Cytochrome oxidase 2D6 gene polymorphism in primary open-angle glaucoma with various effects to ophthalmic timolol

Effect of genotype on individual response to the pharmacological treatment of glaucoma: a systematic review and meta-analysis

The social impact of glaucoma is worth of note: primary open-angle glaucoma (POAG) is one of the leading causes of irreversible blindness worldwide, affecting some 68.56 million people with overall prevalence of 2.4%. Since one of the main risk factors for the development of POAG is the increase of intraocular pressure (IOP) causing retinal ganglion cells death, the medical treatment of POAG consists in the use of drugs endowed with neuroprotective effect and able to reduce IOP. These drugs include beta-blockers, prostaglandin analogues, carbonic anhydrase inhibitors, alpha or cholinergic agonists and rho kinase inhibitors. However, not all the patients respond to the same extent to the therapy in terms of efficacy and safety. Genetics and genome wide association studies have highlighted the occurrence of mutations and polymorphisms influencing the predisposition to develop POAG and its phenotype, as well as affecting the response to pharmacological treatment. The present systematic review and meta-analysis aims at identifying genetic variants and at verifying whether these can influence the responsiveness of patients to therapy for efficacy and safety. It follows the most updated Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 recommendations. The literature search was conducted consulting the most relevant scientific databases, i.e. PubMed/MEDLINE, Scopus, Web of Science and Public Health Genomics and Precision Health Knowledge Base up to June 14th, 2023. The search retrieved 1026 total records, among which eight met the eligibility criteria for inclusion in the analysis. The results demonstrated that the most investigated pharmacogenetic associations concern latanoprost and timolol, and that efficacy was studied more in depth than safety. Moreover, the heterogeneity of design and paucity of studies prompt further investigation in randomized clinical trials. In fact, adequately powered and designed pharmacogenetic association studies are needed to provide body of evidence with good certainty for a more appropriate use of medical therapy in POAG.PROSPERO registration: CRD42023434867.

Effect of CYP2D6*4, CYP2D6*10 polymorphisms on the safety of treatment with timolol maleate in patients with glaucoma

OBJECTIVES

Timolol maleate is used for the treatment of glaucoma and metabolized by cytochrome CYP2D6 in the liver. The aim of this study was the evaluation of the influence of CYP2D6*4 and CYP2D6*10 gene polymorphisms on the safety of medications containing 0.5% of timolol maleate as glaucoma treatment in patients with primary open-angle glaucoma (POAG).

METHODS

105 patients with POAG were prescribed glaucoma medications, containing 0.5% timolol maleate. The safety of glaucoma treatment was determined by electrocardiography (ECG) (to assess heart rate (HR) and PQ interval) and blood pressure (BP) measurements. The real-time polymerase chain reaction method was used for the detection of single nucleotide polymorphisms (SNP).

RESULTS

The risk of adverse drug reactions was higher in patients with the CYP2D6*4 GA genotype compared with GG: mean HR change at 1 month (2.88 ± 4.68 and 6.44 ± 5.57, p<0.001) and 6 months (5.14 ± 8.93 and 7.88 ± 5.65, p<0.001), mean PQ interval change at 1 (0.01 ± 0.031 and 0.02 ± 0.022, p=0.003) and 6 months (0.01 ± 0.032 and 0.02 ± 0.024, p=0.003). The risk of adverse drug reactions was higher in patients with the CYP2D6*10 CT genotype compared with CC: mean HR change at 1 month (2.94 ± 4.65 and 6.34 ± 5.66, p<0.001) and 6 months (5.20 ± 8.90 and 7.78 ± 5.75, p<0.001), mean PQ interval change at 1 (0.01 ± 0.032 and 0.02 ± 0.021, p=0.014) and 6 months (0.01 ± 0.033 and 0.02 ± 0.022, p=0.014).

CONCLUSIONS

CYP2D6*4 and CYP2D6*10 gene polymorphisms may affect a higher risk of timolol-induced bradycardia and increased PQ interval of treatment medications containing 0.5% of timolol maleate in patients with POAG.

Analysis of the Responsiveness of Latanoprost, Travoprost, Bimatoprost, and Tafluprost in the Treatment of OAG/OHT Patients

Aim

Within the clinical setting, some patients have been identified as lacking in response to PGAs. This meta-analysis study aimed to evaluate the responsiveness of latanoprost, travoprost, bimatoprost, and tafluprost in OAG/OHT patients, latanoprost nonresponders (LNRs), and the IOP-reducing efficacy and safety.

Methods

A literature search was conducted on PubMed, Embase, and the Cochrane Controlled Trials Register. The primary clinical endpoint was the number of responders at the end of the study. The secondary clinical endpoint was the IOP reduction at the endpoint from baseline. Safety evaluation included five common adverse events: conjunctival hyperemia, hypertrichosis, ocular burning, ocular itching, and foreign-body sensation.

Results

Eleven articles containing ten RCTs were included in this meta-analysis study. The results highlighted that, in the OAG/OHT population, there was no statistically significant difference in the responsiveness of the four PGAs. Bimatoprost had a better IOP-reducing efficacy than latanoprost. There was no significant difference in the IOP-reducing efficacy of travoprost, latanoprost, and tafluprost. In LNRs, the responsiveness of bimatoprost, travoprost, and latanoprost did not show statistical differences. Bimatoprost reduced IOP with a greater extent than latanoprost and travoprost in LNRs, while there was no significant difference in the IOP-reducing efficacy of travoprost and latanoprost. No serious adverse events occurred with the treatment of the four PGAs. The prevalence of conjunctival hyperemia due to bimatoprost or tafluprost was significantly higher than that of latanoprost. Other adverse events had no significant difference between the four drugs.

Conclusion

The existing studies cannot prove that latanoprost, travoprost, bimatoprost, and tafluprost have different responsiveness in OAG/OHT patients. Switching to bimatoprost or travoprost cannot achieve a significant improvement in responsiveness in LNRs. Bimatoprost has a better IOP-reducing efficacy than latanoprost and travoprost. No serious adverse events occurred during treatment with any medication we studied.

Efficacy of TIMOLOL nasal spray as a treatment for epistaxis in hereditary hemorrhagic telangiectasia. A double-blind, randomized, placebo-controlled trial

Hereditary hemorrhagic telangiectasia is a rare vascular genetic disease. Epistaxis is the most frequent and disabling manifestation, and timolol appears to be a new therapeutic option as non-selective beta-blockers have in vitro and in vivo anti-angiogenic properties. Our main objective was to evaluate the efficacy of TIMOLOL nasal spray as a treatment for epistaxis in hereditary hemorrhagic telangiectasia. This study is a single-center, randomized, phase 2, double-blind placebo-controlled study with an allocation ratio of 1:1. It was proposed to patients with hereditary hemorrhagic telangiectasia monitored at the French Reference Center, and we included patients aged over 18 years, diagnosed with hereditary hemorrhagic telangiectasia and epistaxis. The treatment was self-administered by the patient with a posology of one spray (50 µL) of timolol 0.5% or placebo in each nostril twice a day for 28 consecutive days. The primary efficacy endpoint was mean monthly epistaxis duration, assessed by monitoring epistaxis grids. A total of 58 patients were randomized and treated. The baseline characteristics were similar in the 2 groups. Mean monthly epistaxis duration measured at 3 months was not significantly different in the 26 patients receiving the drug in comparison with the placebo group (p = 0.54). Toxicity was low and no severe adverse events were reported. One limitation is that we included all HHT patients with nosebleeds and did not take into account history of nasal surgery or nasal crusts. Timolol, administered by nasal spray at a dose of 0.25 mg in each nostril twice a day for 28 consecutive days, did not improve epistaxis in patients with hereditary hemorrhagic telangiectasia at 4 months after the beginning of the treatment.

[Pharmacogenetics of timolol]

In recent years, β-adrenergic blockers have become the first choice drugs for glaucoma treatment. Timolol holds the main position among them, being a part of most combined antiglaucoma preparations. The use of timolol maleate in clinical practice may be accompanied by severe side effects affecting different organs and systems. The fact that cells with β-adrenergic receptors are widely common within the human body explains pharmacodynamic effects of timolol maleate. Because of these undesirable side effects, timolol maleate often evokes negative reaction from doctors and patients, which to certain extent limits its usage in ophthalmological practice. Obviously, efficacy and safety of timolol administration depends on individual characteristics making personalized approach necessary for every patient. Such particular approach, being the foundation of personalized medicine, increases efficacy and safety of timolol while reducing costs by using targeted doses.

In vitro metabolism of alectinib, a novel potent ALK inhibitor, in human: contribution of CYP3A enzymes

1. The in vitro metabolism of alectinib, a potent and highly selective oral anaplastic lymphoma kinase inhibitor, was investigated. 2. The main metabolite (M4) in primary human hepatocytes was identified, which is produced by deethylation at the morpholine ring. Three minor metabolites (M6, M1a, and M1b) were also identified, and a minor peak of hydroxylated alectinib (M5) was detected as a possible precursor of M4, M1a, and M1b. 3. M4, an important active major metabolite, was produced and further metabolized to M6 by CYP3A, indicating that CYP3A enzymes were the principal contributors to this route. M5 is possibly produced by CYP3A and other isoforms as the primary step in metabolism, followed by oxidation to M4 mainly by CYP3A. Alternatively, M5 could be oxidized to M1a and M1b via an NAD-dependent process. None of the non-CYP3A-mediated metabolism appeared to be major. 4. In conclusion, this study suggests that involvement of multiple enzymes in the metabolism of alectinib reduces its potential for drug-drug interactions.

Roles of CYP2C19 Gene Polymorphisms in Susceptibility to POAG and Individual Differences in Drug Treatment Response

Background

The aim of this study was to investigate the roles of cytochrome P450 2C19 (CYP2C19) polymorphisms in primary open-angle glaucoma (POAG) susceptibility and individual responses to drug treatment.

Material/Methods

This case-control study consisted of 93 cases with POAG and 125 controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze CYP2C19 single-nucleotide polymorphisms (SNPs). After timolol treatment, patients were classified into side effect (SE) group and non-side effect (NSE) group. According to drug treatment responses, patients were divided into 3 groups: excellent group (Ex) (IOP ≥8 mm Hg); utility group (Ut) (5 <IOP ≤8 mm Hg), and ineffective group (In) (IOP ≤5 mm Hg). Data analysis was performed using SPSS software.

Results

We found no statistical differences in the alleles and genotypes frequencies of CYP2C19 between the case group and the control group (both P>0.05). Frequencies of extensive metabolizer phenotype and poor metabolizer phenotype or poor metabolizer phenotype and intermediate metabolizer phenotype were significantly different between the SE group and NSE group (both P<0.05). The distribution of intermediate metabolizer phenotype and extensive metabolizer phenotype were significantly different among Ex group, Ut group, and In group (all P<0.05).

Conclusions

We found no evidence that CYP2C19 polymorphisms are associated with susceptibility to POAG. However, different CYP2C19 metabolizer phenotypes were identified and observed to have important effects on the individual differences in drug treatment response.

Personalized Medicine in Ophthalmology: From Pharmacogenetic Biomarkers to Therapeutic and Dosage Optimization

Rapid progress in genomics and nanotechnology continue to advance our approach to patient care, from diagnosis and prognosis, to targeting and personalization of therapeutics. However, the clinical application of molecular diagnostics in ophthalmology has been limited even though there have been demonstrations of disease risk and pharmacogenetic associations. There is a high clinical need for therapeutic personalization and dosage optimization in ophthalmology and may be the focus of individualized medicine in this specialty. In several retinal conditions, such as age-related macular degeneration, diabetic macular edema, retinal vein occlusion and pre-threshold retinopathy of prematurity, anti-vascular endothelial growth factor therapeutics have resulted in enhanced outcomes. In glaucoma, recent advances in cytoskeletal agents and prostaglandin molecules that affect outflow and remodel the trabecular meshwork have demonstrated improved intraocular pressure control. Application of recent developments in nanoemulsion and polymeric micelle for targeted delivery and drug release are models of dosage optimization, increasing efficacy and improving outcomes in these major eye diseases.

Breast cancer medications and vision: effects of treatments for early-stage disease

This review concerns the effects on vision and the eye of medications prescribed at three phases of treatment for women with early-stage breast cancer (BC): (1) adjuvant cytotoxic chemotherapy, (2) adjuvant endocrine therapy, and (3) symptomatic relief. The most common side effects of cytotoxic chemotherapy are epiphora and ocular surface irritation, which can be caused by any of several different regimens. Most notably, the taxane docetaxel can lead to epiphora by inducing canalicular stenosis. The selective-estrogen-receptor-modulator (SERM) tamoxifen, long the gold-standard adjuvant-endocrine-therapy for women with hormone-receptor-positive BC, increases the risk of posterior subcapsular cataract. Tamoxifen also affects the optic nerve head more often than previously thought, apparently by causing subclinical swelling within the first 2 years of use for women older than ∼50 years. Tamoxifen retinopathy is rare, but it can cause foveal cystoid spaces that are revealed with spectral-domain optical coherence tomography (OCT) and that may increase the risk for macular holes. Tamoxifen often alters the perceived color of flashed lights detected via short-wavelength-sensitive (SWS) cone response isolated psychophysically; these altered perceptions may reflect a neural-response sluggishness that becomes evident at ∼2 years of use. The aromatase inhibitor (AI) anastrozole affects perception similarly, but in an age-dependent manner suggesting that the change of estrogen activity towards lower levels is more important than the low estrogen activity itself. Based on analysis of OCT retinal thickness data, it is likely that anastrozole increases the tractional force between the vitreous and retina. Consequently, AI users, myopic AI users particularly, might be at increased risk for traction-related vision loss. Because bisphosphonates are sometimes prescribed to redress AI-induced bone loss, clinicians should be aware of their potential to cause scleritis and uveitis occasionally. We conclude by suggesting some avenues for future research into the visual and ocular effects of AIs, particularly as relates to assessment of cognitive function.

Association of CYP2D6 single-nucleotide polymorphism with response to ophthalmic timolol in primary open-angle Glaucoma--a pilot study

OBJECTIVES

We aimed to investigate whether CYP2D6 polymorphisms were associated with the intraocular pressure (IOP)-lowering effect and systemic complications (especially bradycardia) of ophthalmic timolol.

METHODS

One hundred twenty-three primary open-angle glaucoma subjects (123 eyes) were treated with 0.5% aqueous formulations of ophthalmic timolol. IOP and heart rate were measured before and after timolol administration. DNA was extracted from venous leukocytes of all the subjects. Two single-nucleotide polymorphisms (SNPs) of CYP2D6, for example, rs16947 (2850C>T, R296C) and rs1135840 (4180C>G, S486T), were detected by restriction fragment length polymorphism analysis.

RESULTS

Neither rs16947 (P = 0.339) nor rs1135840 (P = 0.903) genotype was statistically correlated with the IOP-lowering effect of timolol eye drops. The rs16947 genotype was significantly associated with occurrence of bradycardia in primary open-angle glaucoma patients (P = 0.021). The patients with rs16947 CT (P = 0.043) or TT (P = 0.043) were more inclined to bradycardia than those with rs16947 CC, although there was no significant difference between CT and TT (P = 0.177). The analysis of variance showed no significant difference in heart rate (P = 0.559) among GG, GC, and CC groups.

CONCLUSIONS

CYP2D6 SNP rs16947 may confer susceptibility to timolol-induced bradycardia. Patients with CC genotype were unlikely to suffer from timolol-induced bradycardia, whereas those with TT genotype were found to suffer from timolol-induced bradycardia.

Development of novel drugs for ocular diseases: possibilities for individualized therapy

In clinical ophthalmology, new and old drug regimens are available for the treatment of major eye diseases, including potentially blinding conditions, such as glaucoma, and various macular diseases. In glaucoma, therapeutic treatment mainly deals with control of intraocular pressure at low levels but the clinical courses of patients can be very variable. Very often, specific drug combinations and dosages have to be formulated for individual glaucoma patients. In neovascular age-related macular degeneration, choroidal neovascularization can lead to progressive and irreversible visual impairment if not treated early. In recent years, clinical trials using photodynamic therapy with verteporfin and various anti-VEGF antibodies, such as ranibizumab and bevacizumab, have enhanced the treatment outcomes of neovascular age-related macular degeneration. In diabetic macular edema, intravitreal triamcinolone acetonide and anti-VEGF therapy are effective in some patients. Again, responses to treatment are not uniform in all macular patients. Traditional herbal medicine has long been known to play a role in the practice of personalized formulations in Asia. Potential preventive and therapeutic effects have been claimed in individual eye patients. Meanwhile, advanced technologies in molecular biology have led to identification of genes associated with many eye diseases and development of the concept of individual medicine, in which the genotype of a person can be used as a basis for disease prediction or prophylactic treatments. Moreover, pharmacogenomic studies have demonstrated the association of various genotypes or haplotypes with responses to drug therapies, providing hope for tailormade personalized treatments. The combination of genotypic information with clinical features for the prescription of treatment modes in eye diseases is under vigorous research.

Molecular complexity of primary open angle glaucoma: current concepts

Glaucoma is a group of heterogeneous optic neuropathies with complex genetic basis. Among the three principle subtypes of glaucoma, primary open angle glaucoma (POAG) occurs most frequently. Till date, 25 loci have been found to be linked to POAG. However, only three underlying genes (Myocilin, Optineurin and WDR36) have been identified. In addition, at least 30 other genes have been reported to be associated with POAG. Despite strong genetic influence in POAG pathogenesis, only a small part of the disease can be explained in terms of genetic aberration. Current concepts of glaucoma pathogenesis suggest it to be a neurodegenerative disorder which is triggered by different factors including mechanical stress due to intra-ocular pressure, reduced blood flow to retina, reperfusion injury, oxidative stress, glutamate excitotoxicity, and aberrant immune response. Here we present a mechanistic overview of potential pathways and crosstalk between them operating in POAG pathogenesis.

Genetic diversity and medicinal drug response in eye care

BACKGROUND

Individual variation in drug response and adverse drug reactions are a serious problem in medicine. This inter-individual variation in drug response could be due to multiple factors such as disease determinants, environmental and genetic factors. Much has been published in the literature in recent years about the potential of pharmacogenetic testing and individualized medicine. The development of personalized medicine is truly an exciting area of research.

METHODS

This pharmacogenetic concept in ophthalmology has existed for more than a century. Although substantial studies that link genetic variants to inter-individual difference in drug response have been reported in several diseases such as cancer and heart diseases, such studies are progressing slowly in the eye field. In this short article, an attempt has been made to summarize these results.

RESULTS

Recently, there have been some small-scale studies that seem to associate the drug response to the genotype of patients in two major eye disorders, namely age-related macular degeneration (ARMD) and glaucoma.

CONCLUSION

These studies are still in their infancy, and do not suggest that a pharmacogenetic basis of drug development is a credible concept and can become reality in the future. This is because most drug responses involve a large number of genes that have several polymorphisms and it is unlikely that any one single gene dictates the drug response. Therefore, a polygenic approach, whole genome single nucleotide polymorphism (SNP) analysis and a molecular understanding of disease itself may provide a better insight in the future about genetic predisposing factors for adverse drug reactions.