Changing paradigms of anti-VEGF in the Indian scenario

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.

Efficacy and Cost-Effectiveness of Anti-VEGF for Treating Diabetic Retinopathy in the Indian Population

Purpose

In the present study, we aimed to evaluate the efficacy, safety, and cost-effectiveness of the anti-vascular endothelial growth factor (anti-VEGF), namely ranibizumab (RBZ) or bevacizumab (BVZ), after either focal or grid or scatter laser photocoagulation, for the treatment of diabetic macular edema (DME) in the Indian population.

Methods

Retrospective data were collected in the Regional Institute of Ophthalmology, Kolkata, India between January 2018 and June 2019. Seventy-seven eyes received 3 consecutive monthly intravitreal injections of RBZ (0.5 mg) and were followed by prompt laser photocoagulation (within 7–10 days after the third injection). Similarly, 51 eyes received 3 consecutive monthly intravitreal injections of BVZ (1.25 mg), an off-label drug, and were followed by prompt laser therapy. Safety assessments of the therapy, as well as surrogate markers of biochemical derangements related to diabetic retinopathy (DR), were also investigated at the end of 12 months.

Results

Seventy-seven subjects who were given a treatment of RBZ+laser therapy showed average 6.87±5.53 letters gain in their best-corrected visual acuity (BCVA) score, whereas the ones treated with off-label BVZ+ laser therapy demonstrated improvement in BCVA of an average 6.82±5.76 letters in “Early Treatment Diabetic Retinopathy Study” (ETDRS) chart. The study also highlights the cost-effectiveness of both RBZ+laser and BVZ+laser therapies for the treatment of DME in DR. The results demonstrated that a subject has to pay 20.951 times more cost (in INR) for RBZ+laser therapy compared to BVZ+laser therapy, to get an almost similar outcome.

Conclusion

BVZ is found to be the more attractive option for treating DME in DR for its cost-friendliness over RBZ in terms of BCVA outcome, as well as the safety perspectives, at least for the economically backward population in developing countries, like India.

Klebsiella Cluster Endophthalmitis following Intravitreal Bevacizumab: Role of Early Detection, Pars Plana Vitrectomy, and Intracameral Moxifloxacin

AIM

To report the clinical profile, outcomes of early vitrectomy for cluster endophthalmitis developing after intravitreal Bevacizumab (IVB), and discuss the role of prophylactic intracameral moxifloxacin for eyes undergoing combined cataract surgery with IVB.

METHODS

Single center, retrospective analysis of 35 consecutive eyes developing post-IVB inflammation.

RESULTS

Of the 35 eyes that were administered IVB (27 eyes 'IVB alone' and 8 eyes 'IVB with cataract surgery'). Endophthalmitis developed in 28 eyes, 6 eyes were managed with Intravitreal antibiotic (IVAB) alone, while 22 eyes required early vitrectomy. Only one eye undergoing a combined phacoemulsification with IVB developed endophthalmitis. Majority(26/28) of the eyes achieved visual acuity equal to/greater than pre-IVB injection vision over a period of 3.15 ± 3.2 months.

CONCLUSION

Early detection and prompt PPV were effectual for achieving good functional outcomes in our cluster of post-IVB Klebsiella endophthalmitis. Intracameral moxifloxacin was protective in cases undergoing combined cataract surgery with IVB.

Neuroprotective Potential of Pituitary Adenylate Cyclase Activating Polypeptide in Retinal Degenerations of Metabolic Origin

Pituitary adenylate cyclase-activating polypeptide (PACAP1-38) is a highly conserved member of the secretin/glucagon/VIP family. The repressive effect of PACAP1-38 on the apoptotic machinery has been an area of active research conferring a significant neuroprotective potential onto this peptide. A remarkable number of studies suggest its importance in the etiology of neurodegenerative disorders, particularly in relation to retinal metabolic disorders. In our review, we provide short descriptions of various pathological conditions (diabetic retinopathy, excitotoxic retinal injury and ischemic retinal lesion) in which the remedial effect of PACAP has been well demonstrated in various animal models. Of all the pathological conditions, diabetic retinopathy seems to be the most intriguing as it develops in 75% of patients with type 1 and 50% of patients with type 2 diabetes, with concomitant progression to legal blindness in about 5%. Several animal models have been developed in recent years to study retinal degenerations and out of these glaucoma and age-related retina degeneration models bear human recapitulations. PACAP neuroprotection is thought to operate through enhanced cAMP production upon binding to PAC1-R. However, the underlying signaling network that leads to neuroprotection is not fully understood. We observed that (i) PACAP is not equally efficient in the above conditions; (ii) in some cases more than one signaling pathways are activated; (iii) the coupling of PAC1-R and signaling is stage dependent; and (iv) PAC1-R is not the only receptor that must be considered to interpret the effects in our experiments. These observations point to a complex signaling mechanism, that involves alternative routes besides the classical cAMP/protein kinase A pathway to evoke the outstanding neuroprotective action. Consequently, the possible contribution of the other two main receptors (VPAC1-R and VPAC2-R) will also be discussed. Finally, the potential medical use of PACAP in some retinal and ocular disorders will also be reviewed. By taking advantage of, low-cost synthesis technologies today, PACAP may serve as an alternative to the expensive treatment modelities currently available in ocular or retinal conditions.

A Multinational Comparison of Anti-Vascular Endothelial Growth Factor Use: The United States, the United Kingdom, and Asia-Pacific

PURPOSE

A comparison of anti-vascular endothelial growth factor (anti-VEGF) medication use across multiple countries.

CLINICAL RELEVANCE

Anti-VEGF medication use is now considered first-line treatment for numerous retinal diseases globally. Exploring medication choices, costs within each healthcare system, policy challenges, emerging treatments, and patient access all provide insight into a newly recognized and major public health issue.

METHODS

All data presented in this review are available through the published English literature in PubMed, non-peer-reviewed trade publications, and reported surveys. The following search terms were used: anti-VEGF OR bevacizumab OR ranibizumab OR aflibercept OR pegaptanib OR conbercept AND trends OR survey OR cost OR patterns OR preference. Countries with large populations and available data included the United States, United Kingdom, China, India, Korea, Singapore, and Australia. Population and economic statistics were obtained from published reports from the World Bank, World Health Organization, and Commonwealth Fund.

RESULTS

Anti-VEGF medication use and costs are significant aspects of patient and healthcare system expenditures in each nation and may have an especially large potential economic burden in India and China. Bevacizumab use comprises the majority of anti-VEGF medication use in the United States and Singapore, although aflibercept use is growing rapidly. Paradoxically, data demonstrate that there is a significant trend in medication choice toward ranibizumab and aflibercept among practice settings outside of the United States, such as the United Kingdom, China, South Korea, and Australia. The price of anti-VEGF medications ranged from US $30 (ziv-aflibercept) to US $1950 (ranibizumab and aflibercept). Ranibizumab's price ranged from US $240 in India to US $1950 in the United States. Conbercept in China costs approximately US $1150 per dose.

CONCLUSIONS

Outside of the United States, many nations are using a majority of more expensive anti-VEGF medications, which may lead to increased costs and decreased access. Increasing the availability of safely compounded anti-VEGF medications will likely improve access, create patient/provider choice, and decrease relative healthcare costs for the growing burden of retinal diseases globally.

A study on the contamination of injection bevacizumab on storage of multidose vials

Purpose:

The aim of this study is to establish the safety of storage and reuse of bevacizumab vials for 1 week with multiple vial punctures.

Methods:

This was an experimental microbiological study conducted at tertiary care hospital. The study samples included bevacizumab vials that had been used for injecting patients by the pooling method. Vials were stored and sampled in a manner that replicated their proposed clinical use. Contamination of vials was evaluated on the basis of microbial culture and validated by positive and negative controls. The probability of obtaining such results purely by chance was calculated.

Results:

A total of 210 samples from 30 vials were evaluated along with 210 positive and 210 negative controls. No growth was seen in any of the bevacizumab samples. The probability of obtaining 210 consecutive sterile samples just by chance is <5.547 × 10⁻⁶ (0.000005547).

Conclusion:

The vials showed no contamination on storage for 7 days in an ordinary refrigerator. Thus, we conclude that the rate of contamination of bevacizumab vials on storage for 7 days in a refrigerator is likely to be insignificant. The results need to be validated by other studies replicating this protocol.

Vitrectomy in the management of diabetic macular edema in treatment-naïve patients

OBJECTIVE

To determine the efficacy of vitrectomy in eyes with treatment-naïve diabetic macular edema (DME).

METHODS

Consecutive patients with treatment-naïve DME who underwent pars plana vitrectomy with internal limiting membrane peeling at a single institution were identified from the electronic medical records. Morphologic and visual acuity changes from baseline were analyzed at both the primary temporal endpoint (6 months) and the final examination with the investigators. The primary outcome measures included changes in best-corrected visual acuity (BCVA) and central retinal thickness (CRT).

RESULTS

Forty-four eyes of 44 patients were included in this retrospective study. The mean BCVA improved significantly from baseline until the 6-month primary endpoint (1.35 logMAR vs 0.83 logMAR, p < 0.001) and stabilized through the final examination (0.77 logMAR). The BCVA improved by at least 0.1, 0.3, and 0.6 logMAR in 26 (60%), 24 (55%), and 14 (32%) of eyes, respectively, whereas it worsened by 0.3 logMAR in only 1 (2%) eye. Final BCVA correlated inversely with duration of diabetes (p = 0.01), presence of an epiretinal membrane (p = 0.02), and initial visual acuity (p = 0.03). Mean CRT decreased significantly from baseline through 6 months (595 µm vs 266 µm; p < 0.001), and edema recurred in only 3 eyes (6%), one of which was subsequently treated with intravitreal bevacizumab.

CONCLUSIONS

Pars plana vitrectomy significantly improves macular edema and visual acuity in eyes with treatment-naïve DME. Prospective randomized trials are needed to better determine the efficacy of early vitrectomy.

Retrospective hospital-based analysis of age-related macular degeneration patterns in India: 5-year follow-up

PURPOSE

To provide a detailed analysis of age-related macular degeneration (AMD) with a 5-year follow-up at a Tertiary Eye Care Center in India.

METHODS

In this retrospective institutional study, 408 eyes of 204 subjects (100 males) with a diagnosis of AMD with minimum 5-year follow-up were included. Data collected included demographics, details of the ocular exam, special investigations performed, treatment offered, complications, and systemic diseases, if any.

RESULTS

The median age was 74.24 ± 8.23 years. Median follow-up was 5.77 years. The visual acuity (VA) at baseline and last visit was 0.74 ± 0.12 (Snellen's equivalent 20/100) and 0.54 ± 0.12 logarithm of the minimum angle of resolution (Snellen's equivalent 20/50; P = 0.032) in patients with choroidal neovascular membrane (CNVM). The most common complaint was decreased vision (94.5%). AMD (any stage) was found to be bilateral in 93% of patients at baseline and 197 patients (96.56%) at 5 years. Seventeen eyes had active CNVM (12 of these were occult) at presentation. At baseline, 43 eyes had a disciform scar. Three hundred twenty-one eyes had dry AMD at baseline (geographic atrophy - 12 [3.7%] eyes). Five-year conversion rate into wet AMD and geographic atrophy was 2.87% and 3.12%. Median number of anti-vascular endothelial growth factor injections administered per patient was 2.8 ± 1.2. CNVM bilaterality was low (7.5%).

CONCLUSION

Patients with AMD in India presented later in the course of the disease. Bilateral advanced AMD and geographic atrophy were uncommon. Five-year conversion rate into wet AMD and geographic atrophy was 2.87% and 3.12%.