New Treatments for Glaucoma

Abstract
Aggregation of mutated myocilin (MYOC), a protein found in the endoplasmic reticulum (ER) of trabecular
meshwork (TM) cells, disrupts the outflow of aqueous humor from the eye, causing increase in intraocular
pressure (IOP), progressive retinal ganglion cell (RGC) death, and degeneration of the optic nerve, leading to
primary open-angle glaucoma (POAG), characterized by irreversible vision loss. About 5% of POAG and 35 %
of juvenile open-angle glaucoma (JOAG) patients exhibit glaucoma that is driven by the aggregation of mutant
forms of MYOC. Our research team identified the endoplasmic reticulum (ER)-residing Hsp90 isoform, glucose-
regulated protein 94 (Grp94), as necessary for the assembly of mutant myocilin aggregates. In fact, our group
demonstrated that Grp94 inhibitors are effective in vivo to treat this hereditary glaucoma. Interestingly, Grp94
inhibition also prevents the IOP driven by steroids; a condition that leads to a secondary steroid-induced
glaucoma (SIG). These data suggest that Grp94 inhibitors have the potential to treat any open-angle glaucoma.
Current glaucoma treatments, such as beta blockers and prostaglandin analogs, only treat the symptoms of the
disease and not the underlying cause. Our approach through Grp94 inhibition, represents a unique opportunity
to treat mutant MYOC-driven POAG and allow persons afflicted with SIG to maintain their steroid regimens
without sacrificing their vision. This application aims to secure funds for the optimization of Grp94 inhibitors to
improve selectivity, modulation of physicochemical properties that are appropriate for ocular administration, and
conduct pre-clinical evaluation of the optimized candidates in animal models. Preliminary work at the University
of Notre Dame and the University of Florida has established that selective inhibition of Grp94 via eye drops can
offer a safe and effective therapeutic option to treat hereditary forms of glaucoma by utilizing a mechanism of
action that differs from currently available agents, potentially without adverse effects. In this Phase 1, Grannus
will optimize the efficacy, selectivity over other Hsp90 isoforms, and the physicochemical properties of Grp94
inhibitors using a rational, structure-based approach to construct a new lead compound. Aim 1. Synthesis of
rationally designed Grp94 inhibitors using the data gathered from solution of the co-crystal structures and prior
structure-activity relationship studies. The working hypothesis is that introduction of conformational constraint
and different functional groups into current Grp94-selective inhibitor scaffolds will increase the selectivity (over
other Hsp90 isoforms), binding affinity, and drug-like properties of the designed analogs. Aim 2. Evaluate the
Grp94 inhibitors prepared in Aim 1 for their effectiveness in in vitro models of myocilin aggregation. Effective
compounds will undergo additional analyses for in vivo efficacy, safety and distribution measurement
experiments. Upon completion of the proposed work, we will have identified a lead compound with improved
pharmacokinetic and pharmacodynamic profile to progress further into IND-enabling studies. The results from
Phase II will serve toward completion of an IND-application and subsequently, initiation of clinical studies.Project Narrative
The proposal addresses the need for the development of a safer and more effective therapeutic agent to treat
glaucoma. We will prepare compounds that inhibit Grp94, a protein, when dysregulated, is found to cause
glaucoma. The proposed work is essential for identifying a lead compound for pre-clinical studies that will differ
from current anti-glaucoma drugs by treating the underlying cause rather than only treat the symptoms of
glaucoma, thus providing relief or a cure without the adverse effects.