Ocular toxicity of intravitreous adalimumab (Humira) in the rabbit

Challenges for further successful development of tumor necrosis factor targeting therapies for uveitis

INTRODUCTION

Uveitis is a heterogeneous group of ocular conditions characterized by inflammation of the uveal tract and is one of the leading causes of vision impairment. In developed countries, noninfectious uveitis (NIU) represents most cases and is challenging to treat due to its severity, chronicity, and high recurrence rates. The advent of anti-tumor necrosis factor-α (anti-TNF-α) agents have dramatically improved outcomes and changed treatment paradigms in NIU.

AREAS COVERED

The index article summarizes the present experience of anti-TNF-α agents in NIU pharmacotherapy and highlights the barriers to further research and development of anti-TNF-α agents for uveitis. Common challenges faced in NIU clinical drugs trials, specific difficulties in anti-TNF-α drug development, and promising competitor drug candidates are discussed and evaluated.

EXPERT OPINION

Anti-TNF-α agents have revolutionized NIU pharmacotherapy and greatly improved outcomes with good safety profiles. The great success of systemic infliximab and adalimumab in NIU treatment has resulted in little impetus for further development of this class of medication. Attempts have been made to deliver anti-TNF-α agents intravitreally but that has not been successful thus far. With expiring patents, competition from biosimilars and newer, novel molecules, it may not be viable to continue pursuing anti-TNF-α drug development.

Behçet's disease uveitis

Uveitis in Behçet's disease (BD) is frequent (40% of cases) and is a major cause of morbidity. The age of onset of uveitis is between 20 and 30 years. Ocular involvement includes anterior, posterior or panuveitis. It is non-granulomatous. Uveitis may be the first sign of the disease in 20% of cases or it may appear 2 or 3 years after the first symptoms. Panuveitis is the most common presentation and is more commonly found in men. Bilateralisation usually occurs on average 2 years after the first symptoms. The estimated risk of blindness at 5 years is 10-15%. BD uveitis has several ophthalmological features that distinguish it from other uveitis. The main goals in the management of patients are the rapid resolution of intraocular inflammation, prevention of recurrent attacks, achievement of complete remission, and preservation of vision. Biologic therapies have changed the management of intraocular inflammation. The aim of this review is to provide an update previous article by our team on pathogenesis, diagnostic approaches, identification of factors associated with relapse and the therapeutic strategy of BD uveitis.

Behçet's Disease Uveitis

Uveitis in Behçet's disease (BD) is frequent (40% of cases) and is a major cause of morbidity. The age of onset of uveitis is between 20 and 30 years. Ocular involvement includes anterior, posterior, or panuveitis. Uveitis may be the first sign of the disease in 20% of cases or it may appear 2 or 3 years after the first symptoms. Panuveitis is the most common presentation and is more commonly found in men. Bilateralization usually occurs on average 2 years after the first symptoms. The estimated risk of blindness at 5 years is 10-15%. BD uveitis has several ophthalmological features that distinguish it from other uveitis. The main goals in the management of patients are the rapid resolution of intraocular inflammation, the prevention of recurrent attacks, the achievement of complete remission, and the preservation of vision. Biologic therapies have changed the management of intraocular inflammation. The aim of this review is to provide an update to a previous article by our team on pathogenesis, diagnostic approaches, and the therapeutic strategy of BD uveitis.

Perspectives of Therapeutic Drug Monitoring of Biological Agents in Non-Infectious Uveitis Treatment: A Review

Biological drugs, especially those targeting anti-tumour necrosis factor α (TNFα) molecule, have revolutionized the treatment of patients with non-infectious uveitis (NIU), a sight-threatening condition characterized by ocular inflammation that can lead to severe vision threatening and blindness. Adalimumab (ADA) and infliximab (IFX), the most widely used anti-TNFα drugs, have led to greater clinical benefits, but a significant fraction of patients with NIU do not respond to these drugs. The therapeutic outcome is closely related to systemic drug levels, which are influenced by several factors such as immunogenicity, concomitant treatment with immunomodulators, and genetic factors. Therapeutic drug monitoring (TDM) of drug and anti-drug antibody (ADAbs) levels is emerging as a resource to optimise biologic therapy by personalising treatment to bring and maintain drug concentration within the therapeutic range, especially in those patients where a clinical response is less than expected. Furthermore, some studies have described different genetic polymorphisms that may act as predictors of response to treatment with anti-TNFα agents in immune-mediated diseases and could be useful in personalising biologic treatment selection. This review is a compilation of the published evidence in NIU and in other immune-mediated diseases that support the usefulness of TDM and pharmacogenetics as a tool to guide clinicians’ treatment decisions leading to better clinical outcomes. In addition, findings from preclinical and clinical studies, assessing the safety and efficacy of intravitreal administration of anti-TNFα agents in NIU are discussed.

A comprehensive review of intravitreal immunosuppressants and biologicals used in ophthalmology

Systemic immunosuppressants and biologicals have been a valuable tool in the treatment of inflammatory diseases and malignancies. The safety profile of these drugs has been debatable, especially in localized systems, such as the eye. This has led to the search for fairly local approaches, such as intravitreal, subconjunctival, and topical route of administration. Immunosuppressants have been used as a second-line drug in patients intolerable to corticosteroids or those who develop multiple recurrences on weaning corticosteroids. Similarly, biologicals have also been used as the next line of therapy, when adequate control of inflammation could not be attained or immunosuppressants were contraindicated to patients. Intravitreal immunosuppressants, such as methotrexate and sirolimus, have been extensively studied in noninfectious posterior uveitis, whereas limited studies have established the efficacy of intravitreal biologicals, such as infliximab and adalimumab. Most of these drugs have shown good safety profile and tolerability in animal studies alone and have not been studied further in human subjects. However, most of the studies in literature are single-case reports or case series which limits the level of evidence. In this comprehensive review, we discuss the mechanism of action, pharmacodynamics, pharmacokinetics, indications, efficacy, and side effects of different intravitreal immunosuppressants and biologicals that have been studied in literature.

Identifying and Treating Ocular Manifestations in Psoriasis

Psoriasis is a chronic immune-mediated inflammatory skin condition that commonly presents with red, thickened, and scaling plaques. Given the prominent cutaneous manifestations of psoriasis, more subtle ophthalmic findings of the disease may initially go undetected, with the potential for significant ocular morbidity. Associated ocular disease can involve nearly any structure of the eye, with the eyelids most commonly being affected, resulting in relatively common signs and symptoms of ocular surface discomfort. The presence of intraocular inflammation (i.e., uveitis) or retinal involvement carry a heightened risk of vision loss, and are often more difficult to diagnose outside of the ophthalmology clinic. Early detection and treatment of ocular disease can limit morbidity and are critical to the management of these patients, which requires coordination of care between dermatologists and ophthalmologists. The objective of this article was to review the most common ocular conditions that affect psoriatic patients, when to consider referral to an ophthalmologist, and to summarize the adverse ocular effects of current psoriasis treatments.

Old and New Challenges in Uveitis Associated with Behçet's Disease

Behçet’s disease (BD) is a systemic vasculitis disease of unknown origin occurring in young people, which can be venous, arterial or both, classically occlusive. Ocular involvement is particularly frequent and severe; vascular occlusion secondary to retinal vasculitis may lead to rapid and severe loss of vision. Biologics have transformed the management of intraocular inflammation. However, the diagnosis of BD is still a major challenge. In the absence of a reliable biological marker, diagnosis is based on clinical diagnostic criteria and may be delayed after the appearance of the onset sign. However, therapeutic management of BD needs to be introduced early in order to control inflammation, to preserve visual function and to limit irreversible structural damage. The aim of this review is to provide current data on how innovations in clinical evaluation, investigations and treatments were able to improve the prognosis of uveitis associated with BD.

The effects of intravitreal adalimumab injection on pseudophakic macular edema

Objective

Pseudophakic macular edema is a frequent complication following cataract surgery. Inflammation is a major etiologic factor in the development of pseudophakic cystoid macular edema. Tumor necrosis factor-alpha has an important role in ocular inflammation. Adalimumab (Humira) is an inhibitor of tumor necrosis factor-alpha that has been approved in the United States. An open-label, uncontrolled, prospective, interventional study of five consecutive patients (5 eyes) with cystoid macular edema who were treated with off-label intravitreal adalimumab at Khalili Hospital was conducted. Slit-lamp examination and optical coherence tomography were done for all patients.

Results

No statistically significant difference was detected between best corrected visual acuity and central macular thickness before and after injection in pseudophakic macular edema. One patient developed uveitis approximately 2 weeks after injection. Based on the results, adalimumab does not appear to be an effective treatment for pseudophakic macular edema, and it may cause uveitis. Caution should be exercised when using this drug.

Trial registration Iranian Registry of Clinical Trials IRCT2016100430130N1, 2016.12.03, Retrospectively registered

Ocular toxicity of intravitreal golimumab in a rabbit model

Background/aim

To investigate the effect of intravitreal golimumab on rabbit retina histopathology.

Materials and methods

Sixteen albino New Zealand rabbits were divided into three groups. The right eye of each rabbit in groups I, II, and III received a single intravitreal injection of 5 mg/0.05 mL (6 eyes), 10 mg/0.1 mL (6 eyes), or 20 mg/0.2 mL (4 eyes) golimumab, while left eyes served as controls with the same volume of a balanced salt solution injection. All animals were examined using slit-lamp biomicroscopy and indirect ophthalmoscopy before and after intravitreal injection and at days 1 and 7. Animals were euthanized on day 7 and the eyes were enucleated for immunohistochemistry evaluation and electron microscopic examination of the retinas.

Results

For groups I, II, and III, the number of cells in the outer nuclear layer and the inner nuclear layer was decreased compared to those in the control groups. In group I, the percentage of caspase-3 staining of the outer nuclear layer was significantly higher than that in the control. For groups II and III, TUNEL and caspase-3 staining percentages in the outer and inner nuclear layers were found to be significantly higher than those for the control groups. In the ganglion cell layer, for groups I, II, and III, neither TUNEL nor caspase-3 staining percentages showed any significant difference between two groups. No significant dose-dependent relationship was found for increasing doses of golimumab in all layers. Myelin figures and karyorrhexis in the photoreceptor cells were prominent in electron microscopy of the golimumab-injected eyes.

Conclusion

Golimumab caused apoptosis in both photoreceptors and bipolar cells of the rabbit retina. Potential retinal toxicity of intravitreal golimumab should be considered if an intravitreal administration is planned.

A review of ocular adverse events of biological anti-TNF drugs

The recent introduction of biological agents has revolutionized the treatment of chronic immune-inflammatory diseases; however, this new therapy did not come without significant side effects.Through large controlled studies indicating decrease in the number of uveitis flares, the role of TNF inhibitors therapy for non-infectious uveitis gained more ground. Paradoxically to its therapeutic effect, there are reports associating these drugs with the onset or recurrence of inflammatory eye disease.A number of studies have suggested possible roles for anti-TNF-α agents in precipitating or worsening an underlying inflammatory process, including the hypothesis of a disequilibrium in cytokine balance, but to date the mechanisms responsible for these adverse events are not fully understood.A PubMed literature search was performed using the following terms: ophthalmic complication, uveitis, inflammatory eye disease, optic neuritis, neuropathy, adverse events, anti-TNF, TNF alpha inhibitor, infliximab, etanercept, adalimumab, golimumab, certolizumab, and biologics. The data presented in this study was mainly derived from the use of TNF inhibitors in rheumatology, essentially because these drugs have been used for a longer period in this medical field.Many of the ocular adverse events reported on this review may be considered a paradoxical effect of anti-TNF therapy. We found a variety of data associating new onset of uveitis with anti-TNF therapy for rheumatic conditions, predominantly under etanercept.In conclusion, although there is increasing data on ocular adverse events, it remains to be seen whether the suggested link between TNF inhibitors and the onset of ocular inflammation is substantiated by more quality data. Nevertheless, the awareness of potential treatment side effects with anti-TNF should be highlighted.

ARMANDODASILVA, FIALHO SILVIALIGORIO, LIBER ANDREMAURICIO, YOUNG LUCYHWAYUE, VENTURA DORAFIX. Intravitreal injection of polysorbate 80: a functional and morphological study

ABSTRACT Objective : to determine the functional and morphological effects at rabbits retina of PS80 concentration used in the preparation of intravitreal drugs. Methods: eleven New Zealand rabbits received a intravitreal injection of 0.1ml of PS80. As control, the contralateral eye of each rabbit received the same volume of saline. Electroretinography was performed according to a modified protocol, as well as biomicroscopy and retina mapping before injection and seven and ten days after. Animals were euthanized in the 30th day and the retinas were analyzed by light microscopy. Results: eyes injected with PS80 did not present clinical signs of intraocular inflammation. Electroretinography did not show any alteration of extent and implicit time of a and b waves at scotopic and photopic conditions. There were no morphological alterations of retinas at light microscopy. Conclusion: intravitreal injection of PS80 in the used concentration for intravitreal drug preparations do not cause any functional or morphological alterations of rabbit retinas. These results suggest that PS80 is not toxic to rabbit retinas and may be safely used in the preparation of new lipophilic drugs for intravitreal injection.

Anti-angiogenesis through noninvasive to minimally invasive intraocular delivery of the peptide CC12 identified by in vivo-directed evolution

Anti-vascular endothelial growth factor (VEGF) therapies are widely used for the treatment of neovascular fundus diseases such as diabetic retinopathy. However, these agents need to be injected intravitreally, because their strong hydrophilicity and high molecular weight prevent them from penetrating cell membranes and complex tissue barriers. Moreover, the repeated injections that are required can cause infection and tissue injury. In this study, we used in vivo-directed evolution phage display technology to identify a novel dodecapeptide, named CC12, with the ability to penetrate the ocular barrier in a noninvasive (via conjunctival sac instillation) or minimally invasive (via retrobulbar injection) manner. KV11, an antiangiogenesis peptide previously demonstrated to inhibit pathological neovascularization in the retina, was then used as a model antiangiogenesis cargo for CC12. We found that conjugation of KV11 peptide with CC12 peptide facilitated the delivery of KV11 to the retina, resulting in significant inhibition of retinal neovascularization development via topical application without tissue toxicity. Collectively, our data of multilevel evaluations demonstrate that CC12 may enable the noninvasive to minimally invasive intraocular delivery of antiangiogenic therapeutics.

Preclinical safety evaluation of a recombinant AAV8 vector for X-linked retinoschisis after intravitreal administration in rabbits

X-linked retinoschisis (XLRS) is a retinal disease caused by mutations in the gene encoding the protein retinoschisin (RS1) and one of the most common causes of macular degeneration in young men. Currently, no FDA-approved treatments are available for XLRS and a replacement gene therapy could provide a promising strategy. We have developed a novel gene therapy approach for XLRS, based on the administration of AAV8-scRS/IRBPhRS, an adeno-associated viral vector coding the human RS1 protein, via the intravitreal route. On the basis of our prior study in an Rs1-KO mouse, this construct transduces efficiently all the retinal layers, resulting in an RS1 expression similar to that observed in the wild-type and improving retinal structure and function. In support of a clinical trial, we carried out a study to evaluate the ocular safety of intravitreal administration of AAV8-scRS/IRBPhRS into 39 New Zealand White rabbits. Two dose levels of vector, 2e(10) and 2e(11) vector genomes per eye (vg/eye), were tested and ocular inflammation was monitored over a 12-week period by serial ophthalmological and histopathological analysis. A mild ocular inflammatory reaction, consisting mainly of vitreous infiltrates, was observed within 4 weeks from injection, in both 2e(10) and 2e(11) vg/eye groups and was likely driven by the AAV8 capsid. At 12-week follow-up, ophthalmological examination revealed no clinical signs of vitreitis in either of the dose groups. However, while vitreous inflammatory infiltrate was significantly reduced in the 2e(10) vg/eye group at 12 weeks, some rabbits in the higher dose group still showed persistence of inflammatory cells, histologically. In conclusion, intravitreal administration of AAV8-scRS/IRBPhRS into the rabbit eye produces a mild and transient intraocular inflammation that resolves, at a 2e(10) vg/eye dose, within 3 months, and does not cause irreversible tissue damages. These data support the initiation of a clinical trial of intravitreal administration of AAV8-scRS/IRBPhRS in XLRS patients.

Ocular biocompatibility evaluation of hydroxyl-functionalized graphene

We have presented our recent efforts on genotoxicity and intraocular biocompatibility of hydroxylated graphene (G-OH) prepared by ball milling. We have previously demonstrated that the as-synthesized G-OH could be considered as an excellent alternative for graphene oxide which had been applied widely. Following our last report on G-OH, we carried out detailed studies on genotoxicity and in vivo biocompatibility of G-OH in this work. Less than 5% enhanced caspase-3 level was observed for cells exposed to more than 50 μg/mL G-OH over 72 h, suggesting G-OH caused cell apoptosis was slight. The G-OH induced DNA damage was also found to be mild since expression of p53 and ROS regeneration level was quite low even at high concentration of G-OH over a long time. Cell viability was found to be higher than 90% with 50 μg/mL G-OH and 80% with 100 μg/mL G-OH using flow cytometry. Comet results suggested that less than 5% tail could be found with 100 μg/mL G-OH. TEM results confirmed that G-OH could penetrate into and out of the cytoplasm by means of endocytosis and exocytosis without causing damage on cell membranes. In vivo biocompatibility of G-OH was studied by intravitreal injection of G-OH into rabbits. The ocular fundus photography results showed that G-OH could be diffused in the vitreous body gradually without any damage caused. Injection of G-OH had caused few damages on eyesight related functions such as intraocular pressure, electroretinogram and histological structures of the retina.

Intravitreal Adalimumab in Active Noninfectious Uveitis: A Pilot Study

PURPOSE

To evaluate the short-term efficacy of intravitreal adalimumab (IVA) for the treatment of eyes with active noninfectious uveitis.

METHODS

Consecutive eyes with active noninfectious uveitis were injected with IVA at 0, 2, then every 4 weeks for total of 26 weeks.

RESULTS

Six out of 7 patients (12 of 13 eyes) completed 26 weeks of treatment. One patient (1 eye) failed treatment. Seven out of 12 eyes had improvement of ≥2 ETDRS lines. Three out of three eyes had resolution of anterior chamber cells. And 9 of 10 eyes with vitreous haze had zero haze at 26 weeks. Five out of 8 eyes with macular edema had complete resolution. Median fluorescein angiography score improved from 14 to 4 on last follow-up.

CONCLUSIONS

IVA was effective in controlling the inflammation, decreasing the macular edema, and improving the best corrected visual acuity in the majority of eyes in this series.

Retinal function and morphology in the rabbit eye after intravitreal injection of the TNF alpha inhibitor adalimumab

Aim

To study the effects of the tumor necrosis factor alpha inhibitor adalimumab on rabbit retina after injection into the vitreous body.

Methods

Forty-eight rabbits of mixed strain (9–12 months old, weighing ≈ 3.5 kg) were randomized into four groups. Adalimumab was injected at one of two concentrations (1.25 mg or 2.5 mg) into the eyes of two groups, and balanced salt solution into the eyes of the third group. The fourth group acted as controls. Full-field electroretinography (ffERG) was performed before injection and 1 and 6 weeks post-injection. At 6 weeks post-injection the rabbits were euthanized and the sectioned retinas were studied. Retinal histology was studied with hematoxylin–eosin staining. Immunohistochemical analysis was performed on rods, cones, rod bipolar cells, horizontal cells, amacrine cells and Müller cells.

Results

No significant difference in ffERG amplitudes or implicit times was observed between the four groups at any time point. Histological and immunohistochemical findings were similar in all groups.

Conclusions

Injection of adalimumab into the vitreous body of healthy rabbits, at doses up to 2.5 mg, does not appear to be toxic to the rabbit retina.

Intravitreal tumor necrosis factor-alpha inhibitors for neovascular age-related macular degeneration suboptimally responsive to antivascular endothelial growth factor agents: a pilot study from the Pan American Collaborative Retina Study Group

PURPOSE

To compare the short-term visual and anatomic outcomes after intravitreal injections of 2 different tumor necrosis factor-α inhibitors to continued antivascular endothelial growth factor (VEGF) therapy in eyes with choroidal neovascularization (CNV) secondary to age-related macular degeneration that responded suboptimally to anti-VEGF agents.

METHODS

Retrospective comparative case series of 26 eyes. Eyes were injected intravitreally with 1 mg infliximab, 2 mg infliximab, 2 mg adalimumab, or 1.25 mg bevacizumab. The main outcomes measured were the best-corrected visual acuity (BCVA) and the central macular thickness (CMT) at 3 months of follow-up.

RESULTS

The mean log minimal angle of resolution BCVA changed from 1.04±0.23 at baseline to 1.06±0.51 at 3 months (P=0.9455) in the 1-mg infliximab group; 0.94±0.48 at baseline to 0.85±0.43 in the 2-mg infliximab group (P=0.2802); 1.58±0.50 at baseline to 1.38±0.43 in the adalimumab group (P=0.1116); and 1.08±0.1 at baseline to 1.03±0.16 in the bevacizumab group (P=0.9928). The mean CMT changed from 387±54 μm at baseline to 342±108 μm (P=0.1053) in the 1-mg infliximab group; 301±42 μm at baseline to 284±73 μm (P=0.4854) in the 2-mg infliximab group; remained unchanged at 348±106 μm (P=0.308) in the adalimumab group; and 362±66 μm to 340±27 μm in the bevacizumab group (P=0.4622). Adverse events included uveitis in 37.5% (6/16) of eyes injected with infliximab.

CONCLUSION

Intravitreal infliximab and adalimumab do not appear to benefit eyes with CNV that responded suboptimally to anti-VEGF agents. Intravitreal injections of infliximab may elicit a severe intraocular inflammatory reaction.

intravitreal tumor necrosis factor inhibitors in the treatment of refractory diabetic macular edema: a pilot study from the Pan-American Collaborative Retina Study Group

PURPOSE

The purpose of this study was to report the short-term visual and anatomical outcomes after intravitreal injections of two different tumor necrosis factor α inhibitors in eyes with refractory diabetic macular edema.

METHODS

An interventional, retrospective, multicenter study of 39 eyes with refractory diabetic macular edema that were injected with adalimumab (n = 5 for 2 mg) or infliximab (n = 15 for 1 mg; n = 19 for 2 mg). The main outcome measures were the best-corrected visual acuity and the central macular thickness at 3 months of follow-up.

RESULTS

In the 1-mg infliximab group, the logarithm of the minimal angle of resolution best-corrected visual acuity improved from 1.49 ± 0.58 at baseline to 1.38 ± 0.56 at 3 months (P = 0.6991). In the 2-mg infliximab group, the logarithm of the minimal angle of resolution best-corrected visual acuity worsened from 0.76 ± 0.54 to 1.03 ± 0.69 at 3 months (P = 0.5995). In the adalimumab group, the logarithm of the minimal angle of resolution best-corrected visual acuity improved from 1.44 ± 0.77 to 1.08 ± 0.85 at 3 months (P = 0.2500). The central macular thickness in the 1-mg infliximab group decreased from 459 ± 125 μm at baseline to 388 ± 131 μm at 3 months (P = 0.1178). In the 2-mg infliximab group, the central macular thickness remained unchanged from 378 ± 97 μm at baseline to 349 ± 118 μm at 3 months (P = 0.2162). In the adalimumab group, the central macular thickness remained unchanged from 521 ± 163 μm at baseline to 526 ± 390 μm at 3 months (P = 0.1250). There were no systemic side effects reported in any of the patients. However, laboratory markers for autoimmunity were not done. None of the eyes injected with either adalimumab or 1 mg of infliximab had adverse ocular events. In the 2-mg infliximab group, 42% (8 of 19) of eyes developed severe uveitis. Three of these eyes (37.5%) required pars plana vitrectomy. The uveitis in the remaining five eyes resolved with topical steroid therapy.

CONCLUSION

Both intravitreal adalimumab and infliximab do not appear to benefit eyes with refractory diabetic macular edema. Intravitreal injections of infliximab may elicit a severe intraocular inflammatory reaction.

Intravitreal adalimumab for refractory uveitis-related macular edema

OBJECTIVE

To evaluate the safety and efficacy of intravitreal adalimumab injections on refractory cystoid macular edema (CME) secondary to noninfectious uveitis.

DESIGN

Prospective, noncomparative, interventional case series.

PARTICIPANTS

Eight consecutive patients with controlled uveitis and chronic, refractory CME who had failed steroid treatment.

INTERVENTION

Intravitreal adalimumab injections were given monthly for 3 months.

MAIN OUTCOME MEASURES

Mean change in central retinal thickness (CRT) on optical coherence tomography (OCT); secondary objective was the mean change in best-corrected visual acuity (BCVA).

RESULTS

Five of the eight patients completed the 6-month follow-up. For all 5 patients, the changes in BCVA from baseline to 3 months were not statistically significant (P=0.070). Similarly, the change in BCVA from baseline to 6 months was not statistically significant (P=1.0). The mean CRT at baseline was 692 microm. The changes from baseline to 3 months were not statistically significant (P=0.466); the changes from baseline to 6 months were also not statistically significant (P=0.808). We did not observe any ocular or systemic adverse effects.

CONCLUSIONS

Intravitreal adalimumab showed no efficacy in improving BCVA or reducing CRT in patients with chronic uveitic macular edema.

Interaction of intravitreal combination drugs and the effect on the targeted site

BACKGROUND

After evaluating experimentally the diffusion processes in the retina using peroxidase as a tracer material (previously published work), we found that junctional complexes of the retinal pigment epithelium and retinal capillaries were the major impediment to free diffusion between the retina and choroidal-retinal blood vessels. These experiments indicated that to achieve high therapeutic concentrations of medications inside the eye, it was necessary to administer them by intravitreal injection. Soon after initial experimental work the necessity of combining antibiotics or antibiotics with steroids became obvious. As the use of intravitreal injection grew over the last 2 decades, so did the concept of combination therapy.

METHODS

This review describes potential causes of drug-drug interaction and the rationale for combination therapy when injected into the vitreous cavity, encompassing publications between 1971 and 2008.

RESULTS

We describe the conditions that can cause physical-chemical interactions between the medications and the need for combination therapy for treatment of various intraocular disease processes.

CONCLUSIONS

The intravitreal injection of medication and their combinations has become a part of standard care for many diseases of the retina and choroid. This article reviews the potential interaction of nontoxic doses of medications when injected simultaneously in the vitreous cavity, and disease processes that are now treated with these combination therapies.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

Intravitreal administration of the anti-tumor necrosis factor agent infliximab for neovascular age-related macular degeneration

PURPOSE

To present our preliminary experience on intravitreal administration of an anti-tumor necrosis factor (TNF) monoclonal antibody for neovascular age-related macular degeneration (AMD).

DESIGN

Prospective, noncomparative series of 3 patients previously treated with an anti-vascular endothelial growth factor agent.

METHODS

Two intravitreal injections of 0.05 ml containing infliximab were administered in the first (1 and 2 mg, 2 months apart), second (2 mg each, 2 months apart), and third patient (2 mg each, 3 months apart). Best-corrected visual acuity (BCVA) and central foveal thickness (CFT) were monthly assessed for up to 7 months.

RESULTS

In the first patient, BCVA increased from 20/200 to 20/100 and CFT decreased from 462 to 386 microm, 2 months after the first injection. The condition was further improved after the second injection (BCVA, 20/40; CFT, 210 microm), but recurrence occurred 7 months post-baseline. In the second patient, BCVA increased from 20/200 to 20/70 and CFT decreased from 512 to 420 and 184 microm, 2 and 4 months post-baseline, respectively. In the third patient, clinical improvement was documented after the first injection. A second injection attributable to recurrence resulted in improvement of BCVA from 20/100 to 20/30 and decrease of CFT from 388 to 282 microm, 2 months after the second injection.

CONCLUSIONS

These findings, although insufficient to consider "off-label" treatment with intravitreal infliximab, provide in vivo evidence of a pathogenetic link of locally produced and/or acting TNF to neovascular AMD. A randomized study of consecutive intravitreal injections of infliximab for AMD may be warranted.

Intravitreal administration of the anti-TNF monoclonal antibody infliximab in the rabbit

BACKGROUND

Tumor necrosis factor (TNF) is known to play an important role in various immune-mediated ocular diseases; intravenous administration of the anti-TNF monoclonal antibody infliximab has proved beneficial in such cases. Since intravitreal injection (when available) is a substitute for systemic administration of various drugs targeting the eye, we aimed to evaluate the safety of intravitreal injection of infliximab in the rabbit eye.

METHODS

Seven groups of New Zealand white rabbits (four animals in each group) received a single unilateral intravitreal injection (0.1 ml) of increasing doses of infliximab (namely 1, 2, 5, 8, 10 or 20 mg infliximab [Remicade]) or a sham injection respectively. Slit-lamp biomicroscopy, fundoscopy and electrophysiology recordings, i.e. scotopic, photopic and flicker responses, were performed at baseline and after 1, 5, 10, 15, 30 and 45 days. Infliximab-injected eyes were compared with sham-injected and with uninjected fellow eyes (n = 28). Animals were euthanized on day 45 for histopathological examination of the retinas.

RESULTS

Clinical examination and electrophysiological testing were consistently unremarkable after either sham or 1 mg or 2 mg infliximab injections. In contrast, electrophysiological recordings were significantly reduced in a dose-dependent manner from day 1 through day 45, after 5, 8, 10 and 20 mg infliximab injections. Flicker responses were the most sensitive in detecting the lower toxic dose of 5 mg. Histopathological findings were similar in uninjected and sham-injected eyes, as well as after 1 mg or 2 mg infliximab injections. Consistent with the functional abnormalities, retinal deformities and diffuse edema were observed after injection of 5 mg or higher doses of infliximab.

CONCLUSIONS

Intravitreal infliximab may be safely administered up to a dose of 2 mg in the rabbit eye. Such doses can be used in the design of future clinical trials assessing the effects of infliximab for selected patients with immune-mediated ocular conditions.