Cancer

Coding Dimension ID: 
280
Coding Dimension path name: 
Cancer
Funding Type: 
Disease Team Therapy Development - Research
Grant Number: 
DR2A-05309
Investigator: 
Name: 
Type: 
Co-PI
Type: 
Partner-PI
ICOC Funds Committed: 
$19 999 563
Disease Focus: 
Melanoma
Cancer
Collaborative Funder: 
NIH
Stem Cell Use: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 

Science has made great progress in the treatment of certain cancers with targeted and combination therapies, yet prolonged remissions or cures are rare because most cancer therapies only inhibit cell growth and/or reduce such growth but do not stop the cancer.

The study investigators propose to develop an Investigational New Drug (IND) and fully enroll a phase I clinical trial within the grant period to genetically redirect the patient’s immune response to specifically attack the cancer starting from hematopoietic (blood) stem cells (HSC) in patients with advanced forms of the aggressive skin cancer malignant melanoma. Evaluation of immune system reconstitution, effectiveness and immune response during treatment will use imaging with Positron Emission Tomography (PET) scans.

The HSC treatment approach has been validated in extensive studies in the laboratory. The investigators of this grant have recently initiated a clinical trial where adult immune cells obtained from blood are genetically modified to become specific killer cells for melanoma. These cells are administered back to patients. The early data from this study is encouraging in terms of the ability to generate these cells, safely administer them to patients leading to beneficial early clinical effects. However, the adult immune cells genetically redirected to attack cancer slowly decrease over time and lose their killer activity, mainly because they do not have the ability to self-renew.

The advantage of the proposed HSC method over adult blood cells is that the genetically modified HSC will continuously generate melanoma-targeted immune killer cells, hopefully providing prolonged protection against the cancer. The IND filing with the FDA will use the modified HSC in advanced stage melanoma patients. By the end of year 4, we will have fully accrued this phase 1 clinical trial and assessed the value of genetic modification of HSCs to provide a stable reconstitution of a cancer-fighting immune system. The therapeutic principles and procedures we develop will be applicable to a wide range of cancers and transferrable to other centers that perform bone marrow and HSC transplants.

The aggressive milestone-driven IND timeline is based on our:
1) Research that led to the selection and development of a blood cell gene for clinical use in collaboration with the leading experts in the field,
2) Wealth of investigator-initiated cell-based clinical research and the Human Gene Medicine Program (largest in the world with 5% of all patients worldwide),
3) Experience filing a combined 15 investigator initiated INDs for research with 157 patients enrolled in phase I and II trials, and
4) Ability to have leveraged significant institutional resources of on-going HSC laboratory and clinical research contributed ~$2M of non-CIRM funds to pursue the proposed research goals, including the resulting clinical trial.

Statement of Benefit to California: 

Cancer is the leading cause of death in the US and melanoma incidence is increasing fastest (~69K new cases/year). Treatment of metastatic melanoma is an unmet local and national medical need (~9K deaths/year) striking adults in their prime (20-60 years old). Melanoma is the second greatest cancer cause of lost productive years given its incidence early in life and its high mortality once it metastasizes. The problem is severe in California, with large populations with skin types sensitive to the increased exposure to ultraviolet light. Most frequently seen in young urban Caucasians, melanoma also strikes other ethnicities, i.e., steady increases of acral melanoma in Latinos and African-Americans over the past decades.

Although great progress has been made in the treatment of certain leukemias and lymphomas with targeted and combination therapies, few options exist for the definitive treatment of late stage solid tumors. When cancers like lung, breast, prostate, pancreas, and melanoma metastasize beyond surgical boundaries, prolonged remissions or cures are rare and most cancer therapies only inhibit cell growth and/or reduce such growth but do not stop the cancer.

Our proposal, the filing of an IND and the conduct of a phase 1 clinical trial using genetically modified autologous hematopoietic stem cells (HSC) for the immunotherapy of advanced stage melanoma allowing sustained production of cancer-reactive immune cells, has the potential to address a significant and serious unmet clinical need for the treatment of melanoma and other cancers, increase patient survival and productivity, and decrease cancer-related health care costs.

The advantage of the proposed HSC methodology over our current work with peripheral blood cells is that genetically modified stem cells will continuously generate melanoma-targeted immune cells in the patient’s body providing prolonged protection against the cancer. The therapeutic principles and procedures developed here will be applicable to a wide range of cancers. Good Manufacturing Practices (GMP) reagents and clinical protocols developed by our team will be transferable to other centers where bone marrow and peripheral blood stem cell transplantation procedures are done.

Progress Report: 
  • A strategy in the treatment of cancer by harnessing the immune system, called adoptive cell therapy, is to use an individual’s own immune cells (T cells) and genetically modify them to target them to kill the cancer. Our emerging clinical data demonstrates that these gene-modified T cells are very active in killing tumor cells initially, but they lose their ability to function within a few weeks. This experience points to the need to have a continuous source of gene-modified cells to maintain the ability to kill cancer cells. In this study, we hypothesize that gene-modified stem cells will allow a sustained production of active T cells with antitumor activity. Since there is a delay in the appearance of the T cells that come from stem cells to get out of the bone marrow and into the blood, we will give patients both gene-modified T cells for a first wave of antitumor activity and gene-modified stem cells which will provide a bridge until the stem cells have produced more T cells. The purpose of the current study is to give gene-modified T cells in combination with gene-modified stem cells to reprogram the immune system to recognize and kill cancer cells that have the NY-ESO-1 protein with sustained killing activity. The patient’s own white blood cells and stem cells from their blood are modified in the laboratory using genetic techniques to express a specific receptor against cancer cells. Gene modification of cells involves the transfer of foreign genetic material (DNA) into a cell, in this case the immune system cells and stem cells. This process will endow the recipient immune cells and descendants of the stem cells with the ability to eliminate cancer cells that express the cancer specific protein, NY-ESO-1. The specific receptor against cancer cells that will be transferred to the immune cells and stem cells is called NY-ESO-1 T cell receptor (or TCR). In this study, the gene-modified immune cells will be given in combination with the gene-modified stem cells.
  • To date, we have manufactured a batch of the lentiviral vector necessary to transfer the NY-ESO-1 TCR into stem cells and have demonstrated that this vector can gene-modify human stem cells. Preclinical safety studies are currently ongoing. We have demonstrated that when mouse stem cells are gene-modified with this lentiviral vector, the stem cells take up residence in the bone marrow and produce appropriate blood cells. There is no detrimental effect on the blood cells that are derived from the stem cells. In vitro assays have also been performed to assess whether the lentiviral vector could potentially transform cells. These studies are ongoing but interim data suggests that there the lentiviral vector has no transforming potential. A preclinical study is also ongoing in mice to assess the safety of combining the gene-modified T cells and stem cells in mice. In addition, a preclinical study was performed to demonstrate that the stem cells are able to be specifically eliminated using ganciclovir, which provides a safety feature in case there was a problem when translating this research to humans. The vector includes a suicide gene which we have shown can be used to kill cells if necessary.
  • Preparations are ongoing towards opening a clinical trial. The manufacturing process is being optimized, and clinical documents have been submitted to internal committees for review.
Funding Type: 
Disease Team Therapy Development III
Grant Number: 
DR3-06965
Investigator: 
Institution: 
Type: 
PI
Institution: 
Type: 
Co-PI
Institution: 
Type: 
Partner-PI
ICOC Funds Committed: 
$12 726 396
Disease Focus: 
Cancer
Solid Tumor
Blood Cancer
Collaborative Funder: 
UK
Stem Cell Use: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Most normal tissues are maintained by a small number of stem cells that can both self-renew to maintain stem cell numbers, and also give rise to progenitors that make mature cells. We have shown that normal stem cells can accumulate mutations that cause progenitors to self-renew out of control, forming cancer stem cells (CSC). CSC make tumors composed of cancer cells, which are more sensitive to cancer drugs and radiation than the CSC. As a result, some CSC survive therapy, and grow and spread. We sought to find therapies that include all CSC as targets. We found that all cancers and their CSC protect themselves by expressing a ‘don’t eat me’ signal, called CD47, that prevents the innate immune system macrophages from eating and killing them. We have developed a novel therapy (anti-CD47 blocking antibody) that enables macrophages to eliminate both the CSC and the tumors they produce. This anti-CD47 antibody eliminates human cancer stem cells when patient cancers are grown in mice. At the time of funding of this proposal, we will have fulfilled FDA requirements to take this antibody into clinical trials, showing in animal models that the antibody is safe and well-tolerated, and that we can manufacture it to FDA specifications for administration to humans.

Here, we propose the initial clinical investigation of the anti-CD47 antibody with parallel first-in-human Phase 1 clinical trials in patients with either Acute Myelogenous Leukemia (AML) or separately a diversity of solid tumors, who are no longer candidates for conventional therapies or for whom there are no further standard therapies. The primary objectives of our Phase I clinical trials are to assess the safety and tolerability of anti-CD47 antibody. The trials are designed to determine the maximum tolerated dose and optimal dosing regimen of anti-CD47 antibody given to up to 42 patients with AML and up to 70 patients with solid tumors. While patients will be clinically evaluated for halting of disease progression, such clinical responses are rare in Phase I trials due to the advanced illness and small numbers of patients, and because it is not known how to optimally administer the antibody. Subsequent progression to Phase II clinical trials will involve administration of an optimal dosing regimen to larger numbers of patients. These Phase II trials will be critical for evaluating the ability of anti-CD47 antibody to either delay disease progression or cause clinical responses, including complete remission. In addition to its use as a stand-alone therapy, anti-CD47 antibody has shown promise in preclinical cancer models in combination with approved anti-cancer therapeutics to dramatically eradicate disease. Thus, our future clinical plans include testing anti-CD47 antibody in Phase IB studies with currently approved cancer therapeutics that produce partial responses. Ultimately, we hope anti-CD47 antibody therapy will provide durable clinical responses in the absence of significant toxicity.

Statement of Benefit to California: 

Cancer is a leading cause of death in the US accounting for approximately 30% of all mortalities. For the most part, the relative distribution of cancer types in California resembles that of the entire country. Current treatments for cancer include surgery, chemotherapy, radiation therapy, biological therapy, hormone therapy, or a combination of these interventions ("multimodal therapy"). These treatments target rapidly dividing cells, carcinogenic mutations, and/or tumor-specific proteins. A recent NIH report indicated that among adults, the combined 5-year relative survival rate for all cancers is approximately 68%. While this represents an improvement over the last decade or two, cancer causes significant morbidity and mortality to the general population as a whole.

New insights into the biology of cancer have provided a potential explanation for the challenge of treating cancer. An increasing number of scientific studies suggest that cancer is initiated and maintained by a small number of cancer stem cells that are relatively resistant to current treatment approaches. Cancer stem cells have the unique properties of continuous propagation, and the ability to give rise to all cell types found in that particular cancer. Such cells are proposed to persist in tumors as a distinct population, and because of their increased ability to survive existing anti-cancer therapies, they regenerate the tumor and cause relapse and metastasis. Cancer stem cells and their progeny produce a cell surface ‘invisibility cloak’ called CD47, a ‘don’t eat me signal’ for cells of the native immune system to counterbalance ‘eat me’ signals which appear during cancer development. Our anti-CD47 antibody counters the ‘cloak’, enabling the patient’s natural immune system to eliminate the cancer stem cells and cancer cells. Our preclinical data provide compelling support that anti-CD47 antibody might be a treatment strategy for many different cancer types, including breast, bladder, colon, ovarian, glioblastoma, leiomyosarcoma, squamous cell carcinoma, multiple myeloma, lymphoma, and acute myelogenous leukemia.

Development of specific therapies that target all cancer stem cells is necessary to achieve improved outcomes, especially for sufferers of metastatic disease. We hope our clinical trials proposed in this grant will indicate that anti-CD47 antibody is a safe and highly effective anti-ancer therapy that offers patients in California and throughout the world the possibility of increased survival and even complete cure.

Progress Report: 
  • We have previously developed a new therapeutic candidate, the anti-CD47 humanized antibody, Hu5F9-G4, which demonstrates potent anti-cancer activity in animal models of malignancy. The goal of CIRM DTIII Grant DR3-06965 is to conduct initial phase I clinical trials of this antibody in advanced cancer patients. We originally proposed to conduct two separate Phase I clinical trials: one in solid tumor patients with advanced malignancy (commenced in August 2014), the other in relapsed, refractory AML patients (anticipated to start in September 2015). The primary endpoints for these trials will be to assess safety and tolerability, and additional endpoints include obtaining information about the dosing regimen for subsequent clinical investigations, and initial efficacy assessments.
  • CD47 is a dominant anti-phagocytosis signal that is expressed on all types of human cancers assessed thus far. It binds to SIRPα, an inhibitory receptor on macrophages, and in so doing, blocks the ability of macrophages to engulf and eliminate cancer cells. Hu5F9-G4 blocks binding of CD47 to SIRPα, and restores the ability of macrophages to engulf or phagocytose cancer cells. In pre-clinical cancer models, treatment with Hu5F9-G4 shrunk tumors, eliminated metastases, and in some cases resulted in long-term protection from cancer recurrence. These results suggest that Hu5F9-G4 leads to elimination of cancer stem cells in addition to differentiated cancer cells.
  • We have developed Hu5F9-G4 for human clinical trials by demonstrating safety and tolerability in pre-clinical toxicology studies. These studies also indicated that we can achieve serum levels associated with potent efficacy in pre-clinical models. The regulatory agencies (FDA in the U.S., and MHRA in the U.K.) reviewed the large package of pre-clinical data describing Hu5F9-G4, and approved our requests to commence separate Phase I clinical trials in solid tumor and AML patients. The solid tumor trial commenced at Stanford in August 2014 and has been designed to assess patients in separate groups, or cohorts, treated with increasing doses of Hu5F9-G4. The trial is ongoing as primary endpoints have not been met. The acute myeloid leukemia trial has been given regulatory approval in the U.K., and will start enrolling patients in September 2015. In summary, during the last year, the Hu5F9-G4 clinical trials have made substantial progress and all milestones have been met.
Funding Type: 
Genomics Centers of Excellence Awards (R)
Grant Number: 
GC1R-06673-A
Investigator: 
Institution: 
Type: 
PI
Type: 
Co-PI
ICOC Funds Committed: 
$40 000 000
Disease Focus: 
Brain Cancer
Cancer
Developmental Disorders
Heart Disease
Cancer
Genetic Disorder
Stem Cell Use: 
iPS Cell
Adult Stem Cell
Cancer Stem Cell
Cell Line Generation: 
iPS Cell
Public Abstract: 

The Center of Excellence in Stem Cell Genomics will bring together investigators from seven major California research institutions to bridge two fields – genomics and pluripotent stem cell research. The projects will combine the strengths of the center team members, each of whom is a leader in one or both fields. The program directors have significant prior experience managing large-scale federally-funded genomics research programs, and have published many high impact papers on human stem cell genomics. The lead investigators for the center-initiated projects are expert in genomics, hESC and iPSC derivation and differentiation, and bioinformatics. They will be joined by leaders in stem cell biology, cancer, epigenetics and computational systems analysis. Projects 1-3 will use multi-level genomics approaches to study stem cell derivation and differentiation in heart, tumors and the nervous system, with implications for understanding disease processes in cancer, diabetes, and cardiac and mental health. Project 4 will develop novel tools for computational systems and network analysis of stem cell genome function. A state-of-the-art data management program is also proposed. This research program will lead the way toward development of the safe use of stem cells in regenerative medicine. Finally, Center resources will be made available to researchers throughout the State of California through a peer-reviewed collaborative research program.

Statement of Benefit to California: 

Our Center of Excellence for Stem Cell Genomics will help California maintain its position at the cutting edge of Stem Cell research and greatly benefit California in many ways. First, diseases such as cardiovascular disease, cancer, neurological diseases, etc., pose a great financial burden to the State. Using advanced genomic technologies we will learn how stem cells change with growth and differentiation in culture and can best be handled for their safe use for therapy in humans. Second, through the collaborative research program, the center will provide genomics services to investigators throughout the State who are studying stem cells with a goal of understanding and treating specific diseases, thereby advancing treatments. Third, it will employ a large number of “high tech” individuals, thereby bringing high quality jobs to the state. Fourth, since many investigators in this center have experience in founding successful biotech companies it is likely to “spin off” new companies in this rapidly growing high tech field. Fifth, we believe that the iPS and information resources generated by this project will have significant value to science and industry and be valuable for the development of new therapies. Overall, the center activities will create a game-changing network effect for the state, propelling technology development, biological discovery and disease treatment in the field.

Progress Report: 
  • This grant has enabled a plethora of activities in California Stem Cell Genomics. The Stanford Administrative Core for the Center of Excellence in Stem Cell Genomics (CESCG) has been established and is responsible for overseeing joint center activities, and the administration of center-initiated projects (CIP) 1 and 2, and several collaborative research projects (CRP). In the first year of the award the CESCG administration organized monthly telephone conference calls to share research progress and coordinate activities across the Center. On May 1, 2015 the CESCG held its first center-wide retreat in a one-day event at Clark Center on the campus of the Stanford Medical School. The two CIPs have made significant progress. CIP1 has generated a valuable resource of 38 induced pluripotent stem cell lines and established a reliable platform for high throughput derivation of human induced pluripotent stem cell-derived cardiomyocytes for use in downstream high throughput toxicity and drug pharmacology screening assays. CIP2 has completed the first human single cell brain analysis and is in the process of deriving a single cell pancreatic map. We have launched our collaborative research progress grant. Following on the receipt of applications in October 2014 and successful review in January 2015, the Administrative Core at Stanford has also issued subcontract awards for 3 CRPs managed by the CESCG from the Northern California site – two comprehensive project awards CRP-C2 to Daniel Geschwind of UCLA and CRP-C3 to Arnold Kriegstein of UCSF, and a regular project award CRP-R4 to Jeremy Sanford of UCSC. These activities will transform stem cell research in California and continue its preeminence in this area.
Funding Type: 
New Faculty Physician Scientist
Grant Number: 
RN3-06510
Investigator: 
Institution: 
Type: 
PI
ICOC Funds Committed: 
$2 800 536
Disease Focus: 
Neurological Disorders
Brain Cancer
Cancer
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 

Chemotherapy for cancer is often life saving, but it also causes a debilitating syndrome of impaired cognition characterized by deficits in attention, concentration, information processing speed, multitasking and memory. As a result, many cancer survivors find themselves unable to return to work or function in their lives as they had before their cancer therapy. These cognitive deficits, colloquially known as "chemobrain" or "chemofog," are long-lasting and sometimes irreversible. For example, breast cancer survivors treated with chemotherapy suffer from cognitive disability even 20 years later.

These cognitive problems occur because chemotherapy damages the neural stem and precursor cells necessary for the health of the brain's infrastructure, called white matter. We have discovered a powerful way to recruit the stem/precursor cells required for white matter repair that depends on an interaction between the electrical cells of the brain, neurons, and these white matter stem/precursor cells. In this project, we will determine the key molecules responsible for the regenerative influence of neurons on these white matter stem cells and will develop that molecule (or molecules) into a drug to treat chemotherapy-induced cognitive dysfunction. If successful, this will result in the first effective treatment for a disease that affects at least a million cancer survivors in California.

Statement of Benefit to California: 

Approximately 100,000 Californians are diagnosed with cancer each year, and the majority of these people require chemotherapy. While cancer chemotherapy is often life saving, it also causes a debilitating neurocognitive syndrome characterized by impaired attention, concentration, information processing speed, multitasking and memory. As a result, many cancer survivors find themselves unable to return to work or function in their lives as they had before their cancer therapy. These cognitive deficits, colloquially known as "chemobrain" or "chemofog" are long-lasting; for example, cognitive deficits have been demonstrated in breast cancer survivors treated with chemotherapy even 20 years later. With increasing cancer survival rates, the number of people living with cognitive disability from chemotherapy is growing and includes well over a million Californians. Presently, there is no known therapy for chemotherapy-induced cognitive decline, and physicians can only offer symptomatic treatment with medications such as psychostimulants.

The underlying cause of "chemobrain" is damage to neural stem and precursor cell populations. The proposed project may result in an effective regenerative strategy to restore damaged neural precursor cell populations and ameliorate or cure the cognitive syndrome caused by chemotherapy. The benefit to California in terms of improved quality of life for cancer survivors and restored occupational productivity would be immeasurable.

Progress Report: 
  • Cancer chemotherapy can be lifesaving but frequently results in long-term cognitive deficits. This project seeks to establish a regenerative strategy for chemotherapy-induced cognitive dysfunction by harnessing the potential of the interactions between active neurons and glial precursor cells that promote myelin plasticity in the healthy brain. In the first year of this award, we have made on-track progress towards establishing a working experimental model system of chemotherapy-induced neurotoxicity that faithfully models the human disease both in terms of the cellular damage as well as functional deficits in cognition. We have also been able to identify several therapeutic candidate molecules that we will be studying in the coming years of the project to ascertain which of these candidates are sufficient to promote OPC population repletion and neuro-regeneration after chemotherapy exposure.
  • Cancer chemotherapy can be lifesaving but frequently results in long-term cognitive deficits. This project seeks to establish a regenerative strategy for chemotherapy-induced cognitive dysfunction by harnessing the potential of the interactions between active neurons and glial precursor cells that promote myelin plasticity in the healthy brain. In the first year of this award, we have made on-track progress towards establishing a working experimental model system of chemotherapy-induced neurotoxicity that faithfully models the human disease both in terms of the cellular damage as well as functional deficits in cognition. Using this model, we have found that the oligodendroglial precursor cell population depletion following chemotherapy is due not only to a direct effect of the chemotherapy on the OPCs, but also due to alterations in the microenvironmental milieu of the brain that normally maintains this population of cells. We have also been able to identify several therapeutic candidate molecules that we will be studying in the coming years of the project to ascertain which of these candidates are sufficient to promote OPC population repletion and neuro-regeneration after chemotherapy exposure.
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: 
Basic Biology V
Grant Number: 
RB5-06978
Investigator: 
Type: 
PI
ICOC Funds Committed: 
$1 161 000
Disease Focus: 
Solid Tumor
Cancer
Stem Cell Use: 
Cancer Stem Cell
oldStatus: 
Closed
Public Abstract: 

Tumors contain a heterogeneous mix of cancer cells with distinct features, including subsets of particularly aggressive stem-like cells. Since a single cancer stem cell can self-renew, divide, and differentiate to reconstitute the heterogeneity of an entire tumor, the ability of one cell to evade therapy or surgical resection could lead to tumor re-growth and disease relapse.

Few, if any, individual markers have been capable of identifying cancer stem cells among distinct tumor types. It is therefore remarkable that we have detected enrichment of CD61 on stem-like cells within tumor biopsies from many different drug-resistant samples of lung, breast, pancreatic, and brain tumors from mice or humans.

CD61 promotes a stem-like reprogramming event, since ectopic expression CD61 induces stemness, including self-renewal, tumor-forming ability, and resistance to therapy. CD61 drives these behaviors by activating a signaling pathway which can be inhibited to reverse stemness and sensitize tumors to therapy.

Our project is focused on learning how CD61 drives this cancer stem cell program, and how the increase in CD61 could be prevented or reversed. If successful, our work will provide valuable new insight into a cancer stem cell program that is unexpectedly shared among a variety of solid tumor types.

Statement of Benefit to California: 

The American Cancer Society estimates 171,330 new cancer cases will be diagnosed in California this year, a 10th of the national total. As part of an NCI-designated comprehensive cancer, we are uniquely positioned to translate our basic science research into clinical impact for the cancer patients within our community.

From a clinical perspective, the understanding gained from our proposed studies will broadly benefit patients in California who will be diagnosed with an epithelial cancer this year, including 25,360 new breast cancer patients and 18,720 new lung cancer patients. Gaining fundamental insight into how these cancers are reprogrammed to become more stem cell-like as they acquire resistance to therapy will facilitate development of new strategies to prevent or reverse this behavior to benefit these large numbers of patients who live in California. In addition, our work will also yield new diagnostic tools that could identify which patients might respond to certain therapies.

At the basic science level, our project will also serve to elucidate the mechanisms by which cancer stem cells contribute to cancer progression and response to therapy. During the course of our project, we will be able to train more people in California to work on this cutting-edge research, and to establish a foundation for the logical design of anti-cancer therapies targeting this unique cancer stem cell population.

Progress Report: 
  • Cancers are often treated based on their underlying disease phenotype or molecular drivers. While these targeted strategies may provide some initial benefit, they tend to fail over time as tumors develop resistance mechanisms. Cancer stem cells, traditionally defined as a small population of “pre-existing” cells responsible for initiating a tumor, have been implicated as a major contributor to drug resistance. Although small in number, it is thought the population of cancer stem cells within a tumor could survive therapy to regenerate an entire tumor over time or spread to distant sites.
  • We suggest an alternate scenario in which any cell within a tumor could be “converted” into a cancer stem-like cell. We have now demonstrated that exposing epithelial cancer cells to different types of stress, including cancer therapies, induces a subset of markers and functions attributed to traditional cancer stem cells. The goal of our project is to understand how a protein called CD61 drives this reprogramming event so that we can design approaches to interfere with this pathway in order to lock cancer cells into a less aggressive and more therapy-responsive state.
  • In the past year, we have defined a common subset of cancer stem cell features that are induced by CD61 in response to multiple types of cellular stress. These stresses represent those that a tumor cell might encounter within its microenvironment, including nutrient deprivation, hypoxia, or cancer therapy. Interestingly, we have also discovered that these changes are reversible and that tumor cells can be “primed” to respond to stress so that they can rapidly adopt the stem-like features to evade the effects of therapy.
  • We have also identified specific upstream drivers required for the induction of CD61 by stress, and we have shown that they are necessary and sufficient to trigger CD61. In addition, we are beginning to understand how CD61 orchestrates the conversion of an epithelial cancer cell into a stem-like cancer cell by altering the location and function of downstream signaling proteins. Work in the upcoming year will focus on identifying specific steps along the pathway that could be manipulated therapeutically to prevent this reprogramming of cancer cells that contributes to drug resistance and disease progression.
Funding Type: 
Early Translational IV
Grant Number: 
TR4-06867
Investigator: 
Name: 
Type: 
Co-PI
ICOC Funds Committed: 
$4 075 668
Disease Focus: 
Prostate Cancer
Cancer
Stem Cell Use: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Metastatic disease and the castration resistance remain tremendous challenges in the treatment of prostate cancer. New targeted treatments, such as the ant-testosterone medication enzalutamide, have improved the survival of men with advanced disease, but a majority develops treatment resistance. The field of cancer stem cells hypothesizes that treatment resistance emerges because stem cells are inherently resistant to our current therapies and eventually repopulate tumors. One mechanism by which cancer stem cells resist therapy is through acquisition of an epithelial to mesenchymal transition (EMT), a phenomenon of normal development used by cancers to survive and metastasize. Our laboratory has shown that prostate cancers undergo an EMT that leads to invasion, metastasis and treatment resistance. N-cadherin, a critical regulator of EMT, is expressed in most castration resistant prostate cancers (CRPC) and is sufficient to promote treatment resistance. We therefore developed antibodies against N-cadherin, which are able to inhibit growth, metastasis and progression of prostate cancers in vivo. The goal of this translational application is to move this promising treatment from the laboratory to the clinic by making the antibody human, making it bind more strongly, and then testing it for toxicity, behavior and anti-tumor activity. At the completion of this project, we will be poised to manufacture this lead molecule and move expeditiously to Phase I clinical studies.

Statement of Benefit to California: 

Prostate cancer is the second leading cause of cancer-related death in Californian men. With an aging population, this problem is expected to continue to grow despite recent advances in treatment. The goal of this application is to develop a novel antibody targeting a cancer stem cell target in hormone and treatment refractory prostate cancer. The benefit to the California, if successful, will be the development of a novel therapy against this common disease.

Progress Report: 
  • Metastatic disease and the castration resistance remain tremendous challenges in the treatment of prostate cancer. New targeted treatments, such as the anti-testosterone medication enzalutamide, have improved the survival of men with advanced disease, but a majority develops treatment resistance. The field of cancer stem cells hypothesizes that treatment resistance emerges because stem cells are inherently resistant to our current therapies and eventually repopulate tumors. One mechanism by which cancer stem cells resist therapy is through acquisition of an epithelial to mesenchymal transition (EMT), a phenomenon of normal development used by cancers to survive and metastasize. Our laboratory has shown that prostate cancers undergo an EMT that leads to invasion, metastasis and treatment resistance. N-cadherin, a critical regulator of EMT, is expressed in most castration resistant prostate cancers (CRPC) and is sufficient to promote treatment resistance. We therefore developed antibodies against N-cadherin, which are able to inhibit growth, metastasis and progression of prostate cancers in vivo. The goal of this translational application is to move this promising treatment from the laboratory to the clinic by making the antibody human, making it bind more strongly, and then testing it for toxicity, behavior and anti-tumor activity. At the completion of this project, we will be poised to manufacture this lead molecule and move expeditiously to Phase I clinical studies.
  • At this juncture in the project, we have made our two original lead antibodies into human ones that would not elicit an immune response in patients. We have begun to test these “humanized” antibodies and they appear to retain the properties of the mouse ones from which they were derived. We have also generated additional candidate antibody drugs through screening of a library containing millions of candidate antibodies. We have narrowed these candidates down to approximately 9, and are continuing to work to prioritize these based on activity. Finally, we have begun the process of maturing these lead candidates to bind more tightly to N-cadherin, the target, hypothesizing that this will further improve the efficacy of these drugs moving forward. Over the coming months, we will finalize selection of 2-3 lead antibodies and begin testing them in animal experiments as the next step toward realizing the goal of testing them in patients.
Funding Type: 
New Faculty II
Grant Number: 
RN2-00904
Investigator: 
ICOC Funds Committed: 
$2 381 572
Disease Focus: 
Lung Cancer
Cancer
Respiratory Disorders
Stem Cell Use: 
Adult Stem Cell
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

Lung cancer is the most deadly cancer worldwide and accounts for more deaths than prostate cancer, breast cancer and colon cancer combined. Non small cell lung cancer (NSCLC) accounts for about 85% of all lung cancers. The current 5-year survival rate for all stages of NSCLC is only 15%. Although early stage lung cancer has a much better survival rate. Current therapeutic strategies of chemotherapy, radiation therapy and trials with new targeted therapies have only demonstrated, at best, extension in survival by a few months. Clearly, a novel approach is required to develop new therapies for this devastating disease and to detect the disease at an early stage. Cancer stem cells have been identified as the initial cell in the formation of carcinomas. Chemotherapy, radiation and even targeted therapies are all designed to eliminate dividing cells. However, cancer stem cells “hide out” in the quiescent phase of growth. This provides an explanation as to why our cancer therapies may produce an initial response but are often unsuccessful in curing patients. Lung cancer develops through a series of step wise changes that result in the progression of pre-malignant lesions to invasive lung cancer. The mechanisms of how lung cancer develops are not known and if we can prevent the formation of pre-malignant lesions, we will likely be able to prevent lung cancer. We have discovered a subpopulation of stem cells that circulates in the blood and is essential for normal lung repair. Blocking these cells from entering the lung results in a pre-malignant condition in the lungs. We have also identified a subpopulation of stem cells in the lung that is responsible for generating pre-malignant lung cancer lesions. We hypothesize that the interaction between the stem cells in the blood and the stem cells in the lung are critical to prevent lung cancer. We plan to use cutting edge technologies to characterize these different stem cell populations in the lung, and determine how they form pre-malignant lung cancer lesions. We also plan to use preclinical models to try to prevent lung cancer by giving additional stem cells derived from the blood as a therapy. Lastly, we plan to determine whether levels of stem cells in the blood in patients may be used as a blood test to measure the chance of recurrence of lung cancer after therapy. The long term goals of our work are to develop a screening test for lung cancer stem cells that can predict which patients are at high risk for developing lung cancer in order to diagnose lung cancer at an early stage, and to potentially develop a new stem cell based therapy for preventing and treating lung cancer.

Statement of Benefit to California: 

According to the Center for Health Statistics, California Department of Health Services, 13,427 people died of lung cancer in the state of California in 2005. This is more than the deaths attributed to breast, prostate and colon cancers combined. The devastating effects of this disease on the citizens of California and the health care costs involved are enormous. Most cases of lung cancer occur in smokers, but non smokers, people exposed to second hand smoke and ex-smokers are also at risk. In addition, of special concern to California residents, is that exposure to air pollution is associated with an increased risk of lung cancer. Current therapeutic strategies for lung cancer are in general only able to prolong survival by a few months, especially for late stage disease. One reason for this may be that the cancer initiating stem cell is resistant to these therapies. Understanding the stem cell populations involved in repair of the lung and how these cells may give rise to lung cancer is important for potentially generating new therapeutic targets for lung cancer. We propose to study the stem cell populations of the lung that are crucial for normal airway repair and characterize the putative cancer initiating stem cell in the lung. We have also found stem cells in the blood that are critical for normal airway repair and we plan to test their role in the prevention of premalignant lung cancer lesions. We also plan to test whether levels of these stem cells in the blood may be used as a biomarker of lung cancer. Ultimately, the ability to perform a screening test to detect lung cancer at an early stage, and the development of new therapies for lung cancer will be of major benefit to the citizens of California.

Progress Report: 
  • We identified a putative tumor-initiating stem/progenitor cell that goes rise to smoking-associated non small cell lung cancer (NSCLC). We examined 399 NSCLC samples for this tumor-initiating stem/progenitor cell and found that the presence of this cell in the tumor gave rise to a significantly worse prognosis and was associated with metastatic disease. This stem/progenitor cell is known to be important for repair of the airway and is present in precancerous lesions. We believe that this cell undergoes aberrant repair after smoking injury, which leads to lung cancer. We are currently trying to identify the genetic and epigenetic mechanisms involved in this aberrant repair as a means to identify a novel therapy to prevent the development of lung cancer. The presence of these stem/progenitor cells may also be used as a biomarker of poor prognostic NSCLC even in early stage disease.
  • We have identified markers on these stem/progenitor tumor-initiating cells and identified sub-populations of these cells. We are now determining the stem cell capabilities of each of these sub-populations. We are using a model of the development of lung cancer to determine if giving a stem/progenitor cell sub-population for repair can prevent NSCLC from developing.
  • We examined the blood of patients diagnosed with a lung nodule for circulating epithelial stem/progenitor cells. We found that the presence of these cells in the blood of patients predicted the presence of a subtype of NSCLC as compared to a benign lung nodule. We are currently obtaining many more blood samples from patients to further determine whether circulating epithelial stem/progenitor cells could be used as a biomarker of early NSCLC.
  • We have found a stem cell that is important for lung repair after injury that is located in a protected niche in the airway. After repeated injury, for example in smokers, these stem cells persist in an abnormal location on the surface of the airway and replicate and form precancerous areas in the lung. The presence of these stem cells in lung cancer tumors was associated with a poor prognosis with an increased chance of relapse and metastasis.This was especially true in current and former smokers. We therefore believe we have found a putative stem cell that is a tumor initiating cell for lung cancer. We developed a method to isolate these lung stem cells and to profile these cells and developed in vitro and in vivo models to assess their stem cell properties. Finally, we examined human blood samples to assess levels of surrogate markers of these stem cells to assess whether we could use this as a biomarker to predict the presence or absence of lung cancer in patients with a lung nodule.
  • We found a stem cell that is important for lung repair after injury that we believe may form precancerous areas in the lung. We are characterizing these stem cells and identifying pathways involved in normal repair and aberrant repair that leads to lung cancer. We are also isolating this stem cell population and other cell populations from the airway and inducing genetic changes to determine the tumor initiating cell/s for lung cancer. We are also examining the effect the environment may have on the regulation of genes in these stem cells, in precancerous areas and in lung cancers. Finally, we are examining human blood samples to assess levels of surrogate markers of these stem cells to assess whether we could use this as a biomarker to predict the presence or absence of lung cancer in patients with a lung nodule.
  • During this period of funding we discovered a method to reproducibly recover stem cells from human airways and grow them in a dish into mature airway cells. We also discovered the role that certain metabolic cell processes play in regulating the repair after airway injury. We believe that an inability to shut off these processes leads to abnormal repair and lung cancer and are actively investigating this. We are also determining whether the stem cells we isolate from the airways are the stem cells for lung cancer and how they might give rise to lung cancer.
  • In the last year of funding we identified a novel mechanism that tightly controls airway stem cell proliferation for repair after injury. We found that perturbing this pathway results in precancerous lesions that can ultimately lead to lung cancer. Correcting the abnormalities in this pathway that are seen in smokers could allow the development of targeted chemoprevention strategies to prevent the development of precancerous lesions and therefore lung cancer in at risk populations. We also continued our work on trying to identify a cell of origin for squamous lung cancer and identifying the critical drive mutations that are required for squamous lung cancer to develop.
  • During this reporting period we discovered and published on how reactive oxygen species drive proliferation of airway basal stem cells. We found that this pathway is critical for homeostasis of the airway epithelium and perturbing this pathway results in precancerous lesions. Interestingly, these precancerous lesions are able to resolve over time, which is similar to the situation in smokers who develop precancerous lesions that almost always resolve. We now have a model to study the driver mutations that take precancerous lesions to invasive squamous lung cancer and with this model we can start to identify novel therapies to prevent the development of precancerous lesions and/or progression of precancerous lesions. We also developed a model of precancerous lesions in a dish which allows us to screen for compounds that promote or resolve these premalignant lesions. Our overall goal is to use these models to develop a targeted chemoprevention strategy for squamous lung cancer.
Funding Type: 
Early Translational III
Grant Number: 
TR3-05641
Investigator: 
Institution: 
Type: 
PI
Institution: 
Type: 
Co-PI
ICOC Funds Committed: 
$5 217 004
Disease Focus: 
Brain Cancer
Cancer
Stem Cell Use: 
Adult Stem Cell
Cell Line Generation: 
Cancer Stem Cell
oldStatus: 
Active
Public Abstract: 

While current treatment strategies for high-grade glioma can yield short term benefits, their inability to eradicate the highly tumorigenic cancer stem cell population results in disease recurrence in the vast majority of patients. Stem cells and some cancer cells (the targets of our therapy) share many common characteristics, including the ability to self-renew and grow indefinitely. These cancer stem cells are also resistant to many standard therapies including radiation and chemotherapy, creating a critical need for novel therapies that will efficiently eliminate this cell population. We propose here to develop and optimize a therapeutic strategy, termed “adoptive T cell therapy", that will eliminate the brain tumor stem cell population by re-directing a patient’s immune cells, specifically T cells, to recognize and destroy tumor stem cells. Our goal is a therapy in which a single administration of tumor-specific T cells results in long-term anti-glioma protection. Our approach builds on previous findings that T cells, when reprogrammed, can potently kill glioma stem cells. Furthermore, we will exploit the self-renewing stem cell-like properties of a defined T cell population (central memory T cells) to establish reservoirs of long-lasting tumor-directed T cells in patients with glioma, and thereby achieve durable tumor regression with a glioma-specific T cell product. Our findings can then be applied to cancers besides glioma, including tumors that metastasize to brain.

Statement of Benefit to California: 

The goal of this project is to develop a novel and promising immunotherapy utilizing genetically modified T cells to target glioma stem cells in order to improve cure rates for patients with high-grade malignant glioma. Our strategy, in which a single administration of tumor-specific T cells results in long-term anti-glioma protection, has the potential to provide significant therapeutic benefit to patients with brain tumors, for which there is a dearth of effective treatment options. Further, the tumor-specificity of this therapy is intended to improve the quality of life for patients with high-grade gliomas by reducing treatment related side-effects of conventional therapies. Moreover, due to the high cost hospital stays and treatments usually required for patients with advanced disease, this therapy, by generating long-lasting anti-cancer immunity, has the potential to significantly reduce the costs of health care to California and its citizens. Carrying out these proposed studies will have further economic benefit for California through the creation and maintenance of skilled jobs, along with the purchasing of equipment and supplies from in-state companies. This project will also yield long-reaching benefit through continuing to build the larger CIRM community that is establishing California as a leader in stem-cell and biomedical research both nationally and internationally.

Progress Report: 
  • While current treatment strategies for high-grade glioma can yield short term benefits, their inability to eradicate the highly tumorigenic cancer stem cell population results in disease recurrence in the vast majority of patients. Stem cells and some cancer cells (the targets of our therapy) share many common characteristics, including the ability to self-renew and grow indefinitely. These stem cell-like cancer cells are also resistant to many standard therapies including radiation and chemotherapy, creating a critical need for novel therapies that will efficiently eliminate this cell population. The goal of this project is to develop and optimize a therapeutic strategy, termed “adoptive T cell therapy,” that will eliminate the brain tumor stem cell population by re-directing a patient’s immune cells, specifically T cells, to recognize and destroy tumor stem cells. Our goal is a therapy in which a single administration of tumor-specific T cells results in long-term anti-glioma protection. Our approach builds on our previous pre-clinical and clinical findings that T cells, when reprogrammed, can potently kill glioma stem cells.
  • Over the past year, our group has developed and characterized an optimized next-generation adoptive T cell therapy platform for targeting the glioma-associated antigen IL13Rα2. As such, T cells were modified to express a chimeric antigen receptor (CAR) to recognize and kill IL13Rα2-expressing glioma cells. This T cell platform incorporates several improvements in CAR design and T cell engineering, including improved receptor signaling and the utilization of central memory T cells (Tcm) as the starting cell population for CAR-engineering for enhanced long-term persistence of the cells after they are administered to patients. Importantly, we now demonstrate that this optimized IL13Rα2-specific CAR Tcm therapeutic product mediates superior antitumor efficacy and improved T cell persistence as compared to our previous first-generation IL13Rα2-specific T cells. These findings are significant as they suggest the potential for improving the transient anti-glioma responses for patients, as observed in two Phase I clinical trials by our group at City of Hope, with this optimized next-generation platform.
  • The variability of gliomas, including the known differences between populations of glioma stem-like cells, is a critical barrier to the development of a therapy with the potential to mediate complete and durable remission of this disease. We have therefore hypothesized that a multi-targeted therapeutic approach will be required to achieve elimination of glioma stem-like cells and achieve longer lasting regression of high-grade glioma. To devise an effective multi-target therapy, one must first identify the potentially useful T cell target antigens and variations in their expression between patients and within individual tumors. The ideal target will be highly expressed on tumor cells, including stem-like cells, and not found on normal brain or other tissues. To this end, we have assembled a cohort of 35 patient samples in commercial tissue arrays and 45 patient specimens from the CoH Department of Pathology. Within this group of 80 patient tumors we have begun to examine expression of potential T cell targets, such as IL13Rα2, HER2, EGFR, and others. The goal is to find a set of target antigens that would encompass the maximum number of tumors and, in particular, the cancer stem-like cells within an individual tumor.
  • Our progress thus far has set the stage for our team to develop a potent multi-antigen specific T cell therapy that can “box-in” tumor variability. This clinically translatable platform has the potential to provide new treatment options for this devastating disease.
  • While current treatment strategies for glioblastoma (GBM) can yield short term benefits, their inability to eradicate the highly tumorigenic cancer stem cell population results in disease recurrence in the vast majority of patients. Stem cells and some cancer cells (the targets of our therapy) share many common characteristics, including the ability to self-renew and grow indefinitely. These stem cell-like cancer cells are also resistant to many standard therapies including radiation and chemotherapy, creating a critical need for novel therapies that will efficiently eliminate this cell population. The goal of this project is to develop and optimize a therapeutic strategy, termed “adoptive T cell therapy,” that will eliminate the brain tumor stem cell population by re-directing a patient’s immune cells, specifically T cells, to recognize and destroy tumor stem cells. Our goal is a therapy in which administration of tumor-specific T cells targeting combinations of antigens expressed on the cell surface of glioma stem-like cells results in long-term anti-glioma protection. Our approach builds on our previous pre-clinical and clinical findings that T cells, when reprogrammed, can potently kill glioma stem cells.
  • Thus far, our group has developed and characterized an optimized next-generation adoptive T cell therapy platform for targeting the glioma-associated antigen IL13Rα2. As such, T cells were modified to express a chimeric antigen receptor (CAR) to recognize and kill IL13Rα2-expressing glioma cells. This T cell platform incorporates several improvements in CAR design and T cell engineering over previous versions, including improved receptor signaling and the utilization of central memory T cells (Tcm) as the starting cell population for CAR-engineering (enhancing long-term persistence of the cells after they are administered to patients). Importantly, we now demonstrate that this optimized IL13Rα2-specific CAR Tcm therapeutic product mediates superior antitumor efficacy and improved T cell persistence as compared to our previous first-generation IL13Rα2-specific T cells. We further demonstrate that intracranial (i.c.) delivery of the IL13Rα2-specific CAR T cells outperforms intravenous (i.v.) delivery in orthtotopic mouse models of human glioblastoma, providing the clinical rational for local i.c. delivery. These findings are significant as they suggest the potential of this optimized next-generation platform to improve upon the transient anti-glioma patient responses observed in two Phase I clinical trials completed by our group at City of Hope. Based on these earlier results we have submitted an Investigational New Drug (IND) application to the Food and Drug Administration (FDA) to initiate a single agent IL13Rα2-specific CAR T cell clinical trial. This clinical trial will provide a foundation for the ultimate goal of this CIRM ET award: development of a combination CAR T cell approach to overcome the high-degree of GBM heterogeneity.
  • This antigenic variability of gliomas, including differences between populations of glioma stem-like cells, is a critical barrier to the development of an immunotherapy with the potential to mediate complete and durable disease remission. We hypothesize that a multi-targeted therapeutic approach will be required to achieve elimination of glioma stem-like cells and achieve longer lasting regression of high-grade glioma. To devise an effective multi-target therapy, we are first identifying potentially useful T cell target antigens, and assessing variations in their expression between patients and within individual tumors. Ideal targets will be highly expressed on tumor cells, including stem-like cells, and not found on normal brain or other tissues. To this end, we have assembled a cohort of 35 patient samples in commercial tissue arrays and 45 patient specimens from the CoH Department of Pathology. Within this group of 80 patient tumors we have been examining expression of potential T cell targets, such as IL13Rα2, HER2, EGFR/EGFRvIII, and others. Our goal is to define a set of target antigens encompassing the maximum number of tumors and, in particular, the cancer stem-like cells within individual tumors. Based on this analysis, we are currently developing and optimizing CAR T cells targeting HER2 and EGFRvIII.
  • Our progress is thus continuing to set the stage for developing a potent multi-antigen specific T cell therapy that can “box-in” tumor variability. Our clinically translatable platform has the potential to provide new treatment options for this devastating disease.
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.

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