INTRAVITREAL DEXAMETHASONE IMPLANT IN RETINITIS PIGMENTOSA–RELATED CYSTOID MACULAR EDEMA

Fluocinolone acetonide implant (Iluvien®) for macular edema associated with retinitis pigmentosa: A case report

PURPOSE

Macular edema can be observed in 20% of patients with retinitis pigmentosa (RP) and is often responsible of central vision impairment. Intraocular administration of corticosteroids (either triamcinolone or dexamethasone implant) has been found to be effective in that indication. We here describe the first report of a successful bilateral administration of fluocinolone acetonide implant in a patient with steroid-dependent macular edema associated to RP.

METHODS

Case report.

CASE REPORT

A 34-year female patient with RP was referred for a one-year bilateral persistent ME. She had been refractory either to topical or to general carbonic anhydrase inhibitors. Bilateral off-label administration of 0.7 mg dexamethasone implant (Ozurdex®, Allergan, CA) was therefore decided. Efficacy and tolerance were very good in both eyes. Still, every four-month injections were required to maintain the macula dry. Off-label use of 0.19 mg fluocinolone acetonide (FAc) implant (Iluvien®, Alimera Sciences, GA) was then proposed and injected, first, in the right eye and, two-years after, in the left eye. No recurrences of the edema were observed from then on, i.e., for 3 years in the right eye and for 1 year in the left eye.

CONCLUSION

Intravitreal fluocinolone acetonide could represent a promising means in the therapeutic management of persistent steroid-dependent ME related to RP.

The double-edged sword of inflammation in inherited retinal degenerations: Clinical and preclinical evidence for mechanistically and prognostically impactful but treatable complications

We present retrospective data from our clinical research efforts of the past several years alongside a review of past and current clinical and preclinical data independently by several investigators supporting our clinical evidence for the importance of inflammation in inherited retinal degenerations (IRDs). We show how inflammation is a complicating factor in IRDs but, if recognized and managed, also a great opportunity to mitigate disease severity immediately, improve patient prognosis and quality of life, extend the treatment windows for gene-specific and agnostic therapeutic approaches, mitigate the impact of inflammatory complications on the accurate estimate of vision changes in IRD natural history studies, improve the chances of safer outcomes following cataract surgery, and potentially reduce the likelihood of inflammatory adverse events and augment the efficacy of viral vector-based treatment approaches to IRDs. Manuscript contribution to the field. Inflammation has been suspected to be at play in IRDs since the beginning of the 1900s and became a research focus through the early 1990s but was then largely abandoned in favor of genetic-focused research. Thanks to regained cognizance, better research tools, and a more holistic approach to IRDs, the recent reappraisal of the role of inflammation in IRDs has brought back to the surface its importance. A potential confounder in natural history studies and a limiting factor in clinical trials if not accounted for, inflammation can be managed and often offers an opportunity for immediately improved prognosis and outcomes for IRD patients. We present our retrospective clinical evidence for connections with a measurable secondary autoimmune component that can develop in IRDs and contribute to vision loss but is at least in part treatable. We also present ample lines of evidence from the literature corroborating our clinical observations at the preclinical level.

Management of Cystoid Macular Edema in Retinitis Pigmentosa: A Systematic Review and Meta-Analysis

Background

To date, various treatments for cystoid macular edema (CME) in retinitis pigmentosa (RP) have been reported. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of current treatments for RP-CME.

Methods

PubMed, Embase and the Cochrane library were searched from inception to August 2021. ClinicalTrials.gov, WHO ICTRP and ISRCTN were also searched for relevant studies. Only studies published in English were included. The RoB 2 tool was used to evaluate the risk of bias of randomized controlled trials (RCTs), and the MINORS scale was used to assess the methodological quality of non-RCTs. Review manager (Revman) was used to pool the data. The primary outcomes included the change of central macular thickness (CMT) and best-corrected visual acuity (BCVA) from baseline. The secondary outcomes included fluorescein angiography (FA) leakage, rebound of CME and adverse effects.

Results

Thirty-two studies were included in the current systematic review and 7 studies were used for meta-analysis. Treatments for RP-CME included oral and topical carbonic anhydrase inhibitors (CAIs), systematic and local steroids, anti-VEGF therapy, NSAIDS, grid LASER photocoagulation, subliminal micropulse LASER, vitrectomy, lutein supplement and oral minocycline. CAIs and local steroids were proved to be effective in reducing CMT. The effects of anti-VEGF reagents varied among studies. Regarding other treatments, only one study for each method fitted the inclusion criteria, so the evidence was very limited.

Conclusion

Topical CAIs, oral CAIs and local steroids are effective in treating RP-CME. However, due to the overall inferior design and small patient number of the included studies, the quality of evidence was poor. Systematic steroids, LASER, NSAIDS and vitrectomy may also be effective, nevertheless, considering the limited number of studies, no conclusion could be drawn regarding these treatments. More well-designed and conducted studies are needed in this field.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021273979, identifier CRD42021273979.

Mitigating the pro-oxidant state and melanogenesis of Retinitis pigmentosa: by counteracting mitochondrial dysfunction

Retinitis pigmentosa (RP) is a group of mitochondrial diseases characterized by progressive degeneration of rods and cones leading to retinal loss of light sensitivity and, consequently, to blindness. To date, no cure is available according to the clinical literature. As a disease associated with pigmentation-related, pro-oxidant state, and mitochondrial dysfunction, RP may be viewed at the crossroads of different pathogenetic pathways involved in adverse health outcomes, where mitochondria play a preeminent role. RP has been investigated in a number of experimental and clinical studies aimed at delaying retinal hyperpigmentation by means of a number of natural and synthetic antioxidants, as well as mitochondrial cofactors, also termed mitochondrial nutrients (MNs), such as alpha-lipoic acid, coenzyme Q10 and carnitine. One should consider that each MN plays distinct-and indispensable-roles in mitochondrial function. Thus, a logical choice would imply the administration of MN combinations, instead of individual MNs, as performed in previous studies, and with limited, if any, positive outcomes. A rational study design aimed at comparing the protective effects of MNs, separately or in combinations, and in association with other antioxidants, might foresee the utilization of animal RP models. The results should verify a comparative optimization in preventing or effectively contrasting retinal oxidative stress in mouse RP models and, in prospect, in human RP cases.

Mechanisms of Photoreceptor Death in Retinitis Pigmentosa

Retinitis pigmentosa (RP) is the most common cause of inherited blindness and is characterised by the progressive loss of retinal photoreceptors. However, RP is a highly heterogeneous disease and, while much progress has been made in developing gene replacement and gene editing treatments for RP, it is also necessary to develop treatments that are applicable to all causative mutations. Further understanding of the mechanisms leading to photoreceptor death is essential for the development of these treatments. Recent work has therefore focused on the role of apoptotic and non-apoptotic cell death pathways in RP and the various mechanisms that trigger these pathways in degenerating photoreceptors. In particular, several recent studies have begun to elucidate the role of microglia and innate immune response in the progression of RP. Here, we discuss some of the recent progress in understanding mechanisms of rod and cone photoreceptor death in RP and summarise recent clinical trials targeting these pathways.

Retinitis Pigmentosa and Retinal Degenerations: Deciphering Pathways and Targets for Drug Discovery and Development

Inherited retinal diseases (IRDs) are a group of retinopathies generally caused by genetic mutations. Retinitis pigmentosa (RP) represents one of the most studied IRDs. RP leads to intense vision loss or blindness resulting from the degeneration of photoreceptor cells. To date, RP is mainly treated with palliative supplementation of vitamin A and retinoids, gene therapies, or surgical interventions. Therefore, a pharmacologically based therapy is an urgent need requiring a medicinal chemistry approach, to validate molecular targets able to deal with retinal degeneration. This Review aims at outlining the recent research efforts in identifying new drug targets for RP, especially focusing on the neuroprotective role of the Wnt/β-catenin/GSK3β pathway and apoptosis modulators (in particular PARP-1) but also on growth factors such as VEGF and BDNF. Furthermore, the role of spatiotemporally expressed G protein-coupled receptors (GPR124) in the retina and the emerging function of histone deacetylase inhibitors in promoting retinal neuroprotection will be discussed.

Intravitreal Dexamethasone Implant as a Sustained Release Drug Delivery Device for the Treatment of Ocular Diseases: A Comprehensive Review of the Literature

Drug delivery into the vitreous chamber remains a great challenge in the pharmaceutical industry due to the complex anatomy and physiology of the eye. Intravitreal injection is the mainstream route of drug administration to the posterior segment of the eye. The purpose of this review is to assess the current literature about the widening use of the intravitreal 0.7 mg dexamethasone (Dex) implant, and to provide a comprehensive collection of all the ocular disorders that benefit from Dex administration. Although anti-vascular endothelial growth-factors (VEGFs) have been largely indicated as a first-choice level, the Dex implant represents an important treatment option, especially in selected cases, such as vitrectomized eyes or patients in whom anti-VEGF failed or are contraindicated. In this article, the safety profile as well as the list of the possible complications related to intravitreal Dex injection are also discussed.

Short-term outcomes of subtenon triamcinolone acetonide injections in patients with retinitis pigmentosa-associated cystoid macular edema unresponsive to carbonic anhydrase inhibitors

PURPOSE

To investigate the functional and anatomical results of subtenon triamcinolone acetonide injection (TA) in eyes with retinitis pigmentosa (RP) that had cystoid macular edema (CME) unresponsive to carbonic anhydrase inhibitors (CAIs).

MATERIALS AND METHODS

This is a prospective, interventional study. Forty-eight consecutive eyes that underwent subtenon TA for CME due to RP were recorded. Central macular thickness (CMT), best-corrected visual acuities (BCVAs) and intraocular pressures (IOPs) were evaluated before and after injection at 2nd week, 1st month, 2nd month and 3rd month, respectively. Spectral-domain optical coherence tomography (SD-OCT) was used to show anatomic findings. Complications such as cataract and glaucoma were recorded.

RESULTS

A total of 48 eyes of 42 patients with a mean age of 36.25 ± 15.59 years (range 13 to 63 years) and a mean follow-up of 4.45 ± 0.74 months (range 4 to 6 months) were recorded in the study. The mean initial BCVA increased from 1.09 ± 0.52 to 0.54 ± 0.29 logarithmic minimum angle of resolution (log MAR) (p < 0.001) at 3 months after injection and the mean central macular thickness decreased from 591.45 ± 209.55 µm to 270.83 ± 95.48 µm (p < 0.001). The mean iOP increased from 13.58 ± 2.87 mmHg to 15.91 ± 2.47 mmHg (p < 0.001). Multiple injections (3 injections) in 1 eye, 2 injections in 4 eyes and 1 injection in rest of the eyes were performed at 3-month intervals. Complications such as glaucoma and cataract were not observed in any patient during and after the treatment.

CONCLUSION

In the present study, a significant improvement in visual acuity and CMT were observed in eyes with subtenon TA for CME due to RP unresponsive to CAIS. Further studies with a long follow-up period of the population are required to investigate the role of subtenon TA of CME due to RP.

The urokinase-type plasminogen activator system as drug target in retinitis pigmentosa: New pre-clinical evidence in the rd10 mouse model

Retinitis pigmentosa (RP) is characterized by progressive loss of vision due to photoreceptor degeneration leading to secondary inflammation. The urokinase-type plasminogen activator (uPA) system contributes to retinal inflammation, but its role in RP is unknown. In the rd10 mouse model of RP, we addressed this question with the use of the peptide UPARANT designed to interact with the uPA system. UPARANT was systemically administered from post-natal day (PD) 10 to PD30 when its efficacy in RP rescue was investigated using electroretinographic recordings, Western blot and immunocytochemistry. Temporal profile of protein expression in the uPA system was also investigated. UPARANT reduced both Müller cell gliosis and up-regulated levels of inflammatory markers and exerted major anti-apoptotic effects without influencing the autophagy cascade. Rescue from retinal cell degeneration was accompanied by improved retinal function. No scotopic phototransduction was rescued in the UPARANT-treated animals as determined by the kinetic analysis of rod-mediated a-waves and confirmed by rod photoreceptor markers. In contrast, the cone photopic b-wave was recovered and its rescue was confirmed in the whole mounts using cone arrestin antibody. Investigation of the uPA system regulation over RP progression revealed extremely low levels of uPA and its receptor uPAR both of which were recovered by HIF-1α stabilization indicating that HIF-1 regulates the expression of the uPA/uPAR gene in the retina. Ameliorative effects of UPARANT were likely to occur through an inhibitory action on up-regulated activity of the αvβ3 integrin/Rac1 pathway that was suggested as a novel target for the development of therapeutic approaches against RP.

A RANDOMIZED PAIRED-EYE TRIAL OF INTRAVITREAL DEXAMETHASONE IMPLANT FOR CYSTOID MACULAR EDEMA IN RETINITIS PIGMENTOSA

PURPOSE

To evaluate the efficacy and safety of intravitreal dexamethasone (DEX) implant in retinitis pigmentosa patients with cystoid macular edema (CME).

METHODS

In this randomized, noncontrolled, paired-eye, single crossover clinical trial, one eye of retinitis pigmentosa patients with bilateral CME with central macular thickness of >250 µm was randomized to intravitreal DEX implant while the fellow eye was observed. Both eyes were started on topical dorzolamide. At Month 6, DEX implant was eligible for both eyes when CME was >250 µm. Patients were followed up until Month 12. Primary outcome measures were the central macular thickness and best-corrected visual acuity changes from baseline at Month 2.

RESULTS

Fourteen patients with bilateral RP-CME were included. Study eyes showed significant central macular thickness decrease (median, -147.5 µm; P = 0.001) and best-corrected visual acuity improvement (median, +6 letters; P = 0.001) at Month 2, but not at Month 6. Intravitreal DEX implant at Month 6 produced comparable efficacy to baseline treatment in 11 fellow eyes and 12 study eyes. Topical dorzolamide did not show significant therapeutic efficacy. During 12 months, elevated intraocular pressure of >21 mmHg and cataract progression were observed in 14.3% and 40.0% of study eyes.

CONCLUSION

Intravitreal DEX implant can both reduce macular thickness and improve vision in RP-CME, while repeated injection is required.

Emerging Drug Therapies for Inherited Retinal Dystrophies

Worldwide, 1 in 2000 people suffer from inherited retinal dystrophies (IRD). Individuals with IRD typically present with progressive vision loss that ultimately results in blindness. Unfortunately, effective treatment options are not widely available due to the genetic and clinical heterogeneity of these diseases. There are multiple gene, cell, and drug-based therapies in various phases of clinical trials for IRD. This mini-review documents current progress made in drug-based clinical trials for treating IRD.