Currently, there are no effective treatments to preserve cognitive function in AD patients and the recent series of disappointing clinical trials highlight the need to explore alternative pathways. To this end, NeuroLucent Inc. and its academic partner, RFUMS, are developing small molecule compounds designed as allosteric modulators of the ryanodine receptor (RyR), a high conductance calcium channel in the ER membrane, as candidates for clinical testing. In human AD patients? brains, induced neurons from AD patient fibroblasts, and in AD mouse models, increased RyR2 isoform expression is observed in early disease stages across familial and sporadic cases. In neurons from AD mouse models and human samples, RyR-evoked calcium release is significantly increased and directly contributes to synaptic dysfunction and loss, increased amyloid and tau pathology, disrupted memory function, and other AD-defining features. We and others have demonstrated that treating AD mice with dantrolene, a RyR channel stabilizer, resulted in exciting therapeutic effects. The combined results demonstrate normalized calcium signaling (Chakroborty et al., 2012a; Oule et al., 2012; Stutzmann et al., 2006), normal synaptic transmission and plasticity (Chakroborty et al., 2012a), restored synaptic structure and integrity (Briggs et al., 2014), reduced A??and phospho-tau levels (Chakroborty et al., 2012a; Oule et al., 2012; Peng et al., 2012), restored RyR isoform levels (Chakroborty et al., 2012a; Oule et al., 2012), and improved performance on memory tests (Oule et al., 2012; Peng et al., 2012; Stutzmann lab, unpublished data). These data support a strong case for stabilizing RyR function, with a focus on RyR2, as a novel therapeutic strategy for AD. The objective of this study is to design, test, and optimize compounds that will function as RyR negative allosteric modulators, serving to suppress excessive calcium release while maintaining physiological functions. The central hypothesis is that development and optimization of small molecule RyR stabilizers will generate therapeutic leads for clinical testing in early AD and MCI patients, and protect cognitive abilities through the preservation of calcium homeostasis and synaptic function. This will be accomplished with the following Aims: 1. Synthesize and optimize RyR2 targeted allosteric modulators for CNS targets. This will use iterative medicinal chemistry procedures and ADME testing in collaboration with Sanford Burnham Prebys and WuXi AppTec CRO partners. 2. Optimize biological efficacy of RyR compounds using rapid screening assays in cell culture systems and neurons from AD patients and mice. Initial screening will use automated fluorometric testing of RyR-evoked calcium signals in cultured cells and transformed neurons from AD patients, followed by in vivo treatment studies in AD mice. The significance to public health is the development of an effective and novel treatment for AD. The identification of a lead compound by NeuroLucent and positioning for IND filing would be the next stage following this STTR project.
The objective of this study is to develop a series of small molecule compounds for the purpose of stabilizing dysregulated calcium signaling in early-stage AD patients and people at risk for converting to AD-like dementia. The rationale is based on findings that disruptions in ryanodine-receptor mediated calcium signaling are a central component of AD pathogenesis, and, treatment with compounds that modulate the ryanodine receptor provide broad-spectrum therapeutic effects in human neurons from AD patients and in AD mouse models. Developing these compounds through a small business-academic partnership has a high potential for success in the clinic.
