Genetic predictive biomarkers of anti-VEGF treatment response in patients with neovascular age-related macular degeneration

Ocular Pharmacology

Treatment of ocular diseases presents unique challenges and opportunities for the clinician and for the clinical pharmacologist. Ophthalmic pharmaceuticals, typically given as liquids, require consideration of solubility, physiological pH, and osmolarity, as well as sterility and stability, which in turn requires optimal pharmaceutics. Ocular tissue levels are challenging to obtain in humans, and the clinical pharmacokinetics is typically blood levels, which are primarily related to safety, rather than efficacy. The eye is a closed compartment with multiple physiological barriers with esterases and transporters, but relatively little cytochrome oxidases. Delivery routes include topical, intravitreal, and systemic. Patient dosing involves not only adherence issues common to all chronic diseases, but also performance requirements on eye drop instillation. Therapeutically, ocular diseases and their pharmacological treatments include both those analogous to systemic diseases (e.g., inflammation, infection, and neuronal degeneration) and those unique to the eye (e.g., cataract and myopia).

Neovascular age-related macular degeneration: disease pathogenesis and current state of molecular biomarkers predicting treatment response-a scoping review

Age-related macular degeneration is a major cause of blindness, and the development of anti-vascular endothelial growth factor (VEGF) intravitreal treatments has revolutionised the management of the disease. At the same time, new challenges and unmet needs arose due to the limitations of the current therapeutic options. Neovascularisation development during the course of the disease has a complex pathogenetic mechanism, and several biomarkers and their association with treatment outcomes have been investigated. We reviewed the relevant literature about neovascularisation development and biomarkers related to response to treatment. Improving our knowledge on the field can improve patient outcomes and offer personalised care.

Application of Machine Learning to Ranking Predictors of Anti-VEGF Response

Age-related macular degeneration (AMD) is a heterogeneous disease affecting the macula of individuals and is a cause of irreversible vision loss. Patients with neovascular AMD (nAMD) are candidates for the anti-vascular endothelial growth factor (anti-VEGF) treatment, designed to regress the growth of abnormal blood vessels in the eye. Some patients fail to maintain vision despite treatment. This study aimed to develop a prediction model based on features weighted in order of importance with respect to their impact on visual acuity (VA). Evaluations included an assessment of clinical, lifestyle, and demographic factors from patients that were treated over a period of two years. The methods included mixed-effects and relative importance modelling, and models were tested against model selection criteria, diagnostic and assumption checks, and forecasting errors. The most important predictors of an anti-VEGF response were the baseline VA of the treated eye, the time (in weeks), treatment quantity, and the treated eye. The model also ranked the impact of other variables, such as intra-retinal fluid, haemorrhage, pigment epithelium detachment, treatment drug, baseline VA of the untreated eye, and various lifestyle and demographic factors. The results identified variables that could be targeted for further investigation in support of personalised treatments based on patient data.

Genetic Aspects of Age-Related Macular Degeneration and Their Therapeutic Potential

Age-related macular degeneration (AMD) is a complex and multifactorial disease, resulting from the interaction of environmental and genetic factors. The continuous discovery of associations between genetic polymorphisms and AMD gives reason for the pivotal role attributed to the genetic component to its development. In that light, genetic tests and polygenic scores have been created to predict the risk of development and response to therapy. Still, none of them have yet been validated. Furthermore, there is no evidence from a clinical trial that the determination of the individual genetic structure can improve treatment outcomes. In this comprehensive review, we summarize the polymorphisms of the main pathogenetic ways involved in AMD development to identify which of them constitutes a potential therapeutic target. As complement overactivation plays a major role, the modulation of targeted complement proteins seems to be a promising therapeutic approach. Herein, we summarize the complement-modulating molecules now undergoing clinical trials, enlightening those in an advanced phase of trial. Gene therapy is a potential innovative one-time treatment, and its relevance is quickly evolving in the field of retinal diseases. We describe the state of the art of gene therapies now undergoing clinical trials both in the field of complement-suppressors and that of anti-VEGF.

Genetic Association Analysis of Anti-VEGF Treatment Response in Neovascular Age-Related Macular Degeneration

Anti-VEGF treatment for neovascular age-related macular degeneration (nAMD) has been FDA-approved in 2004, and since then has helped tens of thousands of patients worldwide to preserve vision. Still, treatment responses vary widely, emphasizing the need for genetic biomarkers to robustly separate responders from non-responders. Here, we report the findings of an observational study compromising 179 treatment-naïve nAMD patients and their reaction to treatment after three monthly doses of anti-VEGF antibodies. We show that established criteria of treatment response such as visual acuity and central retinal thickness successfully divides our cohort into 128 responders and 51 non-responders. Nevertheless, retinal thickness around the fovea revealed significant reaction to treatment even in the formally categorized non-responders. To elucidate genetic effects underlying our criteria, we conducted an undirected genome-wide association study followed by a directed replication study of 30 previously reported genetic variants. Remarkably, both approaches failed to result in significant findings, suggesting study-specific effects were confounding the present and previous discovery studies. Of note, all studies so far are greatly underpowered, hampering interpretation of genetic findings. In consequence, we highlight the need for an extensive phenotyping study with sample sizes exceeding at least 15,000 to reliably assess anti-VEGF treatment responses in nAMD.

Biomarkers as Predictive Factors of Anti-VEGF Response

Age-related macular degeneration is the main cause of irreversible vision in developed countries, and intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the current gold standard treatment today. Although anti-VEGF treatment results in important improvements in the course of this disease, there is a considerable number of patients not responding to the standardized protocols. The knowledge of how a patient will respond or how frequently retreatment might be required would be vital in planning treatment schedules, saving both resource utilization and financial costs, but today, there is not an ideal biomarker to use as a predictive response to ranibizumab therapy. Whole blood and blood mononuclear cells are the samples most studied; however, few reports are available on other important biofluid samples for studying this disease, such as aqueous humor. Moreover, the great majority of studies carried out to date were focused on the search for SNPs in genes related to AMD risk factors, but miRNAs, proteomic and metabolomics studies have rarely been conducted in anti-VEGF-treated samples. Here, we propose that genomic, proteomic and/or metabolomic markers could be used not alone but in combination with other methods, such as specific clinic characteristics, to identify patients with a poor response to anti-VEGF treatment to establish patient-specific treatment plans.

VEGFA Haplotype and VEGF-A and VEGF-R2 Protein Associations with Exudative Age-Related Macular Degeneration

Our study aimed to reveal the associations between VEGFA SNPs (rs1570360, rs699947, rs3025033, and rs2146323), their haplotypes, VEGF-A and VEGF-R2 serum concentrations, and early and exudative AMD. A total of 339 subjects with early AMD and 419 with exudative AMD groups, and 374 healthy subjects, were genotyped for four VEGFA SNPs (rs1570360, rs699947, rs3025033, and rs2146323). VEGF-A and VEGFR-2 serum concentrations were measured in exudative AMD and controls. The results revealed that rs3025033 G allele was significantly associated with lower odds of exudative AMD under the dominant model (OR = 0.67; 95% CI: 0.49–0.80; p = 0.0088) and additive (OR = 0.7; 95% CI: 0.54–0.90; p = 0.0058) models after Bonferroni correction. In the female group, rs3025033 AG genotype was associated with exudative AMD under the codominant model (OR = 0.57; 95% CI: 0.37–0.87; p = 0.009) and G allele under the dominant (OR = 0.55; 95% CI: 0.37–0.82; p = 0.0032) and additive models (OR = 0.60; 95% CI: 0.42–0.84; p = 0.0028). Haplotype analysis revealed that individuals carrying rs1570360, rs699947, rs3025033, and rs2146323 haplotype A-A-G-A had decreased risk of exudative AMD (OR = 0.46, 95% CI: 0.23–0.90; p = 0.023). The VEGF-A and VEGF-R2 serum concentrations did not differ between study groups; we found that patients with exudative AMD carrying at least one C allele at rs699947 have statistically significantly higher VEGF-A serum concentrations compared to AA genotype carriers (485.95 (945.93) vs. 194.97 (-), respectively, p = 0.046). In conclusion, we found that VEGFA rs3025033 and haplotype rs1570360A-rs699947A-rs3025033G- rs2146323A play a protective role for exudative AMD in the Caucasian population. Furthermore, rs699947 is associated with elevated VEGF-A serum concentrations in exudative AMD.

VEGF gene polymorphisms regulate human retinal vascular endothelial cell proliferation and apoptosis through ASF/SF2-associated alternative splicing

This study investigated the effects of single nucleotide polymorphisms (SNPs) of the VEGF （vascular endothelial growth factor） gene, which are associated with susceptibility to age-related macular degeneration (AMD), on the expression of VEGF proteins (VEGF₁₆₅ and VEGF_165b) and their role in cell proliferation and apoptosis in human retinal vascular endothelial cells (hRVECs). Cell viability and VEGF₁₆₅ and VEGF_165b expressions were evaluated in hRVECs transfected with VEGF genes containing different SNPs (rs3025039, rs3025033, and rs10434). The Cell Counting Kit 8 assay, quantitative real-time PCR, western blotting, TUNEL assay, and enzyme-linked immunosorbent assay were used to examine the effects of VEGF gene SNPs on cell viability, VEGF₁₆₅ and VEGF_165b expressions, and cell apoptosis in hRVECs. The interaction and localization of the RNA-binding protein alternative splicing factor/splicing factor 2 (ASF/SF2) were assessed using RNA pull-down. Although VEGF₁₆₅ expression decreased, VEGF_165b levels increased significantly in hRVECs transfected with rs3025039, which decreased cell viability and induced apoptosis. The SNPs rs3025033 and rs10434 had no significant effects on VEGF_165b protein production and apoptosis; however, they promoted cell proliferation. SNPs affected the interaction between RNA and ASF/SF2, a splicing factor for intron retention. Insulin-like growth factor-1 treatment induced the expression of VEGF₁₆₅, but not VEGF_165b, whereas SRPIN340 treatment, an inhibitor of ASF/SF2, increased VEGF_165b protein levels. VEGF gene sequence variations affected hRVEC proliferation and apoptosis via alternative gene splicing. Thus, the regulation of splicing via ASF/SF2 could be a potential strategy in treating pathological neovascularization in patients with AMD.

Ziv-aflibercept for Better Regulating Neovascular Age-Related Macular Degeneration (ZEBRA): A Prospective, Randomized Trial

OBJECTIVE

The purpose of this study is to determine if ziv-aflibercept is a safe and effective maintenance drug for nAMD.

STUDY DESIGN AND METHODS

This is a randomized, prospective, single-blinded trial. Inclusion criteria were active nAMD, prior anti-VEGF treatment, and BCVA ≤20/200. The treatment group received ziv-aflibercept. The control group continued their existing anti-VEGF regimen. The main outcome measures were BCVA, CFT, and safety.

RESULTS

Mean baseline BCVA was 1.58 ± 0.44 logMAR and 1.71 ± 0.39 logMAR in the control (n = 27) and treatment (n = 29) groups, respectively. After 24 months, the mean change in BCVA was 0.11 in the control group (equivalent to a loss of 5 ETDRS letters) and 0.01 logMAR in the treatment group (p = .48). Baseline CFT was 257 ± 33 μm and 247 ± 30 μm in the control and treatment groups, respectively, and after 24 months mean change in CFT was 26 μm and -5 μm (p = .24). There were no ocular or systemic adverse events during the study.

CONCLUSION

Ziv-aflibercept is a safe and effective as a maintenance drug for patients with nAMD. It may represent a cost-effective alternative to aflibercept and second-line therapy for eye resistant bevacizumab or ranibizumab.

Meta-Analysis of the Pharmacogenetics of ARMS2 A69S Polymorphism and the Response to Advanced Age-Related Macular Degeneration

Age-related macular degeneration (AMD) causes irreversible vision loss, and targeted anti-vascular endothelial growth factor (VEGF) therapy is now the most common and effective treatment. The aim of this meta-analysis is to discuss whether genetic polymorphism of ARMS2 A69S could confer susceptibility to advanced AMD with the response to anti-VEGF treatment. We performed a meta-analysis of relevant published studies selected through electronic databases. A total of 21 preferred studies regarding the association between ARMS2 gene and anti-VEGF treatment response in advanced AMD were generally included in the meta-analysis. The pooled results demonstrated that the carriage of G allele for ARMS2 A69S presented a better clinical prognosis for advanced AMD treated with anti-VEGF drugs (OR = 1.38, 95% CI = 1.13-1.69, p = 0.002). In addition, in the subgroup analysis based on ethnicity, ARMS2 polymorphisms were more likely to be a positive responder for East Asian patients (OR = 1.67, 95% CI = 1.29-2.16, p < 0.001). This meta-analysis through a series of rigorous methodology data demonstrated a significant association between ARMS2 A69S polymorphism and the anti-VEGF treatment response in advanced AMD, especially among East Asian population. Numerous well-designed, randomized, multicenter clinical trials with large sample size are required to validate the association.

Investigation of circRNA Expression Profiles and Analysis of circRNA-miRNA-mRNA Networks in an Animal (Mouse) Model of Age-Related Macular Degeneration

PURPOSES

To (i) identify dysregulated circular RNAs (circRNAs) and (ii) elucidate their potential functions in an animal (mouse) model of choroidal neovascularization (CNV), a prominent feature of neovascular age-related macular degeneration (AMD).

METHODS

Expression profiles for circRNA were identified by microarray analysis. Selected circRNAs were confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Bioinformatic analyses of identified circRNAs were performed to predict (i) circRNA/microRNA interactions and (ii) occurrence of competing endogenous RNA (ceRNA) networks. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were applied to predict both the biological functions and potential pathways of the altered parental genes involved in CNV.

RESULTS

Microarray analysis indicated that 100 circRNAs in RPE-choroid-sclera complexes from CNV mice were significantly altered compared with those from control mice (fold change≥1.5, p < .05). Of these, six were validated by qRT-PCR, and included up-regulated mmu_circRNA_20332 and mmu_circRNA_19388, and down-regulated mmu_circRNA_36481, mmu_circRNA_006555, mmu_circRNA_012588, and mmu_circRNA_005578. GO analysis revealed that the altered parental genes involved in ceRNA networks were mostly enriched in immune system processes and portions of neurons. KEGG analysis revealed that these altered parental genes were also amplified in extracellular matrix (ECM)-receptor interactions, chemokine signaling pathways, and advanced glycation end-product (AGE)-receptors for advanced glycation end-product (RAGE) signaling pathways in diabetic complications.

CONCLUSION

The study identified statistically significant differences between CNV-mouse circRNAs and control mouse circRNAs, suggesting that circRNAs play vital roles in the pathogenesis of CNV. It is, therefore, reasonable to consider circRNAs as potential therapeutic targets for regulating CNV in AMD patients.

Predictive genetics for AMD: Hype and hopes for genetics-based strategies for treatment and prevention

Age-related macular degeneration (AMD) is a complex disease with multiple genetic and environmental risk factors. In the age of molecular genetics, many investigators have established a link between genes and development or progression of the disease. This later evolved to determine whether phenotypic features of AMD have distinct genetic profiles. Molecular genetics have subsequently been introduced as factors in risk assessment models, increasing the predictive value of these tools. Models seek to predict either development or progression of disease, and different AMD-related genes aid our understanding of these respective features. Several investigators have attempted to link molecular genetics with treatment response, but results and their clinical significance vary. Ocular and systemic biomarkers may interact with established genes, promising future routes of ongoing clinical assessment. Our understanding of AMD molecular genetics is not yet sufficient to recommend routine testing, despite its utility in the research setting. Clinicians must be wary of misusing population-based risk models from genetic and biomarker associations, as they are not necessarily relevant for individual counseling. This review addresses the known uses of predictive genetics, and suggests future directions.

[Molecular and genetic aspects of age-related macular degeneration and glaucoma]

In most cases, age-related macular degeneration (AMD) and glaucoma are considered multi-factor diseases that lead to irreversible blindness in senior population of developed countries. Among different types of these diseases, around 5% are monogenic. Studying their molecular and genetic aspects can lay the basis for improvement of diagnostic methods, prognosis of the risks of development, manner of progression and treatment outcomes, as well as creation of new therapy methods. The article reviews modern understanding of the etiopathogenesis of AMD and glaucoma and describes their interrelations.

AFLIBERCEPT AFTER RANIBIZUMAB INTRAVITREAL INJECTIONS IN EXUDATIVE AGE-RELATED MACULAR DEGENERATION: The ARI2 Study

Treatment-resistant pigment epithelial detachments can be effectively treated with aflibercept switch therapy. Patients were treated with 3 monthly intravitreal injections and then a Q6 regimen. Mean pigment epithelial detachment height and volume were statistically reduced after the switch at primary endpoint (12 weeks), and best-corrected visual acuity also improved steadily throughout the duration of the study.

Purpose:

To analyze the efficacy of aflibercept switch treatment for regression of pigment epithelial detachment (PED) in patients previously treated with ranibizumab.

Methods:

Multicenter, prospective, nonrandomized clinical trial. One eye of patients presenting neovascular age–related macular degeneration with PED of more than 250 μm in height, with persistent fluid, was included. Patients had to have received at least six ranibizumab intravitreal injections during the 12 months before enrollment. Patients were switched from ranibizumab pro re nata to aflibercept (fixed regimen, 3 monthly intravitreal injections, and then Q6). Main outcome measure was change in PED height from baseline to Week 12 after switch. Secondary outcomes were best-corrected visual acuity and PED volume changes.

Results:

Eighty four patients were included. Mean delay between last ranibizumab intravitreal injection and switch was 44.7 days. Mean maximal PED height at baseline visit was 347 μm (±109) and reduced to a mean of 266 μm (±114) at Week 12 (P < 0.001) and 288.2 μm at Week 32 (P < 0.001). Mean PED volume was reduced from 1.3 mm³ to 0.98 mm³ at Week 12 (P < 0.001). Best-corrected visual acuity improved by 3.3 Early Treatment Diabetic Retinopathy Study letters at Week 32 (P = 0.003).

Conclusion:

Aflibercept switch therapy seems to be effective on large PED in patients previously treated with pro re nata ranibizumab.

Genetics and genetic testing for age-related macular degeneration

Considerable advances have been made in our understanding of age-related macular degeneration (AMD) genetics over the past decade. The genetic associations discovered to date are estimated to account for approximately half of AMD heritability, and functional studies of these variants have revealed new insights into disease pathogenesis, leading to the development of potential novel therapies. There is furthermore growing interest in genetic testing for predicting an individual's risk of AMD and offering personalised preventive or therapeutic treatments. We review the progress made so far in AMD genetics and discuss the possible applications for genetic testing.

Encapsulated Cell Technology-Based Delivery of a Complement Inhibitor Reduces Choroidal Neovascularization in a Mouse Model

Purpose

Age-related macular degeneration (AMD) is a slowly progressing disease, and risk appears to be tied to an overactive complement system. We have previously demonstrated that mouse choroidal neovascularization (CNV) and smoke-induced ocular pathology can be reduced with an alternative pathway (AP) inhibitor fusion protein consisting of a complement receptor-2 fragment linked to the inhibitory domain of factor H (CR2-fH) when delivered systemically. Here we developed an experimental approach with genetically engineered encapsulated ARPE-19 cells to produce CR2-fH intravitreally.

Methods

ARPE-19 cells were generated to stably express CR2 or CR2-fH, microencapsulated using sodium alginate, and injected intravitreally into 2-month-old C57BL/6J mice. CNV was induced using argon laser photocoagulation 4 weeks postinjection. Presence of capsules and progression of CNV was analyzed using optical coherence tomography. Bioavailability of CR2-fH was evaluated in retina sections by immunohistochemistry, and efficacy as an AP inhibitor by C3a ELISA.

Results

Secretion of CR2-fH or CR2 from encapsulated ARPE-19 cells was confirmed. An efficacious concentration of CR2-fH capsules to reduce CNV was identified. Bioavailability studies showed that CR2-fH was present in capsules and retinas of injected mice, and reduced CNV-associated ocular C3a production.

Conclusions

These findings indicate that the AP inhibitor CR2-fH, when generated intravitreally, can reduce CNV in mouse.

Translational Relevance

Encapsulated ARPE-19 cells secreting CR2-fH or perhaps other antiangiogenic or prosurvival factors might be useful as a potential therapeutic tool to treat age-related macular degeneration.

Age, sex, and type of medication predict the effect of anti-VEGF treatment on central retinal thickness in wet age-related macular degeneration

Purpose

Randomized clinical trials studying the effects of VEGF inhibition on wet age-related macular degeneration (wAMD) are designed so that the effects of individually varying risk factors on the treatment response are eliminated. The influence of these risk factors can be studied in large data sets from real-life experience.

Patients and methods

All 2,255 patients diagnosed with wAMD requiring anti-VEGF treatment in at least one eye over more than 9 years in a defined Danish population with 0.9 million inhabitants were studied. The predictive value of eye laterality, sex, current smoking status, type of anti-VEGF compound, membrane position, membrane type, leakage area, number of injections, number of visits, age, time to follow-up, visual acuity, and central retinal thickness (CRT) at baseline on change in CRT after three monthly injections with anti-VEGF compound followed by treatment pro re nata for up to 12 months was assessed.

Results

After 12 months, 67 patients had died, 903 had had stable CRT for at least 6 months, and 1,285 patients had not achieved stable CRT. The reduction in CRT was −84.8±118.3 μm, whereas the increase in visual acuity was 2.2±14.7 Early Treatment Diabetic Retinopathy Study letters. The risk factors included contributed to 64% of the variation in CRT reduction. High age and high CRT at baseline predicted high CRT reduction, whereas more injections, treatment with ranibizumab, and male sex predicted a low CRT reduction.

Conclusion

Age, sex, and type of anti-VEGF medication can be used to plan treatment and inform patients about the expected response of anti-VEGF treatment in wAMD.

GWAS study using DNA pooling strategy identifies association of variant rs4910623 in OR52B4 gene with anti-VEGF treatment response in age-related macular degeneration

Pooled DNA based GWAS to determine genetic association of SNPs with visual acuity (VA) outcome in anti-vascular endothelial growth factor (anti-VEGF) treated neovascular age-related macular degeneration (nAMD) patients. We performed pooled DNA based GWAS on 285 anti-VEGF treated nAMD patients using high density Illumina 4.3 M array. Primary outcome was change in VA in Early Treatment Diabetic Retinopathy Study (ETDRS) letters after 6 months of anti-VEGF treatment (patients who lost ≥5 ETDRS letters classified as non-responders and all remaining classified as responders). GWAS analysis identified 44 SNPs of interest: 37 with strong evidence of association (p < 9 × 10⁻⁸), 2 in drug resistance genes (p < 5 × 10⁻⁶) and 5 nonsynonymous changes (p < 1 × 10⁻⁴). In the validation phase, individual genotyping of 44 variants showed three SNPs (rs4910623 p = 5.6 × 10⁻⁵, rs323085 p = 6.5 × 10⁻⁴ and rs10198937 p = 1.30 × 10⁻³) remained associated with VA response at 6 months. SNP rs4910623 also associated with treatment response at 3 months (p = 1.5 × 10⁻³). Replication of these three SNPs in 376 patients revealed association of rs4910623 with poor VA response after 3 and 6 months of treatment (p = 2.4 × 10⁻³ and p = 3.5 × 10⁻², respectively). Meta-analysis of both cohorts (673 samples) confirmed association of rs4910623 with poor VA response after 3 months (p = 1.2 × 10⁻⁵) and 6 months (p = 9.3 × 10⁻⁶) of treatment in nAMD patients.

Association between VEGF-A and VEGFR-2 polymorphisms and response to treatment of neovascular AMD with anti-VEGF agents: a meta-analysis

Aims

The purpose of this study is to investigate whether gene polymorphisms of the vascular endothelial growth factor A (VEGF-A) and its receptor (VEGFR-2) have a pharmacogenetics effect on the anti-VEGF treatment for neovascular age-related macular degeneration (nAMD).

Methods

We carried out a meta-analysis focusing on the relationship between VEGF-related gene polymorphisms and treatment response of nAMD.

Results

For the single nucleotide polymorphisms (SNPs) within VEGF-A and VEGFR-2, anti-VEGF treatment was much more effective in patients with nAMD having rs833061 (CC vs TT:OR=2.222, 95% CI 1.252 to 3.944, p=0.006; CT vs TT: OR=2.537,95% CI 1.478 to 4.356, p=0.001 and CC vs CT+TT: OR=2.362, 95% CI 1.414 to 3.946, p=0.001), particularly for Asians (CC vs TT: OR=2.903, 95% CI 1.150 to 7.330, p=0.024; CT vs TT: OR=3.849, 95% CI 1.522 to 9.733, p=0.004 and CC vs CT+TT: OR=3.339, 95% CI 1.369 to 8.145, p=0.008, respectively). In subgroup analysis, rs833061 was more likely to be a predictor of response to anti-VEGF therapy specifically when ranibizumab (RBZ) only regime was adopted or visual acuity (VA) was taken as the standardised assessment of outcome. No association with response to anti-VEGF treatment was detected for the other eight polymorphisms.

Conclusions

Pharmacogenetics of VEGF-A polymorphism rs833061 may play a positive role in response to anti-VEGF therapy for nAMD.

Influence of CFH, HTRA1 and ARMS2 polymorphisms in the response to intravitreal ranibizumab treatment for wet age-related macular degeneration in a Spanish population

AIM

To determine whether gene polymorphisms of the major genetic risk loci for age-related macular degeneration (AMD): ARMS2 (rs10490923), the complement factor H (CFH) (rs1410996) and HTRA1 (rs11200638) influence the response to a treatment regimen with ranibizumab for exudative AMD.

METHODS

This study included 100 patients (100 eyes) with exudative AMD. Patients underwent a treatment with ranibizumab injections monthly during three months. Reinjections were made when the best corrected visual acuity (BCVA) decrease five letters (ETDRS) or central subfield retinal thickness gained 100 µm in optical coherence tomography image. Genotypes (rs10490923, rs1410996 and rs11200638) were analyzed using TaqMan probes or polymerase chain reaction-restricted fragment length polymorphisms analysis.

RESULTS

There were no statistically significant differences in allelic distribution of CFH (rs1410996), ARMS2 (rs10490923) and HTRA1 (rs11200638) polymorphisms regarding to response to ranibizumab treatment.

CONCLUSION

Ranibizumab treatment response is not related to CFH (rs1410996), ARMS2 (rs10490923) and HTRA1 (rs11200638) poymorphisms.

Age-Related Macular Degeneration: Genetics and Biology

Age-related macular degeneration (AMD), widely prevalent across the globe, is a major stakeholder among adult visual morbidity and blindness, not only in the Western world but also in Asia. Several risk factors have been identified, including critical genetic factors, which were never imagined 2 decades ago. The etiopathogenesis is emerging to demonstrate that immune and complement-related inflammation pathway members chronically exposed to environmental insults could justifiably influence disease morbidity and treatment outcomes. Approximately half a dozen physiological and biochemical cascades are disrupted in the AMD disease genesis, eventually leading to the distortion and disruption of the subretinal space, subretinal pigment epithelium, and Bruch membrane, thus setting off chaos and disorder for signs and symptoms to manifest. Approximately 3 dozen genetic factors have so far been identified, including the recent ones, through powerful genomic technologies and large robust sample sizes. The noteworthy genetic variants (common and rare) are complement factor H, complement factor H-related genes 1 to 5, C3, C9, ARMS2/HTRA1, vascular endothelial growth factor A, vascular endothelial growth factor receptor 2/KDR, and rare variants (show causal link) such as TIMP3, fibrillin, COL4A3, MMP19, and MMP9. Despite the enormous amount of scientific information generated over the years, diagnostic genetic or biomarker tests are still not available for clinicians to understand the natural course of the disease and its management in a patient. However, further research in the field should reduce this gap not only by aiding the clinician but also through the possibilities of clinical intervention with complement pathway-related inhibitors entering preclinical and clinical trials in the near future.

Risk factors and biomarkers of age-related macular degeneration

A biomarker can be a substance or structure measured in body parts, fluids or products that can affect or predict disease incidence. As age-related macular degeneration (AMD) is the leading cause of blindness in the developed world, much research and effort has been invested in the identification of different biomarkers to predict disease incidence, identify at risk individuals, elucidate causative pathophysiological etiologies, guide screening, monitoring and treatment parameters, and predict disease outcomes. To date, a host of genetic, environmental, proteomic, and cellular targets have been identified as both risk factors and potential biomarkers for AMD. Despite this, their use has been confined to research settings and has not yet crossed into the clinical arena. A greater understanding of these factors and their use as potential biomarkers for AMD can guide future research and clinical practice. This article will discuss known risk factors and novel, potential biomarkers of AMD in addition to their application in both academic and clinical settings.

Ocular pharmacology

Ophthalmic diseases include both those analogous to systemic diseases (eg, inflammation, infection, neuronal degeneration) and not analogous (eg, cataract, myopia). Many anterior segment diseases are treated pharmacologically through eye drops, which have an implied therapeutic index of local therapy. Unlike oral dosage forms administered for systemic diseases, eyedrops require patients not only to adhere to treatment, but to be able to accurately perform-ie, instill drops correctly. Anatomical and physiological barriers make topical delivery to the anterior chamber challenging-in some cases more challenging than absorption through the skin, nasal passages, or gut. Treatment of the posterior segment (eg, vitreous, retina, choroid, and optic nerve) is more challenging due to additional barriers. Recently, intravitreal injections have become a standard of care with biologics for the treatment of macular degeneration and other diseases. Although the eye has esterases, hydroxylases, and transporters, it has relatively little CYP450 enzymes. Because it is challenging to obtain drug concentrations at the target site, ocular clinical pharmacokinetics, and thus pharmacokinetic-pharmacodynamic interactions, are rarely available. Ophthalmic pharmaceuticals require consideration of solubility, physiological pH, and osmolarity, as well as sterility and stability, which in turn requires optimal pharmaceutics. Although applied locally, ocular medications may be absorbed systemically, which results in morbidity and mortality (eg, systemic hypotension, bronchospasm, and bradycardia).

Pharmacogenetics of Complement Factor H Y402H Polymorphism and Treatment of Neovascular AMD with Anti-VEGF Agents: A Meta-Analysis

The purpose of this study is to investigate whether the Y402H polymorphism (rs1061170, a T-to-C transition at amino acid position 402) in the complement factor H (CFH) gene have a pharmacogenetics effect on the anti-vascular endothelial growth factor (VEGF) treatment for neovascular age-related macular degeneration (AMD). We performed a meta-analysis using databases including PubMed and EMBASE to find relevant studies. 13 published association studies were selected for this meta-analysis, including 2704 patients. For the CFH Y402H polymorphism, anti-VEGF treatment was much less effective in AMD patients with the CFH CC genotype (CC versus TT: odds ratio (OR) = 55, 95% confidence interval (CI), 0.31 to 0.95, P = 0.03; CC versus CT: OR = 0.60, 95% CI, 0.40 to 0.91, P = 0.02; and CC versus CT + TT: OR = 0.59, 95% CI, 0.38 to 0.90, P = 0.02, respectively). In subgroup analysis, CFH Y402H polymorphism was more likely to be a predictor of response for Caucasians (CC versus CT+TT: OR = 0.63, 95% CI, 0.42 to 0.95, P = 0.03). In conclusion, pharmacogenetics of CFH Y402H polymorphism may play a role in response to anti-VEGF treatment for neovascular AMD, especially for Caucasians.