient transduction of subcutaneous glioma models as compared to virus by itself
  • - confirming that enhanced transduction efficiency by MSC-RCR achieves more rapid tumor growth inhibition, as compared to 'naked' RCR alone, when applied to suicide gene therapy in subcutaneous tumor models of human glioma
  • - confirming that hMSC-mediated RCR delivery does not increase vector biodistribution to normal tissues, nor incur any increased risk of secondary leukemogenesis
  • Interestingly, through these studies we have found considerable variability in tumor-homing migration activity and intratumoral migration activity between hMSC isolates from different sources, a finding that may have significant implications for the development of hMSC-based clinical products. We are continuing to characterize additional hMSC isolates from various tissue sources, and are preparing a manuscript to publish these results.
  • Furthermore, based on our favorable results as described above, indicating the enhanced efficiency of tumor transduction and growth inhibitory effects when suicide gene therapy is delivered by MSC-RCR, as compared to RCR alone, we have fulfilled the success criteria for each of our milestone tasks in Year 1, and are currently proceeding with Year 2 studies.
  • Modified viruses can be used to infect tumor cells and alter the tumor cell to make anti-tumor proteins. We have developed a type of replication-competent virus that efficiently infects rapidly dividing cancer cells, but not normal brain cells. This virus is currently being tested clinically in patients with malignant brain tumors. However, to administer therapeutic virus into the brain, the virus is injected right into the center of the tumor, or in around the margins of the cavity after surgical removal of most of the tumor. Yet, human brain tumors are often found as diffusely spreading foci in the brain and may be difficult to eliminate by locally-administered replication-competent retrovirus (RCR) vectors alone. In this project, we propose to use a type of adult stem cell, called a "mesenchymal stem cell" (MSC), as a delivery system for the RCR vectors. Human mesenchymal stem cells (hMSCs) have been shown to have natural tumor-homing abilities, and can migrate to tumor foci and penetrate through into the interior of tumor masses.
  • During this project period, we have established and optimized manufacturing methods to engineer hMSCs into "aircraft carriers" that release our tumor-selective RCR vectors, which we then confirmed can efficiently spread a non-therapeutic marker gene to brain tumor cells. We have further confirmed that the use of hMSCs as a cellular delivery system for RCR vectors achieves more rapid spread of the vectors through the tumor mass, as compared to injecting the virus by itself, both in tumor models implanted under the skin as well as implanted in the brain. We have also obtained initial results demonstrating that hMSC delivery of RCR vectors does not result in unwanted spread of virus to normal tissues outside the brain. This stem cell-based RCR vector delivery system, which we have so far tested and validated using a marker gene, in our current studies is now being applied to delivery of a therapeutic anti-tumor 'suicide' gene. We have also initiated discussions with the UC Davis Stem Cell Institute to develop clinical grade manufacturing processes for hMSC-based RCR vector producer cells, and with a San Diego-based biotech partner, Tocagen Inc., toward the initiation of a clinical trial to test this strategy in brain tumor patients in the near future.
  • Modified viruses that have been engineered to serve as gene delivery vehicles ('vectors") can be used to infect tumor cells and alter the tumor cell to make anti-tumor proteins. We have developed a type of replication-competent virus that efficiently infects rapidly dividing cancer cells, but not normal brain cells. This virus is currently being tested clinically in patients with malignant brain tumors. However, to administer therapeutic virus into the brain, the virus is injected right into the center of the tumor, or in around the margins of the cavity after surgical removal of most of the tumor. Yet, human brain tumors are often found as diffusely spreading foci in the brain and may be difficult to eliminate by locally-administered replication-competent retrovirus (RCR) vectors alone. In this project, we propose to use a type of adult stem cell, called a "mesenchymal stem cell" (MSC), as a delivery system for the RCR vectors. Human mesenchymal stem cells (hMSCs) have been shown to have natural tumor-homing abilities, and can migrate to tumor foci and penetrate through into the interior of tumor masses.
  • Through this project, we have been able to establish and optimize manufacturing methods to engineer hMSCs into "aircraft carriers" that release our tumor-selective RCR vectors, which we then confirmed can efficiently spread a non-therapeutic marker gene to brain tumor cells. We have further confirmed that the use of hMSCs as a cellular delivery system for RCR vectors achieves more rapid spread of the vectors through the tumor mass, as compared to injecting the virus by itself, both in tumor models implanted under the skin as well as implanted in the brain. We have also confirmed that hMSC delivery of RCR vectors does not result in unwanted spread of virus to normal tissues outside the brain. We have now employed this stem cell-based RCR vector platform to deliver a therapeutic anti-tumor 'suicide' gene, and we have shown that stem cell-mediated vector delivery results in longer survival compared to delivery of the virus by itself. We have also initiated discussions with the UC Davis Stem Cell Institute to develop clinical grade manufacturing processes for hMSC-based RCR vector producer cells, and with a San Diego-based biotech partner, Tocagen Inc., toward developing a clinical trial to test this strategy in brain tumor patients in the near future.
  • Gene therapy can be used to alter the genome of cancer cells and induce them to make anti-tumor proteins. We have developed a highly efficient gene delivery vehicle (known as a “vector”) derived from a modified virus, which efficiently spreads though brain tumors and infects and permanently alters the genome of cancer cells, but does not infect normal brain cells. This modified virus, called a “replication-competent retrovirus (RCR) vector”, is currently being evaluated in clinical trials on-going at multiple sites throughout California to treat patients with malignant brain tumors, with highly encouraging results. However, to administer the therapeutic virus into brain tumors, the virus is injected directly into the center of the tumor, or around the margins of the cavity after surgical removal of most of the tumor. Yet, human brain tumors often diffusely spread into the surrounding normal brain tissue, and may be difficult to eliminate with a locally-injected RCR vector by itself. Therefore, in this project, we evaluated the use of a type of adult stem cell, called a "mesenchymal stem cell", as a delivery system for RCR vectors. Human mesenchymal stem cells (hMSCs) have been shown to have natural tumor-homing abilities, and can migrate to tumor foci and penetrate throughout the interior of tumor masses.
  • Through this project, we have established and optimized manufacturing methods to engineer hMSCs into "aircraft carriers" that release our tumor-selective RCR vectors, which we then confirmed can efficiently spread both a non-therapeutic “reporter gene”, as well as a therapeutic “suicide gene” to brain tumors. We have further confirmed that the use of hMSCs as a carrier system for delivery of RCR vectors results in more rapid spread of the vectors through the tumor mass, as compared to injecting the virus by itself, in human brain tumor models implanted both under the skin as well as in the brain. We have also confirmed that, when this hMSC -based RCR vector delivery system is employed to deliver an anti-tumor 'suicide' gene, the faster spread of the virus delivered by the stem cell carrier translates into more rapid shrinkage of tumors implanted under the skin, and prolongs survival in intracranial brain tumor models. In the final project period, we have also obtained results demonstrating that hMSC delivery of RCR vectors injected into intracranial brain tumors does not result in unwanted spread of virus to normal tissues outside the brain. We have initiated discussions with the UC Davis Stem Cell Institute to develop clinical grade manufacturing processes for hMSC-based RCR vector producer cells, and with a San Diego-based biotech partner, Tocagen Inc., toward the initiation of a clinical trial to test this strategy in brain tumor patients in the near future.
Funding Type: 
Early Translational II
Grant Number: 
TR2-01789
Investigator: 
ICOC Funds Committed: 
$3 341 758
Disease Focus: 
Blood Cancer
Cancer
Stem Cell Use: 
Cancer Stem Cell
Cell Line Generation: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Cancer is the leading cause of death for individuals under 85. Relapse and metastatic disease are the leading causes of cancer related mortality. Anti-apoptotic BCL2 family member overexpression has been shown to promote disease progression in both chronic myeloid leukemia (CML) and prostate cancer. Andr., the emergence of cancer stem cells (CSC) promotes apoptosis resistance in the bone marrow metastatic microenvironment. While targeted therapy with BCR-ABL inhibitors has improved survival of patients with chronic phase CML, the prevalence has doubled since 2001 with over 22,000 people living with CML in the US in 2009. Unfortunately, a growing proportion of patients become intolerant or simply cannot afford full dose BCR-ABL inhibitor therapy and thus, progress to advanced phase disease with a 5 year survival rate of less than 30%. Although prostate cancer prevalence was high at 2.26 million in 2007, distant disease was relatively rare at 5%. However, like blast crisis CML, metastatic prostate cancer survival was only 30% over 5 years.
Overexpression of B-cell lymphoma/leukemia-2 (BCL2) family genes has been observed in human blast crisis CML and advanced prostate cancer and may fuel CSC survival. Recent RNA sequencing data demonstrate that human CSC express a panoply of anti-apoptotic Bcl-2 isoforms in response to extrinsic signals in vivo, indicating that a pan BCL2 inhibitor will be required to abrogate CSC survival. Through binding and anti-tumor studies, a potent inhibitor of BCL2 pro-survival family proteins, BI-97C1, has been identified which inhibits the binding of BH3 peptides to Bcl-XL, Bcl-2, Mcl-1 and Bfl1-1 with nanomolar IC50 values. Notably, BI-97C1 potently inhibits growth of human prostate cancer in a xenograft model as well as blast crisis CML CSC engrafted in RAG2-/-c-/- mice while exerting minimal cytotoxicity toward bax-/-bak-/- cells. Because BI-97C1 inhibits all six anti-apoptotic Bcl-2 family members including Bcl-2, Mcl-1 (myeloid cell leukemia 1), Bcl-XL (BCL2L1), Bfl-1 (BCL-2A1), Bcl-W (BCL2L2) and Bcl-B (BCL2L10) proteins, with improved chemical, plasma and microsomal stability relative to apogossypol, we anticipate that it will have clinical utility for targeting apoptosis resistant human CSC in two malignancies with proven reliance on BCL2 signaling – blast crisis CML and advanced prostate cancer.
Thus, anti-apoptotic BCL2 family member inhibition with BI-97C1 could represent a vital component of a potentially curative strategy for advanced malignancies that may obviate the need for costly continuous tyrosine kinase inhibitor therapy by increasing sensitivity to therapy. Elimination of CSC contributing to therapeutic resistance, the primary cause of cancer death, is of high clinical importance and thus, development of a small molecule pan-BCL2 inhibitor would fulfill a vital unmet medical need, fuel California biotechnology stem cell R&D efforts and decrease health care costs for patients with cancer.

Statement of Benefit to California: 

Cancer is the leading cause of death for individuals under 85 and usually results from metastatic disease in the setting of therapeutic recalcitrance. Anti-apoptotic BCL2 family member overexpression has been shown to promote disease progression in both chronic myeloid leukemia and prostate cancer. Moreover, the emergence of quiescent cancer stem cells promotes apoptosis resistance in the bone marrow niche for. While targeted BCR-ABL inhibition has resulted in improved survival of patients with chronic phase CML, the prevalence has doubled since 2001 with over 22,000 people living with CML in the US in 2009 (http://www.leukemia-lymphoma.org). Unfortunately, a growing proportion of patients become intolerant or simply cannot afford full dose BCR-ABL inhibitor therapy as a result of spiraling annual costs and thus, progress to advanced phase disease with a 5 year survival rate of less than 30%. Although prostate cancer prevalence was high at 2.26 million in 2007, distant disease was relatively rare at 5%. Like CML, metastatic prostate cancer survival was only 30% over 5 years (http://seer.cancer.gov/statfacts/html/prost.html#prevalence <http://seer.cancer.gov/statfacts/html/prost.html#prevalence> ). Like blast crisis CML, prostate cancer progression and metastasis is associated with BCL2 overexpression. Thus, anti-apoptotic BCL2 family member inhibition with BI-97C1 could represent a vital component of a potentially curative strategy for advanced malignancies that may obviate the need for costly continuous tyrosine kinase inhibitor therapy by increasing sensitivity to therapy. Elimination of CSC contributing to therapeutic resistance, the primary cause of cancer death, is of high clinical importance and thus, development of a small molecule pan-BCL2 inhibitor would fulfill a vital unmet medical need, fuel California biotechnology stem cell R&D efforts and decrease health care costs for patients with cancer.

Progress Report: 
  • Overexpression of Bcl-2 family genes may fuel CSC survival. Recent RNA sequencing data demonstrate that human CSC express a panoply of antiapoptotic Bcl-2 isoforms in response to extrinsic signals in vivo, indicating that a pan Bcl-2 inhibitor will be required to abrogate CSC survival. Sabutoclax inhibits growth of blast crisis CML CSC engrafted in RAG2-/-c-/- mice with minimal cytotoxicity toward bax-/-bak-/- cells. Because sabutoclax inhibits all six antiapoptotic Bcl-2 family members including Bcl-2, Mcl-1, Bcl-XL, Bfl-1, Bcl-W and Bcl-B proteins, with good chemical, plasma and microsomal stability, we anticipate that it will have clinical utility for targeting apoptosis resistant human CSC in malignancies
  • Significant progress against milestones in the first year was accomplished and we have made early progress on several milestones projected for Year 2. During this 6 month reporting period, sabutoclax was licensed by a biotech company, Oncothyreon. The license was previously held by Coronado Biosciences. Dr. Pellecchia (SBMRI ) continues to provide sabutoclax to Dr. Jamieson for use in cellular and in vivo studies. SBMRI conducted QC analyses (integrity and purity) on samples’ used in preclinical studies and provided comparative analyses of compound produced by the CMO produced by different methods of synthesis. Importantly, the sabutoclax manufacturing process was optimized allowing scale-up of drug. In formulation studies, a method was developed and qualified that separates impurities and degradation compounds from sabutoclax for quantitation of the drug. Additional solubility and stability studies were performed by Oncothyreon to identify an IV formulation that could be used for both nonclinical studies and the clinic. Several pilot PK studies in mice, rats and dogs, planned for Year 2, were also conducted by Oncothyreon. Through whole transcriptome RNA sequencing Dr. Jamieson showed that Bcl-W was up-regulated in CP and BC progenitors compared to normal CB progenitors. Previous qRT-PCR results for Mcl-1 were confirmed, showing that the long isoform was preferentially expressed in BC CML. Results for Bcl-2 and Mcl-1 were also confirmed at the protein level by FACS analysis and immunohistochemistry of bone marrow (BM) from mice engrafted with human CML CD34+ LSC.
  • Sabutoclax treatment ablated BC CML progenitor cells in vivo and in vitro. Colony formation of BC CML (vs normal progenitor cells) was decreased by sabutoclax in a dose dependent manner. When CML cells were co-cultured with stromal cells or in stroma conditioned media, BCL-2 mRNA expression was increased and colony formation was improved. Knockdown of endogenous BCL2 in BC CML cells by shRNA resulted in decreased colony formation. Preliminary results suggest that BM is a protective niche for BC CML CSC and that sabutoclax may target these niche protected cells.
  • In BC CML engrafted mice, dasatinib increased quiescent BC CML cell engraftment in mouse BM measured by FACS for cell cycle markers. Sabutoclax decreased BCL-2 and MCL1 protein expression by immunohistochemistry staining and decreased quiescent BC CML CSC in BM however sabutoclax increased TUNEL staining in BM suggesting that while dasatinib may increase the number of quiescent BC CML CSC, sabutoclax may do the reverse.
  • High doses of sabutoclax administered in combination with dasatinib resulted in a significant decrease in human cell engraftment in BM versus dasatinib alone. Mice serially transplanted with tissues from combination treated mice had increased survival compared to serial transplants of single agent treated tissues. Human CD34+ cells from the BM of combination treated mice had more cells in cycle than CD34+ cells compared to the BM of mice treated with dasatinib alone. The frequency of CD34+BCL2+ and CD34+MCL1+ BC LSC were significantly lower in BM treated with a combination of sabutoclax and dasatinib suggesting that sabutoclax and dasatinib may act synergistically to increase survival of BC CML engrafted mice.
  • Dormant cancer stem cells (CSC) contribute to therapeutic resistance and relapse in chronic myeloid leukemia (CML) and other recalcitrant malignancies. Cumulative data demonstrate that overexpression of BCL2 family pro-survival splice isoforms fuels quiescent CSC survival in human blast crisis (BC) CML. Whole transcriptome RNA sequencing data, apoptosis PCR array and splice isoform specific qRT-PCR demonstrate that human CSC express anti-apoptotic long BCL2 isoforms in response to extrinsic signals in the marrow niche, indicating that a pan BCL2 inhibitor will be required to abrogate CSC survival. Sabutoclax, a novel pan BCL2 inhibitor, prevents survival of BC CSC engrafted in RAG2-/-c-/- mice, commensurate with downregulation of pro-survival BCL2 splice isoforms and proteins, and sensitizes CSC to a BCR-ABL inhibitor, dasatinib, while exerting minimal cytotoxicity toward normal hematopoietic stem cells. Because sabutoclax inhibits all six anti-apoptotic BCL2 family members, with good chemical, plasma and microsomal stability, in addition to a scaleable production process, we anticipate that it will have broad clinical utility for targeting apoptosis resistant quiescent human CSC in a number of recalcitrant malignancies as featured in our recent lead article (Goff D et al, Cell Stem Cell. 2013 Mar 7;12(3):316-28).
  • Significant progress against milestones in the second year was accomplished and we have made early progress on several milestones projected for Year 3. Whole transcriptome RNA sequencing, qRT-PCR array and splice isoform specific qRT-PCR analysis performed on FACS purified progenitors derived from 8 CP, 8 BC and 6 normal samples demonstrated splice isoform switching favoring pro-survival long isoform expression during progression from CP to blast BC CML and in CSC engrafted in the bone marrow (BM) niche. Both human BCL2 and MCL1 protein expression co-localized with engrafted human leukemic CD34+ cells in the bone marrow epiphysis and served as important biomarkers of response to sabutoclax. Importantly, intravenous treatment with sabutoclax reduced BC CML CSC survival in both marrow and splenic niches at doses that spared normal hematopoietic stem cells in RAG2-/-gamma c-/- xenograft models established with cord blood CD34+ cells.
  • While dasatinib treatment alone increased serially transplantable quiescent BC CML CSC in BM, sabutoclax decreased CSC survival commensurate with upregulation of short pro-apoptotic and downregulation of long anti-apopoptotic BCL2 family isoforms. While previous studies involved intraperitoneal administration, in the last 12 months we have focused on a more clinically relevant intravenous (IV) administration schedule with IV sabutoclax administered alone or in combination with oral dasatinib. In these studies, sabutoclax sensitized quiescent CSC to dasatinib resulting in a significant decrease in CSC survival versus dasatinib alone. Moreover, mice serially transplanted with human cells from combination treated mice had increased survival compared to serial transplants of single agent treated tissues. Human CD34+ cells from the BM of combination treated mice had more cells in cycle than CD34+ cells compared to the BM of mice treated with dasatinib alone. The frequency of CD34+BCL2+ and CD34+MCL1+ BC CSC were significantly lower in BM treated with a combination of sabutoclax and dasatinib suggesting that the combination acts synergistically to decrease CSC survival and increase the lifespan of CSC engrafted mice.
  • During this 12-month reporting period, sabutoclax production was successfully scaled up by two separate CMOs, Syncom and Norac. Dr. Pellecchia (SBMRI) provided flash chromatography purified sabutoclax to Dr. Jamieson for use in cellular and in vivo studies in addition to conducting QC analyses (integrity and purity) on scaled up sabutoclax formulations produced by Norac (4g) and Syncom (30g) in different vehicles. In formulation studies, a flash chromatography method was developed and qualified that separates impurities and degradation compounds from sabutoclax. Additional solubility and stability studies were performed to identify an IV Solutol formulation, compared with the previous IP DMSO/PBS Tween formulation, which could be used for both pre-clinical studies and in future clinical trials. Pilot PK studies in mice and rats were conducted with the Solutol formulated sabutoclax and showed weight loss associated with impurities that could be readily removed by standard flash chromatography. As a result, ssabutoclax production will include flash chromatography to enhance purity and stability and this material will be used for further PK and PD studies. In conclusion, we are on track to accomplish our milestones as set forth in the grant and anticipate that sabutoclax will form the basis of combination clinical studies aimed at eradicating quiescent CSC in a broad array of refractory malignancies.
  • Recent cancer stem cell research performed by ourselves and others has bolstered interest in BCL2 family member expression and inhibition in chronic myeloid leukemia (CML), acute myeloid leukemia (AML) and breast cancer (Goff DJ et al Cell Stem Cell 2013; Lagadinou ED et al Cell Stem Cell 2013; Vaillant F et al Cancer Cell 2013). Overexpression of pro-survival BCL2 family genes has been linked to therapeutic resistance driven by dormant, self-renewing CSC. Thus, the BCL2 family represents an attractive therapeutic target that may provide the potential to reduce relapse rates. Because of the greater proclivity for alternative splicing in humans compared with mice, our CIRM ETll funded research has focused on whole transcriptome RNA sequencing, splice isoform specific qRT-PCR and BCL2 PCR array analysis of FACS-purified CSC from patients with CML and CSC derived from human blast crisis CML engrafted RAG2-/-gc-/- mouse models.
  • A Pan-BCL2 inhibitor renders bone-marrow-resident human leukemia stem cells sensitive to tyrosine kinase inhibition. Cell Stem Cell. 2013 Mar 7;12(3):316-28) was featured in a lead article in Cell Stem Cell in March. This study also led to a number of disclosures relating to unique self-renewal and survival gene splice isoform based CSC detection and patient prognostication strategies. As a result, pan BCL2 targeting has generated considerable interest from academic and pharmaceutical investigators who would like to adopt the approach of dormant CSC sensitization to agents that target dividing cells, including tyrosine kinase inhibitors, chemotherapy and radiation therapy.
Funding Type: 
Research Leadership
Grant Number: 
LA1-01747
Investigator: 
ICOC Funds Committed: 
$5 919 616
Disease Focus: 
Brain Cancer
Cancer
Cell Line Generation: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Stem cells have the remarkable ability to renew themselves and to generate multiple different cell types. This allows them to generate normal tissues during development and to repair tissues following injury, but at the same time, renders them highly susceptible to mutations that can result in cancer. Only by understanding the signals that control growth and differentiation of stem cells can we learn to harness their regenerative capacity and restrain their malignant potential. The research described in this proposal is aimed at elucidating the role of neural stem cells in development, regeneration and tumor formation in the cerebellum.
Our previous studies identified a population of neural stem cells in the developing cerebellum. We now propose to use genetic approaches to mark these cells and identify the cell types that they generate during normal development. In addition, we plan to examine the capacity of these cells to regenerate the cerebellum following radiation. Finally, we propose to study the ability of these cells to give rise to brain tumors, and use the models that result from these studies to develop and test novel approaches to therapy. These studies will pave the way towards use of stem cells for repair of neurological damage and help develop more effective treatments for patients with brain tumors.

Statement of Benefit to California: 

We have previously identified a novel population of neural stem cells in the cerebellum. This proposal is focused on understanding the role of these cells in normal development, regeneration and tumor formation. It has the potential to benefit California in a number of important ways.

1. Treatment of Brain Damage: Radiation is the most commonly used treatment for brain tumors, and children who receive this treatment often suffer severe side effects, including a progressive loss of intellectual function. By studying the ability of cerebellar stem cells to repair brain tissue, we will advance the treatment of patients suffering from brain damage due to radiation therapy. The knowledge we gain may also be more broadly applicable, advancing the use of stem cells to repair damage due to congenital brain disorders, trauma and stroke.

2. Treatment of Brain Tumors: Medulloblastoma and astrocytoma are the most common brain tumors in children. By examining the role of stem cells in development of these tumors, we will deepen our understanding of how brain tumors form, and develop novel approaches to treating them. Moreover, we will create new model systems that can be used to test these therapies, with the hope of moving the most effective ones forward towards trials in patients.

3. Technology: Our research will culminate in the invention and generation of new drugs and approaches to therapy that will be made available for licensing by the academic institutions in California, such as {REDACTED} and its collaborators, and developed by pharmaceutical companies based in the State.

4. Collaboration: Our work is multidisciplinary and translational in nature. As such, it will require collaboration with other investigators, including stem cell biologists, neurobiologists, cancer biologists and chemists involved in experimental therapeutics. Once discoveries are made that may be of benefit to patients, we will also work with clinicians to move these discoveries towards the clinic. Californians will be the likely first beneficiaries of these therapies because the clinical trials will be conducted here and we will make an effort to make sure that Californians have immediate access to these therapies when they become standard. By bringing together investigators from various fields and focusing their attention on clinically relevant problems, our studies will advance the translational potential of stem cell research in California.

Progress Report: 
  • The goal of our studies is to determine the role of neural stem cells in the development, regeneration and tumor formation in the cerebellum. By understanding the role of stem cells, we hope to learn to use them for repair of neurological damage and to develop more effective treatments for patients with brain tumors.
  • The aims of our studies are: (1) To identify the cell types generated by cerebellar stem cells during normal development; (2) To determine the capacity of cerebellar stem cells to repair damage caused by radiation or disease; and (3) To determine whether cerebellar stem cells can give rise to the pediatric brain tumor medulloblastoma.
  • We have made significant progress toward our goals over the last year. In particular, we have identified genetic markers that allow us to trace the fate of cerebellar stem cells during normal development. In addition, we have demonstrated that cerebellar stem cells carrying cancer-causing genes can give rise to medulloblastoma. Importantly, this finding has allowed us to create stem cell-based models of medulloblastoma that can be used to test drugs that may be useful for treating the disease. Over the next few years, we hope to use this information to develop more effective therapies for children suffering from medulloblastoma.
  • The goal of our studies is to determine the role of neural stem cells in the development, regeneration and tumor formation in the cerebellum. By understanding the role of stem cells, we hope to learn to use them for repair of neurological damage and to develop more effective treatments for patients with brain tumors.
  • The aims of our studies are: (1) To identify the cell types generated by cerebellar stem cells during normal development; (2) To determine the capacity of cerebellar stem cells to repair damage caused by radiation or disease; and (3) To determine whether cerebellar stem cells can give rise to the pediatric brain tumor medulloblastoma.
  • We have made significant progress toward our goals over the last year. In particular, we have identified genetic markers that allow us to trace the fate of cerebellar stem cells during normal development. In addition, we have demonstrated that cerebellar stem cells carrying cancer-causing genes can give rise to medulloblastoma. Importantly, this finding has allowed us to create stem cell-based models of medulloblastoma that can be used to test drugs that may be useful for treating the disease. Our screening efforts over the past year have begun to identify compounds that inhibit the growth of human medulloblastoma tumor cells. Over the next few years, we hope to use this information to develop more effective therapies for children suffering from medulloblastoma.
  • The goal of our studies is to determine the role of neural stem cells in development, regeneration, and tumor formation in the cerebellum. By understanding the role of stem cells, we hope to learn to use them for repair of neurological damage and to develop more effective treatments for patients with brain tumors.
  • We have made significant progress towards our goals during the past year. We have identified new drugs that potently inhibit the growth of medulloblastoma, the most common malignant brain tumor in children. This work could lead to development of new, more effective therapies for medulloblastoma in patients. In addition, we have developed new models for several types of brain tumors, including one that resembles the most aggressive form of medulloblastoma, and several that model choroid plexus tumors. These models are valuable resources for studying the biology and therapeutic responsiveness of these diseases. Over the next few years, we will continue in our efforts to develop more effective therapies for children suffering from aggressive brain tumors.
  • The goal of our studies is to elucidate the role of neural stem cells in development, regeneration, and tumor formation in the cerebellum. By understanding the role of stem cells, we hope to learn to use them for repair of neurological damage and to develop more effective treatments for patients with brain tumors.
  • We have made significant progress towards our goals in the past year. Using animal models developed in our lab, we have uncovered new mechanisms and pathways that drive the growth and metastasis of medulloblastoma, the most common malignant brain tumor in children. In addition, we have identified molecular pathways that are de-regulated in choroid plexus carcinoma, a rare brain tumor with a poor prognosis that occurs most frequently in children. Our work has also led to the identification of new drugs that inhibit the growth of medulloblastoma and choroid plexus carcinoma. In the coming year, we will continue in our efforts to understand these aggressive cancers and develop new, more effective therapies for children who suffer from them.
  • The goal of our studies is to elucidate the role of neural stem cells in development, regeneration, and tumor formation in the cerebellum. By understanding the role of stem cells, we hope to learn to use them for repair of neurological damage and to develop more effective treatments for patients with brain tumors.
  • We have made significant progress towards our goals in the past year. Using animal models developed in our lab, including those that propagate patient-derived primary tumors, we have uncovered new mechanisms and pathways that drive the growth and metastasis of medulloblastoma, the most common malignant brain tumor in children. In addition, we have identified molecular pathways that are de-regulated in choroid plexus carcinoma, a rare brain tumor with a poor prognosis that occurs most frequently in children. In the coming year, we will continue in our efforts to understand these aggressive cancers and develop new, more effective therapies for children who suffer from them.
Funding Type: 
New Faculty I
Grant Number: 
RN1-00561
Investigator: 
Type: 
PI
ICOC Funds Committed: 
$2 392 397
Disease Focus: 
Blood Cancer
Cancer
Stem Cell Use: 
Adult Stem Cell
Cancer Stem Cell
Cell Line Generation: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Various cells and organs in the human body originate from a small group of primitive cells called stem cells. Human cancer cells were also recently found to arise from a group of special stem cells, called cancer stem cells (CSCs). At present, cancer that has spread throughout the body (metastasized) is difficult to treat, and survival rates are low. One major reason for therapeutic failure is that CSCs are relatively resistant to current cancer treatments. Although most mature cancer cells are killed by treatment, resistant CSCs will survive to regenerate additional cancer cells and cause a recurrence of cancer. As opposed to other human stem cells, CSCs have their own unique molecules on their cell surface. This project aims to develop agents that specifically target the unique cell surface molecules of CSCs. These agents will have the potential to eradicate cancer from the very root, i.e., from the stem cells (CSCs) that produce mature cancer cells. In this project, we will develop agents that specifically target leukemia stem cells to determine the feasibility of our approach. Leukemia is the fourth most common cause of cancer death in males and the fifth in females. If our approach is successful, we can use the same approach for other cancer types. To develop these specific agents, we will screen a library of billions of molecules to identify those that specifically target the unique cell surface molecules of leukemia stem cells (LSCs). After we identify these specific molecules, we will optimize their structure to increase their specific binding to LSCs. Specific binding to LSCs is crucial, as the optimized molecules will be able to uniquely kill LSCs and spare normal blood cells.

Many leukemia patients need stem cell transplantation during treatment. There are two approaches to harvesting stem cells for transplantation: those harvested from patients themselves and those harvested from healthy donors. Stem cells harvested from healthy donors need to genetically match patients’ cells. Otherwise, these transplanted cells from the donor recognize the recipient’s (host or patient) cells as non-self cells and attack these cells. This response leads to a serious disease called graft-versus-host disease (GVHD). It is often difficult to find matched donors. Stem cells harvested from patients are usually not used for the treatment of acute leukemia because they are contaminated with LSCs that will lead to recurrence of leukemia after transplantation. If this project is successful, the targeting agents developed in this project can be used to eliminate the contaminating LSCs and decrease the leukemia recurrence after transplantation.

Statement of Benefit to California: 

Acute leukemia is the sixth most common cause of cancer death in males and females in California. The outcome for acute leukemia is poor and over 70% of patients will die from this disease. This project aims to develop therapeutic agents that specifically target leukemia stem cells and therefore eradicate leukemia from its root. These agents can also be used for stem cell transplantation. Many leukemia patients need stem cell transplantation during treatment. There are two approaches to harvesting stem cells for transplantation: those harvested from patients themselves and those harvested from healthy donors. Stem cells harvested from healthy donors need to genetically match patients’ cells. Otherwise, these transplanted cells from the donor recognize the recipient’s (host or patient) cells as non-self cells and attack these cells. This response leads to a serious disease called graft-versus-host disease (GVHD). It is often difficult to find matched donors. This is especially true in California because of the genetically diversified population. Stem cells harvested from patients are usually not used because they are contaminated with leukemia stem cells that will lead to recurrence of leukemia after transplantation. If this project is successful, the targeting agents developed in this project can be used to eliminate the contaminated leukemia cells and decrease the likelihood of leukemia recurrence after transplantation.

The ligands developed in this project can be used for targeted therapy for leukemia. Since no such ligands have been identified so far that specifically target leukemia stem cells, these ligands can be patented and eventually commercialized. This may have huge financial benefits to California. If this project is successful, the same approach can be used to treat other cancers and for the development of more commercialized drugs.

If this grant is funded, it will secure my career as a physician-scientist in stem cell and cancer research. The physician-scientist is a diminishing breed in that it is difficult for physicians to do research while meeting the huge demands of the clinic. However, there is a huge gap between basic research and clinical applications. This gap is in part traced to the fact that it is difficult to find researchers who know and can integrate clinical needs with basic research. I consider myself a promising physician-scientist who has received extensive, rigorous and systematic training in medical science and basic research ([REDACTED]). If this grant is funded, I will not only carry out this important research, but this will also give me protected time for this research.

Progress Report: 
  • Human cancer cells were recently found to arise from a group of special stem cells, called cancer stem cells (CSCs). At present, cancer that has spread throughout the body (metastasized) is difficult to treat, and survival rates are low. One major reason for therapeutic failure is that CSCs are relatively resistant to current cancer treatments. Although most cancer cells are killed by treatment, resistant CSCs will survive to regenerate additional cancer cells and cause a recurrence of cancer. As opposed to other human stem cells, CSCs may have some unique molecules that can be targeted for cancer treatment. This project is to use such technologies as our patented one-bead one-compound technology (OBOC) to develop small molecules that can specifically target cancer stem cells. With OBOC, trillions copies of small molecules are synthesized in tiny beads around 90 microns. During development, millions of molecules can be screened against cancer stem cells with hours to days. So far, we have identified six molecules that target CSC. Currently, we are optimizing these molecules to increase their efficiency of these molecules on CSC. Once fully developed, these molecules will have the potential to eradicate cancer from the very root, i.e., from the stem cells (CSCs) that produce mature cancer cells.
  • Acute myeloid leukemia is a group of serious blood malignant diseases. The treatment outcome is poor, in large part, to the fact that a small group of cells named leukemia stem cells can survive treatment, regenerate more leukemic cells and cause recurrence. This project aims to improve the treatment outcomes of acute leukemia by eradicating leukemia stem cells. During the previous two years, we identified several small molecules that can specifically bind to leukemia stem cells. Over the last one year, we determined that one of these small molecules has the potential to work like a “smart missile” to guide the delivery of chemotherapeutic drugs to leukemia stem cells. More specifically, we linked this small molecule on the surface of nanoparticles that are small particles with the size of about 1/100th of one micron (much smaller than the width of a human hair). Inside of these nanoparticles, we can load chemotherapeutic drugs. We found that our small molecules can specifically attach the nanoparticles to leukemia stem cells, and deliver the drug load to the inside of the cells. Therefore, these “smart” nanoparticles can potentially target leukemia stem cells, and eradicate leukemia from the very root. Furthermore, chemotherapeutic drugs formulated in these nanoparticles are less toxic, suggesting that high-dose chemotherapeutic drugs can be given to patients to treat leukemia without increasing the horrendous toxicity associated with regular chemotherapy.
  • Acute myeloid leukemia is a group of serious blood malignant diseases. The treatment outcome is poor, in large part, due to the fact that a small group of cells named leukemia stem cells can survive treatment, regenerate more leukemic cells and cause recurrence. This project aims to improve the treatment outcomes of acute leukemia by eradicating leukemia stem cells. We identified one molecule that can specifically bind to leukemia stem cells. We also developed nanoparticles that are small particles with the size of about 1/100th of one micron (much smaller than the width of a human hair). Inside of these nanoparticles, we can load chemotherapeutic drugs, such as daunorubicin that is one of the two drugs used for the upfront treatment of acute leukemia. When we attached the stem cell-targeting molecules on the surface of nanoparticles, these nanoparticles work like “small missiles” that can seek and delivery daunorubicin into leukemia stem cells. We have shown that these “smart” nanoparticle can delivery chemotherapeutic drug daunorubicin to leukemia cells directly isolated from clinical patient specimens, and kills these cells more efficient that the regular nanoparticles. Therefore, these “smart” nanoparticles can potentially target leukemia stem cells, and eradicate leukemia from the very root. Furthermore, chemotherapeutic drugs formulated in these nanoparticles are less toxic, suggesting that high-dose chemotherapeutic drugs can be given to patients to treat leukemia without increasing the horrendous toxicity associated with regular chemotherapy.
  • Acute myeloid leukemia (AML) is the most common acute leukemia in adults and a very serious disease. Most AML cells arise from a group of special stem cells, named leukemia stem cells (LSCs). One major reason for treatment failure is that LSCs are relatively resistant to current treatments. Although most leukemia cells are killed by treatment, resistant LSCs will survive to regenerate additional leukemia cells and cause a recurrence of leukemia. Recently, we have developed a small molecule that can recognize and bind to AML LSCs. We have also developed tiny particles named nanomicelles. These nanomicelles have a size of about 1-2/100th of one micron (one millionth of a meter), and can be loaded with chemotherapy drug called daunorubicin that can kill LSCs. In this project, we will coat the drug-loaded nanomicelles with small molecules that specifically bind and kill LSCs. In patient’s body, these drug-loaded nanomicelles will work like “smart bombs”, and deliver a high concentration of daunorubicin to kill LSCs. Over the last one year, we found that these LSC-targeting nanomicelles could target and kill LSC more efficiently that free daunorubicin or nanomicelles that do not target LSC. We also found that, compared to free daunorubicin commonly used in the treatment of AML now, daunorubicin in nanomicelles could raise the blood daunorubicin concentration by more than 20 times. This is clinically significant as leukemia cells and LSC are located inside blood vessels and bone, and have direct contact with blood. Therefore, increase in blood daunorubicin concentration may represent more efficiency in killing leukemia and LSC.
  • Acute myeloid leukemia (AML) is the most common acute leukemia in adults and a very serious disease. Most AML cells arise from a group of special stem cells, named leukemia stem cells (LSCs). One major reason for treatment failure is that LSCs are relatively resistant to current treatments. Although most leukemia cells are killed by treatment, resistant LSCs will survive to regenerate additional leukemia cells and cause a recurrence of leukemia. Recently, we have developed a small molecule that can recognize and bind to AML LSCs. We have also developed tiny particles named nanomicelles. These nanomicelles have a size of about 1-2/100th of one micron (one millionth of a meter), and can be loaded with chemotherapy drug called daunorubicin that can kill LSCs. In this project, we will coat the drug-loaded nanomicelles with small molecules that specifically bind and kill LSCs. In patient’s body, these drug-loaded nanomicelles will work like “smart bombs”, and deliver a high concentration of daunorubicin to kill LSCs. Over the last one year, we found that daunorubicin-loaded nanomicelles could significantly increase the blood daunorubicin concentration by 20-35 times after intravenous administration. This is clinically significant as leukemia cells and leukemia stem cells are mainly located inside blood vessels. Therefore, increase in blood daunorubicin concentration by nanomicelles means leukemia and leukemia stem cells are exposed to 20-35 times more daunorubicin than regular chemotherapy. one of the major toxicity of daunorubicin is toxicity to the heart. As acute myeloid leukemia usually occurs in elderly patients, many of them already have heart diseases that prevent them from receiving the most effective chemotherapeutic drug daunorubicin. We found that, when compared to the standard daunorubicin, daunorubicin in nanomicelle has 3-5 folds less toxicity to the heart. In addition, the toxicity to other vital organs, such as liver and spleen, is significantly decreased. Compared to the standard daunorubicin, daunorubicin in nanomicelles dramatically increases the drug efficacy in killing cancer cells and prolonging the survival in animal models.
Funding Type: 
New Faculty I
Grant Number: 
RN1-00557
Investigator: 
ICOC Funds Committed: 
$2 286 900
Disease Focus: 
Blood Cancer
Cancer
Anemia
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 

During an individual’s lifetime, blood-forming cells in the bone marrow called hematopoietic stem cells (HSCs) supply all the red and white blood cells needed to sustain life. These blood stem cells are unique because they can make an identical copy of themselves (self-renew). Disorders of the blood system can be terminal, but such diseases may be cured when patients are treated with a bone marrow transplant. Unfortunately, bone marrow is in short supply due to limited availability of donors, and it is not yet possible to expand HSCs outside of the human body; HSCs that are removed from their native environment, or niche, rapidly lose their ability to self-renew and thus cannot sustain hematopoiesis in a transplant recipient. Furthermore, attempts to make blood stem cells from embryonic stem cells (ESCs) have also proved unsuccessful to date because these “tailored HSCs” are defective in self-renewal as well. These problems suggest that our understanding of the biology of HSCs is not sufficient to foster their maintenance or generation. To address this issue, we propose to study hematopoietic stem cells in the context of mammalian development; the entire complement of a person’s HSCs is made in a very short time window during the first trimester of pregnancy. By increasing our understanding of how HSCs are made and acquire self-renewal in vivo, we hope to develop better methods of generating HSCs in vitro and learn to provide the missing cues to coax them into becoming fully functional, self-renewing hematopoietic stem cells. Specifically, we plan to investigate how the fate decision that delineates blood cells from their embryonic precursor, called specification, is maintained at the molecular level. Second, we are interested in what cell type human HSCs descend from so as to understand what precursor to look for when attempting to differentiate ESCs into blood stem cells. Finally, we plan to apply molecular analyses to the property of self-renewal by looking at cell populations that cover a spectrum with regards to self-renewal: HSCs, cultured HSCs (not self-renewing), HSC precursors (not self-renewing), and ESCs differentiated to non-self-renewing HSCs. These comparisons will help define the molecular regulation of self-renewal, and place ESC-derived progenitors on the spectrum of self-renewal. Through these studies, we hope to better understand blood stem cells as they are made and maintained during human development with the ultimate goal to provide wider access to stem cell-based therapies.

Statement of Benefit to California: 

Funding of research to understand hematopoietic stem cell (HSC) biology offers rewards beyond the pursuit of knowledge. HSCs are responsible for providing all of the blood cells in the body, including both red cells that carry oxygen and white cells that mediate immunity. Inherited disorders affecting HSCs and their progeny are responsible for diseases such as sickle cell anemia, Severe Combined Immunity Disorder (SCID), and leukemia; these devastating ailments change the lives of thousands of people in California every year, and currently most are incurable without a bone marrow or cord blood transplant. Due to the limited availability of donors, other alternatives, such as differentiating embryonic stem cells (ESCs) into HSCs, are being explored. One critical fault of ESC-derived progenitors is their inability to “self-renew”, i.e. produce more of themselves, thus eliminating their usefulness for transplantation. However, a deeper understanding of the developmental and molecular processes that create functional HSCs that can self-renew may ultimately make the goal of deriving HSCs from ESCs attainable. Research into the mechanisms of self-renewal may also improve treatments of cancers such as leukemia, as these diseases are a function of over-proliferation of cells caused by uncontrolled self-renewal; targeting genes or proteins involved in abnormal self-renewal programs may provide more specific cancer fighting drugs, and would likely foster collaborations with biotechnology companies. Furthermore, as all stem cells in the body have the ability to self-renew, a clear understanding of self-renewal mechanisms will benefit all stem cell research, and could have a positive effect in a wide range of biomedical specialties.

Progress Report: 
  • The goal of this grant is to investigate the cell intrinsic mechanisms that govern hematopoietic stem cell specification and self-renewal. During the second year of this award, we have further elucidated the regulatory mechanisms that dictate hematopoietic fate specification by validating the target genes that Scl/tal1 activates and represses in vivo (Aim 1). We have also shown that loss of Scl results not only results in loss of all blood cells, but also causes defective arterio-venous identity that precludes generation of hemogenic endothelium and hematopoietic stem cells. We have defined the phenotype of hemogenic endothelium and emerging HSCs in both mouse and human embryos (Aim 2), and identified novel markers that can be used to isolate developing HSCs at distinct stages, as well as to purify functional HSCs further (Aim 3). We have also established an inducible lentiviral based expression system that will now be used to test functionally candidate HSC regulators that were identified by comparing gene expression profiles between freshly isolated HSCs and dysfunctional HSCs that were expanded in culture or generated from human ES cells. We hope that these studies will provide better understanding of the key regulatory mechanisms that govern HSC properties, and ultimately lead to development of improved methods for generation of functional HSCs in culture.
  • Our work has focused on defining mechanisms that govern the specification and self-renewal of hematopoietic stem cells during mouse and human development. Using gene targeted mouse ES cells and mouse embryos, we defined the transcriptional programs that are regulated by Scl, the master regulator for blood formation. We discovered that Scl not only establishes the transcriptional programs that are critical for specifying hemogenic endothelium and hematopoietic stem cells, but it also represses heart development. Strikingly, in the absence of Scl, hemogenic endothelium in embryonic hematopoietic tissues becomes converted to cardiogenic fate, and gives rise to fully functional, beating cardiomyocytes.
  • In order to define the key programs that distinguish self-renewing HSCs from their downstream progenitors or the compromised HSPCs (hematopoietic stem/progenitor cells) that were generated in vitro, we performed microarray analysis for human phenotypic HSCs from various sources. We identified novel markers for human HSCs that can be used to purify transplantable HSCs to a higher purity. We have identified key molecular defects in HSCs that are expanded in culture, or generated from human ES cells. We have further validated that dysregulation of certain Hox genes is a major bottleneck for generating functional HSCs from human ES cells. Future studies are focused on establishing methods that would allow correction of the compromised HSC regulatory networks in cultured HSCs.
  • We have defined key regulatory mechanisms that are required for generation and maintenance of blood forming stem cells. We showed that transcription factor Scl is critical for specifying hemogenic endothelium from where blood stem cells emerge, and moreover, we discovered and unexpected repressive function for Scl to suppress cardiomyogenesis; in the absence of Scl, the blood vessels in start to generate beating cardiomyocytes. We have also identified factors that are critical for blood stem cells to maintain the unique properties: to self-renew (make more of themselves) and engraft (interact with the niche cells that support them). We will now continue to define how these key regulators act so that we can design better strategies to generate blood stem cells as well as heart muscle precursors for therapeutic applications.
  • The goal of this grant was to define mechanisms that govern blood stem cell specification and self-renewal. We have completed the studies on hematopoietic fate specification by defining how Scl/tal1 establishes hemogenic endothelium. We documented that, in addition to Scl’s critical function in activating blood cell regulators, Scl also has to repress heart factors to prevent the misspecification of blood precursors to heart muscle. We documented that Scl controls blood and heart regulators through enhancers that have been primed for activation prior to Scl action (Aim 1). We identified a new surface marker that is expressed in hemogenic endothelium and blood forming cells in the yolk sac (Lyve1), which provides new tools to investigate the origin of blood stem and progenitor cells during development (Aim 2). We identified GPI-80 as a novel marker for transplantable blood stem cells during human fetal development (Aim 2, 3). Taking advantage of this new marker for blood stem cells, we narrowed down the critical defects in the dysfunctional blood precursors that are generated from human ES cells, or expanded in culture from fetal liver blood stem cells (Aim 3). We showed that the inability to induce HOXA cluster genes and other novel blood stem cell regulators that cannot be sustained in culture hinder the generation of blood stem cells from pluripotent cells, and further validated these novel regulators using lentiviral knockdown and overexpression. These findings will now be used to develop novel strategies to generate blood stem cells in culture.
Funding Type: 
New Faculty I
Grant Number: 
RN1-00550
Investigator: 
ICOC Funds Committed: 
$3 063 450
Disease Focus: 
Solid Tumor
Cancer
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 

Cancer is responsible for approximately 25% of all deaths in the US and other developed countries. For women, breast and lung cancers and for men, cancers of prostate and lung are the most prevalent and the most common cause of deaths from cancer. While a large number of treatment modalities such as surgery, chemotherapy, radiation therapy, etc. have been developed, we still are far from finding a cure for most cancers. So, more research is needed to understand the basic processes that are subverted by cancer cells to gain a proliferative advantage. In addition, cancer patients show a great deal of heterogeneity in the course and outcome of the disease. Therefore it is important to be able to predict the clinical outcome of the patients so that appropriate therapies can be administered. Clinical outcome prediction is based generally on tumor burden and degree of spread with additional information provided by histological type and patient demographics. However, patients with similar tumor characteristics still show heterogeneity in the course and outcome of disease. Thus, accurate sub-classification of patients with similar clinical outcomes is required for development of more efficacious therapies.

One important molecular process that is altered in cancer is the epigenetic regulation of gene expression. In humans, DNA is tightly wrapped around a core of proteins called histones to form chromatin—the physiologically relevant form of the genome. The histones can be modified by small chemical molecules which can affect the structure of chromatin, allowing for a level of control on gene expression. The patterns of occurrences of the histone modifications throughout chromatin are highly regulated and affect all molecular processes that are based on DNA. This information which is heritable but not encoded in the sequence of DNA is referred to as ‘epigenetics.’

A challenge in biology is to understand how histone modifications which can number to more than 150, contribute to normal gene regulation and how their alterations contribute to development of cancer stem cells. These cells are thought to be responsible for maintain the bulk of the tumor and need to be completely eradicated if we were to cure a given cancer. By studying primary cancer tissues and viruses that cause tumor, we have found that one histone modification plays a critical role in transforming a normal call to a tumor cell, potentially generating a cancer stem cell. We have found that he same histone modifications can be used as a biomarker to predict clinical outcome of patients. We now propose to study this process in more depth, discover other important histone modifications that contribute to cancer development and progression and use this knowledge to develop standard, simple and robust assays for predicting clinical outcome of cancer patients. Our work may also lead to identification important molecules that can be targeted for cancer therapy.

Statement of Benefit to California: 

Cancer is a devastating disease that is becoming more prevalent as the population ages. While scientists have developed a general framework of how cancer initiates, there remains significant gaps in our knowledge about how cancer arises from a normal cell. One difficulty with studying cancer is the heterogeneity in the types of cells that exist within a given cancer tissue. Some of these cells have recently been shown to have stem cell-like properties and when isolated can reestablish the original tumor. These ‘cancer stem cells’ are thought to be responsible for maintaining the bulk of the tumor and need to be completely eradicated if we were to cure a given cancer. There is also a great deal of differences in the course and outcome of cancers with seemingly similar attributes, making application of appropriate therapies difficult. Our proposal aims to understand some of the basic processes that may contribute to development of cancer stem cells and to use this knowledge to develop proper clinical tests for prediction of cancer patients’ clinical outcome. This would be beneficial for people of California as it may lead to personalization of cancer therapy. Our work may also lead to identification of critical molecules that need to be therapeutically targeted to improve rates of cancer therapy. Identification of such molecules may lead to innovative discoveries and patents that may be exploited by the biotech industry in California, and thereby improve the economy of California as well.

Progress Report: 
  • Cancer is a genetic disease but epigenetic processes also contribute to cancer development and progression. Epigenetic processes include molecular pathways that modify the DNA itself or the proteins that are associated with DNA (i.e. histones), thereby affecting how the genetic information is used to maintain cellular states. Cancer cells exploit the normal epigenetic processes to their advantage to support uncontrolled growth and evade host defense mechanisms. Our proposal aims to understand the epigenetic requirements for cancer initiation and progression and how they can be used to develop prognostic assays that can predict cancer clinical outcome or response to therapeutics. We have made significant progress in all of our aims. We are discovering new basic principles governing epigenetic processes in human embryonic stem cells versus more differentiated cell types and understanding how these principles are implemented and regulated by the different types of cells. We have also shown that epigenetics can be used for cancer prognostic purposes as well as for prediction of response to specific cancer chemotherapeutics.
  • The goal of this proposal is to understand the dynamics of chromatin in various cellular differentiation states and how alteration of this dynamic may contribute to cancer development and progression. Our major findings are outlined as follows and further elaborated below.
  • 1) Among the various acetylation sites of histones, H3K18ac has a unique distribution in hESCs and is specifically affected during oncogenic transformation. As part of a screen to discover upstream regulators of this modification site (described in previous reports), we identified a non-coding RNA that is required for maintenance of H3K18ac, expression of SOX2 and its target genes, and growth of hESCs.
  • 2) We have discovered a highly novel and unanticipated role for histone acetylation. We have found that global histone acetylation and deacetylation coupled with flux of acetic acid in and out of the cells acts as a buffering system for regulation of intracellular pH. This phenomenon is a fundamental biological process and occurs in hESCs, cancer cells as well as normal differentiated human cells. (A paper reporting this finding is currently being reviewed at Nature.)
  • 3) We are continuing our efforts on the role of linker histone H1.5 in transcriptional regulation of terminally differentiated cells vs hESCs. This is a continuation project from a CIRM SEED grant. A manuscript on this project was submitted to Cell but was not accepted. We have performed additional experiments and preparing a new manuscript.
  • I. A non-coding RNA is required for hESC growth.
  • This aim was designed to understand how the global levels of histone modifications are regulated. As reported in previous progress reports, we carried out a kinase screen in which ~800 kinases were knocked down individually using siRNAs and the levels of two histone modifications were examined. We validated the top hits which were reported last year. The most significant effect on histone modifications, especially H3K18ac, was observed in knockdown of TPRXL (tetra-peptide repeat homeobox-like). We found that knockdown of TPRXL causes ~50-70% reductions in the global levels of H3K18ac specifically, suggesting that TPRXL is required for maintenance of a portion of H3K18ac throughout the genome. It turned out that the identification of TPRXL was a fortuitous finding. TPRXL is not a kinase but has been mis-annotated as a kinase in certain databases, hence its inclusion in the kinase siRNA library. TPRXL is a member of the TPRX homeobox gene family and is designated as a non-functional retrotransposed pseudogene (Booth and Holland, 2007). It is suggested that TPRXL was generated by reverse transcription of TPRX1 mRNA which was then integrated near an enhancer active in placenta. Consistently, TPRXL has a very high expression in placenta compared to other tissues. Subsequent to integration, TPRXL sequence has diverged from that of TPRX1 in an unusual way. In certain regions, such as over the homebox domain, TPRXL has retained 81% nucleotide identity but only 66% amino acid identity compared to TPRX1 (Booth and Holland, 2007). Despite its designation, TPRXL could possibly be a functional retrogene as it is transcribed and contains two potential open reading frames (ORFs). One ORF can code for a short protein (139 a.a.) that would contain the homeodomain and a polyglutamine stretch. Another ORF codes for a longer protein that would consist mostly of a long polyserine/proline stretch.
  • Epigenetic processes include molecular pathways that modify the DNA or the proteins that are associated with DNA (i.e. histones), thereby affecting how the genetic information is used to maintain cellular states. Thus epigenetics plays an important role in normal biology and disease. When deregulated, epigenetic processes could contribute to disease development and progression. Since embryonic stem cells (ESCs) and cancer cells share the capacity to divide indefinitely, our proposal aims to understand the epigenetic requirements for such capacity. We have found that a particular epigenetic process, which we previously linked to cancer progression, may contribute to regulation of DNA replication in human ESCs. We have also discovered how epigenetic processes could in novel ways exert control over metabolic state of the cell. Finally, we have discovered how chromatin – the complex of DNA and histones – at specific sets of gene families is differentially compacted in differentiated cell types vs. human ESCs. Altogether, we are providing novel insights into the functions of various epigenetic processes and how they may differ in stem cells vs. other normal and cancer cell types.
  • Epigenetic processes include molecular pathways that modify the DNA or the proteins that are associated with DNA (i.e. histones), thereby affecting how the genetic information is read. Epigenetics plays an important role in normal biology and disease because it can affect how genes are turned on and off. Deregulation of epigenetic processes indeed contributes to disease development and progression including cancer. Our proposal has aimed to understand how the epigenome exerts its control over gene regulation. We have found that in addition to gene regulation, on epigenetic process is unexpectedly linked to control of cellular physiology. We have shown that dynamic acetylation of histone proteins regulates intracellular level of acidity, providing an unprecedented function for the epigenome. Our data provides plausible explanations for why ESCs contain in general higher levels of histone acetylation than other cell types and why certain cancers with low levels of histone acetylation are more aggressive. In a separate study, we have found that replication of DNA in ESCs is associated with a unique epigenetic signature that is not found in differentiated cells or other rapidly dividing cell types such as cancer. We have proposed that this molecular property of replication in ESCs may be an important determinant of continual cell division without malignancy, fundamentally distinguishing ESC-specific from cancer-like cell division. Altogether, we are providing novel insights into the functions of various epigenetic processes and how they may be similar or differ in stem cells vs. other normal and cancer cell types.

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