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.