Abstract
Purpose :
Kinase inhibitors, particularly inhibitors of Rho kinases (ROCKs), lower intraocular pressure in animal models and in humans and may have utility in treating diseases of the retina as well. Aerie has successfully developed the ROCK inhibitor netarsudil as a topical treatment for glaucoma (Rhopressa™). For posterior segment disorders, a variety of kinases have been implicated in disease pathology, particularly kinases with pro-inflammatory activity such a Janus kinases (JAKs). Novel Rho kinase inhibitors (deLong, et al. ARVO 2017, ARVO 2018) have been identified with significant inhibitory activity against JAKs. These molecules were optimized for potency and compatibility with biodegradable materials for use in intravitreal implants.
Methods :
Initial kinase inhibition screens demonstrated that the SARs between potent ROCK activity and potent JAK activity were similar, but differentiatable. By creating a tight feedback cycle between in vitro biologists and their synthetic chemistry partners, a cycle time of less than a month allowed for rapid progress. In-house kinase assays run biweekly provided SAR data on ROCK, JAK as well as other potentially beneficial kinases to chemists who modified the next round of compounds accordingly. Active compounds were further screened in cellular assays to ensure that the compounds could penetrate and inhibit their intracellular targets. Cell-based JAK assays were developed based on phosphorylation of STAT3 and STAT5.
Results :
Modifications were made to three independent regions of the kinase inhibitors: isoquinoline ring substitution, the linker region, and the placement of heteroatoms in the terminal ring structure. By optimizing each region individually and then combining the results, sub-nanomolar potency at JAK, as well as ROCK, was achieved. A range of selectivity was also created, with >3 logs of differentiation between JAK and ROCK potency among the molecules. In addition, a range of solubilities was generated, as the optimal solubility for a drug in a sustained-release intravitreal implant is not yet known.
Conclusions :
This approach to the creation of new molecules has led to potent JAK-selective, potent ROCK-selective, and balanced ROCK/JAK inhibitors with nanomolar potency in cell-based assays, compatibility with common biodegradable polymers, and stability under physiological conditions. This class of inhibitors is under further study.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.