Sustained-release steroids for the treatment of diabetic macular edema

Improved triamcinolone acetonide-eluting contact lenses based on cyclodextrins and high hydrostatic pressure assisted complexation

Contact lenses (CLs) constitute an advantageous platform for the topical release of corticosteroids due to their prolonged contact with the eye. However, the lipophilic nature of corticosteroids hampers CLs' ability to release therapeutic amounts. Two approaches to improve loading and release of triamcinolone acetonide (TA) from poly(2-hydroxyethyl methacrylate)-based hydrogels were investigated: adding 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) to the monomers solution before polymerization (HEMA/i-CD) and an hydrogels' post-treatment with HP-β-CD (HEMA/p-CD). The effect of HP-β-CD and sterilization by high hydrostatic pressure (HHP) on the hydrogel properties (water content, oxygen and ion permeability, roughness, transmittance, and stiffness) was evaluated. The HEMA/i-CD hydrogels had stronger affinity for TA, sustaining its release for one day. HHP sterilization promoted the formation of cyclodextrin-TA complexes within the hydrogels, improving their drug-loading capacity »60 %. Cytotoxicity and irritability tests confirmed the safety of the therapeutic CLs. TA released from the hydrogels permeated through ocular tissues ex vivo and showed anti-inflammatory activity. Finally, a previously validated mathematical model was used to estimate the ability of the TA-loaded CLs to deliver therapeutic drug concentrations to the posterior part of the eye. Overall, HP-β-CD-containing CLs are promising candidates for the topical ocular application of TA as an alternative delivery system to intraocular injections.

Glucocorticoids Promote Extracellular Matrix Component Remodeling by Activating YAP in Human Retinal Capillary Endothelial Cells

Remodeling of extracellular matrix (ECM) components of endothelial cells is the main cause of retinal vascular basement membrane (BM) thickening, which leads to the initiation and perpetuation of microvasculopathy of diabetic retinopathy (DR). Excessive amounts of glucocorticoids (GCs) are related to the presence and severity of DR, however transcriptional effects of GCs on the biology of human retinal capillary endothelial cells (HRCECs) and its impacts on DR are still unclear. Here, we showed that GC (hydrocortisone) treatment induced ECM component [fibronectin (FN) and type IV collagen (Col IV)] expression and morphological changes in HRCECs via the glucocorticoid receptor (GR), which depended on the nuclear translocation of YAP coactivator. Mechanistically, GCs induced stress fiber formation in HRCECs, while blocking stress fiber formation inhibited GC-induced YAP nuclear translocation. Overexpression of FN, but not Col IV, activated YAP through the promotion of stress fiber formation via ECM-integrin signaling. Thus, a feedforward loop is established to sustain YAP activity. Using mRNA sequencing of HRCECs with overexpressed YAP or GC treatment, we found a similarity in Gene Ontology (GO) terms, differentially expressed genes (DEGs) and transcription factors (TFs) between the two RNA-seq datasets. In vivo, YAP was activated in retina vascular ECs of STZ-induced diabetic mice, and TF prediction analysis of published RNA-seq data of dermal vascular ECs from T2DM patients showed that GR and TEAD (the main transcription factor for YAP) were enriched. Together, GCs activate YAP and promote ECM component (FN and Col IV) remodeling in retinal capillary endothelial cells, and the underlying regulatory mechanism may provide new insights into the vascular BM thickening of the retina in the early pathogenesis of DR.

Les œdèmes maculaires

L’œdème maculaire est une augmentation de volume de la macula, zone centrale de la rétine, responsable de l’acuité visuelle. Des symptômes visuels handicapent la vie de millions de patients atteints d’œdème maculaire secondaire à une maladie chronique et parfois aiguë de la rétine. Les protéines qui neutralisent la voie du facteur de croissance de l’endothélium vasculaire (VEGF) ou les glucocorticoïdes, au prix d’injections intraoculaires répétées pendant des années, limitent les symptômes visuels. Mieux comprendre pourquoi et comment l’œdème se forme et comment les molécules thérapeutiques exercent un effet anti-œdémateux permettra de mieux prévenir la survenue de cette complication rétinienne handicapante et cécitante.

A New Approach for Diabetic Macular Edema Treatment: review of clinical practice results with 0.19 mg fluocinolone acetonide intravitreal implant including vitrectomized eyes

PURPOSE OF REVIEW

Fluocinolone acetonide is a synthetic fluorinated glucocorticoid. It has selective and potent agonist properties by binding to the cytosolic glucocorticoid receptor with high affinity; it is devoid of mineralocorticoid activity. Two extended-release (i.e. lasting up to 3 years) drug delivery systems containing fluocinolone acetonide (FAc) have been approved by the FDA for intravitreal use: Retisert ® (Bausch&Lomb, New Jersey, USA) and Iluvien ® (Alimera Sciences, Atlanta, USA). The former contains 0.59 mg of FAc, which is approved for the treatment of chronic noninfectious posterior segment uveitis. The latter contains a dose of 0.19 mg of FAc and is approved for the treatment of diabetic macular edema and here we review the results published in the clinical literature relating to its use in the treatment of diabetic macular edema (DME).

RECENT FINDINGS

The 0.19 mg FAc implant (Iluvien®) is a new approved treatment approach for DME. It is a non-biodegradable implant that continuously releases a microdose of FAc into the vitreous cavity for up to three years. It is effective in chronic DME with the added value of decreasing the treatment burden of multiple intravitreal injections. Recently, clinical practice studies are reporting its efficacy and safety profile (intra-ocular pressure rise and cataract), as well as its use in clinical setting not included in clinical trial such as vitrectomized eyes.

SUMMARY

The FAc implant has demonstrated in clinical practice results that mirror the results of the clinical trials efficacy wise. Regarding its safety profile, cataract is a common complication, however, intra-ocular pressure rises may be lower than the ones reported in trials. The implant has shown effectiveness in vitrectomized eyes. An increasing evidence of real-world studies have supported utility of the implant in DME patients. It's extended-release format for up to 3 years benefits to the patient and carer as it means fewer injections and visits to the clinic.

Dexamethasone implant in the management of diabetic macular edema from clinician's perspective

The aim of this article is to provide an overview of characteristics and principles of use of dexamethasone implant in patients with diabetic macular edema (DME). The condensed information about patient selection, dosing, and postinjection management is provided to make the clinician’s decisions easier in real-life practice. DME is a common complication of diabetes and the leading cause of visual loss in the working-age population. Inflammation plays an important role in the pathogenesis of DME. The breakdown of the blood–retinal barrier involves the expression of inflammatory cytokines and growth factors, including vascular endothelial growth factor (VEGF). Steroids have proved to be effective in the treatment of DME by blocking the production of VEGF and other inflammatory cytokines, by inhibiting leukostasis, and by enhancing the barrier function of vascular endothelial cell tight junctions. Dexamethasone intravitreal implant has demonstrated efficacy in the treatment of DME resistant to anti-VEGF therapy and in vitrectomized eyes. Data from clinical trials suggest that dexamethasone implant can be considered as first-line treatment in pseudophakic eyes. Dexamethasone implant is also the first-line therapy in patients not suited for anti-VEGF therapy, pregnant women, and patients unable to return for frequent monitoring. It has been shown that the maximum effect of dexamethasone implant on visual gain and retinal thickness occurs approximately 2 months after injection. Various treatment regimens are used in real-life situations, and reported reinjection intervals were usually <6 months. The number of retreatments needed decreased over time. Treatment algorithms should be personalized. Postinjection management and follow-up should consider potential adverse events such as intraocular pressure elevation and cataract.

Changes in intraocular pressure after intravitreal fluocinolone acetonide (ILUVIEN): real-world experience in three European countries

Aims

The ILUVIEN Registry Safety Study is an ongoing, multicentre, open-label, observational study collecting real-world data on the safety and effectiveness of the 0.2 µg/day fluocinolone acetonide (FAc) implant in patients treated according to the European label requirements.

Methods

Patients included in this analysis were treated for the licensed indication of chronic diabetic macular oedema (cDMO; that is, DMO that persists or recurs despite treatment). Data presented in the current analysis were collected from patient records up to 6 March 2017. Visual acuity (VA) data, including mean change in VA over time and at last observation, intraocular pressure (IOP) over the course of the study, IOP events, use of IOP-lowering therapy and cup:disc ratio were analysed. Information on additional DMO treatments post-FAc implant was also captured.

Results

Five hundred and sixty-three patients (593 eyes) were enrolled on the study. Mean IOP for the overall population remained within the normal range throughout follow-up and 76.7% of patients did not require IOP-lowering therapy following treatment with the FAc implant. Sixty-nine per cent of eyes did not require additional DMO treatments. Mean VA in the overall population increased from 51.9 letters at baseline to 55.6 letters at month 12, with a significant increase of 2.9 letters at last observation. Patients with short-term cDMO experienced greater VA gains than those with long-term cDMO.

Conclusions

The results of this analysis are comparable with those of other studies, including the Fluocinolone Acetate for Macular Edema study. The study reinforces the good safety and effectiveness profile of FAc, and demonstrates the benefit of early FAc treatment.

Short-Term Results of Intravitreal Triamcinolone Acetonide Combined with Cataract Surgery for Diabetic Macular Edema in Japan: In the Era of Anti-Vascular Endothelial Growth Factor Therapy

PURPOSE

To evaluate the effectiveness of an intravitreal triamcinolone acetonide injection (IVTA) combined with cataract surgery for diabetic macular edema (DME) resistant to anti-vascular endothelial growth factor (anti-VEGF) therapy.

PROCEDURE

IVTA combined with cataract surgery was performed on 29 eyes of patients with DME (aged 70.5 ± 6.2 years) who were refractive to anti-VEGF treatments. The visual acuity, central retinal thickness (CRT), and the central retinal sensitivity were assessed at 1, 4, 12, and 24 weeks after the treatment.

RESULTS

The visual acuity improved significantly from 0.49 ± 0.30 logMAR units to 0.35 ± 0.33 logMAR units at 24 weeks after the treatment (p < 0.05; repeated ANOVA). The CRT decreased significantly from 435.1 ± 112.3 μm to 350.8 ± 123.3 μm at 12 weeks after the treatment (p < 0.05). The retinal sensitivity threshold also improved significantly from 18.2 ± 4.3 dB to 20.4 ± 3.8 dB at 4 weeks after the treatment (p < 0.05).

CONCLUSIONS

IVTA combined with cataract surgery is effective for successful treatment of eyes with DME refractive to anti-VEGF therapy.

Mechanisms of macular edema: Beyond the surface

Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.

Real-world experience with 0.2 μg/day fluocinolone acetonide intravitreal implant (ILUVIEN) in the United Kingdom

Aims

To compare safety outcomes and visual function data acquired in the real-world setting with FAME study results in eyes treated with 0.2 μg/day fluocinolone acetonide (FAc).

Methods

Fourteen UK clinical sites contributed to pseudoanonymised data collected using the same electronic medical record system. Data pertaining to eyes treated with FAc implant for diabetic macular oedema (DMO) was extracted. Intraocular pressure (IOP)-related adverse events were defined as use of IOP-lowering medication, any rise in IOP>30 mm Hg, or glaucoma surgery. Other measured outcomes included visual acuity, central subfield thickness (CSFT) changes and use of concomitant medications.

Results

In total, 345 eyes had a mean follow-up of 428 days. Overall, 13.9% of patients required IOP-lowering drops (included initiation, addition and switching of current drops), 7.2% had IOP elevation >30 mm Hg and 0.3% required glaucoma surgery. In patients with prior steroid exposure and no prior IOP-related event, there were no new IOP-related events. In patients without prior steroid use and without prior IOP-related events, 10.3% of eyes required IOP-lowering medication and 4.3% exhibited IOP >30 mm Hg at some point during follow-up. At 24 months, mean best-recorded visual acuity increased from 51.9 to 57.2 letters and 20.8% achieved ≥15-letter improvement. Mean CSFT reduced from 451.2 to 355.5 μm.

Conclusions

While overall IOP-related emergent events were observed in similar frequency to FAME, no adverse events were seen in the subgroup with prior steroid exposure and no prior IOP events. Efficacy findings confirm that the FAc implant is a useful treatment option for chronic DMO.

Ascorbic acid repletion: A possible therapy for diabetic macular edema?

Macular edema poses a significant risk for visual loss in persons with diabetic retinopathy. It occurs when plasma constituents and fluid leak out of damaged retinal microvasculature in the area of the macula, causing loss of central vision. Apoptotic loss of pericytes surrounding capillaries is perhaps the earliest feature of diabetic vascular damage in the macula, which is also associated with dysfunction of the endothelium and loss of the otherwise very tight endothelial permeability barrier. Increased oxidative stress is a key feature of damage to both cell types, mediated by excess superoxide from glucose-induced increases in mitochondrial metabolism, as well as by activation of the receptor for advanced glycation end products (RAGE). The latter in turn activates multiple pathways, some of which lead to increased oxidative stress, such as those involving NF-ĸB, NADPH oxidase, and endothelial nitric oxide synthase. Such cellular oxidative stress is associated with low cellular and plasma ascorbic acid levels in many subjects with diabetes in poor glycemic control. Whether repletion of low ascorbate in retinal endothelium and pericytes might help to prevent diabetic macular edema is unknown. However, cell culture studies show that the vitamin prevents high-glucose and RAGE-induced apoptosis in both cell types, that it preserves nitric oxide generated by endothelial cells, and that it tightens the leaky endothelial permeability barrier. Although these findings need to be confirmed in pre-clinical animal studies, it is worth considering clinical trials to determine whether adequate ascorbate repletion is possible and whether it might help to delay or even reverse early diabetic macular edema.

Future opportunities in diabetic retinopathy research

PURPOSE OF REVIEW

The risk of vision loss from diabetic retinopathy has fallen dramatically over the past 3 decades with improvements in diabetes and blood pressure treatments, and with advances in laser surgery and intraocular drug delivery. Nevertheless, diabetes continues to be a major cause of blindness. This study summarizes the state of the art in diabetic retinopathy research and provides a perspective on opportunities for future investigations.

RECENT FINDINGS

New insights into the pathophysiology of diabetes and diabetic retinopathy will improve metabolic control. Structure-function analyses are revealing new details of diabetic retinopathy. Intraocular drug therapy provides improved visual outcomes. Together these steps will yield better means to detect and quantify vision loss, and to develop patient-specific treatments to preserve vision for persons with diabetes.

SUMMARY

Retinopathy is one of the most successfully treated complications of diabetes and will continue to be an important area of research for patients and their families.