Update on Anti-Vascular Endothelial Growth Factor Safety for Retinopathy of Prematurity

Validation of WINROP algorithm as screening tool of retinopathy of prematurity among Egyptian preterm neonates

BACKGROUND

Retinopathy of prematurity (ROP) is a leading cause of preventable childhood blindness worldwide. Proper screening for ROP can prevent loss of vision. WINROP (weight, insulin-like growth factor 1, neonatal, retinopathy of prematurity) is an online surveillance system based on gestational age, birth weight and weekly weight gain that can predict infants at risk of sight-threatening retinopathy of prematurity.

AIMS

To evaluate the diagnostic accuracy of WINROP algorithm in detecting sight-threatening ROP in Egyptian preterm neonates.

METHODS

Birth weight (BW), gestational age (GA) and weekly weight measurement of 365 preterm infants were prospectively entered into WINROP algorithm. Based on these inputs, the algorithm would output and a screening was performed as is standard. Sensitivity, specificity, and predictive values were calculated by comparing WINROP outcomes with ROP screening outcomes.

RESULTS

Of the infants included in the study the mean GA was ±31.24 and mean BW was ±1508.78. A high risk WINROP alarm was triggered in 62 infants of whom 16 infants develop type 1 or type 2 ROP. These infants had associated comorbidities including sepsis, Intraventricular hemorrhage (IVH), Necrotizing enterocolitis (NEC), history of transfusion of packed red blood cells (RBCS) and history of platelet transfusion. A low risk WINROP alarm was triggered in 303 infants of whom 15 infants developed type 1 or type 2ROP. WINROP showed a sensitivity of 51.6%, a specificity of 86.2%, a positive predictive value (PPV) of 52.8% and a negative predictive value (NPV) of 95% for detection of type 1 or type 2 ROP.

CONCLUSION

WINROP has low sensitivity and high specificity for detection of ROP. It may help in ROP prediction but can't be used alone. Modification of WINROP algorithm taking into account other risk factors may improve sensitivity and reduce number for ROP examination.

Role of mammalian target of rapamycin in the formation and progression of retinopathy of prematurity-like vascular abnormalities in neonatal rats

Retinopathy of prematurity (ROP), a retinal disease that can occur in premature infants, can lead to severe visual impairment. In this study, we examined the preventive and therapeutic effects of mammalian target of rapamycin complex 1 (mTORC1) inhibition on abnormal retinal blood vessels in a rat model of ROP. To induce ROP-like vascular abnormalities, rats were subcutaneously treated with KRN633, an inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinase, on postnatal day 7 (P7) and P8. KRN633-treated (ROP) rats were treated subcutaneously with the mTORC1 inhibitor rapamycin according to preventive and therapeutic protocols, i.e., from P11 to P13 (P11-P13) and from P14 to P20 (P14-P20), respectively. To compare with the effects of VEGF inhibition, KRN633 was administered according to similar protocols. Changes in retinal vasculature, phosphorylated ribosomal protein S6 (pS6), a downstream indicator of mTORC1 activity, and the proliferative status of vascular cells were evaluated at P14 and P21 using immunohistochemistry. Rapamycin treatment from P11 to P13 prevented increases in arteriolar tortuosity, capillary density, and the number of proliferating vascular cells, and eliminated pS6 immunoreactivity in ROP rats. KRN633 treatment at P11 and P12 (P11/P12) also prevented the appearance of ROP-like retinal blood vessels. Rapamycin treatment from P14 to P20 failed to attenuate arteriolar tortuosity but prevented increases in capillary density and proliferating vascular cell number at the vascular front, but not at the central zone. KRN633 treatment from P14 to P20 significantly reduced abnormalities in the retinal vasculature; however, the effects were inferior to those of KRN633 treatment on P11/P12. These results suggest that activation of the mTORC1 pathway in proliferating endothelial cells contributes to the appearance and progression of ROP-like retinal blood vessels. Therefore, inhibition of mTORC1 may be a promising approach for selectively targeting abnormal retinal blood vessels in ROP.

FGF21 via mitochondrial lipid oxidation promotes physiological vascularization in a mouse model of Phase I ROP

Hyperglycemia in early postnatal life of preterm infants with incompletely vascularized retinas is associated with increased risk of potentially blinding neovascular retinopathy of prematurity (ROP). Neovascular ROP (Phase II ROP) is a compensatory but ultimately pathological response to the suppression of physiological postnatal retinal vascular development (Phase I ROP). Hyperglycemia in neonatal mice which suppresses physiological retinal vascular growth is associated with decreased expression of systemic and retinal fibroblast growth factor 21 (FGF21). FGF21 administration promoted and FGF21 deficiency suppressed the physiological retinal vessel growth. FGF21 increased serum adiponectin (APN) levels and loss of APN abolished FGF21 promotion of physiological retinal vascular development. Blocking mitochondrial fatty acid oxidation also abolished FGF21 protection against delayed physiological retinal vessel growth. Clinically, preterm infants developing severe neovascular ROP (versus non-severe ROP) had a lower total lipid intake with more parenteral and less enteral during the first 4 weeks of life. Our data suggest that increasing FGF21 levels in the presence of adequate enteral lipids may help prevent Phase I retinopathy (and therefore prevent neovascular disease).

CD8+ T Cells Promote Pathological Angiogenesis in Ocular Neovascular Disease

BACKGROUND

CD4⁺ (cluster of differentation) and CD8⁺ T cells are increased in the ocular fluids of patients with neovascular retinopathy, yet their role in the disease process is unknown.

METHODS

We describe how CD8⁺ T cells migrate into the retina and contribute to pathological angiogenesis by releasing cytokines and cytotoxic factors.

RESULTS

In oxygen-induced retinopathy, flow cytometry revealed the numbers of CD4⁺ and CD8⁺ T cells were increased in blood, lymphoid organs, and retina throughout the development of neovascular retinopathy. Interestingly, the depletion of CD8⁺ T cells but not CD4⁺ T cells reduced retinal neovascularization and vascular leakage. Using reporter mice expressing gfp (green fluorescence protein) in CD8⁺ T cells, these cells were localized near neovascular tufts in the retina, confirming that CD8⁺ T cells contribute to the disease. Furthermore, the adoptive transfer of CD8⁺ T cells deficient in TNF (tumor necrosis factor), IFNγ (interferon gamma), Prf (perforin), or GzmA/B (granzymes A/B) into immunocompetent Rag1^-/- mice revealed that CD8⁺ T cells mediate retinal vascular disease via these factors, with TNF influencing all aspects of vascular pathology. The pathway by which CD8⁺ T cells migrate into the retina was identified as CXCR3 (C-X-C motif chemokine receptor 3) with the CXCR3 blockade reducing the number of CD8⁺ T cells within the retina and retinal vascular disease.

CONCLUSIONS

We discovered that CXCR3 is central to the migration of CD8⁺ T cells into the retina as the CXCR3 blockade reduced the number of CD8⁺ T cells within the retina and vasculopathy. This research identified an unappreciated role for CD8⁺ T cells in retinal inflammation and vascular disease. Reducing CD8⁺ T cells via their inflammatory and recruitment pathways is a potential treatment for neovascular retinopathies.

Role of Anti-Vascular Endothelial Growth Factor (Anti-VEGF) in the Treatment of Retinopathy of Prematurity: A Narrative Review in the Context of Middle-Income Countries

The rise in preterm births and higher survival rates of premature infants have led to a global increase in retinopathy of prematurity (ROP), a vasoproliferative retinal disorder common in premature infants. ROP is one of the leading causes of childhood blindness. Clinical manifestation of ROP ranges from mild abnormal retinal neovascularization to bilateral retinal detachment and vision loss. The incidence of ROP is higher in middle income countries, including India, which has the highest number of global preterm births. Low birth weight and low gestational age are the primary risk factors for ROP; however, anemia, cardiac defects, blood transfusion, apnea, sepsis, respiratory distress syndrome, high exposure to oxygen and poor postnatal weight gain may also contribute to its development. India has stringent ROP screening guidelines revised in 2018, and screening of infants with either birth weight <2000 grams or gestational age <34 weeks is mandated. With an improved understanding of the pathogenesis of ROP in the past decades and advances in clinical research, treatment for ROP has evolved from cryotherapy to laser retinal ablation. Most recently, anti-vascular endothelial growth factor (anti-VEGF) drugs have emerged as a favorable treatment option for zone-I and II ROP. This article reviews the current approaches for ROP treatment in India with a particular focus on anti-VEGF drugs. The article also integrates the understanding of safety and risk-benefit evaluation of the current approaches in ROP management. The review concluded that there is a need to increase the ROP screening not only for preterm and low birth weight but also for optimal gestational age infants with healthy birth weight. Anti-VEGF therapies have shown improved efficacy, although studies are required to establish the long-term safety.

Systemic Cytokines in Retinopathy of Prematurity

Retinopathy of prematurity (ROP), a vasoproliferative vitreoretinal disorder, is the leading cause of childhood blindness worldwide. Although angiogenic pathways have been the main focus, cytokine-mediated inflammation is also involved in ROP etiology. Herein, we illustrate the characteristics and actions of all cytokines involved in ROP pathogenesis. The two-phase (vaso-obliteration followed by vasoproliferation) theory outlines the evaluation of cytokines in a time-dependent manner. Levels of cytokines may even differ between the blood and the vitreous. Data from animal models of oxygen-induced retinopathy are also valuable. Although conventional cryotherapy and laser photocoagulation are well established and anti-vascular endothelial growth factor agents are available, less destructive novel therapeutics that can precisely target the signaling pathways are required. Linking the cytokines involved in ROP to other maternal and neonatal diseases and conditions provides insights into the management of ROP. Suppressing disordered retinal angiogenesis via the modulation of hypoxia-inducible factor, supplementation of insulin-like growth factor (IGF)-1/IGF-binding protein 3 complex, erythropoietin, and its derivatives, polyunsaturated fatty acids, and inhibition of secretogranin III have attracted the attention of researchers. Recently, gut microbiota modulation, non-coding RNAs, and gene therapies have shown promise in regulating ROP. These emerging therapeutics can be used to treat preterm infants with ROP.

The Relationship between the Aqueous VEGF Level and the Severity of Type 1 Retinopathy of Prematurity

Purpose: To analyze the relationship between the severity of type 1 retinopathy of prematurity (ROP) and the level of vascular endothelial growth factor (VEGF) in aqueous fluid. Methods: The aqueous VEGF levels of 49 patients (88 eyes) with type 1 ROP were retrospectively analyzed. These eyes were categorized into three groups according to the severity of disease: aggressive retinopathy of prematurity (A-ROP), threshold of ROP (T-ROP), and type 1 pre-threshold ROP (P-T-1). The differences in aqueous VEGF levels among these three groups were compared. The relationship between the aqueous VEGF level and the retinal changes of ROP, including the vessel tortuosity in zone I, and the location and stage of the ROP lesions, were also analyzed. Results: The aqueous VEGF level of the A-ROP group was the highest among the three groups, followed by those of the T-ROP and P-T-1 groups. The aqueous VEGF level was negatively correlated with the zone and the stage of the ROP diseases, while it was positively correlated with the venous tortuosity in zone I and had no relevance with the artery tortuosity in zone I. Conclusions: The aqueous VEGF level in A-ROP was the highest in type I ROP. The location of the ROP lesions and the venous tortuosity in zone I correlated with the aqueous VEGF level and could indicate the severity of ROP.

Evaluation of Neurodevelopmental Outcomes in Premature Twins (Multigestations) with Retinopathy of Prematurity Receiving Anti-VEGF: A Comparison Study

Purpose

To assess possible neurodevelopmental delay (NDD) following intravitreal antivascular endothelial growth factor (VEGF) injection in neonates with retinopathy of prematurity (ROP).

Methods

In this retrospective cohort study, neurodevelopmental milestones in patients with a history of ROP and intravitreal bevacizumab (IVB) injection were compared with other gestations that received either no treatment or only a laser for treatment.

Results

One hundred and twenty-five neonates (of 59 multi-gestation pregnancies) were included in this study (with the range of age 1–7 years old). Sixty-five (51.18%) were male and sixty-two (48.81%) were female. The mean gestational age (GA) and birth weight of all neonates were 29.69 ± 1.57 weeks (ranges: 26–33 weeks) and 1312.50 ± 269.33 grs (ranges: 730–2100 grs). None of the neurodevelopmental outcomes were statistically different when two subgroups in group A (IVB vs. control) were compared. None of the differences between IVB and laser treated subgroups is statistically significant, except for “reaching for toys,” which was delayed in the laser treated subgroup (6.6 ± 2.5 and 6.9 ± 2.5 months in IVB and laser treated subgroups, respectively).

Conclusion

In neonates with ROP, there is no linear correlation between intravitreal anti-VEGF injection and neurodevelopmental delay.

A systematic review and meta-analysis of preanalytical factors and methodological differences influencing the measurement of circulating vascular endothelial growth factor

BACKGROUND

Intraocular treatment with antibodies targeting vascular endothelial growth factor (anti-VEGF) inhibits pathological vessel growth in adults and preterm infants. Recently, concerns regarding the impact of anti-VEGF treatment on systemic VEGF levels in preterm infants have been raised. Earlier studies suggest that preanalytical and methodological parameters impact analytical VEGF concentrations, but we have not found a comprehensive systematic review covering preanalytical procedures and methods for VEGF measurements.

OBJECTIVE

This review aimed to evaluate the most critical factors during sample collection, sample handling, and the analytical methods that influence VEGF levels and therefore should be considered when planning a prospective collection of samples to get reproducible, comparable results.

MATERIAL AND METHODS

PubMed and Scopus databases were searched 2021/Nov/11. In addition, identification of records via other methods included reference, citation, and Google Scholar searches. Rayyan QCRI was used to handle duplicates and the selection process. Publications reporting preanalytical handling and/or methodological comparisons using human blood samples were included. Exclusion criteria were biological, environmental, genetic, or physiological factors affecting VEGF. The data extraction sheets included bias assessment using the QUADAS-2 tool, evaluating patient selection, index-test, reference standard, and flow and timing. Concentrations of VEGF and results from statistical comparisons of analytical methods and/or preanalytical sample handling and/or different sample systems were extracted. The publications covering preanalytical procedures were further categorized based on the stage of the preanalytical procedure. Meta-analysis was used to visualize VEGF concentrations among healthy individuals. The quality of evidence was rated according to GRADE.

RESULTS

We identified 1596 publications, and, after the screening process, 43 were considered eligible for this systematic review. The risk of bias estimation was difficult for 2/4 domains due to non-reported information. Four critical steps in the preanalytical process that impacted VEGF quantification were identified: blood drawing and the handling before, during, and after centrifugation. Sub-categorization of those elements resulted in nine findings, rated from moderate to very low evidence grade. The choice of sample system was the most reported factor. VEGF levels (mean [95% CI]) in serum (n = 906, 20 publications), (252.5 [213.1-291.9] pg/mL), were approximated to ninefold higher than in plasma (n = 1122, 23 publications), (27.8 [23.6-32.1] pg/mL), based on summarized VEGF levels with meta-analysis. Notably, most reported plasma levels were below the calibration range of the used method.

CONCLUSION

When measuring circulating VEGF levels, choice of sample system and sample handling are important factors to consider for ensuring high reproducibility and allowing study comparisons. Protocol: CRD42020192433.

Aggressive Posterior Retinopathy of Prematurity: Long-Term Outcomes Following Intravitreal Bevacizumab

PURPOSE

The purpose of this study is to review the neonatal and early childhood course of children who were treated with intravitreal bevacizumab for APROP and identify any long term limitations these children face years after treatment.

METHODS

This retrospective consecutive case series reviewed both ophthalmologic and pediatric medical records to determine ocular and neurologic function following treatment with a single injection of intravitreal bevacizumab (IVB) for APROP. Patient records were reviewed to identify the gestational age, average birth weight, gender, post-menstrual age (PMA) at the time of injection, regression status, rescue therapy events, final visual acuity, final refraction, ophthalmologic diagnoses and complications, neurologic diagnoses, and duration of follow up.

RESULTS

The study included 43 eyes from 13 male and 9 female children. The average gestational age was 24 weeks and average birth weight was 625.2 grams. The average follow-up was 4.08 years (range: 1.85-7.36 years). The average PMA at time of bevacizumab injection was 35.59 weeks. Thirty-five eyes eventually received laser photocoagulation at an average PMA of 53.17 weeks. All eyes in this study demonstrated regression without progression to retinal detachment. At last follow up, 67% (29/43) of eyes were able to discern letters or shapes, with an average visual acuity of 20/37. 16 (72%) children were diagnosed with perinatal neurological disorders. 59% (n = 13) developed chronic neurological impairment, 77% (n = 10) of whom developed neurodevelopmental delay. Several infants were diagnosed with endocrine disease or genetic syndromes.

CONCLUSIONS

Extreme prematurity is associated with significant morbidity. Nearly all infants (92%) who developed chronic neurologic disease were diagnosed with neurologic disease during the perinatal period. Intravitreal bevacizumab, often with adjuvant photocoagulation, led to regression without detachment in 100% of eyes, with most verbal children retaining functional vision.

Ten Years of Knowledge of Nano-Carrier Based Drug Delivery Systems in Ophthalmology: Current Evidence, Challenges, and Future Prospective

The complex drug delivery barrier in the eye reduces the bioavailability of many drugs, resulting in poor therapeutic effects. It is necessary to investigate new drugs through appropriate delivery routes and vehicles. Nanotechnology has utilized various nano-carriers to develop potential ocular drug delivery techniques that interact with the ocular mucosa, prolong the retention time of drugs in the eye, and increase permeability. Additionally, nano-carriers such as liposomes, nanoparticles, nano-suspensions, nano-micelles, and nano-emulsions have grown in popularity as an effective theranostic application to combat different microbial superbugs. In this review, we summarize the nano-carrier based drug delivery system developments over the last decade, particularly review the biology, methodology, approaches, and clinical applications of nano-carrier based drug delivery system in the field of ocular therapeutics. Furthermore, this review addresses upcoming challenges, and provides an outlook on potential future trends of nano-carrier-based drug delivery approaches in ophthalmology, and hopes to eventually provide successful applications for treating ocular diseases.

Neurodevelopmental outcomes in preterm infants with retinopathy of prematurity

Over the past decade there has been a paradigm shift in the treatment of retinopathy of prematurity (ROP) with the introduction of antivascular endothelial growth factor (anti-VEGF) treatments. Anti-VEGF agents have the advantages of being easier to administer, requiring less anesthesia, having the potential for improved peripheral vision, and producing less refractive error than laser treatment. On the other hand, it is known that intravitreal administration of anti-VEGF agents lowers VEGF levels in the blood and raises the theoretical concern of intraocular anti-VEGF causing deleterious effects in other organ systems, including the brain. As a result, there has been increased attention recently on neurodevelopmental outcomes in infants treated with anti-VEGF agents. These studies should be put into context with what is known about systemic comorbidities, socioeconomic influences, and the effects of extreme prematurity itself on neurodevelopmental outcomes. We summarize what is known about neurodevelopmental outcomes in extremely preterm infants with ROP, discuss the implications for determining the neurodevelopmental status using neurodevelopmental testing as well as other indicators, and review the existing literature relating to neurodevelopmental outcomes in babies treated for ROP.