Persistent diabetic macular edema: Definition, incidence, biomarkers, and treatment methods

Intravitreal antivascular endothelial growth factor (anti-VEGF) treatment has drastically improved the visual and anatomical outcomes in patients with diabetic macular edema (DME); however, success is not always guaranteed, and a proportion of these eyes demonstrate persistent DME (pDME) despite intensive treatment. While standardized criteria to define these treatment-resistant eyes have not yet been established, many studies refer to eyes with no clinical response or an unsatisfactory partial response as having pDME. A patient is considered to have pDME if the retinal thickness improves less than 10-25% after 6 months of treatment. A range of treatment options have been recommended for eyes with pDME, including switching anti-VEGF agents, using corticosteroids and/or antioxidant drugs in adjunct with anti-VEGF therapy, and vitrectomy. In addition, multimodal imaging of DME eyes may be advantageous in predicting the responsiveness to treatment; this is beneficial when initiating alternative therapies. We explore the literature on persistent DME regarding its defining criteria, incidence, the baseline biological markers that may be useful in anticipating the response to treatment, and the available treatment options.

Switching to ziv-aflibercept in resistant diabetic macular edema non responsive to ranibizumab injection

Background

Diabetic macular edema (DME) is a leading cause of visual loss in diabetic patients and is managed using multiple anti-vascular endothelial growth factor (VEGF) agents such as bevacizumab, ranibizumab and aflibercept. The present study evaluates effectiveness of intravitreal injection of ziv-aflibercept in resistant diabetic macular edema.

Methods

This is a prospective interventional study that was carried out on 59 eyes of 40 diabetic patients with diabetic macular edema resistant to three prior consecutive ranibizumab injections. On all patients, thorough ophthalmic evaluation including optical coherence tomography was performed. In patients with persistent intraretinal or subretinal fluid, ziv- aflibercept 1.25 mg (0.05 ml) was administered by intravitreal injection monthly during the 6 month study period from June to December 2019.

Results

The central macular thickness (CMT) decreased significantly from 395.08 ± 129.9 um at baseline to 282.39 ± 95.278, 245.36 ± 79.861 and 201.17 ± 54.042 after 1, 3 and 6 months of treatment respectively (p < 0.001). Best corrected visual acuity (BCVA) in log MAR units was significantly improved from 0.95 ± 0.21 to 0.51 ± 0.23 after 6 months (p = 0.001). After treatment, negative correlations were detected between age, number of injections, duration of DM and level of glycated hemoglobin (HbA1c) and variation of both CMT and BCVA. The only significant predictor for low final CMT after 6 months of injection was the CMT after 3 months of injection (p = 0.001).

Conclusion

Ziv-aflibercept is a highly effective and safe drug in cases of DME resistant to previous ranibizumab injections especially in low-income countries.

Trial registration

This study was retrospectively registered at clinicaltrials.gov (ID: NCT04290195) on 28-2-2020.

Intravitreal Ziv-Aflibercept in Patients With Diabetic Macular Edema Refractory to Intravitreal Bevacizumab

BACKGROUND AND OBJECTIVE

To evaluate the efficacy of intravitreal ziv-aflibercept (IVZ) in patients with diabetic macular edema (DME) resistant to intravitreal bevacizumab (IVB).

PATIENTS AND METHODS

This prospective study was conducted in patients with persistent DME. Patients were switched to IVZ no longer than 6 weeks after the last three consecutive monthly IVB treatments and monitored over a course of 12 weeks. Changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and macular volume on optical coherence tomography were compared.

RESULTS

A total of 59 eyes (38 patients) were included. Mean BCVA improved from 0.84 to 0.71 logMAR (P = .001) after first IVZ treatment and remained significant. In a subgroup analysis, this significance was observed only in the group with baseline visual acuity of less than 20/50. Mean CMT decreased from 479 μm to 364 μm (P = .004) after the first IVZ injections and remained significant.

CONCLUSION

IVZ may be best reserved for patients with persistent DME after initial failure with bevacizumab, with less likelihood for anatomic or functional improvement in those with mild persistent DME. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:145-151.].

Fufang Xueshuantong alleviates diabetic retinopathy by activating the PPAR signalling pathway and complement and coagulation cascades

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Xueshuantong (FXST) is a traditional Chinese patent medicine composed of Panax notoginseng (Burkill) F.H.Chen (Araliaceae), Salvia miltiorrhiza Bunge (Lamiaceae), Astragalus propinquus Schischkin (Leguminosae), and Scrophularia ningpoensis Hemsl. (Scrophulariaceae). It has been widely used for the treatment of diabetic retinopathy (DR) and exerts a positive clinical therapeutic effect.

AIM OF THE STUDY

The aim of this study was to observe the effect of FXST on diabetic rat retinas and investigate its pharmacological mechanism for improving DR.

METHODS

The diabetic rat model was established by intraperitoneal injection of streptozotocin. The rats were divided into a normal group, diabetic group, and FXST group. The rats in the FXST group were treated with FXST by intragastric administration for 12 weeks while other rats were given the same volume of normal saline. The haemodynamic parameters of the central retinal artery in the rats were measured by ultrasound. Haematoxylin-eosin staining was utilised to observe the pathological structural changes in the retina. The apoptosis of retinal nerve cells was detected by terminal deoxynucleotidyl transferase dUTP nick end labelling. RNA sequencing was used to screen the differentially expressed genes (DEGs), and enrichment analyses were performed. The DEGs were validated through real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

The peak systolic velocity, end diastolic velocity, and mean velocity decreased while the resistance index and pulsatility index increased in the diabetic rat retinas. FXST also improved haemodynamics. In contrast with the diabetic group, FXST allayed the disorder and oedema of the retinal structure in addition to reversing the reductions in retinal thickness and retinal ganglion cell number. It also decreased the apoptosis index of retinal cells. A total of 1134 DEGs were identified by RNA sequencing in the FXST group compared to the diabetic group, including 814 upregulated genes and 320 downregulated genes. These genes were enriched in the complement and coagulation cascades as well as the peroxisome proliferator-activated receptor (PPAR) signalling pathway. Several DEGs, including PPAR gamma, perilipin 4, acyl-CoA dehydrogenase long chain, CD55 molecule, and plasminogen activator urokinase, were identified by qRT-PCR, and the results were consistent with the RNA sequencing data.

CONCLUSIONS

FXST alleviates DR by improving the haemodynamics and morphological alterations of diabetic rat retinas, which are mediated by complement and coagulation cascades and the PPAR signalling pathway.

Ziv-aflibercept: A cost-effective, off-label, highly potent antagonist of vascular endothelial growth factor

Ziv-aflibercept (Zaltrap^® ), a recombinant fusion protein that binds diffusible vascular endothelial growth factor (VEGF), is approved for the treatment of metastatic colorectal carcinoma. Its molecular structure is the same as aflibercept (Eylea^® ), thus making it an attractive option for the off-label treatment of chorioretinal vascular conditions. Ziv-aflibercept is distributed in 4 and 8 ml vials for intravenous use, and its cost after compounding is similar to bevacizumab. Studies with retinal pigment epithelium cytotoxicity, animal histologic sections and electroretinography have demonstrated its safety, and mathematical modelling combined with over four dozen clinical publications from different ophthalmic centres throughout the world attest to its efficacy. No appreciable differences in visual or anatomic outcomes between 1.25 mg (0.05 ml) and 2.5 mg (1.0 ml) doses have been noted. The long duration of action combined with the low cost make ziv-aflibercept an attractive anti-VEGF treatment option, especially in low- and middle-income countries where its popularity is increasing.

Comparison of intravitreal ziv-aflibercept and bevacizumab monotherapy in treatment-naive polypoidal choroidal vasculopathy

Purpose

To report the visual and anatomical outcomes of intravitreal ziv-aflibercept (IVZ) and bevacizumab (BVZ) monotherapy in treatment-naive polypoidal choroidal vasculopathy (PCV).

Methods

This was a retrospective case series of 16 eyes (8 eyes each in IVZ and BVZ groups). The study period was from January 2016 to March 2018. The inclusion criteria were treatment-naive PCV patients who were treated with either IVZ or BVZ monotherapy on pro re nata protocol and followed up monthly for 6 months. The change in best-corrected visual acuity (BCVA), central macular thickness (CMT), and pigment epithelial detachment (PED) height was measured at baseline and 6 months.

Results

A total of 16 eyes were studied. IVZ group had an improvement in BCVA by 0.15 logarithm of minimum angle of resolution (logMAR; approximately 1.5 lines) at 6 months, whereas BVZ group had a reduction in BCVA by 0.21 logMAR (approximately 2 lines) (P = 0.027). Five patients and one patient in IVZ and BVZ groups, respectively, had ≥5 letters gain of BCVA. IVZ group had significant reduction in PED height (P = 0.048), whereas the change in CMT was not significant at 6 months (P = 0.681). The mean number of injections (2.87 ± 0.83 in IVZ and 2.25 ± 0.89 BVZ group; P = 0.168) and longest treatment-free interval (3.00 ± 2.20 months in IVZ and 2.12 ± 1.96 months in BVZ group; P = 0.41) were not significantly different.

Conclusion

The visual and anatomical outcomes in terms of PED reduction in treatment-naive PCV patients were better in IVZ group compared with BVZ. IVZ monotherapy is a viable, cost-effective alternative in these patients with good safety profile.

Correlation analysis of fundus autofluorescence, spectral domain optical coherence tomography, and visual function in patients with diabetic macular oedema treated with intravitreal ziv-aflibercept

PURPOSE

The aim of this study was to evaluate the correlations between fundus autofluorescence and morphologic parameters as well as visual function in patients with diabetic macular oedema treated with intravitreal ziv-aflibercept.

METHODS

A total of 34 eyes of 20 patients with untreated diabetic macular oedema received an intravitreal injection of ziv-aflibercept at baseline, and 1 and 2 months later. The baseline, 1-month, and two-month best corrected visual acuity determination, contrast sensitivity, spectral domain optical coherence tomography, mean central macular thickness, mean macular cube volume, mean macular cube average thickness, and fundus autofluorescence (decreased, normal, or increased; and single or multiple spots) were measured. Correlation analysis with a determination of Spearman's rank correlation coefficient, regression analysis, agreement between investigators, and Friedman's test were used for statistical analyses.

RESULTS

A direct correlation was observed between baseline fundus autofluorescence and macular cube average thickness at 1 month (r = 0.51, p = 0.020) and between fundus autofluorescence at 1 month and baseline macular cube average thickness (r = 0.50, p = 0.021). Regression analysis showed a coefficient of determination of 0.29 (p = 0.016) between baseline fundus autofluorescence and macular cube average thickness at 1 month.

CONCLUSION

In patients with diabetic macular oedema, the pretreatment baseline degree of foveal fundus autofluorescence might be helpful in predicting macular cube average thickness in patients undergoing treatment with intravitreal ziv-aflibercept in the short term.

Evaluation of aflibercept and ziv-aflibercept binding affinity to vascular endothelial growth factor, stability and sterility after compounding

Purpose

To investigate the binding affinity, stability, and sterility of aflibercept and ziv-aflibercept to vascular endothelial growth factor (Holash et al. in Proc Natl Acad Sci USA 99(17):11393–11398, 2002. 10.1073/pnas.172398299) after compounding and storage for up to 28 days at 4 °C and − 8 °C.

Methods

Tuberculin-type 1-mL syringes were prepared containing aflibercept (40 mg/mL) and ziv-aflibercept (25 mg/mL). Samples were stored at 4 °C and − 8 °C for 0, 14, and 28 days and evaluated for the binding affinity of anti-VEGF to VEGF and stability using enzyme-linked immunosorbent assays. The evaluation of sample sterility was performed.

Results

Laboratory trials with aflibercept and ziv-aflibercept showed preservation of the drug-binding capability to recombinant VEGF when stored in plastic syringes for up to 28 days at 4 °C and − 8 °C. No significant decrease in mass or concentration were observed. Microbiologic evaluations did not detect contamination in the syringes.

Conclusions

The current study corroborates that compounded anti-VEGF drugs aflibercept and ziv-aflibercept do not loose stability or binding affinity and do not become contaminated if prepared under sterile conditions and stored at 4 °C or − 8 °C for 14 or 28 days.

Two-year outcomes of intravitreal ziv-aflibercept

AIM

To assess the two-year outcome of intravitreal ziv-aflibercept (IVZ) in eyes with macular diseases.

METHODS

Consecutive subjects with various macular diseases that received six or more of 0.05 mL IVZ (1.25 mg) injections with at least 1 year follow-up were included. Outcome measures were best-corrected visual acuity (BCVA) (logarithm of the minimum angle of resolution) and central macular thickness (CMT) on spectral domain optical coherence tomography. Paired comparison was done using Wilcoxon signed-rank test calculator.

RESULTS

107 eyes of 91 subjects received IVZ and were followed with mean±SD follow-up interval of 1.48±0.44 months following treat and extend or pro-re-nata protocol. The distribution included neovascular macular degeneration (42 eyes), diabetic macular oedema (32 eyes) and macular oedema secondary to retinal vein occlusion (11 eyes). Fifty eyes were naive, while 57 eyes were previously treated. Combining all disease categories, CMT decreased significantly by 133.0±153.0 µm at the 24-month follow-up (P<0.001) with BCVA gain of 0.35±0.37 at the 24-month follow-up (P<0.001) with mean number of injections of 8.5 at month 12, 2.4 between 12 and 18 month and 1.7 between 18 and 24 month. Ocular and systemic adverse effects included one episode of transient uveitis and one instance of central retinal artery occlusion after 1121 injections.

CONCLUSIONS

IVZ appears safe and efficacious in the therapy of macular diseases through 2 years.

Intravitreal Ziv-Aflibercept: Clinical Effects and Economic Impact

During the past decade, drugs that inhibit the actions of vascular endothelial growth factor (VEGF) have become standard-of-care treatment for a variety of chorioretinal vascular conditions. The off-label, intravitreal use of ziv-aflibercept (Zaltrap) has provided clinicians with an additional cost-effective drug. The commercial preparation of ziv-aflibercept contains the same aflibercept (VEGF-trap) molecule as Eylea but has a much higher osmolarity (1000 mOsm/kg vs 300 mOsm/kg). Initial concerns regarding cytotoxicity and long-term safety of intravitreal ziv-aflibercept have been largely negated after a series of publications failed to identify adverse ocular and systemic side effects. Both treatment-naive and anti-VEGF‒resistant cases of neovascular age-related macular degeneration (nAMD), diabetic macular edema (DME), retinal vein occlusion (RVO), and choroidal neovascular membrane (CNVM) may respond as well to ziv-aflibercept as to aflibercept. A higher dose of ziv-aflibercept (2 mg in 0.08 mL) does not cause any adverse effects during short-term follow-up period (1 month). Data from various sources suggest that ziv-aflibercept may be as cost effective as bevacizumab, thereby making it an attractive treatment option in low- and middle-income countries. However, problems with off-label use, compounding, and counterfeiting limit its availability in many countries. Data from prospective, randomized, multicenter clinical trials are still required to convince physicians and regulatory bodies of its clinical efficacy and potential as early therapy.

Aflibercept, bevacizumab or ranibizumab for diabetic macular oedema: recent clinically relevant findings from DRCR.net Protocol T

PURPOSE OF REVIEW

The aim of this study was to provide clinically relevant findings from the DRCR.net Protocol T, a multicentre randomized clinical trial comparing intravitreous aflibercept, repackaged (compounded) bevacizumab and ranibizumab for vision-impairing centre-involved diabetic macular oedema (DME).

RECENT FINDINGS

At 1 year, all three antivascular endothelial growth factor (anti-VEGF) drugs, on average, improved visual acuity. There was no difference among drugs in mean change in visual acuity from baseline among eyes with baseline Snellen equivalent visual acuity of 20/32 to 20/40, whereas aflibercept yielded superior vision outcomes among eyes with baseline visual acuity of 20/50 to 20/320. At 2 years, aflibercept remained superior, on average, to bevacizumab, but not ranibizumab, among eyes with baseline visual acuity of 20/50 to 20/320. Over 2 years, in post-hoc area-under-the-curve analysis, aflibercept vision outcomes were superior to bevacizumab or ranibizumab among these eyes. All three drugs had comparable ocular and systemic safety profiles. The substantial cost differential between aflibercept and bevacizumab raises challenges when safety and efficacy are at odds with cost-effectiveness results.

SUMMARY

When initial visual acuity loss is mild, there are no apparent differences, on average, among aflibercept, bevacizumab and ranibizumab for treating DME. When visual acuity loss is moderate or worse, aflibercept is more likely to improve visual acuity.