Cell-targeted dendrimer-drug conjugates for safe, effective, and convenient neuroprotection in glaucoma - PROJECT SUMMARY Glaucoma is the leading cause of irreversible vision loss globally, affecting more than 80 million individuals. Existing interventions are focused on reduction of intraocular pressure, and are limited by patient non- compliance, lack of efficacy, and post-operative complications, leading to disease progression and vision loss, even in patients receiving treatment. There is a need for neuroprotective treatments that target early glaucoma pathogenesis as a complementary strategy to prevent retinal ganglion cell (RGC) death and vision loss. There is strong evidence that neuroinflammation, mediated by reactive microglia, occurs early in the disease process and contributes significantly to glaucoma pathogenesis. Dual leucine zipper kinase (DLK) and leucine zipper kinase (LZK) activation have also been implicated in RGC death. Addressing either mechanism of glaucoma pathophysiology has potential to prevent vision loss. However, current means of delivering neuroprotective agents are limited in their ability to deliver sufficient concentrations to target cells in a safe, effective, and durable manner. We have engineered hydroxyl dendrimer-n-acetylcysteine conjugates (HD-NAC) that have been shown to safely reduce neuroinflammation in the clinic and to target activated microglia in the retina or optic nerve via intravitreal or systemic administration, respectively, in rat models of glaucoma. Moreover, this formulation was retained in glaucomatous rat eyes for at least 21 days, significantly reduced inflammatory markers in the retina, and significantly improved RGC survival. Here, we propose to advance these findings and further improve outcomes by expanding to glucose-based dendrimers (GD) that selectively target activated microglia AND injured neurons, and to develop HD and GD formulations of a sunitinib analog that will be tested for neuroprotective efficacy along with HD-NAC and GD- NAC in clinically-relevant glaucoma models. We hypothesize that HD and GD will localize primarily in activated microglia and RGCs, respectively, and that delivery of NAC (anti-inflammatory agent) or sunitinib (DLK/LZK inhibitor) directly to the cells involved in glaucomatous vision loss will provide, safe, effective, and durable neuroprotection. Specific Aim 1 will allow us to understand the differential distribution and cell uptake of HD and GD administered intravitreally or systemically in rat translimbal laser and optic nerve crush models of glaucoma. Specific Aim 2 will focus on synthesis, characterization, and in vitro validation of HD- and GD-sunitinib analog. Specific Aim 3 will allow for in vivo evaluation of the neuroprotective efficacy of HD- and GD-NAC and HD- and GD-sunitinib analog in the translimbal laser and optic nerve crush models. Collectively, these Aims will help us understand how modification of the underlying dendrimer design affects distribution and cell uptake in a glaucomatous environment, which mechanism of neuroprotection (anti-inflammatory vs DLK/LZK inhibition) is more potent, and the effect of individually manipulating each cell type (activated microglia, stressed RGCs).
