Plasma Levels of Bevacizumab and Vascular Endothelial Growth Factor After Low-Dose Bevacizumab Treatment for Retinopathy of Prematurity in Infants

Circulating VEGF-A Levels in Relation to Retinopathy of Prematurity and Treatment Effects: A Systematic Review and Meta-Analysis

Topic

Retinopathy of prematurity (ROP) is a severe retinal vascular disorder affecting preterm infants, potentially leading to retinal detachment and blindness. This review aims to elucidate the relationship between systemic VEGF levels and ROP.

Clinical Relevance

This systematic review aims to consolidate evidence from available studies to guide future research and inform clinical practice. In particular, the role of circulating VEGF-A levels in predicting ROP onset and progression, and evaluating the impact of anti-VEGF therapy on these levels, is crucial in ensuring efficacy and safety in patient care.

Methods

Scopus and PubMed were searched to identify studies investigating circulating VEGF-gene products in ROP patients using immunologic assays. Two authors independently screened the literature and extracted data, employing a random-effects meta-analysis to compare VEGF levels as the ratio of means between ROP patients and controls before and after treatment, heterogeneity was reported by I2-statistics. Risks of bias and publication bias were assessed using Quality Assessment of Diagnostic Accuracy Studies-2 and funnel plots/Egger's tests, respectively.

Results

Out of 941 papers, 54 were included, with 26 providing posttreatment data and 31 providing biomarker data. Findings show a significant decrease in VEGF-A levels in the first week after ROP treatment (ratio of means [95% confidence interval] 0.34 [0.25-0.45], I2 = 97%, 17 publications). Anti-VEGF therapy showed a significantly more pronounced decrease (0.31 [0.25-0.38], I2 = 40%, 7 publications) than laser treatment in the first week after treatment (0.77 [0.61-0.97], I2 = 42%, 2 publications, subgroup difference, P < 0.01), among studies with a low risk of bias. Serum samples demonstrated a more marked decrease in VEGF-A than plasma (subgroup difference P < 0.01). However, the use of blood VEGF-A concentration as a biomarker for ROP prediction has shown inconsistent trends. The risk of bias mainly stems from unclear patient selection and lack of sample timing or analytical method details.

Conclusion

While anti-VEGF treatment significantly reduced blood VEGF-A levels in the first week post-ROP treatment, blood VEGF-A levels did not consistently predict ROP development. Heterogeneity in the results underscores the need for optimized analytical methods and emphasizes the importance of considering individual variation in VEGF-A concentrations independent of ROP diagnosis.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Targeting adenosine A2A receptors for early intervention of retinopathy of prematurity

Retinopathy of prematurity (ROP) continues to pose a significant threat to the vision of numerous children worldwide, primarily owing to the increased survival rates of premature infants. The pathologies of ROP are mainly linked to impaired vascularization as a result of hyperoxia, leading to subsequent neovascularization. Existing treatments, including anti-vascular endothelial growth factor (VEGF) therapies, have thus far been limited to addressing pathological angiogenesis at advanced ROP stages, inevitably leading to adverse side effects. Intervention to promote physiological angiogenesis during the initial stages could hold the potential to prevent ROP. Adenosine A2A receptors (A2AR) have been identified in various ocular cell types, exhibiting distinct densities and functionally intricate connections with oxygen metabolism. In this review, we discuss experimental evidence that strongly underscores the pivotal role of A2AR in ROP. In particular, A2AR blockade may represent an effective treatment strategy, mitigating retinal vascular loss by reversing hyperoxia-mediated cellular proliferation inhibition and curtailing hypoxia-mediated neovascularization in oxygen-induced retinopathy (OIR). These effects stem from the interplay of endothelium, neuronal and glial cells, and novel molecular pathways (notably promoting TGF-β signaling) at the hyperoxia phase. We propose that pharmacological targeting of A2AR signaling may confer an early intervention for ROP with distinct therapeutic benefits and mechanisms than the anti-VEGF therapy.

A Network Meta-Analysis of Success Rates following Low Dosage Anti-VEGF for Retinopathy of Prematurity

PURPOSE

To search the low dosage of anti-VEGF best for primary therapies on retinopathy of prematurity (ROP) in terms of success rate.

METHODS

We searched Medline(Pubmed), Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases only for randomized controlled trials that had been reported as of March 3, 2023. We included studies that used bevacizumab, aflibercept and conbercept for ROP with comparable cohorts and treatment criteria. This study was performed according the pre-specified protocol registered with PROSPERO (CRD42021270077) and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis checklist. Those with animal and cell experiments, non-randomized case-control, or single case report were excluded. Frequentist network meta-analyses determined the surface under the cumulative ranking (SUCRA) of the success rate of each dose range group and compared pairs of treatments via STATA 15.

RESULT

Since non-RCT research were excluded, aflflibercept and conbercept studies were excluded. Therefore, only 6 bevacizumab studies were included in final meta-analysis: Inconsistency was not detected in this study via global inconsistent model test, loop inconsistency and local inconsistent model test (p > 0.05). In addition, a consistent model test has been passed in this study (p > 0.05). Little bias was detected via funnel plot. Since bevacizumab adult standard dose of single-injection is 1.25 mg, the concentration groups were converted according to the proportion of adult standard dose, such as 1/2, [1/5, 1/6.25], [1/10, 1/12.5], [1/19.8, 1/78.1], [1/156.3, 1/625]. The SUCRA of [1/10, 1/12.5] dose group were the best of largest probability to achieve success. However, [1/156.3, 1/625] dose group was the worst dose to achieve success in the five dose groups. The success rate ranking of league chart in this study is that [1/10, 1/12.5] > [1/5, 1/6.25] > 1/2 ≈ [1/19.8, 1/78.1] > [1/156.3, 1/625].

CONCLUSIONS

[1/10, 1/12.5] were the best dosage ranges to achieve maximal medicine success. [1/156.3, 1/625] was the worst ineffective in the five dose ranges.

Laser versus Anti-VEGF: A Paradigm Shift for Treatment-Warranted Retinopathy of Prematurity

Retinopathy of prematurity (ROP), a leading cause of childhood blindness, has historically been associated with blindness from overgrowth of blood vessels from the retina into the vitreous that lead to complex retinal detachments. Our understanding of ROP has evolved with the survival of extremely low-birthweight infants and includes not only overgrowth of blood vessels, but also insufficient developmental retinal vascular growth in early phases of the disease. Our current treatments of ROP have focused on methods to improve perinatal and prenatal care, reduce premature birth, and prevent early phases of ROP. Nonetheless, addressing vasoproliferation in treatment-warranted eyes remains the mainstay of management. Two main treatment strategies co-exist today: laser treatment, which has been the standard of care since the 1990s, and anti-VEGF injections, which have been used since early reports in 2007 (Travassos et al. in Ophthalmic Surg Lasers Imaging, 38:233-237, https://doi.org/10.3928/15428877-20070501-09 , 2007, Shah et al. in Indian J Ophthalmol 55:75-76, https://doi.org/10.4103/0301-4738.29505 , 2007, Quiroz-Mercado et al. in Semin Ophthalmol 22:109-125, https://doi.org/10.1080/08820530701420082 , 2007).

A Meta-Analysis of Neurodevelopmental Outcomes following Intravitreal Bevacizumab for the Treatment of Retinopathy of Prematurity

BACKGROUND

Retinopathy of prematurity (ROP) is the most common cause of preventable blindness in preterm infants. First-line treatments include intravitreal bevacizumab (IVB) or laser photocoagulation (LPC).

OBJECTIVES

The aim of the study was to evaluate neurodevelopmental safety of IVB compared to LPC for ROP.

METHODS

MEDLINE, Embase, and Cochrane library were searched up to September 2022. Studies were included with at least 12-month follow-up of primary outcomes such as severe neurodevelopmental impairment (sNDI), cerebral palsy (CP), and hearing impairment (HI). Secondary outcomes were moderate-to-severe neurodevelopmental impairment (msNDI), Bayley Scores of Infant Development (BSID-III), and visual impairment.

RESULTS

1,231 patients from 11 comparative studies were included. Quality of evidence was rated low for all outcomes. IVB was associated with a higher risk for sNDI (risk ratio [RR] = 1.25, 95% confidence interval [CI]: [1.01, 1.53], p = 0.04); and CP (RR = 1.40, CI: [1.08, 1.81], p = 0.01) compared to LPC. There was no significant difference between IVB and LPC for msNDI (RR = 1.15, CI: [0.98, 1.35], p = 0.08) and HI (RR = 1.43, CI: [0.86, 2.39], p = 0.17). BSID-III percentile scores were similar between IVB and LPC, with weighted mean differences of 1.51 [CI = -1.25, 4.27], 2.43 [CI = -1.36, 6.22], and 1.97 [CI = -1.06, 5.01] for cognitive, language, and motor domains, respectively (p > 0.05).

CONCLUSION

To our knowledge, this is the largest meta-analysis on neurodevelopmental outcomes and the first to rigorously examine IVB monotherapy in ROP treatment. Compared to LPC, there was a marginally increased risk for sNDI and CP with IVB but little or no difference in the risk of msNDI and HI. Further randomized studies are needed to strengthen these findings.

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

Purpose

To present updated information on the role of anti-vascular endothelial growth factor (anti-VEGF) therapy for treating retinopathy of prematurity (ROP).

Methods

We searched through PubMed and Scopus databases using the keywords of this article and gathered relevant published articles from the year 2005 to December 2022. The selected articles were classified and summarized, and reasonable conclusions were made accordingly.

Results

Considering the current evidence, anti-VEGF agents are superior to laser therapy for the initial treatment of type 1 ROP in zone 1 or posterior zone 2. However, there is a substantial risk of reactivation or persistent avascular retina after solo treatment with anti-VEGFs, and many cases may require laser therapy within the following weeks or months. Thus, vigilant follow-up examinations are mandatory.

Conclusions

The role of anti-VEGF agents in the treatment of ROP is indispensable. However, future studies are required to improve indications and dosage and determine long-term ocular and systemic safety.

Ocular and developmental outcomes of a dosing study of bevacizumab for retinopathy of prematurity

PURPOSE

To report 2-year ocular and developmental outcomes for infants receiving low doses of intravitreal bevacizumab for type 1 retinopathy of prematurity (ROP).

METHODS

A total of 120 premature infants (mean birthweight, 687 g; mean gestational age, 24.8 weeks) with type 1 ROP were enrolled in a multicenter, phase 1 dose de-escalation study. One eye per infant received 0.25 mg, 0.125 mg, 0.063 mg, 0.031 mg, 0.016 mg, 0.008 mg, 0.004 mg, or 0.002 mg of intravitreal bevacizumab; fellow eyes when treated received one dosage level higher. At 2 years, 70 of 120 children (58%) underwent ocular examinations; 51 (43%) were assessed using the Bayley Scale of Infant and Toddler Development.

RESULTS

Correlation coefficients for the association of total dosage of bevacizumab with Bayley subscales were -0.20 for cognitive (95% CI, -0.45 to 0.08), -0.15 for motor (95% CI, -0.41 to 0.14), and -0.19 for language (95% CI, -0.44 to 0.10). Fourteen children (21%) had myopia greater than -5.00 D in one or both eyes, 7 (10%) had optic nerve atrophy and/or cupping, 20 (29%) had strabismus, 8 (11%) had manifest nystagmus, and 9 (13%) had amblyopia.

CONCLUSIONS

In this study cohort, there was no statistically significant correlation between dosage of bevacizumab and Bayley scores at 2 years. However, the sample size was small and the retention rate relatively low, limiting our conclusions. Rates of high myopia and ocular abnormalities do not differ from those reported after larger bevacizumab doses.

Intravitreal Bevacizumab Is Associated With Prolonged Ventilatory Support in Preterm Infants With Bronchopulmonary Dysplasia

BACKGROUND

Intravitreal bevacizumab (IVB), an anti-vascular endothelial growth factor (VEGF) antibody, is a widely adopted treatment for retinopathy of prematurity (ROP). Although animal studies have demonstrated that IVB inhibits alveologenesis in neonatal rat lung, the clinical influence of IVB on respiratory outcomes has not been studied.

RESEARCH QUESTION

Does IVB affect the respiratory outcome in preterm infants with bronchopulmonary dysplasia?

STUDY DESIGN AND METHODS

We retrospectively assessed very low birth weight (VLBW) preterm infants admitted to our neonatal ICU between January 2016 and June 2021. Furthermore, we evaluated the short-term respiratory outcomes after IVB therapy in VLBW preterm infants requiring ventilatory support at 36 weeks' postmenstrual age (PMA).

RESULTS

One hundred seventy-four VLBW preterm infants with bronchopulmonary dysplasia were recruited. Eighty-eight infants showed ROP onset before being ventilator free, and 78 infants received a diagnosis of the most severe ROP before being ventilator free. Among them, 32 received a diagnosis with type 1 ROP and received IVB treatment. After adjusting for gestational age, birth body weight, and baseline respiratory status, we discovered that IVB is associated significantly with prolonged ventilatory support and a lower likelihood of becoming ventilator free (hazard ratio, 0.53; P = .03).

INTERPRETATION

IVB may have a short-term respiratory adverse effect in patients requiring ventilatory support at 36 weeks' PMA. Therefore, long-term follow-up for respiratory outcomes may be considered in VLBW infants who receive IVB treatment.

Retinopathy of prematurity: Metabolic risk factors

At preterm birth, the retina is incompletely vascularized. Retinopathy of prematurity (ROP) is initiated by the postnatal suppression of physiological retinal vascular development that would normally occur in utero. As the neural retina slowly matures, increasing metabolic demand including in the peripheral avascular retina, leads to signals for compensatory but pathological neovascularization. Currently, only late neovascular ROP is treated. ROP could be prevented by promoting normal vascular growth. Early perinatal metabolic dysregulation is a strong but understudied risk factor for ROP and other long-term sequelae of preterm birth. We will discuss the metabolic and oxygen needs of retina, current treatments, and potential interventions to promote normal vessel growth including control of postnatal hyperglycemia, dyslipidemia and hyperoxia-induced retinal metabolic alterations. Early supplementation of missing nutrients and growth factors and control of supplemental oxygen promotes physiological retinal development. We will discuss the current knowledge gap in retinal metabolism after preterm birth.

RNA-Seq Provides Insights into VEGF-Induced Signaling in Human Retinal Microvascular Endothelial Cells: Implications in Retinopathy of Prematurity

The pathophysiology of retinopathy of prematurity (ROP) is postulated to first involve delayed intraretinal vascularization, followed by intravitreal neovascularization (IVNV). Although intravitreal agents that reduce the bioactivity of vascular endothelial growth factor (VEGF) are used to treat IVNV, concerns exist regarding their effects on intraretinal vascularization. In an experimental ROP model, VEGF receptor 2 (VEGFR2) knockdown in retinal endothelial cells reduced IVNV and promoted intraretinal vascularization, whereas knockdown of a downstream effector, signal transducer and activator of transcription 3 (STAT3) in retinal endothelial cells only reduced IVNV. In this study, we tested the hypothesis that the different pathways involved in VEGF-triggered VEGFR2 signaling and VEGF-triggered STAT3 signaling in retinal endothelial cells would allow us to delineate signaling pathways involved in IVNV from those involved in intraretinal vascularization in ROP. To address our hypothesis, we used RNA-sequencing and pathway enrichment analysis to determine changes in the transcriptome of cultured human retinal microvascular endothelial cells (HRMECs). Of the enriched pathways, inactivation of oncostatin M signaling was predicted by either KDR or STAT3 knockdown in the presence of VEGF. Activation of kinetochore metaphase signaling was predicted by KDR knockdown, whereas inactivation was predicted by STAT3 knockdown in the presence of VEGF. Inactivation of signaling by the Rho family of GTPases was predicted by KDR knockdown, but activation was predicted by STAT3 knockdown in the presence of VEGF. Taken together, our data identified unique signaling pathway differences between VEGF-triggered VEGFR2 and VEGF-triggered STAT3 in HRMECs that might have implications in ROP.