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Retinal and choroidal vascular diseases, with their associated abnormalities in vascular permeability, account for the majority of patients with vision loss in industrialized nations. VEGF is upregulated in ischemic retinopathies such as diabetes and is known to dramatically alter vascular permeability in a number of nonocular tissues via Src kinase--regulated signaling pathways. VEGF antagonists are currently in clinical use for treating the new blood vessels and retinal edema associated with neovascular eye diseases, but such therapies require repeated intraocular injections. We have found that vascular leakage following intravitreal administration of VEGF in mice was abolished by systemic or topical delivery of what we believe is a novel VEGFR2/Src kinase inhibitor; this was confirmed in rabbits. The relevance of Src inhibition to VEGF-associated alterations in vascular permeability was further substantiated by genetic studies in which VEGF injection or laser-induced vascular permeability failed to augment retinal vascular permeability in Src-/- and Yes-/- mice (Src and Yes are ubiquitously expressed Src kinase family members; Src-/- and Yes-/- mice lacking expression of these kinases show no vascular leak in response to VEGF). These findings establish a role for Src kinase in VEGF-mediated retinal vascular permeability and establish a potentially safe and painless topically applied therapeutic option for treating vision loss due to neovascular-associated retinal edema., Introduction Abnormal retinal vascular permeability leading to edema in the area of the macula is the leading cause of vision loss in diseases such as diabetic retinopathy, exudative macular degeneration, [...]

Although phosphoinositide 3-kinases (PI3Ks) play beneficial pro-cell survival roles during tissue ischemia, some isoforms ([gamma], and [delta]) paradoxically contribute to the inflammation that damages these same tissues upon reperfusion. We therefore considered the possibility that selectively inhibiting proinflammatory PI3K isoforms during the reperfusion phase could ultimately limit overall tissue damage seen in ischemia/reperfusion injuries such as myocardial infarction. Panreactive and isoform-restricted PI3K inhibitors were identified by screening a novel chemical family; molecular modeling studies attributed isoform specificity based on rotational freedom of substituent groups. One compound (TG100-115) identified as a selective PI3K [gamma]/3 inhibitor potently inhibited edema and inflammation in response to multiple mediators known to participate in myocardial infarction, including vascular endothelial growth factor and platelet-activating factor; by contrast, endothelial cell mitogenesis, a repair process important to tissue survival after ischemic damage, was not disrupted. In rigorous animal MI models, TG100-115 provided potent cardioprotection, reducing infarct development and preserving myocardial function. Importantly, this was achieved when dosing well after myocardial reperfusion (up to 3 h after), the same time period when patients are most accessible for therapeutic intervention. In conclusion, by targeting pathologic events occurring relatively late in myocardial damage, we have identified a potential means of addressing an elusive clinical goal: meaningful cardioprotection in the postreperfusion time period. edema | inflammation | myocardial infarct | VEGF

Delivery of pharmaceuticals to the posterior segment presents challenges that arise from the anatomy and clearance pharmacokinetics of the eye. Systemic and several local administration options [topical, periocular, intravitreal (IVT) and subretinal] are in clinical use, each with a unique benefit to risk profile shaped by factors including the administered agent, frequency of dosing, achievable pharmaceutical concentrations within posterior segment structures versus elsewhere in the eye or the body, invasiveness of the procedure and the inherent challenges with some administration methods. The use of the suprachoroidal space (SCS), which is the region between the sclera and the choroid, is being explored as a potential approach to target pharmacotherapies to the posterior segment via a minimally invasive injection procedure. Preclinical data on agents such as vascular endothelial growth factor inhibitors and triamcinolone acetonide (TA) indicate that administration via suprachoroidal injection results in more posterior distribution of the pharmacologic agent, with higher exposure to the sclera, choroid, retinal pigment epithelium cells and retina, and lesser exposure to the anterior segment, than observed with IVT administration. Based in part on these findings, clinical trials have explored the efficacy and safety of suprachoroidal administration of pharmacologic therapies in conditions affecting the posterior segment. Data on a proprietary formulation of TA administered by suprachoroidal injection show improvement in anatomic and visual outcomes in subjects with noninfectious uveitis, with the potential to mitigate the known risks of cataract and increased intraocular pressure (IOP) associated with the use of intraocular corticosteroids. Suprachoroidal administration appears to be a promising treatment modality and is also in the early stages of investigation for other possible applications, such as injection of antiglaucoma agents into the anterior SCS for long‐lasting control of elevated IOP, and as a mode of delivery for gene‐ or cell‐based therapies for retinal disorders. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration, diabetic retinopathy, and retinal vein occlusions are complicated by neovascularization and macular edema. Multi-targeted kinase inhibitors that inhibit select growth factor receptor tyrosine kinases and/or components of their down-stream signaling cascades (such as Src kinases) are rationale treatment strategies for these disease processes. We describe the discovery and characterization of two such agents. TG100572, which inhibits Src kinases and selected receptor tyrosine kinases, induced apoptosis of proliferating endothelial cells in vitro. Systemic delivery of TG100572 in a murine model of laser-induced choroidal neovascularization (CNV) caused significant suppression of CNV, but with an associated weight loss suggestive of systemic toxicity. To minimize systemic exposure, topical delivery of TG100572 to the cornea was explored, and while substantial levels of TG100572 were achieved in the retina and choroid, superior exposure levels were achieved using TG100801, an inactive prodrug that generates TG100572 by de-esterification. Neither TG100801 nor TG100572 were detectable in plasma following topical delivery of TG100801, and adverse safety signals (such as weight loss) were not observed even with prolonged dosing schedules. Topical TG100801 significantly suppressed laser-induced CNV in mice, and reduced fluorescein leakage from the vasculature and retinal thickening measured by optical coherence tomography in a rat model of retinal vein occlusion. These data suggest that TG100801 may provide a new topically applied treatment approach for ocular neovascularization and retinal edema. J. Cell. Physiol. 216: 29–37, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Injection of pharmacotherapy into the suprachoroidal space, between the sclera and choroid, is an alternative delivery technique developed with the rationale of providing higher drug concentrations to posterior ocular structures compared with other intraocular and periocular injection procedures. This study was conducted to evaluate the safety and efficacy of suprachoroidally injected triamcinolone acetonide formulation (CLS-TA), a suspension of triamcinolone acetonide, in improving vision among patients with noninfectious uveitis complicated by macular edema (ME). Phase 3 masked, randomized trial. One hundred sixty patients with ME secondary to noninfectious uveitis. Patients were required to have a best-corrected visual acuity (BCVA) of 5 or more Early Treatment Diabetic Retinopathy Study (ETDRS) letters (Snellen equivalent, 20/800) and 70 or fewer ETDRS letters read (Snellen equivalent, 20/40) in the study eye. Patients were randomized 3:2 to suprachoroidally injected CLS-TA or sham treatment, with administrations at day 0 and week 12. The primary end point was improvement from baseline of 15 or more ETDRS letters in BCVA at week 24. The secondary end point was reduction from baseline in central subfield thickness (CST) at week 24. In the CLS-TA arm, 47% of patients gained 15 or more ETDRS letters in BCVA versus 16% in the control arm (P < 0.001), meeting the primary end point. Mean reductions in CST from baseline were 153 μm versus 18 μm (P < 0.001). No serious adverse events (AEs) related to treatment were reported. Corticosteroid-associated AEs of elevated intraocular pressure occurred in 11.5% and 15.6% of the CLS-TA and control groups, respectively. Cataract AE rates were comparable (7.3% and 6.3%, respectively). Patients in the CLS-TA study arm experienced clinically significant improvement in vision relative to the sham procedure, demonstrating the efficacy of suprachoroidal injection of CLS-TA for the treatment of ME in a vision-threatening disorder. [ABSTRACT FROM AUTHOR]

Retinal gene therapy using adeno-associated viruses (AAVs) is constrained by the mode of viral vector delivery. Intravitreal AAV injections are impeded by the internal limiting membrane barrier, while subretinal injections require invasive surgery and produce a limited region of therapeutic effect. In this study, we introduce a novel mode of ocular gene delivery in rhesus macaques using transscleral microneedles to inject AAV8 into the subretinal or suprachoroidal space, a potential space between the choroid and scleral wall of the eye. Using in vivo imaging, we found that suprachoroidal AAV8 produces diffuse, peripheral expression in retinal pigment epithelial (RPE) cells, but it elicited local infiltration of inflammatory cells. Transscleral subretinal injection of AAV8 using microneedles leads to focal gene expression with transduction of RPE and photoreceptors, and minimal intraocular inflammation. In comparison, intravitreal AAV8 shows minimal transduction of retinal cells, but elicits greater systemic humoral immune responses. Our study introduces a novel mode of transscleral viral delivery that can be performed without vitreoretinal surgery, with focal or diffuse transgene expression patterns suitable for different applications. The decoupling of local and systemic immune responses reveals important insights into the immunological consequences of AAV delivery to different ocular compartments surrounding the blood-retinal barrier., (© 2020 The Author(s).)

Purpose: To evaluate choroidal and suprachoroidal changes following suprachoroidal injection of triamcinolone acetonide injectable suspension (CLS-TA), in eyes with macular edema due to retinal vein occlusion (RVO)., Design: Prospective cohort study within a randomized, controlled phase 2 clinical trial., Methods: Enhanced depth imaging optical coherence tomography (EDI-OCT) images were analyzed from 38 eyes of 38 treatment-naïve patients with macular edema due to RVO, enrolled in the prospective Suprachoroidal Injection of Triamcinolone Acetonide with Intravitreal Aflibercept in Subjects with Macular Edema Due to Retinal Vein Occlusion (TANZANITE) study who received either a suprachoroidal injection of CLS-TA with an intravitreal injection of aflibercept (combination arm) or only an intravitreal injection of aflibercept (monotherapy arm), followed by monthly intravitreal aflibercept injections in both arms based on pro re nata criteria., Results: Macular choroidal thickness measured to the outer choroidal vessel lumen (vascular choroidal thickness, VCT), outer choroid stroma (stromal choroidal thickness, SCT), or inner scleral border (total choroidal thickness, TCT) showed no significant changes over 3 months in both study arms (P = .231-.342). Eyes that received combination therapy showed a trend toward thickening of the suprachoroidal space (SCS) compared with monotherapy alone (13.4 μm vs 5.3 μm at 3 months; P = .077). In the 15 eyes that demonstrated a visible SCS at baseline, the SCS expanded significantly after suprachoroidal CLS-TA injection (16.2 μm to 27.8 μm at 3 months; P = .033)., Conclusions: Suprachoroidal injection of CLS-TA does not alter choroidal thickness in eyes with macular edema due to RVO, but may result in expansion of the SCS., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: To evaluate the safety, tolerability, and preliminary efficacy of suprachoroidal injection of triamcinolone acetonide (TA) in patients with noninfectious uveitis., Methods: In this Phase 1/2 open-label clinical study, a single suprachoroidal injection of 4-mg TA in 100 μL was performed in the study eye of patients with noninfectious intermediate, posterior, or pan-uveitis, and follow-up obtained for 26 weeks., Results: Nine individuals with chronic uveitis were enrolled. There were 38 reported adverse events (AEs); most were mild or moderate in severity. Approximately half the AEs were ocular. The most common AE was reported by four subjects who experienced ocular pain at or near the time of the injection. All systemic AEs were unrelated to study drug. No steroid-related increases in intraocular pressure (IOP) were observed and no subject required IOP-lowering medication. All eight efficacy-evaluable subjects had improvements in visual acuity. Four subjects, who did not need additional therapy, had on average a greater than 2-line improvement in visual acuity through week 26. Three of four had macular edema at baseline, and two of three had at least a 20% reduction in macular edema at week 26., Conclusions: The safety and preliminary efficacy data support further investigations of suprachoroidally administered TA as a therapeutic option for the treatment of noninfectious uveitis., Translational Relevance: Targeted suprachoroidal administration of corticosteroid is a potential local route for the treatment of ocular inflammatory disease, which merits further investigation. (www.ClinicalTrials.gov, NCT01789320).

Phosphatidylinositol 3-kinases (PI3Ks) are key elements in the signaling cascades that lie downstream of many cellular receptors. In particular, PI3K delta and gamma isoforms contribute to inflammatory cell recruitment and subsequent activation. For this reason, in a series of preclinical studies, we tested the potential of a recently developed small-molecule inhibitor of these two isoforms, TG100-115 [3-[2,4-diamino-6-(3-hydroxyphenyl)pteridin-7-yl]phenol], as a form of anti-inflammatory therapy for respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). To determine pharmacokinetic profiles, aerosolized formulations of the drug were delivered to mice by a nose-only inhalation route, yielding high pulmonary TG100-115 levels with minimal systemic exposure. Safety assessments were favorable, with no clinical or histological changes noted after 21 days of daily dosing. In a murine asthma model, aerosolized TG100-115 markedly reduced the pulmonary eosinophilia and the concomitant interleukin-13 and mucin accumulation characteristic of this disease. As a functional benefit, interventional dosing schedules of this inhibitor also reduced airway hyper-responsiveness. To model the pulmonary neutrophilia characteristic of COPD, mice were exposed to either intranasal lipopolysaccharide or inhaled smoke. Aerosolized TG100-115 again inhibited these inflammatory patterns, most notably in the smoke model, where interventional therapy overcame the steroid-resistant nature of the pulmonary inflammation. In conclusion, aerosolized TG100-115 displays pharmacokinetic, safety, and biological activity profiles favorable for further development as a therapy for both asthma and COPD. Furthermore, these studies support the hypothesis that PI3K delta and gamma are suitable molecular targets for these diseases.

Background: The synthesis of novel benzotriazine heterocycles was developed independently around the same time by Bischler, Bamberger and Arndt. Over the years, different groups have reported the synthesis of benzotriazine based compounds., Objective: This literature review gives an update on recent benzotriazine compounds and their applications., Conclusion: The benzotriazine core has been used in various drug discovery projects including anticancer, anti-inflammatory and antimalarial programs. Recently, the benzotriazine core was used to develop selective kinase inhibitors targeting SRC, VEGFr2, BCR-ABL and BCR-ABL-T315I. Two benzotriazine based compounds, tirapazamine for the treatment of cancer and TG100801 for the treatment of age-related macular degeneration, have entered clinical trials.

Age-related macular degeneration (AMD) is one of the leading causes of loss of vision in the industrialized world. Attenuating the VEGF signal in the eye to treat AMD has been validated clinically. A large body of evidence suggests that inhibitors targeting the VEGFr pathway may be effective for the treatment of AMD. Recent studies using Src/YES knockout mice suggest that along with VEGF, Src and YES play a crucial role in vascular leak and might be useful in treating edema associated with AMD. Therefore, we have developed several potent benzotriazine inhibitors designed to target VEGFr2, Src, and YES. One of the most potent compounds is 4-chloro-3-{5-methyl-3-[4-(2-pyrrolidin-1-yl-ethoxy)phenylamino]benzo[1,2,4]triazin-7-yl}phenol ( 5), a dual inhibitor of both VEGFr2 and the Src family (Src and YES) kinases. Several ester analogues of 5 were prepared as prodrugs to improve the concentration of 5 at the back of the eye after topical administration. The thermal stability of these esters was studied, and it was found that benzoyl and substituted benzoyl esters of 5 showed good thermal stability. The hydrolysis rates of these prodrugs were studied to analyze their ability to undergo conversion to 5 in vivo so that appropriate concentrations of 5 are available in the back-of-the-eye tissues. From these studies, we identified 4-chloro-3-(5-methyl-3-{[4-(2-pyrrolidin-1-ylethoxy)phenyl]amino}-1,2,4-benzotriazin-7-yl)phenyl benzoate ( 12), a topically administered prodrug delivered as an eye drop that is readily converted to the active compound 5 in the eye. This topically delivered compound exhibited excellent ocular pharmacokinetics and poor systemic circulation and showed good efficacy in the laser induced choroidal neovascularization model. On the basis of its superior profile, compound 12 was advanced. It is currently in a clinical trial as a first in class, VEGFr2 targeting, topically applied compound for the treatment of AMD.

Chronic myelogenous leukemia (CML) is a hematological stem cell disorder caused by increased and unregulated growth of myeloid cells in the bone marrow, and the accumulation of excessive white blood cells. Abelson tyrosine kinase (ABL) is a non-receptor tyrosine kinase involved in cell growth and proliferation and is usually under tight control. However, 95% of CML patients have the ABL gene from chromosome 9 fused with the breakpoint cluster (BCR) gene from chromosome 22, resulting in a short chromosome known as the Philadelphia chromosome. This Philadelphia chromosome is responsible for the production of BCR-ABL, a constitutively active tyrosine kinase that causes uncontrolled cellular proliferation. An ABL inhibitor, imatinib, was approved by the FDA for the treatment of CML, and is currently used as first line therapy. However, a high percentage of clinical relapse has been observed due to long term treatment with imatinib. A majority of these relapsed patients have several point mutations at and around the ATP binding pocket of the ABL kinase domain in BCR-ABL. In order to address the resistance of mutated BCR-ABL to imatinib, 2(nd) generation inhibitors such as dasatinib, and nilotinib were developed. These compounds were approved for the treatment of CML patients who are resistant to imatinib. All of the BCR-ABL mutants are inhibited by the 2(nd) generation inhibitors with the exception of the T315I mutant. Several 3(rd) generation inhibitors such as AP24534, VX-680 (MK-0457), PHA-739358, PPY-A, XL-228, SGX-70393, FTY720 and TG101113 are being developed to target the T315I mutation. The early results from these compounds are encouraging and it is anticipated that physicians will have additional drugs at their disposal for the treatment of patients with the mutated BCR-ABL-T315I. The success of these inhibitors has greater implication not only in CML, but also in other diseases driven by kinases where the mutated gatekeeper residue plays a major role.

In studies aimed toward identifying effective and safe inhibitors of kinase signaling cascades that underlie ischemia/reperfusion (I/R) injury, we synthesized a series of pteridines and pyridopyrazines. The design strategy was inspired by the examination of naturally occurring PI3K inhibitors such as wortmannin and quercetin, and building a pharmacophore-based model used for optimization. Structural modifications led to hybrid molecules which incorporated aminopyrimidine and aminopyridine moieties with ATP mimetic characteristics into the pharmacophore motifs to modulate kinase affinity and selectivity. Elaborations involving substitutions of the 2 and 4 positions of the pyrimidine or pyridine ring and the 6 and 7 positions of the central pyrazine ring resulted in in vivo activity profiles which identified potent inhibitors of vascular endothelial growth factor (VEGF) induced vascular leakage. Pathway analysis identified a diaminopteridine-diphenol as a potent and selective phosphatidylinositol-3-kinase (PI3K) inhibitor. The structure-activity relationship studies of various analogues of diaminopteridine-diphenol-based on biochemical assays resulted in potent inhibitors of PI3K.

TG100435 ([7-(2,6-dichloro-phenyl)-5-methyl-benzo[1,2,4]triazin-3-yl]-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-amine) is a novel multitargeted, orally active protein tyrosine kinase inhibitor. The inhibition constants (K(i)) of TG100435 against Src, Lyn, Abl, Yes, Lck, and EphB4 range from 13 to 64 nM. TG100435 has systemic clearance values of 20.1, 12.7, and 14.5 ml/min/kg and oral bioavailability of 74%, 23%, and 11% in mouse, rat, and dog, respectively. Four oxidation metabolites of TG100435 have been found in human, dog, and rat in vitro and in vivo. The ethylpyrrolidine N-oxide of TG100435 is the predominant metabolite (TG100855; [7-(2,6-dichloro-phenyl)-5-methyl-benzo[1,2,4]triazin-3-yl]-{4-[2-(1-oxy-pyrrolidin-1-yl)-ethoxy]-phenyl}-amine) in human, dog, and rat. TG100855 is 2 to 9 times more potent than the parent compound. Flavin-containing monooxygenases are the primary enzymes mediating the biotransformation. Significant conversion of TG100435 to TG100855 has been observed in rat and dog after oral administration. Systemic exposure of TG100855 is 1.1- and 2.1-fold greater than that of TG100435 in rat and dog after oral dosing of TG100435. Since TG100435 is predominantly converted to the more potent N-oxide metabolite across species in vivo and in vitro, the overall tyrosine kinase inhibition in animal models may be substantially increased after oral administration of TG100435.