Verteporfin photodynamic therapy and anti-angiogenic drugs: potential for combination therapy in exudative age-related macular degeneration

HIF-1α-dependent regulation of angiogenic factor expression in Müller cells by mechanical stimulation

Mechanical stress regulates various biological processes in cells, tissues, and organs as well as contributes to the pathogenesis of various diseases. The retina is subjected to mechanical stress imposed by intraocular pressure as well as by retinal hemorrhage and edema. Responses to mechanical stress have been studied in retinal pigment epithelial cells and Müller cells of the retina, with the former cells having been found to undergo a stress-induced increase in the expression of vascular endothelial growth factor (VEGF), which plays a key role in physiological and pathological angiogenesis in the retina. We here examined the effects of stretch stimulation on the expression of angiogenic factors in cultured human Müller cells. Reverse transcription and quantitative PCR analysis revealed that expression of the VEGF-A gene was increased by such stimulation in Müller cells, whereas that of the angiopoietin 1 gene was decreased. An enzyme-linked immunosorbent assay showed that stretch stimulation also increased VEGF secretion from these cells. Expression of the transcription factor HIF-1α (hypoxia-inducible factor-1α) was increased at both mRNA and protein levels by stretch stimulation, and the HIF-1α inhibitor CAY10585 prevented the effects of mechanical stress on VEGF-A gene expression and VEGF secretion. Furthermore, RNA-sequencing analysis showed that the expression of angiogenesis-related pathway genes was upregulated by stretch stimulation. Our results thus suggest that mechanical stress induces VEGF production in Müller cells in a manner dependent on HIF-1α, and that HIF-1α is therefore a potential therapeutic target for conditions such as diabetic retinopathy, age-related macular degeneration, and retinal vein occlusion.

YAP inhibitor verteporfin suppresses tumor angiogenesis and overcomes chemoresistance in esophageal squamous cell carcinoma

PURPOSE

Targeting angiogenesis is an attractive strategy for the effective treatment of cancer. This study aimed to investigate the anti-cancer activities of YAP inhibitor verteporfin (VP) in esophageal squamous cell carcinoma (ESCC) cells through its inhibitory effect on tumor angiogenesis.

METHODS

Cell proliferation, apoptosis, migration and invasion abilities were estimated by MTT, colony formation, DAPI staining, wound healing and transwell assays, respectively. Human umbilical vein endothelial cell (HUVEC) tube formation assay and chick embryo chorioallantoic membrane (CAM) model were used to observe angiogenesis in vitro and in vivo. The interactions between ESCC cells and HUVECs were assessed by cell chemotactic migration and adhesion assays. The expression levels of angiogenesis-related molecules were detected by Western blot.

RESULTS

We found that VP was potential to inhibit ESCC cell proliferation, migration, invasion and induce apoptosis in the dose-dependent fashion. VP also significantly suppressed proliferation, migration, and tube formation of HUVECs and promoted apoptosis of HUVECs, and reduced angiogenesis in CAM. Moreover, VP inhibited ESCC cell-induced angiogenesis in vitro by decreasing HUVEC chemotactic migration, adhesion and tube formation, and also reduced ESCC cell-induced neovascularization of the CAM in vivo. In addition, VP suppressed the expression of pro-angiogenic molecules such as VEGFA, MMP-2 and β-catenin in ESCC cells. Furtherly, VP increased the chemosensitivity of ESCC-resistant cells to paclitaxel (PTX). The combination of VP and PTX attenuated the resistant cell-mediated angiogenesis in vitro and in vivo.

CONCLUSION

These results reveal for the first time that VP potently inhibits malignant progression and overcomes chemoresistance of ESCC cells via inhibition of tumor angiogenesis. It provides insight into a new strategy for the treatment of ESCC that VP could be a potential drug candidate for targeting tumor angiogenesis.

Novel Programmed Cell Death as Therapeutic Targets in Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a leading cause of severe visual loss among the elderly. AMD patients are tormented by progressive central blurring/loss of vision and have limited therapeutic options to date. Drusen accumulation causing retinal pigment epithelial (RPE) cell damage is the hallmark of AMD pathogenesis, in which oxidative stress and inflammation are the well-known molecular mechanisms. However, the underlying mechanisms of how RPE responds when exposed to drusen are still poorly understood. Programmed cell death (PCD) plays an important role in cellular responses to stress and the regulation of homeostasis and diseases. Apart from the classical apoptosis, recent studies also discovered novel PCD pathways such as pyroptosis, necroptosis, and ferroptosis, which may contribute to RPE cell death in AMD. This evidence may yield new treatment targets for AMD. In this review, we summarized and analyzed recent advances on the association between novel PCD and AMD, proposing PCD's role as a therapeutic new target for future AMD treatment.

Potential Therapeutic Benefit of NAD+ Supplementation for Glaucoma and Age-Related Macular Degeneration

Glaucoma and age-related macular degeneration are leading causes of irreversible blindness worldwide with significant health and societal burdens. To date, no clinical cures are available and treatments target only the manageable symptoms and risk factors (but do not remediate the underlying pathology of the disease). Both diseases are neurodegenerative in their pathology of the retina and as such many of the events that trigger cell dysfunction, degeneration, and eventual loss are due to mitochondrial dysfunction, inflammation, and oxidative stress. Here, we critically review how a decreased bioavailability of nicotinamide adenine dinucleotide (NAD; a crucial metabolite in healthy and disease states) may underpin many of these aberrant mechanisms. We propose how exogenous sources of NAD may become a therapeutic standard for the treatment of these conditions.

Verteporfin blocks Clusterin which is required for survival of gastric cancer stem cell by modulating HSP90 function

Gastric cancer stem cell (GCSC) is implicated in gastric cancer relapse, metastasis and drug resistance. However, the key molecule(s) involved in GCSC survival and the targeting drugs are poorly understood. We discovered increased secreted clusterin (S-Clu) protein expression during the sphere-forming growth of GCSC via mass spectrometry. Overexpression of clusterin was detected in 69/90 (77%) of primary GC tissues and significantly associated with T stage, lymph node metastasis and TNM stage. Depletion of clusterin (Clu, the full-length intracellular clusterin) led to the declustering of GCSC tumorspheres and apoptosis of GCSC. Subsequently, we found clusterin was in complex with heat shock protein 90 beta (HSP90) and involved in regulating the cellular level of HSP90 client proteins. Furthermore, by screening a collection of drugs/inhibitors, we found that verteporfin (VP), a phototherapy drug, blocked clusterin gene expression, decreased the HSP90 client proteins and caused cell death of GCSC. VP treatment is more effective in eradicating GCSCs than in killing GC cells. Both clusterin silencing or VP treatment deterred tumor growth in human GCSC xenografts. These findings collectively suggest that GC patients can promptly benefit from clusterin-targeted therapy as well as VP treatment in combination with or subsequent to conventional chemotherapy for reducing mortality of GC.

Comparison of the efficacy of anti-VEGF monotherapy versus PDT and intravitreal anti-VEGF combination treatment in AMD: a Meta-analysis and systematic review

AIM

To compare the effect of anti-vascular endothelial growth factor (VEGF) monotherapy versus photodynamic therapy (PDT) and anti-VEGF combination treatment in age-related macular degeneration (AMD).

METHODS

A computerized online search was performed using PubMed, Web of Science and the Cochrane Library. Studies that compared anti-VEGF monotherapy with PDT and anti-VEGF combination treatment of AMD and were designed as randomized controlled trials were included. The means and standard deviations of the best-corrected visual acuity (BCVA), central retinal thickness (CRT), number of treatments and proportions of patients who gained BCVA ≥15, 10, 5, or 0 letters at 12(th) month were extracted. A systematic review and Meta-analysis of the comparison of the two approaches was conducted using Review Manager 5.2. Subgroup. A sensitivity analysis was also performed.

RESULTS

Eight studies were included. When the subgroup and sensitivity analysis was conducted, the results indicated that in the findings that included the monotherapy group and PDT (standard fluence, SF) group of Kaiser's study, the patients in the monotherapy group had a better BCVA compared with the combination group at 12(th) month in the PDT (SF) subgroup [weighted mean difference (WMD): 3.54; 95%CI: 0.36 to 6.73; P=0.03], and there were more patients who gained ≥15 letters of BCVA in the monotherapy group compared with the combination group in the total result [odds ratio (OR): 1.41; 95%CI: 1.02 to 1.95; P=0.04]. The same conclusion was obtained in the total result that included the monotherapy group and PDT (reduced fluence, RF) group of Kaiser's study (OR: 1.56; 95%CI: 1.13 to 2.15; P=0.007). However, there were no significant differences in the other indexes between the two therapies.

CONCLUSION

We found that anti-VEGF monotherapy is more effective on the recovery of visual acuity than combination therapy and more researches with lager sample size should be performed to study on the effect of the two therapy approaches on CRT and number of injections.

Combined therapy (intravitreal bevacizumab plus verteporfin photodynamic therapy) versus intravitreal bevacizumab monotherapy for choroidal neovascularization due to age-related macular degeneration: a 1-year follow-up study

PURPOSE

To assess the efficacy and safety of combined intravitreal bevacizumab and low-fluency-rate photodynamic therapy (PDT) in the treatment of choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD) and to compare it with intravitreal bevacizumab monotherapy.

METHODS

A total of 62 eyes of 62 patients with angiographic evidence of CNV were divided into 2 groups: the eyes of one group were treated with a combined therapy of 1 intravitreal bevacizumab injection (1.25 mg) and PDT within 7 days; the eyes of the other group received intravitreal bevacizumab monotherapy. Clinical evidence of complications, best-corrected visual acuity (BVCA) and fluorescein leakage were evaluated. Best-corrected visual acuity and optical coherence tomography (OCT) were tested monthly and followed for 12 months.

RESULTS

In the combined group the mean BCVA increased from 0.61 logMAR before the treatment to 0.54 logMAR at 12 months' follow-up. In the monotherapy group the mean BCVA increased from 0.65 logMAR to 0.60 logMAR at 12 months' follow-up. There was no significant difference in visual acuity outcomes between groups (P > 0.05). In the combined group the mean number of treatments was 1.19 per patient; in the monotherapy group, 5.31 per patient (P < 0.01).

CONCLUSIONS

Combined therapy appears to be an effective option for CNV associated with AMD treatment allowing a significant reduction of intravitreal injections.

Advances in pharmacotherapy for wet age-related macular degeneration

INTRODUCTION

In developed countries, neovascular age-related macular degeneration (AMD) is the leading cause of irreversible central blindness. Although AMD pathogenesis is complex and still not fully understood, many involved mechanisms are already partially known and could be promising targets for future therapies. Currently, anti-VEGF drugs are the standard care of this condition.

AREAS COVERED

This review summarizes both the current available and the emerging pharmacological therapies for the management of neovascular AMD. At first, we briefly focused on anti-VEGF compounds that are commonly used. Then, we reviewed the mechanisms of action and potential advantages of new candidate drugs that are being evaluated in clinical trials.

EXPERT OPINION

Although anti-VEGF drugs have shown mild-term good efficacy and safety profile in the treatment of neovascular AMD, they are far away from being a perfect therapy. Pharmacological research should focus on finding new molecular targets in the AMD pathogenetical pathway and on developing longer lasting agents or new drug delivery systems. Besides the development of new drugs, a better characterization of patients is also needed, taking into account variables such as choroidal neovascularization subtypes and genetic factors, in order to identify a tailored treatment for each patient.

Ranibizumab plus verteporfin photodynamic therapy in neovascular age-related macular degeneration: 12 months of retreatment and vision outcomes from a randomized study

PURPOSE

To investigate the injection frequency and visual acuity (VA) outcomes with combination therapy (ranibizumab plus verteporfin photodynamic therapy, PDT) versus monotherapy (ranibizumab).

METHODS

A total of 40 patients with exudative age-related macular degeneration were randomized 1:1 to ranibizumab 0.3 mg plus single standard verteporfin PDT or ranibizumab 0.3 mg plus sham PDT. Ranibizumab was administered 3 times monthly followed by 'as needed' to month 12 based on predetermined vision/anatomical criteria. Retreatment rates, VA outcomes and safety were assessed.

RESULTS

During months 3-12, combination therapy patients required fewer ranibizumab injections (mean 1.3) compared with monotherapy patients (2.8). Mean VA improved by 9.0 letters with combination therapy versus 7.5 letters in the monotherapy group at month 12. Both treatment regimens were well tolerated.

CONCLUSION

The need for ranibizumab retreatment might be reduced by administering a single verteporfin PDT on the same day as the first ranibizumab injection, without compromising VA outcomes or safety.

Potent and specific antitumor effect of CEA-targeted photoimmunotherapy

Conventional photodynamic therapy (PDT) for cancer is limited by the insufficient efficacy and specificity of photosensitizers. We herein describe a highly effective and selective tumor-targeted PDT using a near-infrared (NIR) photosensitizer, IRDye700DX, conjugated to a human monoclonal antibody (Ab) specific for carcinoembryonic antigen (CEA). The antitumor effects of this Ab-assisted PDT, called photoimmunotherapy (PIT), were investigated in vitro and in vivo. The Ab-IRDye conjugate induced potent cytotoxicity against CEA-positive tumor cells after NIR-irradiation, whereas CEA-negative cells were not affected at all, even in the presence of excess photoimmunoconjugate. We found an equivalent phototoxicity and a predominant plasma membrane localization of Ab-IRDye after both one and six hours of incubation. Either no or little caspase activation and membrane peroxidation were observed in PIT-treated cells and a panel of scavengers for reactive oxygen species showed only partial inhibition of the phototoxic effect. Strikingly, Ab-IRDye retained significant phototoxicity even under hypoxia. We established a xenograft model, which allowed us to sensitively investigate the therapeutic efficacy of PIT by non-invasive bioluminescence imaging. Luciferase-expressing MKN-45-luc human gastric carcinoma cells were subcutaneously implanted into both flanks of nude mice. NIR-irradiation was performed for only the tumor on one side. In vivo imaging and measurement of the tumor size revealed that a single PIT treatment, with intraperitoneal administration of Ab-IRDye and subsequent NIR-irradiation, caused rapid cell death and significant inhibition of tumor growth, but only on the irradiated side. Together, these data suggest that Ab-IRDye-mediated PIT has great potential as an anticancer therapeutics targeting CEA-positive tumors.

In vivo photoactivation without "light": use of Cherenkov radiation to overcome the penetration limit of light

PURPOSE

The poor tissue penetration of visible light has been a major barrier for optical imaging, photoactivatable conversions, and photodynamic therapy for in vivo targets with depths beyond 10 mm. In this report, as a proof-of-concept, we demonstrated that a positron emission tomography (PET) radiotracer, 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)FDG), could be used as an alternative light source for photoactivation.

PROCEDURES

We utilized (18)FDG, which is a metabolic activity-based PET probe, as a source of light to photoactivate caged luciferin in a breast cancer animal model expressing luciferase.

RESULTS

Bioluminescence produced from luciferin allowed for the real-time monitoring of Cherenkov radiation-promoted uncaging of the substrate.

CONCLUSION

The proposed method may provide a very important option for in vivo photoactivation, in particular for activation of photosensitizers for photodynamic therapy and eventually for combining radioisotope therapy and photodynamic therapy.

New insights into the mechanisms for photodynamic therapy-induced cancer cell death

Photodynamic therapy (PDT) is a promising therapeutic modality for cancer treatment; however, a more detailed understanding is needed to improve the clinical use of this therapy. PDT induces cancer cell death by apoptosis, necrosis, and autophagy, and these mechanisms can be concurrently occurred. PDT destroys cancer cells by inducing apoptosis through diverse signaling pathways coupled with Bcl-2 family members, caspases, and apopotosis-inducing factor. When the apoptotic pathway is unavailable, PDT can cause cancer cell death through induction of a necrotic or autophagic mechanism. Autophagy is occurred in a Bax-independent manner and can be stimulated in parallel with apoptosis. PDT directly destroys cancer cells by inducing either apoptotic or necrotic death. PDT also can induce autophagy as a death or a survival mechanism. These mechanisms are dependent on a variety of parameters including the nature of the photosensitizer, PDT dose, and cell genotype. Understanding the complex cross talk between these pathways may improve the effectiveness of PDT. Here, we discuss the interplay between these mechanisms based on recent evidence and suggest prospects with regard to advances in PDT.

Angiostatic kinase inhibitors to sustain photodynamic angio-occlusion

Targeted angiostatic therapy receives major attention for the treatment of cancer and exudative age-related macular degeneration (AMD). Photodynamic therapy (PDT) has been used as an effective clinical approach for these diseases. As PDT can cause an angiogenic response in the treated tissue, combination of PDT with anti-angiogenic compounds should lead to improved therapy. This study was undertaken to test the clinically used small molecule kinase inhibitors Nexavar® (sorafenib), Tarceva® (erlotinib) and Sutent® (sunitinib) for this purpose, and to compare the results to the combination of Visudyne®-PDT with Avastin® (bevacizumab) treatment. When topically applied to the chicken chorioallantoic membrane at embryo development day (EDD) 7, a clear inhibition of blood vessel development was observed, with sorafenib being most efficient. To investigate the combination with phototherapy, Visudyne®-PDT was first applied on EDD11 to close all <100 μm vessels. Application of angiostatics after PDT resulted in a significant decrease in vessel regrowth in terms of reduced vessel density and number of branching points/mm(2) . As the 50% effective dose (ED50) for all compounds was approximately 10-fold lower, Sorafenib outperformed the other compounds. In vitro, all kinase inhibitors decreased the viability of human umbilical vein endothelial cells. Sunitinib convincingly inhibited the in vitro migration of endothelial cells. These results suggest the therapeutic potential of these compounds for application in combination with PDT in anti-cancer approaches, and possibly also in the treatment of other diseases where angiogenesis plays an important role.

Ranibizumab monotherapy versus single-session verteporfin photodynamic therapy combined with as-needed ranibizumab treatment for the management of neovascular age-related macular degeneration

PURPOSE

To compare verteporfin photodynamic therapy combined with intravitreal ranibizumab (combination therapy) versus ranibizumab monotherapy for management of neovascular age-related macular degeneration.

METHODS

Thirty patients (40 eyes) with neovascular age-related macular degeneration were prospectively allocated to combination therapy or monotherapy. In monotherapy, the induction phase consisted of 3 consecutive monthly ranibizumab injections (0.5 mg), while the combination therapy had a single session of photodynamic therapy with intravitreal ranibizumab. Follow-up treatment for either group consisted only of additional as-needed ranibizumab injections. The main outcome measure was that a proportion of eyes losing <15 letters of visual acuity after 12 months.

RESULTS

Except for 1 eye in combination therapy, all eyes in both groups lost <15 letters of visual acuity. At 12 months, there was a mean gain of +12 letters and +3.2 letters for monotherapy and combination therapy, respectively (relative percent change of 32% vs. 7%, P = 0.03). Anatomical improvement was similar in both groups. After induction, the time until ranibizumab retreatment was longer for combination therapy (P = 0.002) while ranibizumab injections were required more frequently with monotherapy (P = 0.015).

CONCLUSION

Ranibizumab monotherapy showed greater improvement in visual acuity versus combination therapy. However, combination therapy required fewer ranibizumab injections. Larger trials need to confirm the findings of this pilot study.

Combined intravitreal ranibizumab and verteporfin photodynamic therapy versus ranibizumab alone for the treatment of age-related macular degeneration

PURPOSE

To compare same-day combined therapy of photodynamic therapy with verteporfin (PDT-V) and intravitreal ranibizumab versus monotherapy with ranibizumab for the treatment of choroidal neovascularization.

METHODS

IN THIS PROSPECTIVE STUDY, THE TOTAL NUMBER OF EYES WAS RANDOMIZED INTO TWO GROUPS: in the first, treatment consisted of a combined therapy of PDT-V and ranibizumab 0.5 mg on the same day; in the second, ranibizumab 0.5 mg in 3 monthly injections. Best-corrected visual acuity (BCVA) and central macular thickness (CMT) on optical coherence tomography (OCT) were recorded before and 6 months after treatment.

RESULTS

A total of 47 eyes of 47 subjects were enrolled in the study. In the combined-therapy group (group 1), the mean baseline BCVA ± standard deviation (SD) was 32.65 ± 11.09 letters (Snellen equivalent, 20/59); in the ranibizumab-alone group (group 2), 29.13 ± 9.03 letters (20/70). At 6 months' follow-up, in group 1 the mean baseline BCVA was 39.06 ± 10.12 letters (20/42); in group 2, 33.87 ± 12.06 letters (20/57). Improvement was significant in both group 1 (P = 0.03) and group 2 (P = 0.002). In group 1, the mean CMT at baseline ± SD was 315 ± 95.49 μm; in group 2, 306.33 ± 71.61 μm. At 6 months' follow-up, in group 1 it was 202 ± 52.02 μm; in group 2, 226 ± 65.58 μm. Reduction was significant in both group 1 (P = 0.0007) and group 2 (P = 0.00001). After 6-months, the rate of retreated eyes was 29.4% in group 1 and 43.3% in group 2. The need for retreatment did not depend on the treatment protocol (P = 0.34).

CONCLUSIONS

From a functional and anatomic point of view, the two treatments showed equivalent efficacy, with fewer retreatments in group 1. No serious adverse events, such as retinal detachment, endophthalmitis, or ocular hypertension occurred in either group.

Effects of combination therapy with verteporfin photodynamic therapy and ranibizumab in patients with age-related macular degeneration

PURPOSE

This open-label, prospective, small-scale study investigated the benefits of same-day verteporfin and intravitreal ranibizumab in patients with predominantly classic, minimally classic or occult subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration.

METHODS

Patients received verteporfin at baseline and at month 3, if leakage persisted. Ranibizumab (0.5 mg) was given at baseline and months 1, 2 and 3, and thereafter at monthly intervals if required. Same-day ranibizumab was given ≥ 1 hr after verteporfin.

RESULTS

Fifteen patients [11 male, four female; mean age 75.5 years (range 54-94 years)] were treated. At day 360, mean visual acuity (VA) had improved by 10.9 letters. An increase of ≥ 15 and ≥ 30 letters (i.e. ≥ 3 and ≥ 6 lines) was observed in seven (47%) patients and one patient (7%), respectively. Mean central retinal thickness (CRT) decreased by 85 μm. At days 7, 14 and 30, CNV perfusion was absent in 14/15 patients. Mean lesion area had reduced from baseline by 23.1% at day 120, 25.5% at day 180 and 23.6% at day 360. There were no visual safety concerns and intraocular pressures remained normal. Only two serious adverse events were recorded over the 12-month period, and neither was considered to be related to treatment.

CONCLUSION

Same-day verteporfin plus ranibizumab improved VA, reduced CRT, prevented CNV perfusion and reduced lesion area safely over 12 months. Further investigation is warranted to confirm whether this combination improves long-term vision and reduces the need for retreatment.

Combined treatment of photodynamic therapy and bevacizumab for choroidal neovascularization secondary to age-related macular degeneration

Purpose

To evaluate the outcome of a combined photodynamic therapy and intravitreal injection of bevacizumab in choroidal neovascularization secondary to age-related macular degeneration.

Methods

Photodynamic therapy (PDT) was administered to 28 eyes followed by 3 consecutive bevacizumab injections. Patients were followed-up for more than 12 months. At baseline, 1, 3, 6, and 12 months post PDT, visual acuity (VA) and central macular thickness were measured using optical coherence tomography.

Results

The mean VA was significantly improved from logarithm of the minimal angle of resolution 0.86 at baseline to 0.69 at 1 month (p = 0.011), 0.63 at 3 months (p = 0.003), 0.64 at 6 months (p = 0.004) and 0.60 at 12 months (p < 0.001). Central macular thickness decreased significantly from 328.3 µm at baseline to 230.0 µm at 6 months and 229.9 µm at 1 year (p < 0.001). Reinjection mean number was 0.4 for 6 months and 0.8 for 12 months. By 1 year, retreatment was performed in 10 eyes (36%).

Conclusions

PDT combined with three consecutive intraviteal bevacizumab injections was effective in improving VA and reducing central macular thickness.

Current and emerging therapies for the treatment of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of vision loss in the industrialized world. In the last few decades, the mainstay of treatment for choroidal neovascularization (CNV) due to AMD has been thermal laser photocoagulation. In the last decade, photodynamic therapy with verteporfin extended treatment for more patients. While both of these treatments have prevented further vision loss in a subset of patients, improvement in visual acuity is rare. Anti-vascular endothelial growth factor A (VEGF) therapy has revolutionized the treatment of AMD-related CNV. Pegaptanib, an anti-VEGF aptamer prevents vision loss in CNV, although the performance is similar to that of photodynamic therapy. Ranibizumab, an antibody fragment and bevacizumab, a full-length humanized monoclonal antibody against VEGF have both shown promising results with improvements in visual acuity with either agent. VEGF trap, a modified soluble VEGF receptor analogue, binds VEGF more tightly than all other anti-VEGF agents and has also shown promising results in early trials. Other treatment strategies to decrease the effect of VEGF have used small interfering ribonucleic acid (RNA) to inhibit VEGF production and VEGF receptor production. Steroids, including anecortave acetate in the treatment and prevention of CNV, have shown promise in controlled trials. Receptor tyrosine kinase inhibitors, such as vatalanib, inhibit downstream effects of VEGF, and have been effective in the treatment of CNV in early studies. Squalamine lactate inhibits plasma membrane ion channels with downstream effects on VEGF, and has shown promising results with systemic administration. Other growth factors, including pigment epithelium-derived growth factor that has been administered via an adenoviral vector has shown promising initial results. In some patients ciliary neurotrophic factor is currently being studied for the inhibition of progression of geographic atrophy. Combination therapy has been investigated, and may prove to be more effective in the management of AMD-associated CNV. Ongoing and future studies will be crucial for optimizing the treatment of patients with AMD.

Baicalein significantly protects human retinal pigment epithelium cells against H₂O₂-induced oxidative stress by scavenging reactive oxygen species and downregulating the expression of matrix metalloproteinase-9 and vascular endothelial growth factor

PURPOSE

Age-related macular degeneration is a leading cause of blindness in the elderly. At a later stage, neovascular or exudative age-related macular degeneration can lead to severe central vision loss that is related to aging-associated cumulative oxidative stress of the human retinal pigment epithelium (hRPE) cells. Early prevention with antioxidants is mandatory. The aim of this study was to determine whether and how baicalein can act as an antioxidant.

METHODS

The methods used included lactate dehydrogenase, 2′,7′-dichloro-fluorescein diacetate, or enzyme-linked immunosorbent assay to measure cell viability, oxygen free radical levels, or the levels of vascular endothelial growth factor (VEGF)/matrix metalloproteinase-9 (MMP-9), respectively.

RESULTS

H₂O₂ dose-dependently reduced the cell viability of hRPE cells. This negative effect was dose-dependently (with a lower effect at 20µM) and significantly counteracted by pretreatment with baicalein (50µM). Treatment with H₂O₂ significantly stimulated the formation of oxygen free radicals. This increase was dose-dependently and significantly blunted by baicalein. Further, treatment with a sublethal dose of H₂O₂ was associated with an upregulation in the levels of VEGF and MMP-9. The increases in these proteins were also dose-dependently (with a lower effect at 20µM) and significantly (50µM) blunted by pretreatment with baicalein.

CONCLUSION

This study supports an antioxidative role for baicalein whereby it protects hRPE cells against H₂O₂-induced oxidative stress by downregulating the levels of VEGF and MMP-9, which are increased by H₂O₂.

Efficacy of intravitreal bevacizumab combined with photodynamic therapy for polypoidal choroidal vasculopathy

PURPOSE

To compare the efficacy of photodynamic therapy (PDT) with or without intravitreal bevacizumab injection for polypoidal choroidal vasculopathy.

DESIGN

Retrospective, comparative, interventional case series.

METHODS

We included 146 eyes of 146 patients with treatment-naïve polypoidal choroidal vasculopathy including the subfoveal region treated with PDT monotherapy or combined with intravitreal bevacizumab injection. Treatments were chosen according to the time period. For eyes that received combination therapy, bevacizumab (1.25 mg) was administrated 1 day before PDT. All eyes were followed up for at least 12 months. Ophthalmic evaluations, including measurement of the best-corrected visual acuity and optical coherence tomography, were performed at every visit. Indocyanine green angiography and fluorescein angiography were performed every 3 months.

RESULTS

Sixty-one eyes were treated with PDT combined with bevacizumab and 85 eyes were treated with PDT monotherapy. The mean best-corrected visual acuity was significantly better in the combined treatment group than in the monotherapy group at 3 months (P = .0016), 6 months (P = .028), 9 months (P = .038), and 12 months (P = .048). However, lesions resolved in 78.7% of eyes in the combined group and in 75.3% in the monotherapy group; the recurrence rates were 43.8% and 40.6%, respectively, and did not differ significantly. The rate of development of subretinal hemorrhage within 1 month from the initial treatment was significantly lower in the combined group than in the PDT monotherapy group (4.5% vs 17.7%; P = .023).

CONCLUSIONS

Photodynamic therapy combined with bevacizumab injection offers significantly better early visual outcomes than PDT alone. Combined treatment did not affect the resolution and recurrence of lesions; however, it decreased the rate of development of PDT-related hemorrhages.

Combination therapy using verteporfin and ranibizumab; optimizing the timing in the CAM model

Combining photodynamic therapy (PDT) using verteporfin (Visudyne) with ranibizumab (Lucentis) can optimize the overall treatment outcome by providing more efficacy in vessel closure, and thus reduce the need for retreatment in patients with wet age-related macular degeneration. In this preclinical study in the chorioallantoic membrane (CAM) of the chicken embryo, we compare the vascular occlusion effects of verteporfin and ranibizumab as monotherapies with those observed in the combined therapy. In order to optimize the combination therapy, we varied the timing and sequence of the PDT and antivascular endothelial growth factor modalities. We observed that 1 day after PDT, the smaller blood vessels (Ø < 70 microm) of the CAM were selectively occluded, but as early as 2 days after PDT, both significant reperfusion and regrowth of new vessels were observed. Both these phenomena could be significantly delayed by application of ranibizumab. Ranibizumab itself did not induce any vascular occlusion. Under the applied conditions of combination therapy, the occlusion of the targeted blood vessels could be significantly extended to 3 days in this model compared with 1 day in the case of verteporfin monotherapy. Thus, in the present preclinical study, we demonstrate that for the applied conditions, the optimal time to administer ranibizumab is 24 h after PDT.

Verteporfin PDT for subfoveal occult CNV in AMD: two-year results of a randomized trial

OBJECTIVE

To determine whether verteporfin photodynamic therapy (PDT) can safely reduce the risk of vision loss in patients with subfoveal occult with no classic choroidal neovascularization (CNV) due to age-related macular degeneration.

RESEARCH DESIGN AND METHODS

Eligible patients were > or =50 years of age with lesion size < or =6 disc areas and best-corrected vision 20/40-20/200. A total of 364 patients with occult with no classic CNV were randomly assigned 2 : 1 to verteporfin PDT (n = 244) or placebo (n = 120). The primary outcome measures were loss of > or =15 and > or =30 letters of visual acuity (VA) from baseline at 12 and 24 months.

CLINICAL TRIAL REGISTRATION

This study was registered with ClinicalTrials.gov on 20 July 2005. ClinicalTrials.gov identifier: NCT00121407.

RESULTS

A total of 37% and 47% of verteporfin-treated patients versus 45% and 53% of placebo recipients lost > or =15 letters of VA at month 12 and month 24, respectively; 16% and 23% of verteporfin-treated patients versus 17% and 25% of placebo recipients lost > or =30 letters at month 12 and month 24, respectively. These differences were not statistically significant. Four (1.6%) verteporfin-treated patients and one placebo patient (who received verteporfin in error) experienced an acute severe VA decrease; all five patients recovered some degree of vision. No unexpected ocular or systemic adverse events were identified.

CONCLUSIONS

Verteporfin PDT in the treatment of occult with no classic CNV was safe and well-tolerated. The differences between the two groups in the primary efficacy variables were not significant. Baseline characteristics and patient selection methods may have contributed to the small treatment effect.

Age-related macular degeneration: current treatments

Purpose:

Although important progress has been made in understanding age-related macular degeneration (AMD), management of the disease continues to be a challenge. AMD research has led to a widening of available treatment options and improved prognostic perspectives. This essay reviews these treatment options.

Design:

Interpretative essay.

Methods:

Literature review and interpretation.

Results:

Current treatments to preserve vision in patients with non-exudative AMD include antioxidant vitamins and mineral supplementations. Exudative AMD is currently most often treated monthly with anti-VEGF intravitreal injections. However, investigators are beginning to experiment with combination therapy and surgical approaches in an attempt to limit the number of treatment and reduce the financial burden on the health care system.

Conclusion:

By better understanding the basis and pathogenesis of AMD, newer therapies will continue to be developed that target specific pathways in patients with AMD, with the hoped for outcome of better management of the disease and improved visual acuity.

Successful combined photodynamic and intravitreal avastin therapy for subfoveal choroidal neovascularization in a child

PURPOSE

To report the results of combined photodynamic therapy with verteporfin and intravitreal Avastin delivered on the same day in the treatment of juvenile subfoveal choroidal neovascularization.

METHODS

Photodynamic therapy with Visudyne at standard fluence rates and intravitreal Avastin were successfully completed under topical anesthesia in a single day treatment session in an 11-year-old girl with subfoveal choroidal neovascularization.

PATIENT

A cooperative 11-year-old girl noted sudden vision loss in her right eye with a previous history of a small nonspecific extrafoveal inferior scar, and was noted to have developed an acute subfoveal choroidal neovascular membrane.

RESULTS

The subfoveal choroidal neovascular membrane regressed without any additional therapy or recurrence over an 18-month period and with recovery of 20/20 vision. There were diffuse mild pigmentary changes in the region of the previous choroidal neovascularization.

CONCLUSION

Choroidal neovascularization in juvenile patients may respond well to a combined photodynamic and intravitreal Avastin therapy delivered in a single day session with excellent recovery of vision and without the need for frequent multiple treatments, which would be difficult in this age group.

Combination photodynamic therapy and intravitreal ranibizumab in neovascular AMD in a north Indian population: a pilot study

PURPOSE

To evaluate photodynamic therapy (PDT) with verteporfin along with intravitreal Ranibizumab in treatment of neovascular age related macular degeneration.

METHODS

This prospective interventional care series included 16 patients (17 eyes) of choroidal neovascularization secondary to neovascular AMD, who were treated with PDT with verteporfin followed by an injection of 0.5mg Ranibuzimab on the same day. The main outcome measures were best corrected visual acuity (VA) as recorded by both Snellen's and ETDRS charts (logMAR), contrast sensitivity (Pelli-Robson Chart), retreatment frequency and frequency of side effects.

RESULTS

Seventeen eyes underwent PDT with verteporfin and intravitreal 0.5mg Ranibizumab, following PDT. Patients were followed up every month for a total period of 6 months. Initial VA ranged from CF to 20/32 and final acuity ranged from CF to 20/20. VA stabilizes (gain/loss <2 lines) in 14 out of 17 eyes (82.24%) and improved in 3 out of 17 (17.65%). Contrast sensitivity improved in 15 out of 17 eyes (82.24%) Lesion type, patient age had no influence on the outcome. There were no cases of ocular/systematic adverse events. Retreatment was required in only 2 out of 17 cases (11.76%) with only a single injection of ranibizumab.

CONCLUSION

The combination of PDT with intravitreal Ranibizumab improves contrast sensitivity and stabilizes vision and reduces the number of retreatments, without significant ocular and/or systematic risks.

Pharmacotherapy for the treatment of choroidal neovascularization due to age-related macular degeneration

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the macula that threatens central vision. It initially occurs in a "dry" form, and can progress to choroidal neovascularization (CNV) or geographic atrophy. It is the leading cause of blindness among European-descended people older than 65 years, with a prevalence of 1.5%. The treatment of CNV in developed nations in 2007 is substantially different than it was in 1997. Focal, photocoagulating, laser therapy was replaced by intravenous verteporfin and then by intravitreal pegaptanib, which is now being replaced by intravitreal ranibizumab and off-label use of bevacizumab. Other than a ranibizumab versus verteporfin trial, there are no published comparative studies of the three approved pharmacological treatments for CNV. Although frequent intravitreal injections are accepted as a current standard of care, their use is still far from ideal. Thus, there is an opportunity for improving therapy of CNV with respect to mechanism-targeted treatments, efficacy, and route of administration.

Milestones in the development of photodynamic therapy and fluorescence diagnosis

Many reviews on PDT have been published. This field is now so large, and embraces so many sub-specialties, from laser technology and optical penetration through diffusing media to a number of medical fields including dermatology, gastroenterology, ophthalmology, blood sterilization and treatment of microbial-viral diseases, that it is impossible to cover all aspects in a single review. Here, we will concentrate on a few basic aspects, all important for the route of development leading PDT to its present state: early work on hematoporphyrin and hematoporphyrin derivative, second and third generation photosensitizers, 5-aminolevulinic acid and its derivatives, oxygen and singlet oxygen, PDT effects on cell organelles, mutagenic potential, the basis for tumour selectivity, cell cooperativity, photochemical internalization, light penetration into tissue and the significance of oxygen depletion, photobleaching of photosensitizers, optimal light sources, effects on the immune system, and, finally, future trends.