Methods for detection and elimination of residual human embryonic stem cells in a differentiated cell product

Methods for detection and elimination of residual human embryonic stem cells in a differentiated cell product

Funding Type: 
Early Translational I
Grant Number: 
TR1-01215
Award Value: 
$5,405,397
Disease Focus: 
Diabetes
Collaborative Funder: 
Victoria, Australia
Stem Cell Use: 
Embryonic Stem Cell
Status: 
Active
Public Abstract: 
Human embryonic stem cells (hESC), and other related pluripotent stem cells, have great potential as starting material for the manufacture of curative cell therapies. This is primarily for two reasons. First, by manipulating cues in their cell culture conditions, these cells can be directed to become essentially any desired human cell type (a property known as pluripotency). Second, hESC have the remarkable capacity to expand rapidly with essentially no change in their identity. At a practical level, this means enough cells to manufacture thousands, and even millions, of therapeutic cell doses can be generated in a matter of weeks. Thus, the biomedical potential is tremendous, but several practical matters remain to be resolved. One of the biggest concerns is that manufacturing processes, i.e., methods to direct “undifferentiated” hESC to become “differentiated” target cell types, have not shown 100% efficiency. That is, some portion of the starting hESC might not differentiate in accordance with the cues given, resulting in a cell therapy product with some contaminating undifferentiated hESC. When undifferentiated hESC are transplanted into animals, they proliferate and differentiate in an uncontrolled, semi-random manner, becoming non-target cell types collectively called a teratoma. Teratomas also occur spontaneously in humans, and consist of a variety of cell types in a disorganized tissue amalgam. Both experimental and spontaneous teratomas are generally benign tumors, and typically can be surgically removed when they become physically problematic due to size or location. While hESC-derived cell therapies have been shown to be effective in animal models of disease, in some instances teratomas have been observed. Thus, the full promise of hESC as source material for novel cell therapies cannot be fully realized until the “teratoma problem” is solved. To date there is no standard method in the field for testing the teratoma potential of a given cell population, nor is there a method for eliminating the potential for teratoma. The proposed project will investigate and establish standardized tests to measure teratoma potential. The tests will be highly sensitive, allowing assurance that large human doses are produced with no risk of teratoma. The project will also investigate a relatively simple method to eliminate undifferentiated hESC in the course of manufacturing. As the last step, the new method will be incorporated into the manufacturing process, the sensitive teratoma tests will be used, and safety data required by the FDA will be collected for a promising new hESC-derived cell therapy for insulin-dependent diabetes. Successful completion of this project will represent a major advance in development of stem cell-derived therapies broadly, and will specifically contribute to the development of a cell therapy for diabetes.
Statement of Benefit to California: 
In large part through CIRM initiatives, California hopes to further establish itself as the world center for stem cell research and stem cell-derived therapies. One major issue standing in the way of stem cell-derived therapy development is the possibility of a teratoma forming after transplant with a stem cell-derived cell therapy. A teratoma is a disorganized tissue amalgam containing various different cell types, and is generally a benign tumor. Teratomas can form in animals transplanted with stem cells, and therefore if some stem cells persist in the stem-cell derived therapy, there exists a possibility that teratomas will form in a patient’s graft. Indeed, putative stem cells have been found in pre-clinical research-grade stem cell-derived cell therapy preparations, and teratomas have been observed in animals treated with those cells. Currently the conditions favorable to teratoma formation are poorly characterized, and methods to reduce the likelihood of teratoma formation have not been developed. The proposed project will establish standardized sensitive methods to measure the teratoma potential of a cell population, will develop a method to reduce or eliminate teratoma potential, and will include both the method to reduce teratoma and the standard measurement of teratoma potential in the development of an actual prospective cell therapy product for the treatment of insulin-dependent diabetes. If successful, this project will remove a significant bottleneck currently holding the development of stem cell-derived cell therapies back, as well as provide essential pre-clinical data for an important stem cell-derived therapy for diabetes, facilitating its clinical testing in diabetics. The State of California will benefit by playing a key role in removing the teratoma bottleneck from the field, as well as in advancing a promising new cell therapy for diabetes, a disease which directly or indirectly affects millions of Californians. Such a therapy could reduce the state's health care costs tremendously.
Progress Report: 

Year 1

ViaCyte is developing a cell therapy for diabetes, which will have a tremendous clinical and societal impact as such a large number of people are afflicted with this disease. The therapy is a combination product comprised of pancreatic progenitor cells transplanted within a device, Encaptra™. A large supply of pancreatic progenitors can be produced with a cell manufacturing process that involves the directed differentiation of human embryonic stem cells (hESC). After transplantation the pancreatic progenitor cells differentiate into functional islets that contain insulin-producing beta cells. Encaptra™ is designed to allow the release of insulin to regulate blood glucose levels while simultaneously protecting the transplanted cells from destruction by the patients’ immune system. The combined product provides a large assurance of safety since cells will be contained and the device is retrievable. This award is focused on product safety, principally the issue of tumorigenicity. Tumor formation is a particular consideration when using hESCs as cell manufacturing starting material since undifferentiated hESCs form a particular type of tumor, called a teratoma, when transplanted into animal models. Therefore, it is important to demonstrate that at the end of the manufacturing process the cell product is largely devoid of undifferentiated hESC and lacks teratoma potential. ViaCyte has been investigating and establishing standardized assays to measure the presence of hESCs and the potential for teratoma formation. In addition, ViaCyte has previously identified several compounds that appear to preferentially kill undifferentiated hESCs while not affecting the viability of pancreatic progenitors. To ensure that Encaptra™ will be fully effective in containing implanted cells in a patient, ViaCyte is developing various assays to ensure the quality of manufactured devices. These newly developed assays will be incorporated into the manufacturing process and data required by the FDA for product safety will be collected. Successful completion of this project will represent a major advance for stem cell-derived therapies and will specifically contribute to establishing a cell therapy for diabetes.

Year 2

ViaCyte is a preclinical company developing a stem cell-based therapy for insulin-dependent diabetes. The therapy is a combination product comprised of pancreatic progenitor cells, pro-islet, encapsulated within a retrievable delivery ENCAPTRA device. After implantation, encapsulated pro-islet differentiates into glucose-responsive, insulin-secreting cells that can regulate normal blood sugar levels in animal models of diabetes. The renewable starting material for pro-islet manufacturing is human embryonic stem cells (hESC) that are directed to differentiate to pancreatic cell product using scalable processes. The bio-stable ENCAPTRA device is designed to fully contain cells and to protect cells from immune attack. The goal is to develop a product that will achieve insulin independence, reduce diabetes-related complications, and eliminate the need for continuous immunosuppressant drugs. This CIRM award is focused on product safety. A large assurance of safety is provided by confining the transplanted cells within the device and by the ability to retrieve the product. Nonetheless, an important preclinical safety assessment of this combination product therapy is the evaluation of its tumorigenicity, i.e. its capacity to form tumors. Upon transplantation into animal models, undifferentiated hESC can generate a teratoma, a tumor that is akin to a particular type of germ cell tumor that can form in humans. There is a possibility that residual, undifferentiated hESC could remain in pro-islet, potentially giving rise to a teratoma. It is unclear whether teratomas can form when undifferentiated hESC are transplanted within ENCAPTRA and if so, what threshold dose of hESC in pro-islet could generate a teratoma. ViaCyte has been investigating and establishing standardized assays to measure the presence of hESC in pro-islet and the potential for teratoma formation. Preliminary tumorigenicity studies of pro-islet were completed with safe outcomes. With these data in hand, formal definitive tumorigenicity studies can be designed and initiated to include in a package to submit to the FDA as ViaCyte seeks approval to test the product in humans. To demonstrate that ENCAPTRA will be effective in containing implanted cells in a patient, ViaCyte is also developing assays to ensure the quality of manufactured devices. These newly developed assays are being incorporated into the cell manufacturing and device manufacturing processes, and data will be collected to show that the product is safe. Successful completion of the objectives of this award will help establish the safety of the product so that clinical trials can be initiated with the goal of developing a game-changing cell therapy for diabetes.

Year 3

ViaCyte is a company developing a stem cell-based therapy for diabetes. The therapy is a combination product, called VC-01™, comprised of human embryonic stem cell (hESC)-derived pancreatic beta cell precursors (PEC-01™ cell product), encapsulated within the Encaptra® drug delivery system (ENCAPTRA device). After implantation, the precursor cells mature into endocrine cells that secrete insulin and other hormones in a regulated manner to control blood sugar levels in animal models of diabetes. hESC are the renewable starting material for cell manufacturing; they are directed to differentiate to PEC-01 cell product using scalable processes. The retrievable ENCAPTRA device is designed to contain cells and to protect cells from immune attack. The goal is to develop a product that will provide insulin independence, reduce diabetes-related complications, and eliminate the need for chronic immunosuppressant drugs. This CIRM award is focused on product safety. An important nonclinical safety assessment of this combination product therapy is the evaluation of its tumorigenicity, i.e., its capacity to form tumors. Upon transplantation into animal models, undifferentiated hESC can generate a teratoma, a tumor that is akin to a particular type of germ cell tumor that can form in humans. Accordingly, to the extent that undifferentiated hESC could potentially remain in the differentiated PEC-01 cell product, these could potentially give rise to a teratoma. Prior to this award, it was unclear whether teratomas will form when undifferentiated hESC are implanted within the ENCAPTRA device and if so, what threshold dose of hESC in PEC-01 would be required to produce a teratoma. ViaCyte received this award to develop methods to assess teratoma potential with in vivo and in vitro assays, and to mitigate potential tumorigenicity risk by ensuring integrity of the encapsulation delivery device. ViaCyte has investigated a standardized assay to measure the presence of hESC in PEC-01 cell product, and preliminary tumorigenicity studies of VC-01 were completed with safe outcomes. With these data in hand, definitive IND-enabling tumorigenicity studies were designed and initiated to include in a package that will be submitted to the FDA as ViaCyte seeks approval to test the product in human clinical trials. A large assurance of safety is provided by confining the transplanted cells within the device and by the ability to retrieve the product. To demonstrate that the ENCAPTRA device will be effective in containing implanted cells in a patient, ViaCyte has also developed assays and performed studies to ensure the integrity of the ENCAPTRA device. Collectively, the data from these studies will form a compelling package to demonstrate the safety of the VC-01 product so that clinical trials can be initiated with the goal of developing a game-changing cell therapy for diabetes.

Year 4

ViaCyte is a company developing a stem cell-based therapy for diabetes. The therapy is a combination product, called VC-01™, comprised of human embryonic stem cell (hESC)-derived pancreatic beta cell precursors (PEC-01™ cell product), encapsulated within the Encaptra® drug delivery system (ENCAPTRA device). After implantation, the precursor cells mature into endocrine cells that secrete insulin and other hormones in a regulated manner to control blood sugar levels in animal models of diabetes. hESC are the renewable starting material for cell manufacturing; they are directed to differentiate to PEC-01 cell product using scalable processes. The retrievable ENCAPTRA device is designed to contain cells and to protect cells from immune attack. The goal is to develop a product that will provide insulin independence, reduce diabetes-related complications, and eliminate the need for chronic immunosuppressant drugs. This CIRM award is focused on product safety. An important nonclinical safety assessment of this combination product therapy is the evaluation of its tumorigenicity, i.e., its capacity to form tumors. Upon transplantation into animal models, undifferentiated hESC can generate a teratoma, a tumor that is akin to a particular type of germ cell tumor that can form in humans. Accordingly, to the extent that undifferentiated hESC could potentially remain in the differentiated PEC-01 cell product, these could potentially give rise to a teratoma. Prior to this award, it was unclear whether teratomas will form when undifferentiated hESC are implanted within the ENCAPTRA device and if so, what threshold dose of hESC in PEC-01 would be required to produce a teratoma. ViaCyte received this award to develop methods to assess teratoma potential with in vivo and in vitro assays, and to mitigate potential tumorigenicity risk by ensuring integrity of the encapsulation delivery device. ViaCyte has investigated a standardized assay to measure the presence of hESC in PEC-01 cell product, and preliminary tumorigenicity studies of VC-01 were completed with safe outcomes. With these data in hand, definitive IND-enabling tumorigenicity studies were designed and initiated to include in a package that will be submitted to the FDA as ViaCyte seeks approval to test the product in human clinical trials. A large assurance of safety is provided by confining the transplanted cells within the device and by the ability to retrieve the product. To demonstrate that the ENCAPTRA device will be effective in containing implanted cells in a patient, ViaCyte has also developed assays and performed studies to ensure the integrity of the ENCAPTRA device. Collectively, the data from these studies will form a compelling package to demonstrate the safety of the VC-01 product so that clinical trials can be initiated with the goal of developing a game-changing cell therapy for diabetes.

© 2013 California Institute for Regenerative Medicine