Year 2

Alzheimer’s disease (AD), the leading cause of dementia, results in profound loss of memory and cognitive function, and ultimately death. In the United States, someone develops AD every 69 seconds and there are over 5 million individuals suffering from AD, including approximately 600,000 Californians. Current treatments do not alter the disease course. The absence of effective therapies coupled with the sheer number of affected patients renders AD a medical disorder of unprecedented need and a public health concern of significant magnitude. Efforts to discover effective treatments for AD are ongoing, but unfortunately, the number of active clinical studies is low and many traditional approaches have failed in clinical testing. An urgent need to develop novel and innovative approaches to treat AD is urgent.
StemCells Inc., proposed to evaluate the use of human neural stem cells as a potential innovative therapy for AD. AD results in neuronal death and loss of connections between surviving neurons. The hippocampus, the part of the brain responsible for learning and memory, is particularly affected in AD. Evidence from previous animal studies shows that transplanting human neural stem cells into the hippocampus improves memory, possibly by providing growth factors that protect neurons from degeneration. Translating this approach to humans could markedly restore memory and thus, quality of life for patients.
In September 2012, the CIRM awarded a loan to StemCells Inc. to partially fund a program to test human neural stem cells in two animal models used by some researchers to study AD and the study was initiated in July of 2013. The goal of this study was chiefly to try to replicate earlier successful experiments with human neural stem cells in these mice in support of an IND filing with the U.S. FDA within four years.
In the first year of the study, the Disease Team actively worked on 5 important scientific milestones in our effort to develop human neural stem cells as a potential therapy for AD. We also held a pre-IND meeting with the FDA in which we shared our plans for the preclinical and clinical studies in AD; the meeting provided helpful guidance and assurances regarding our IND enabling activities.
As of the second year of the study, all of the first 5 scientific milestones have been completed. Specifically, the team conducted three animal studies believed necessary to start testing this therapeutic approach in human patients; these studies were designed to confirm that transplantation of the neural stem cells leads to improved memory in animal models relevant for AD.
Despite seeing a very exciting increase in the number of connections between key hippocampal neurons within the brains of mice treated with human neural stem cells, this did not appear to robustly and consistently improve memory in the animals. Without seeing a significant change in memory performance, the preclinical results of the study did not satisfy one or more of the specific “No/No Go” scientific milestones agreed to with the CIRM. Given this, the loan was subsequently terminated in December 2014 as a consequence of the unanticipated preclinical results.
This study was a partnership between a biotechnology company with unique experience in clinical trials involving neural stem cell transplantation and a leading California-based academic laboratory specializing in AD research. Although disappointing, the results of this study do not negate the potential of neural stem cell transplantation in AD; rather, having reviewed and discussed the data with our collaborators, we believe the data highlight the challenge of obtaining reliable and consistent behavior readouts of memory improvement in animals. Finally, the observed increases in the connections between hippocampal neurons are very interesting and may justify further efforts to improve pre-clinical development for this complex disorder.