Drug Delivery via the Suprachoroidal Space for the Treatment of Retinal Diseases

SUPRACHOROIDAL SPACE IN RHEGMATOGENOUS RETINAL DETACHMENT ASSESSED WITH OPTICAL COHERENCE TOMOGRAPHY: Implications for Potential Future Therapeutic Interventions

PURPOSE

To comprehensively investigate the suprachoroidal space (SCS) in the context of rhegmatogenous retinal detachment (RRD) using swept-source optical coherence tomography.

METHODS

We conducted a post hoc analysis of 90 consecutive patients with a primary RRD. Baseline swept-source optical coherence tomography scans were graded for the presence and thickness of SCS. Available scans of the fellow eye were graded for comparison.

RESULTS

Suprachoroidal space was visible in 31.6% (24/76) of gradable RRD scans, with a mean thickest location measuring 67.0 µ m (SD 25.9), mean thinnest location of 33.8 µ m (SD 11.1), and mean average thickness of 50.0 µ m (SD 16.8). In addition, the SCS was detectable in 28.3% (13/46) of available fellow eye scans, with a mean thickest location measuring 47.0 µ m (SD 41.7), thinnest location of 25.2 µ m (SD 27.6), and mean average thickness of 35.8 µ m (SD 31.4). A statistically significant difference was found between RRD and fellow eyes in all measurements of SCS thickness.

CONCLUSION

In RRD, the SCS serves as a crucial fluid reservoir influenced by dynamic shifts in intraocular hydrostatic and oncotic pressures. We found significant SCS engorgement in RRD eyes compared with fellow eyes, which may facilitate intra-SCS therapies such as suprachoroidal viscopexy or other pharmacologic interventions.

Safety and efficacy of supraciliary dexamethasone implantation for macular oedema: a preliminary comparative study

PURPOSE

To evaluate the efficacy and safety of dexamethasone implantation in the supraciliary (SC) space, a novel and potential effective implantation site, compared to intravitreal (IV) application.

METHODS

This prospective study included 39 eyes of 38 patients with macular oedema (ME) who underwent SC and IV dexamethasone implantation (SC-DEX and IV-DEX). Patients were randomly assigned to treatment groups and followed for 3 months. Preoperative and postoperative assessments included maximum retinal thickness (MRT), change in central retinal thickness between consecutive visits (ΔCRT), intraocular pressure (IOP), and best corrected visual acuity (BCVA).

RESULTS

Both SC-DEX and IV-DEX groups showed significant MRT reductions during at follow-up. In the SC group, MRT significantly decreased at 1st and 3rd months (p = 0.0002 for both), but not at 1st week (p = 0.2517). In the IV-DEX group, significant reductions in MRT were observed at all postoperative visits: 1st week (p = 0.0002), 1st month (p = 0.0004), and 3rd month (p = 0.0003). There were no significant differences in the change in ΔCRT between the SC-DEX and IV-DEX groups at any visit (p > 0.05). IOP did not show significant changes (p > 0.05). BCVA improved significantly in the SC group compared to the IV-DEX group during the first week (p = 0.014). No other perioperative or postoperative sight-threatening complications were noted in either group, including hypotony or endophthalmitis.

CONCLUSION

SC-DEX shows promise as an alternative for managing ME, offering similar effectiveness to IV-DEX with safe profile. Further studies are needed to confirm its long-term safety and efficacy.

Challenges in AAV-Based Retinal Gene Therapies and the Role of Magnetic Nanoparticle Platforms

Retinal diseases, leading to various visual impairments and blindness, are on the rise. However, the advancement of retinal gene therapies offers new hope for treatment of such diseases. Among different vector systems for conferring therapeutic genetic load to retinal cells, adeno-associated viruses (AAVs) have been most intensively explored and have already successfully gained multiple clinical approvals. AAV-based retinal gene therapies have shown great promise in treating retinal disorders, but usually rely on the heavily disruptive administration methods such as subretinal injection. This is because the clinically well-established, minimally invasive alternative of intravitreal injection (IVI) necessitates AAVs to traverse the retinal inner limiting membrane (ILM), which is hard to penetrate in higher eye models, like human or porcine eyes. Additionally, AAVs' natural transduction preference, known as tropism, is commonly not specific to cells of only one target retinal layer, which is another ongoing challenge in retinal gene therapy. This review examines strategies to overcome these obstacles with a focus on the potential of magnetic nanoparticles (MNPs) for improved retinal AAV delivery.

Suprachoroidal Triamcinolone Acetonide Injection to Treat Macular Edema: A Review

Purpose: To review the available literature on the efficacy and safety of suprachoroidal triamcinolone acetonide for the treatment of chorioretinal diseases. Methods: The results of the literature review were analyzed. Results: This review included 17 clinical studies of triamcinolone acetonide administration (6, diabetic macular edema; 1, central retinal vein occlusion [RVO]; 2, branch RVO; 7, noninfectious uveitis; 1, cystoid macular edema after cataract surgery). Overall, suprachoroidal triamcinolone acetonide was shown to be effective in decreasing macular thickness and increasing visual (VA) in cases of chorioretinal diseases. The most frequently reported adverse events were eye pain, cataract, and increased intraocular pressure. Conclusions: Except for 3 sufficiently powered trials of suprachoroidal triamcinolone acetonide for macular edema associated with noninfectious uveitis, most other studies were clinical trials with small samples. These studies found that suprachoroidal triamcinolone acetonide has a satisfactory safety and efficacy profile. Further research with sufficiently large samples is required to confirm the potential role of suprachoroidal triamcinolone acetonide in retinal diseases.

Effectiveness of Suprachoroidal Injection of Triamcinolone Acetonide in Diabetic Macular Edema Following Pars Plana Vitrectomy Using a Modified Custom Microneedle

Purpose

The present study evaluated the efficacy of suprachoroidal injection of Triamcinolone Acetonide (SCTA) in diabetic macular edema (DME) following pars plana vitrectomy (PPV) using a modified microneedle.

Patients and methods

A prospective interventional study was conducted on 60 eyes of 60 patients with centrally involved diabetic macular edema following pars plana vitrectomy (PPV). SCTA was performed at the baseline and repeated after 3 months in case of persistent subretinal or intraretinal fluid, central macular thickness (CMT) more than 300 µm or visual loss by more than one line of the Snellen chart.

Results

The present study detected significant reduction of the CMT from 498.3 ± 94.8 µm at the baseline to 212.3 ± 11.9 µm after 12 months of injection with p < 0.001 and a significant improvement of best corrected visual acuity (BCVA) from 1 (0.9-1.2) at the baseline to 0.5 (0.3-0.7) after 12 months of injection with p < 0.001. The intraocular pressure (IOP) increased significantly after 3 months of injection with p < 0.001 and then gradually declined to its normal level after 6 months. Inner segment/outer segment (IS/OS) disruption was the only significant predictor of the final CMT; however, the number of injections, IS/OS disruption, baseline BCVA and the HbA1C level were the significant predictors of the final BCVA after injection.

Conclusion

Suprachoroidal injection of TA using this microneedle resulted in significant anatomical and functional improvement in previously vitrectomized diabetic macular edema patients with no recorded ocular or systemic adverse events.

Suprachoroidal Drug Delivery for Macular Edema Associated With Noninfectious Uveitis

Purpose: To evaluate clinical trials in the literature that focus on suprachoroidal drug delivery for the treatment of noninfectious uveitis and other posterior segment diseases. Methods: A synthesis of the literature was performed. Results: In 2021, suprachoroidal space triamcinolone acetonide, a corticosteroid delivery system used for the treatment of uveitic macular edema (ME), was approved by the US Food and Drug Administration. The drug-delivery system targets the suprachoroidal space using a microneedle-based device and has a favorable pharmacokinetic profile. Suprachoroidally administered investigational therapies have also been assessed in clinical trials for other posterior segment diseases, including diabetic ME, retinal vein occlusion, age-related macular degeneration, and choroidal melanoma. Conclusions: The safety and efficacy of suprachoroidal corticosteroid injections to treat uveitic ME have been shown in recent phase III clinical trials. Multiple programs are also investigating this modality of drug delivery for use in many other retinal and choroidal pathologies.

SUPRACHOROIDAL SPACE INJECTION TECHNIQUE: Expert Panel Guidance

PURPOSE

To develop professional guidelines for best practices for suprachoroidal space (SCS) injection, an innovative technique for retinal therapeutic delivery, based on current published evidence and clinical experience.

METHODS

A panel of expert ophthalmologists reviewed current published evidence and clinical experience during a live working group meeting to define points of consensus and key clinical considerations to inform the development of guidelines for in-office SCS injection.

RESULTS

Core consensus guidelines for in-office SCS injection were reached and reported by the expert panel. Current clinical evidence and physician experience supported SCS injection as a safe and effective method for delivering retinal and choroidal therapeutics. The panel established consensus on the rationale for SCS injection, including potential benefits relative to other intraocular delivery methods and current best practices in patient preparation, pre- and peri-injection management, SCS-specific injection techniques, and postinjection management and follow-up.

CONCLUSION

These expert panel guidelines may support and promote standardization of SCS injection technique, with the goal of optimizing patient safety and outcomes. Some aspects of the procedure may reasonably be modified based on the clinical setting and physician judgment, as well as additional study.

Vesicular Drug Delivery Systems: Promising Approaches in Ocular Drug Delivery

Ocular drug delivery poses unique challenges due to the complex anatomical and physiological barriers of the eye. Conventional dosage forms often fail to achieve optimal therapeutic outcomes due to poor bioavailability, short retention time, and off-target effects. In recent years, vesicular drug delivery systems have emerged as promising solutions to address these challenges. Vesicular systems, such as liposome, niosome, ethosome, transfersome, and others (bilosome, transethosome, cubosome, proniosome, chitosome, terpesome, phytosome, discome, and spanlastics), offer several advantages for ocular drug delivery. These include improved drug bioavailability, prolonged retention time on the ocular surface, reduced systemic side effects, and protection of drugs from enzymatic degradation and dilution by tears. Moreover, vesicular formulations can be engineered for targeted delivery to specific ocular tissues or cells, enhancing therapeutic efficacy while minimizing off-target effects. They also enable the encapsulation of a wide range of drug molecules, including hydrophilic, hydrophobic, and macromolecular drugs, and the possibility of combination therapy by facilitating the co-delivery of multiple drugs. This review examines vesicular drug delivery systems, their advantages over conventional drug delivery systems, production techniques, and their applications in management of ocular diseases.

Polymeric microneedles for the eye: An overview of advances and ocular applications for minimally invasive drug delivery

Ocular drug delivery is challenging due to the presence of tissue barriers and clearance mechanisms. Most widely used topical formulations need frequent application because of poor permeability, short retention, and low bioavailability. Invasive intraocular injections and implants that deliver drugs at the target site are associated with infections, inflammation, and even vision loss post-use. These gaps can be addressed by a delivery platform that can efficiently deliver drug with minimal tissue damage. Microneedles were introduced as a delivery platform for overcoming dermal barriers with minimal tissue damage. After the successful clinical transition of microneedles in the transdermal drug delivery, they are now being extensively studied for ocular applications. The attributes of minimally invasive application and the capability to deliver a wide range of therapeutics make microneedles an attractive candidate for ocular drug delivery. The current manuscript provides a detailed overview of the recent advancements in the field of microneedles for ocular use. This paper reviews research focusing on polymeric microneedles and their pharmaceutical and biopharmaceutical properties. A brief discussion about their clinical translation and regulatory concerns is also covered. The multitude of research articles supports the fact that microneedles are a potential, minimally invasive drug delivery platform for ophthalmic use.

Cell-cell interaction in the pathogenesis of inherited retinal diseases

The retina is part of the central nervous system specialized for vision. Inherited retinal diseases (IRD) are a group of clinically and genetically heterogenous disorders that lead to progressive vision impairment or blindness. Although each disorder is rare, IRD accumulatively cause blindness in up to 5.5 million individuals worldwide. Currently, the pathophysiological mechanisms of IRD are not fully understood and there are limited treatment options available. Most IRD are caused by degeneration of light-sensitive photoreceptors. Genetic mutations that abrogate the structure and/or function of photoreceptors lead to visual impairment followed by blindness caused by loss of photoreceptors. In healthy retina, photoreceptors structurally and functionally interact with retinal pigment epithelium (RPE) and Müller glia (MG) to maintain retinal homeostasis. Multiple IRD with photoreceptor degeneration as a major phenotype are caused by mutations of RPE- and/or MG-associated genes. Recent studies also reveal compromised MG and RPE caused by mutations in ubiquitously expressed ciliary genes. Therefore, photoreceptor degeneration could be a direct consequence of gene mutations and/or could be secondary to the dysfunction of their interaction partners in the retina. This review summarizes the mechanisms of photoreceptor-RPE/MG interaction in supporting retinal functions and discusses how the disruption of these processes could lead to photoreceptor degeneration, with an aim to provide a unique perspective of IRD pathogenesis and treatment paradigm. We will first describe the biology of retina and IRD and then discuss the interaction between photoreceptors and MG/RPE as well as their implications in disease pathogenesis. Finally, we will summarize the recent advances in IRD therapeutics targeting MG and/or RPE.

A New Generation of Gene Therapies as the Future of Wet AMD Treatment

Age-related macular degeneration (AMD) is an eye disease and the most common cause of vision loss in the Western World. In its advanced stage, AMD occurs in two clinically distinguished forms, dry and wet, but only wet AMD is treatable. However, the treatment based on repeated injections with vascular endothelial growth factor A (VEGFA) antagonists may at best stop the disease progression and prevent or delay vision loss but without an improvement of visual dysfunction. Moreover, it is a serious mental and financial burden for patients and may be linked with some complications. The recent first success of intravitreal gene therapy with ADVM-022, which transformed retinal cells to continuous production of aflibercept, a VEGF antagonist, after a single injection, has opened a revolutionary perspective in wet AMD treatment. Promising results obtained so far in other ongoing clinical trials support this perspective. In this narrative/hypothesis review, we present basic information on wet AMD pathogenesis and treatment, the concept of gene therapy in retinal diseases, update evidence on completed and ongoing clinical trials with gene therapy for wet AMD, and perspectives on the progress to the clinic of "one and done" therapy for wet AMD to replace a lifetime of injections. Gene editing targeting the VEGFA gene is also presented as another gene therapy strategy to improve wet AMD management.

Intravitreal injection of methotrexate in persistent diabetic macular edema: a 6-month study

Background

Diabetic macular edema (DME) affects approximately 10% of patients with diabetes mellitus. This condition can cause blurred or distorted vision, which significantly affects the quality of life of these patients. We evaluated the therapeutic effects of intravitreal methotrexate (MTX) injections on persistent DME.

Methods

This prospective interventional case series included patients with confirmed persistent DME that was unresponsive to previous standard treatments. The patients underwent comprehensive eye examinations and macular imaging with optical coherence tomography (OCT). A single intravitreal MTX injection (400 µg MTX in 0.16 mL solution) was administered, followed by patient assessments at 1, 3, and 6 months after injection. Best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), macular thickness (MT), and central subfield thickness (CST) were measured at baseline and post-injection to evaluate treatment efficacy.

Results

We included 33 eyes of 30 patients with a mean (standard deviation [SD], range) age of 62.7 (8.3, 44 to 77) years, of whom 17 (56.7%) were men and 13 (43.3%) were women. All participants had type 2 diabetes mellitus, with a mean (SD, range) duration of 17.0 (6.8, 10 to 31) years. Most participants (n = 27 eyes, 81.8%) had non-proliferative diabetic retinopathy, and six eyes (18.2%) had regressed proliferative diabetic retinopathy. Four eyes (12.1%) had undergone prior macular laser photocoagulation. The mean (SD) number of prior intravitreal bevacizumab injections was 3.4 (0.8), and 29 eyes (87.8%) had received one intravitreal triamcinolone injection. During the study period, a statistically significant difference was observed in CST (P < 0.05); however, no statistically significant differences were observed in BCDVA, MT, or IOP (P > 0.05). Pairwise comparison revealed a significant decrease in CST at 6 months post-injection compared to the baseline value (P < 0.05). During the investigation period, no side effects of MTX, such as macular edema, retinal tears, vitreous hemorrhage, endophthalmitis, or vision loss, were observed.

Conclusions

A single intravitreal MTX injection significantly reduced CST in patients with persistent DME, without relevant safety concerns. However, no significant improvement in functional outcomes was observed. Therefore, there is no strong evidence to recommend its use as a treatment for pDME. Further studies, preferably randomized clinical trials with long-term follow-ups, are warranted to assess the long-term efficacy, safety, and potential benefits of intravitreal MTX for the treatment of persistent DME.

Hydrogels in Ophthalmology: Novel Strategies for Overcoming Therapeutic Challenges

The human eye's intricate anatomical and physiological design necessitates tailored approaches for managing ocular diseases. Recent advancements in ophthalmology underscore the potential of hydrogels as a versatile therapeutic tool, owing to their biocompatibility, adaptability, and customizability. This review offers an exploration of hydrogel applications in ophthalmology over the past five years. Emphasis is placed on their role in optimized drug delivery for the posterior segment and advancements in intraocular lens technology. Hydrogels demonstrate the capacity for targeted, controlled, and sustained drug release in the posterior segment of the eye, potentially minimizing invasive interventions and enhancing patient outcomes. Furthermore, in intraocular lens domains, hydrogels showcase potential in post-operative drug delivery, disease sensing, and improved biocompatibility. However, while their promise is immense, most hydrogel-based studies remain preclinical, necessitating rigorous clinical evaluations. Patient-specific factors, potential complications, and the current nascent stage of research should inform their clinical application. In essence, the incorporation of hydrogels into ocular therapeutics represents a seminal convergence of material science and medicine, heralding advancements in patient-centric care within ophthalmology.

Long-acting microneedle formulations

The minimally-invasive and painless nature of microneedle (MN) application has enabled the technology to obviate many issues with injectable drug delivery. MNs not only administer therapeutics directly into the dermal and ocular space, but they can also control the release profile of the active compound over a desired period. To enable prolonged delivery of payloads, various MN types have been proposed and evaluated, including dissolving MNs, polymeric MNs loaded or coated with nanoparticles, fast-separable MNs hollow MNs, and hydrogel MNs. These intricate yet intelligent delivery platforms provide an attractive approach to decrease side effects and administration frequency, thus offer the potential to increase patient compliance. In this review, MN formulations that are loaded with various therapeutics for long-acting delivery to address the clinical needs of a myriad of diseases are discussed. We also highlight the design aspects, such as polymer selection and MN geometry, in addition to computational and mathematical modeling of MNs that are necessary to help streamline and develop MNs with high translational value and clinical impact. Finally, up-scale manufacturing and regulatory hurdles along with potential avenues that require further research to bring MN technology to the market are carefully considered. It is hoped that this review will provide insight to formulators and clinicians that the judicious selection of materials in tandem with refined design may offer an elegant approach to achieve sustained delivery of payloads through the simple and painless application of a MN patch.

Update on current pharmacologic therapies for diabetic retinopathy

INTRODUCTION

Diabetic retinopathy is a major cause of visual loss worldwide. The most important clinical findings include diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR).

AREAS COVERED

PubMed was used for our literature review. Articles from 1995 to 2023 were included. Pharmacologic treatment of diabetic retinopathy generally involves the use of intravitreal anti-vascular endothelial growth factor (VEGF) therapy for DME and PDR. Corticosteroids remain important second-line therapies for patients with DME. Most emerging therapies focus on newly identified inflammatory mediators and biochemical signaling pathways involved in disease pathogenesis.

EXPERT OPINION

Emerging anti-VEGF modalities, integrin antagonists, and anti-inflammatory agents have the potential to improve outcomes with reduced treatment burdens.

Suprachoroidal Injection: A Novel Approach for Targeted Drug Delivery

Treating posterior segment and retinal diseases poses challenges due to the complex structures in the eye that act as robust barriers, limiting medication delivery and bioavailability. This necessitates frequent dosing, typically via eye drops or intravitreal injections, to manage diseases, often leading to side effects with long-term use. Suprachoroidal injection is a novel approach for targeted drug delivery to the posterior segment. The suprachoroidal space is the region between the sclera and the choroid and provides a potential route for minimally invasive medication delivery. Through a more targeted delivery to the posterior segment, this method offers advantages over other routes of administration, such as higher drug concentrations, increased bioavailability, and prolonged duration of action. Additionally, this approach minimizes the risk of corticosteroid-related adverse events such as cataracts and intraocular pressure elevation via compartmentalization. This review focuses on preclinical and clinical studies published between 2019 and 2023, highlighting the potential of suprachoroidal injection in treating a variety of posterior segment diseases. However, to fully harness its potential, more research is needed to address current challenges and limitations, such as the need for technological advancements, refinement of injection techniques, and consideration of cost and accessibility factors. Future studies exploring its use in conjunction with biotech products, gene therapies, and cell-based therapies can lead to personalized treatments that can revolutionize the field of ophthalmology.

A Novel Device for Suprachoroidal Drug Delivery to Retina: Evaluation in Nonhuman Primates

Purpose

Evaluation of distribution and tolerance of suprachoroidal injection of indocyanine green (ICG) in nonhuman primates (NHPs) using a novel suprachoroidal (SC) delivery technology.

Methods

Three live and three euthanized African green monkeys were injected with 150 or 200 µL ICG/eye into the SC space of both eyes, 2.5 mm posterior to the limbus in the inferior quadrant, utilizing a novel SC injector. Eyes were analyzed by imaging of scleral flatmounts. Live animals were observed for 24 hours for general health. Ophthalmic evaluation included slit-lamp biomicroscopy, tonometry, fundus imaging, confocal laser ophthalmoscopy, and spectral-domain optical coherence tomography (SD-OCT) before and at 10 minutes and 1, 3, and 24 hours post-injection.

Results

SC dosing was successfully performed in all eyes. Infrared fundus imaging demonstrated ICG distribution throughout the posterior segment, reaching the macula within 24 hours post-injection. No inflammation, intravitreal penetration, SC blebs, retinal detachment, or hemorrhages were detected. No significant changes were observed in retinal thickness by SD-OCT (P = 0.267, ANOVA). A mild, statistically insignificant elevation in intraocular pressure was observed within 10 minutes post-injection (mean ± standard error: 7.28 ± 5.09 mmHg; P = 0.061) and was spontaneously resolved within the first hour after dosing.

Conclusions

Suprachoroidal injection of 150 to 200 µL ICG dye was successfully performed and well tolerated in NHP eyes, with rapid distribution into the macular region and throughout the posterior pole.

Translational Relevance

This novel SC drug delivery system may potentially provide safe and effective delivery of therapeutics to the posterior pole region in humans.

Recent advances and future prospects: current status and challenges of the intraocular injection of drugs for vitreoretinal diseases

Effective drug therapy for vitreoretinal disease is a major challenge in the field of ophthalmology; various protective systems, including anatomical and physiological barriers, complicate drug delivery to precise targets. However, as the eye is a closed cavity, it is an ideal target for local administration. Various types of drug delivery systems have been investigated that take advantage of this aspect of the eye, enhancing ocular permeability and optimizing local drug concentrations. Many drugs, mainly anti-VEGF drugs, have been evaluated in clinical trials and have provided clinical benefit to many patients. In the near future, innovative drug delivery systems will be developed to avoid frequent intravitreal administration of drugs and maintain effective drug concentrations for a long period of time. Here, we review the published literature on various drugs and administration routes and current clinical applications. Recent advances in drug delivery systems are discussed along with future prospects.

Novel Approaches in the Drug Development and Delivery Systems for Age-Related Macular Degeneration

The number of patients with ocular disorders has increased due to contributing factors such as aging populations, environmental changes, smoking, genetic abnormalities, etc. Age-related macular degeneration (AMD) is one of the common ocular disorders which may advance to loss of vision in severe cases. The advanced form of AMD is classified into two types, dry (non-exudative) and wet (exudative) AMD. Although several therapeutic approaches are explored for the management of AMD, no approved therapy can substantially slow down the progression of dry AMD into the later stages. The focus of researchers in recent times has been engaged in developing targeted therapeutic products to halt the progression and maintain or improve vision in individuals diagnosed with AMD. The delivery of anti-VEGF agents using intravitreal therapy has found some success in managing AMD, and novel formulation approaches have been introduced in various studies to potentiate the efficacy. Some of the novel approaches, such as hydrogel, microspheres, polymeric nanoparticles, liposomes, implants, etc. have been discussed. Apart from this, subretinal, suprachoroidal, and port delivery systems have also been investigated for biologics and gene therapies. The unmet potential of approved therapeutic products has contributed to several patent applications in recent years. This review outlines the current treatment options, outcomes of recent research studies, and patent details around the novel drug delivery approach for the treatment of AMD.

Triamcinolone Acetonide Suprachoroidal Injectable Suspension for Uveitic Macular Edema: Integrated Analysis of Two Phase 3 Studies

INTRODUCTION

Macular edema, a common complication of uveitis, may result in vision loss. The aim of this analysis was to report integrated phase 3 trial data for triamcinolone acetonide injectable suspension for suprachoroidal use (SCS-TA) in the treatment of macular edema secondary to noninfectious uveitis using strict inclusion criteria.

METHODS

This analysis included patients with central subfield thickness (CST) ≥ 300 µm and best-corrected visual acuity (BCVA) of ≥ 5 and ≤ 70 Early Treatment Diabetic Retinopathy Study (ETDRS) letters at both screening and baseline who received ≥ 1 study treatment in either PEACHTREE (randomized, double-masked SCS-TA or sham control) or AZALEA (open-label SCS-TA). Patients received SCS-TA 4.0 mg (0.1 ml of 40 mg/ml) or control at baseline and week 12.

RESULTS

In the SCS-TA group (n = 95), 47.4% of patients gained ≥ 15 ETDRS letters from baseline to week 24 versus 16.7% of patients in the control group (n = 60; P < 0.001). Mean change in BCVA in the SCS-TA group was 9.6 letters at week 4 and 13.9 letters at week 24. CST also improved rapidly in the SCS-TA group (mean change: - 158.4 µm at week 4), with sustained reduction throughout the study (mean change: - 163.9 µm at week 24 versus - 19.3 µm in the control group; P < 0.001). No treatment-related serious adverse events (AEs) were reported. Incidence of AEs pertaining to elevated intraocular pressure was 12.6% and 15.0% in the SCS-TA and control groups, respectively; incidence of cataract formation/worsening AEs was 7.4% and 6.7%, respectively.

CONCLUSION

In this integrated analysis utilizing strict inclusion criteria, SCS-TA was found effective in the treatment of patients with macular edema associated with noninfectious uveitis and was generally well tolerated.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02595398, NCT03097315.

Six-month sustained delivery of anti-VEGF from in-situ forming hydrogel in the suprachoroidal space

Patients with wet age-related macular degeneration (AMD) require intravitreal injections of bevacizumab (Bev) or other drugs, often on a monthly basis, which is a burden on the healthcare system. Here, we developed an in-situ forming hydrogel comprised of Bev and hyaluronic acid (HA) crosslinked with poly(ethylene glycol) diacrylate for slow release of Bev after injection into the suprachoroidal space (SCS) of the eye using a microneedle. Liquid Bev formulations were cleared from SCS within 5 days, even when formulated with high viscosity, unless Bev was conjugated to a high molecular-weight HA (2.6 MDa), which delayed clearance until 1 month. To extend release to 6 months, we synthesized in-situ forming Bev-HA hydrogel initially as a low-viscosity mixture suitable for injection and flow in the SCS to cover a large area extending to the posterior pole of the eye where the macula is located in humans. Within 1 h after injection, Bev and HA were crosslinked, which retained Bev for slow release as the hydrogel biodegraded. In vivo studies in the rabbit eye reported Bev release for >6 months, depending on gel formulation and Bev assay. The in-situ forming Bev-HA hydrogel was well tolerated, as assessed by clinical exam, fundus imaging, histological analysis, and intraocular pressure measurement. We conclude that Bev released from an in-situ forming hydrogel may enable long-acting treatments of AMD and other posterior ocular indications.

Suprachoroidal injection of polyzwitterion hydrogel for treating glaucoma

Glaucoma is the primary cause of irreversible blindness worldwide. The current treatments are primarily based on drug usage or surgical operation to reduce intraocular pressure (IOP). However, it is expensive and requires patients to insist on taking the medicine for a long time. The suprachoroidal space (SCS) is the space between the choroid and the sclera, which forms part of the uveovortex pathway in the circulation of aqueous humor. So far, it is still challenging to realize the injection of hydrogels into the SCS with long-term duration. In this work, an in situ-forming polyzwitterionic polycarboxybetaine hydrogel is designed and injected to expand SCS to increase the drainage of aqueous humor from the eye via the uveovortex pathway, thus reducing IOP for at least 6 weeks, while commercial hyaluronic acid hydrogel can only last for about 4 weeks. The clinical ophthalmological safety assessment examination shows that the treatment of polyzwitterion hydrogel is well-tolerated that leads to minimal inflammatory reaction, and histopathology assessment demonstrates that the SCS is expanded after injection of the hydrogel. Further analysis of ultrasound biomicroscopy reveals that there is a strong correlation between IOP reduction and SCS expansion. In short, the polyzwitterion hydrogel developed in this work can prolong the period of IOP reduction by expanding SCS, thus treating ocular hypertension and glaucoma without resorting to drugs or regular surgery.

Diabetic Macular Edema: Current Understanding, Molecular Mechanisms and Therapeutic Implications

Diabetic retinopathy (DR), with increasing incidence, is the major cause of vision loss and blindness worldwide in working-age adults. Diabetic macular edema (DME) remains the main cause of vision impairment in diabetic patients, with its pathogenesis still not completely elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of DR and DME. Currently, intravitreal injection of anti-VEGF agents remains as the first-line therapy in DME treatment due to the superior anatomic and functional outcomes. However, some patients do not respond satisfactorily to anti-VEGF injections. More than 30% patients still exist with persistent DME even after regular intravitreal injection for at least 4 injections within 24 weeks, suggesting other pathogenic factors, beyond VEGF, might contribute to the pathogenesis of DME. Recent advances showed nearly all the retinal cells are involved in DR and DME, including breakdown of blood-retinal barrier (BRB), drainage dysfunction of Müller glia and retinal pigment epithelium (RPE), involvement of inflammation, oxidative stress, and neurodegeneration, all complicating the pathogenesis of DME. The profound understanding of the changes in proteomics and metabolomics helps improve the elucidation of the pathogenesis of DR and DME and leads to the identification of novel targets, biomarkers and potential therapeutic strategies for DME treatment. The present review aimed to summarize the current understanding of DME, the involved molecular mechanisms, and the changes in proteomics and metabolomics, thus to propose the potential therapeutic recommendations for personalized treatment of DME.

Pharmacokinetics of Sirolimus in a Novel Liposome Delivery System in Selected Ocular Tissues and Plasma Following a Single Subconjunctival Injection in Dutch Belted Rabbits

Purpose: To determine the pharmacokinetics of a proprietary liposomal sirolimus (LS) formulation in ocular tissues and plasma following a single subconjunctival (SCJ) injection in Dutch belted rabbits (DBR). Analytical methods for detection of LS in plasma, aqueous humor (AH), vitreous humor (VH), retina, combined retina/choroid/retinal pigment epithelium, sclera, and iris/ciliary body were developed to examine samples. Methods: Thirty male DBR were subconjunctivally injected in both eyes with 0.1 mL of LS of 1,000 μg/mL. At selected times post-injection, ocular tissues and whole blood samples were obtained. Sirolimus concentrations were measured using liquid chromatography/tandem mass spectrometry. Results: No LS was detected in serum or AH at any time. All other examined ocular tissues had quantifiable amounts of LS at all times. LS levels were highest in sclera and lowest in VH, suggesting LS followed the supraciliary and suprachoroidal spaces to reach the posterior segment. Vitreous peak of sirolimus levels occurred at 2 h, and the sclera adjacent to the injection peaked at both 2 and 96 h. LS levels in remaining ocular tissues peaked at 6 h and decreased with time, persisting at presumed therapeutic levels on day 22. Conclusions: LS can quickly diffuse into posterior intraocular tissues after SCJ injection without reaching quantifiable levels in AH or serum in DBR. Peak levels occurred in posterior intraocular tissues at 6 h and persisted in all tissues after 3 weeks. SCJ LS in DBR is safe, has a stable pharmacokinetic profile, and should be considered for further study in human trials for autoimmune ophthalmopathies.

Suprachoroidal triamcinolone acetonide injection: a novel therapy for serous retinal detachment due to Vogt-Koyanagi Harada disease

PURPOSE

To assess the efficacy and safety of Suprachoroidal triamcinolone acetonide injection [SCTA] as an adjunctive therapy in management of Vogt-Koyanagi Harada [VKH] serous retinal detachment.

DESIGN

Prospective parallel group study.

PARTICIPANTS

12 eyes of 6 patients with bilateral multiple serous retinal detachment of VKH in acute phase on systemic steroids.

METHODS

Each patient was received single SCTA injection (SCTA group, n = 6 eyes) and the other non-injected eye (Standard treatment group, n = 6 eyes), patients were followed for 1, 3, and 6 months to assess changes in best corrected visual acuity [BCVA], central foveal thickness [CFT] and intraocular pressure [IOP] between both groups.

MAIN OUTCOME MEASURES

The primary end point was changes in BCVA from baseline till 6^th months follow-up. Secondary end points were changes in CFT and IOP from baseline to 6 months of follow-up.

RESULTS

BCVA at one and three months was significantly better in eyes received SCTA than in non-injected eyes (p-value = 0.026 for each). CFT at one and three months was significantly higher in non-injected eyes than in eyes received SCTA (p-value = 0.028 for each). IOP showed no significant differences between both groups.

CONCLUSIONS

SCTA is an effective adjuvant treatment for VKH serous retinal detachment, without any serious ocular adverse effects or increase in IOP and causing significant reduction in CFT and rapid improvement in BCVA when combined with oral steroids.

A Randomized Trial Comparing Suprachoroidal and Intravitreal Injection of Triamcinolone Acetonide in Refractory Diabetic Macular Edema due to Epiretinal Membrane

Purpose

To compare the efficacy and safety of suprachoroidal and intravitreal injection of triamcinolone acetonide in pseudophakic patients with refractory diabetic macular edema (DME) due to epiretinal membrane (ERM). Study Design. This study is a randomized clinical trial (RCT). Participants. Twenty-three nonvitrectomized pseudophakic eyes of 23 subjects (9 M and 14 F with mean age: 54.8 years) with refractory DME due to ERM.

Methods

The eyes were randomized to suprachoroidal triamcinolone acetonide injection 4 mg/0.1 ml (SCTA) (n = 13 eyes) or intravitreal triamcinolone acetonide 4 mg/0.1 ml (IVTA) (n = 10 eyes) and were evaluated at baseline and 1 and 3 months after injection to assess outcome measures. Main Outcome Measures. Changes in best-corrected visual acuity (BCVA) (primary outcome), central foveal thickness (CFT) by optical coherence tomography (OCT), and intraocular pressure (IOP) measurement (secondary).

Results

Baseline median BCVA (logMAR) was 1.0 (range 0.8–1.0) in both groups, improved within the SCTA group to 0.8 on the 1^st and 3^rd months, while in the IVTA group, median BCVA changed to 0.8 and 0.9 on the 1^st and 3^rd months, respectively. No significant differences were noted between groups regarding BCVA at baseline (P=0.927), and 1^st (P=0.605) and 3^rd months (P=0.313). Regarding mean CFT, no significant differences were observed at baseline (P=0.353) and at the first month (P=0.214) between both groups, while at the third month, CFT was significantly higher in the IVTA group (385 um) than in the SCTA group (323 um) (P=0.028). Mean IOP was significantly higher in the IVTA group (15 mmHg) on 1^st month than in the SCTA group (12 mmHg) (P=0.011); after 3^rd month, IOP was significantly higher within the IVTA group (18 mmHg) than SCTA (14 mmHg) (P=0.028). No significant difference was noted between both groups at baseline IOP (P=0.435).

Conclusions

Both SCTA and IVTA are effective in reduction of CFT and improvement of patients' visual acuity, but with a higher recurrence rate and rise in IOP after IVTA when compared to SCTA. Both treatments have temporary effects with the possibility of recurrence of DME and the need for retreatment.

Retinal findings in glomerulonephritis

The complement system is part of the innate immune system activated by three distinct pathways: classical, lectin and alternative. It is also involved in retinal development and homoeostasis. Dense deposit disease is a rare renal disease associated with mutations in Complement factor H and overactivity of the alternative complement pathway. As well as glomerulonephritis, many affected individuals have retinal drusen and may be at risk of vision loss due to macular atrophy or choroidal neovascularisation. We discuss the reclassification of dense deposit disease as a type of C3 glomerulonephropathy, and hypothesise on the mechanisms of retinal abnormalities. Drusen have also been described in individuals with other types of glomerulonephritis involving abnormalities of the classical (membranoproliferative glomerulonephritis type 1) or lectin (IgA nephropathy, lupus nephritis) complement pathways. Although drusen are found in abnormalities of all three complement pathways, the age at onset, aetiology, and the threat to vision differs. This review describes drusen and other retinal abnormalities associated with the glomerulonephritides due to abnormal activation in each of the three complement activation pathways, and provides the first report of drusen occurring in a patient with the recently reclassified C3 glomerulonephritis with homozygous variant V62I in complement factor H. Optometric management of young patients presenting with retinal drusen is discussed, and complement-based therapies for visual loss are reviewed.

The Future of Stem Cells and Their Derivates in the Treatment of Glaucoma. A Critical Point of View

This review focuses on the clinical translation of preclinical studies, especially those that have used stem cells in the treatment of glaucoma, with an emphasis on optic nerve regeneration. The studies referred to in the review aim to treat optic nerve atrophy, while cell therapies targeting other sites in the eye, such as the trabecular meshwork, have not been addressed. Such complex and varied pathophysiological mechanisms that lead to glaucoma may explain the fact that although stem cells have a high capacity of neuronal regeneration, the treatments performed did not have the expected results and the promise offered by animal studies was not achieved. By analyzing the facts associated with failure, important lessons are to be learned: the type of stem cells that are used, the route of administration, the selection of patients eligible for these treatments, additional therapies that support stem cells transplantation and their mode of action, methods of avoiding the host’s immune response. Many of these problems could be solved using exosomes (EV), but also miRNA, which allows more targeted approaches with minimal side effects.