ViaCyte FAQ (frequently asked questions)
ViaCyte is a clinical-stage company developing transformative cell therapy products for diabetes. Below are answers to commonly asked questions.
PEC-01 cells are a human cell product, developed and manufactured by ViaCyte, composed primarily of pancreatic progenitor cells. PEC-01 cells are manufactured from a line of pluripotent embryonic stem cells (called CyT49) using a carefully controlled directed differentiation process. The differentiation process is designed to yield a cell population that can mature into glucose-responsive, insulin-producing cells. PEC-01 cells, as a result of the directed differentiation, are not pluripotent stem cells. In animal studies, after implantation PEC-01 cells have been shown to further differentiate and mature into pancreatic endocrine cells, including beta cells that secrete human insulin in response to increases in blood glucose.
The PEC-Direct product candidate delivers stem cell-derived PEC-01™ pancreatic progenitor cells in a device designed to allow direct vascularization of the cells. The PEC-Direct product is being developed for the over 100,000 patients in the US alone who are at high risk of acute complications related to their type 1 diabetes (T1D). The PEC-01 progenitor cells are designed to mature into human pancreatic islet cells, including glucose-responsive, insulin-secreting beta cells, following implant. High-risk T1D patients are those who have severe hypoglycemic episodes (SHEs), extreme glycemic lability, and/or impaired awareness of hypoglycemia (IAH). Like an organ transplant, PEC-Direct will be used in conjunction with immune suppression to prevent immune rejection of the implanted cells. If successful, PEC-Direct treatment is expected to reduce or eliminate the incidence of SHE, extreme glycemic lability, and IAH. It is anticipated that patients receiving the PEC-Direct implant will no longer require insulin administration or glucose monitoring.
The high-risk T1D patients for whom the PEC-Direct product is being developed are those who might also be eligible for cadaver islet transplants, a procedure that has proven to be very effective but suffers from a severe lack of donor material as well as other procedural limitations. ViaCyte believes that PEC-Direct could overcome the limitations of cadaver islet transplant by providing an unlimited supply of cells, manufactured under quality-controlled cGMP conditions, and delivered by a safer, more optimal route of administration. While cadaver islets are delivered into the liver, the PEC-Direct product candidate is intended to be implanted under the skin in a manner that would allow for removal of the product should that be deemed necessary. This represents a significant safety advantage relative to delivery into the liver.
There are T1D patients who, despite their best diligence with insulin and other pharmaceutical approaches, are at constant risk of severe hypoglycemic episodes (SHEs), which can lead to hospitalization and even death. Approximately 10-15% of people with T1D may have a combination of impaired awareness of hypoglycemia (IAH; characterized by a reduced or absent ability to detect the symptoms commonly associated with low blood sugars), extreme glycemic lability (also commonly referred to as “brittle diabetes”), and/or an unacceptable incidence of SHEs. For these T1D patients, PEC-Direct could represent a functional cure. While the requirement to take immune suppressive medications with PEC-Direct introduces some risk, it is expected that for these T1D patients, the benefit of a functional cure will far outweigh the potential risk.
Much product development work remains before PEC-Direct will be commercially available as a T1D treatment. However, a great deal of pre-clinical work is complete, and ViaCyte is initiating clinical testing of PEC-Direct in 2017. Although there are numerous factors to consider, it is possible that the PEC-Direct product for high-risk T1D patients could reach the market before the PEC-Encap product candidate.
The PEC-Encap, also known as VC-01, product candidate is a combination of two platform technologies:
(1) the PEC-01™ pancreatic progenitor cell therapy made by the directed differentiation (conversion to a target cell type) of an embryonic stem cell line, and (2) the Encaptra® encapsulation device used to deliver the cells to the patient and protect them from attack by the patient’s immune system. The PEC-01 cell therapy is a population composed primarily of human pancreatic progenitor cells that, following implant, mature into the various cell types of the endocrine pancreas, also known as the Islets of Langerhans. The delivery device is a semi-permeable capsule made of medical-grade plastics, called the Encaptra® drug delivery system. A dose of PEC-01 cells loaded within the Encaptra device is collectively called the PEC-Encap (VC-01) product candidate.
The PEC-Encap product candidate represents an innovative marriage of these two platform technologies. Following implant, the Encaptra device gradually vascularizes, meaning a dedicated blood vessel system grows on the PEC-Encap unit. At the same time, the PEC-01 cells are maturing into functional replacement human islets. By the time the mature beta cells are ready to sense glucose and release insulin (approximately three months following implant), the blood supply has developed to support and provide glucose to the cells, and to receive and carry insulin away to the rest of the body where it is needed.
ViaCyte has early clinical demonstration of the principle of the PEC-Encap approach, having shown that engraftment and differentiation to beta cells is feasible based on analyses at three months post-implant. Optimization efforts are continuing to ensure robust and consistent engraftment with PEC-Encap before exploring higher doses to demonstrate efficacy. ViaCyte remains committed to the development of PEC-Encap, which is expected to be a potentially transformational therapy for the majority of people who use insulin to manage their diabetes, both T1D and T2D. However, for a number of reasons PEC-Direct development may advance more rapidly and make a major impact for the T1D patients at highest risk.
Both PEC-Direct and PEC-Encap are being designed as subcutaneous implants (that is, to be implanted under the skin). Both PEC-Direct and PEC-Encap deploy the PEC-01 pancreatic progenitor cells as the active ingredient that will provide the therapeutic effect. The main difference between the two product candidates is the nature of the device that will be used to deliver and retain the PEC-01 cells.
The PEC-Direct product candidate delivers the PEC-01 pancreatic progenitor cells in a non-immunoprotective device that allows direct vascularization of the cells. The PEC-Direct product is being developed for T1D patients who have severe hypoglycemic episodes, extreme glycemic lability, and/or impaired awareness of hypoglycemia. Given the open nature of the device, patients implanted with the PEC-Direct product, as with organ transplants, are expected to require chronic immune suppression. Thus, it is being developed to treat patients who are at high risk of acute complications related to T1D.
The PEC-Encap (VC-01) product candidate is expected to vastly expand the target patient population. In contrast to the PEC-Direct product, the PEC-Encap product delivers PEC-01 pancreatic progenitor cells in the Encaptra® immunoprotective device. This device prevents any interaction between the PEC-01 cells and the patient’s cells, thus protecting the PEC-01 cells from adaptive and auto immune attack that would otherwise destroy them. The Encaptra Device incorporates a membrane to prevent this cellular interaction, so engraftment and function requires a vascular network to grow on the surface of the device to allow diffusion of nutrients. Biologically, this represents a higher engraftment challenge than that anticipated for the PEC-Direct product candidate. PEC-Encap is currently being evaluated at sub-therapeutic levels in a Phase 1/2 trial in patients with T1D who have minimal to no insulin-producing beta cell function. Because the PEC-01 cells are fully encapsulated in PEC-Encap, we do not expect patients will need chronic immune suppression.
The product candidates are designed to be surgically implanted in a minimally invasive manner. There are many possible implant locations, including placement under the skin (subcutaneously). One of the goals of the STEP ONE trial is to identify the best implant locations and procedures.
The VC-01 product candidate consists of human cells delivered in a macroencapsulation device. It is considered a combination product, and not a medical device per se. The “dose-ranging” VC-01 unit is about half the size of a business card and less than 1 mm thick.
The STEP ONE trial is designed to help answer these questions. In pre-clinical studies, we have tested a product candidate for the animal’s lifespan, which is about a year, and it has still functioned up to that point. The STEP ONE study is designed to evaluate the PEC-Encap™ (VC-01™ ) product candidate for as long as two years.
To deliver the PEC-01 cell replacement therapy, ViaCyte is taking two distinct approaches to addressing the patient’s immune system. These approaches distinguish the PEC-Direct and PEC-Encap product candidates from each other.
In addition to autoimmunity that T1D patients have to diabetes-related antigens, the vast majority of recipients of the PEC-01-based islet cell replacement therapies will have alloimmunity to the delivered cells. That is, the PEC-01 cells are human cells, but because they are not the patient’s own cells, they will also need to be protected from alloimmune rejection, just as an organ transplant is.
In the case of PEC-Direct, the cells will be protected similarly to an organ transplant, with immune suppressive medications. The same types of immune suppressive medications that are currently used with cadaver islet transplants, also known as the “Edmonton protocol”, may be used in the clinical trial of PEC-Direct. Because PEC-Direct is expected to require pharmacological immune suppression, it is intended only for high-risk T1D patients.
In the case of PEC-Encap, the cells are protected using a macroencapsulation device. Pre-clinical animal studies with macroencapsulation devices, including the Encaptra drug delivery system, provided evidence that encapsulated cells are protected from autoimmunity, as well as alloimmunity. Preliminary observations from the STEP ONE clinical trial of PEC-Encap suggest that the Encaptra device is performing its immune protective role in humans as well: no evidence of auto- or allo-immune rejection or sensitization has been observed in patients implanted with the PEC-Encap product candidate.
That depends on many factors, including patient enrollment and interim results. When available, we plan to publish and/or present the final results of the trial in an appropriate scientific forum.
The development of innovative medical products is a highly regulated endeavor that involves establishing safety and efficacy over time. While we are committed to developing the islet cell replacement therapies in a timely fashion, our number one consideration is the well-being of the patients. We are unable to say with certainty how long it will be, assuming development is successful, before these products will be available outside of clinical trials. We appreciate your continued patience and support as we go through the necessary steps of product development.
For the past decade or so, two groups, ViaCyte Inc. and BetaLogics, a division of Janssen Biotech, Inc., have been pushing back the boundaries of science, making breakthrough advances in the development of a stem-cell derived cell replacement therapy for type 1 diabetes. The agreement to combine the intellectual property, expertise and other assets of BetaLogics with ViaCyte further strengthens our advanced program focused on insulin-dependent diabetes and solidifies our leadership in the field.