SURVEY OF OPHTHALMOLOGY VOLUME 54  NUMBER 3  MAY–JUNE 2009
`
`MAJOR REVIEW
`
`Topical Ophthalmic Cyclosporine: Pharmacology
`and Clinical Uses
`Eric Donnenfeld, MD,1 and Stephen C. Pflugfelder, MD2
`
`1Ophthalmic Consultants of Long Island and Connecticut, Rockville Centre, New York, USA;
`and 2Ocular Surface Center, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA
`
`Abstract. Cyclosporine has been used successfully as a systemic immunomodulator for more than two
`decades, and numerous studies have investigated its mechanisms of action. In 2003 an ophthalmic
`formulation, cyclosporine 0.05% ophthalmic emulsion, was approved by the FDA to treat dry eye
`disease. Topical cyclosporine emulsion has also been investigated for treatment of other ocular surface
`disorders that may have an immune-based inflammatory component. In these trials, cyclosporine
`0.05% ophthalmic emulsion has shown efficacy for management of posterior blepharitis, ocular
`rosacea, post-LASIK dry eye, contact lens intolerance, atopic keratoconjunctivitis, graft-versus-host
`disease, and herpetic stromal keratitis. As these disorders are often refractory to other available
`treatments, ophthalmic cyclosporine is a welcome nontoxic adjunct or replacement to potentially toxic
`topical or systemic immunosuppressive therapies. (Surv Ophthalmol 54:321--338, 2009. Ó 2009
`Elsevier Inc. All rights reserved.)
`
` contact
` blepharitis
`atopic keratoconjunctivitis
`Key words.
`disease  graft-versus-host disease  herpetic stromal keratitis
`disease  ocular rosacea
`
`intolerance  dry eye
`lens
` LASIK  meibomian gland
`
`I. Introduction
`Cyclosporine 0.05% ophthalmic emulsion (Restasis;
`Allergan, Inc., Irvine, CA) has been available as an
`FDA-approved treatment for dry eye disease since
`2003. Given its efficacy for treatment of dry eye,
`a number of clinicians and researchers have in-
`vestigated the effectiveness of topical cyclosporine
`emulsion for treatment of other ocular surface and
`corneal conditions. Such disorders include those
`with signs and symptoms that overlap those of dry
`eye disease and those that appear likely to respond
`to immunomodulatory therapy.
`We begin by reviewing what is known about the
`mechanism of action for cyclosporine at the molec-
`ular level and the use of cyclosporine as a systemic
`immunosuppressant to minimize rejection of solid
`
`organ transplants and to treat severe ophthalmic
`inflammatory conditions. We also discuss the chal-
`lenges in developing an effective ophthalmic formu-
`lation of cyclosporine and the effectiveness of its
`tissue penetration after topical ophthalmic adminis-
`tration. Many of
`the pharmacological effects of
`topical ophthalmic cyclosporine administration are
`readily reconciled with our understanding of its
`molecular mechanism of action, although there is
`still much to learn.
`We then review in detail recently conducted
`studies evaluating the effectiveness of topical cyclo-
`sporine treatment
`for ocular disorders such as
`posterior blepharitis/meibomian gland disease,
`ocular rosacea, LASIK-associated dry eye, contact
`lens intolerance, and graft-versus-host disease. We
`
`Ó 2009 by Elsevier Inc.
`All rights reserved.
`
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`0039-6257/09/$--see front matter
`doi:10.1016/j.survophthal.2009.02.002
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`Surv Ophthalmol 54 (3) May--June 2009
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`DONNENFELD AND PFLUGFELDER
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`Fig. 1. Structure of cyclosporine (obtained from United States National Library of Medicine, Chemical Information
`[ChemIDplus Advanced] database. Accessed on March 3, 2008, at http://chem.sis.nlm.nih.gov/chemidplus/
`ProxyServlet?objectHandle5Search&actionHandle5transferStructure&nextPage5chemidheavy.jsp&responseHandle5
`JSP&superlistid5079217600&TRANSFER5true&MOLFILE_REFERENCE5&QF105).
`
`strive to present the best evidence that is currently
`available regarding the efficacy of cyclosporine
`0.05% ophthalmic emulsion in the treatment of
`these ocular disorders. Our aim is
`to provide
`perspectives on how cyclosporine is currently being
`used clinically in the treatment of ocular disorders,
`but not to provide a definitive commentary on
`efficacy or specific recommendations for therapy.
`
`II. Cyclosporine Mechanism of Action
`Cyclosporine is a cyclic undecapeptide produced
`by the fungi Tolypocladium inflatum and Beauveria
`nevus (Fig. 1). Its mechanism of action has been very
`extensively studied because of its widespread use as
`an immunosuppressant to control rejection of solid
`organ transplants and to treat autoimmune diseases.
`Research on its mechanism of action initially
`focused on the molecule’s ability to inhibit activa-
`tion of T lymphocytes. Later it was appreciated that
`cyclosporine had other activities in a variety of cell
`types, such as inhibition of apoptosis. These effects
`of cyclosporine are mediated by binding to two
`cytoplasmic proteins called cyclophilin A and cyclo-
`philin D. Cyclophilins are peptidyl-prolyl
`isomer-
`ases, which are proteins
`that have chaperonin
`activity able to catalyze refolding of other misfolded
`proteins.
`Cyclosporine binding to cyclophilin A ultimately
`causes inhibition of T-lymphocyte activation.37,45
`The cyclosporine-cyclophilin A complex binds to
`and inhibits the activity of the serine/threonine
`
`phosphatase calcineurin (Fig. 2).37,59,70 Calcineurin
`normally dephosphorylates the nuclear factor for
`T-cell activation (NF-AT) in the cytoplasm of cells in
`response to elevated levels of intracellular calcium,
`an indirect consequence of antigen binding to the
`T-cell receptor on the cell surface.45,125 Dephos-
`phorylated NF-AT is transported to the nucleus
`where it promotes transcription of a number of
`genes whose protein products participate in T-cell
`activation, most notably interleukin 2 (IL-2).45,52 It
`is believed that calcineurin is transported to the
`nucleus with NF-AT in order
`to maintain its
`dephosphorylated state. Secreted IL-2 binds to its
`receptors on the T-cell surface, stimulating cell
`division by a self-propagating autocrine and para-
`crine loop. Cyclosporine-mediated inhibition of
`calcineurin blocks dephosphorylation of NF-AT in
`the cytoplasm, thereby preventing its transport to
`the nucleus and preventing increased transcription
`of the IL-2 gene and other genes involved in T-cell
`activation.45,52,125
`The calcineurin/NF-AT system has been best
`studied in T-cells, but is broadly distributed among
`other cell types. Calcineurin is capable of dephos-
`phorylating at least four different isoforms of NF-AT
`with varied roles.52 Evidence suggests that calcineur-
`in/NF-AT signaling is involved in cytokine and
`chemokine production by mast cells and eosino-
`phils.27 Calcineurin/NF-AT signaling is important
`for gene expression in skeletal muscle and
`for cardiac growth and function.27 Calcineurin and
`NF-AT are present in epidermal keratinocytes from
`healthy and psoriasis patients, and cyclosporine-
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`TOPICAL OPHTHALMIC CYCLOSPORINE
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`DNA, and others, such as cytochrome c, activate
`a cascade of latent, apoptosis-specific proteases in
`the cytosol called caspases.39 Cyclosporine binding
`of cyclophilin D can inhibit damage-induced cell
`death in a number of cell types, including neuronal
`and cardiac tissues.72,115,122 Cyclosporine signifi-
`cantly reduced apoptosis of conjunctival epithelial
`cells, as assessed by DNA fragmentation and levels of
`activated caspase-3,
`in an experimental murine
`model of dry eye.114 Evidence suggests that calci-
`neurin inhibition by the cyclosporine--cyclophilin A
`complex may also contribute to inhibition of
`apoptosis by blocking dephosphorylation and con-
`sequent activation of BAD, a proapoptotic protein
`anchored to the outer mitochondrial membrane.123
`
`III. Systemic Use of Cyclosporine as an
`Immunosuppressant and
`Immunomodulator
`Systemically administered cyclosporine was in-
`troduced to prevent rejection of solid organ trans-
`plants in 1983 and has been widely used since for
`kidney, heart, liver, and lung allografts.29,108 Success-
`ful immunosuppression after organ transplantation
`appears to require cyclosporine concentrations in
`the target tissue of 3 to 10 mg/g.46,98,99 To achieve
`this, daily doses of 5 to 15 mg/kg (depending in part
`on the formulation used) are administered orally or
`intravenously,
`resulting in trough cyclosporine
`concentrations
`in serum ranging from 200 to
`400 ng/ml (Neoral [package insert]. East Hanover,
`NJ: Novartis Pharmaceuticals Corp; 2005). The most
`severe side effect of cyclosporine dosing in this
`range is nephrotoxicity.108 Other side effects in-
`clude hypertension, gingival hyperplasia,
`and
`increased risk of opportunistic infections.
`Orally administered cyclosporine is also used for
`treatment of rheumatoid arthritis, moderate to severe
`psoriasis, and inflammatory bowel disease, often in
`combination with other therapeutics.40,41,60,87,92,99
`Lower daily doses (2.5--5 mg/kg) than for transplant
`patients are used for these conditions, resulting in
`lower trough cyclosporine concentrations in serum
`ranging from 75 to 100 ng/ml.40,60,92
`Systemically administered cyclosporine immuno-
`suppressive therapy has been useful
`to control
`rejection following limbal allograft surgery as well
`as for severe ocular inflammatory conditions such as
`uveitis and Behc¸et disease.17,25,30,53,58,63,71,75,78 Daily
`doses of 2 to 5 mg/kg are used, and combinations of
`therapeutics may be employed to reduce the
`cyclosporine dose over the long term.58
`Systemic cyclosporine has been used to supplement
`chemotherapy for retinoblastoma. Cyclosporine is
`
`Fig. 2. Role of calcineurin in T-cell activation. When the
`T-cell receptor on the cell surface is bound by an
`appropriate ligand, a multistep intracellular signaling
`process begins, culminating in the release of calcium.
`Calcium stimulates the phosphatase calcineurin, which
`dephosphorylates the phosphorylated form of NF-AT.
`Dephosphorylated NF-AT can now migrate to the nucleus,
`where it stimulates transcription of the gene for IL-2
`(among many others). The cyclosporine--cyclophilin A
`complex (but not cyclophilin A alone) binds to calcineurin,
`inhibiting its dephosphorylating activity and preventing
`translocation of NF-AT to the nucleus. NF-AT 5 nuclear
`factor for T-cell activation.
`
`mediated inhibition of calcineurin has been dem-
`onstrated in these cells.8,92 Calcineurin and NF-AT
`are present in retinoblastoma cells as well, and
`cyclosporine treatment of retinoblastoma cell lines
`reduced proliferation and induced apoptosis.35
`Additional substrates of the calcineurin phosphatase
`activity, other than NF-AT, have been identified.59
`Clearly there is much to be learned about the roles
`of these signal transduction pathways in various cell
`types, and inhibition of calcineurin activity by the
`cyclosporine--cyclophilin A complex may have ef-
`fects that have not yet been identified. It should be
`noted, however, that the sensitivity of T-cell activa-
`tion to clinically achievable concentrations of
`cyclosporine depends on the relatively low calci-
`neurin levels in those cells. Calcineurin levels in
`cardiac tissues,
`for example, are about 10-fold
`greater than in cells of the immune system, and
`this probably accounting for the less dramatic
`effects of cyclosporine on these cells.27
`Cyclosporine binding to cyclophilin D is thought
`to be primarily responsible for its inhibition of
`apoptosis, or programmed cell death.122 The cyclo-
`sporine--cyclophilin D complex binds to and pre-
`vents opening of the mitochondrial permeability
`transition (MPT) pore.68 Opening of this pore in
`response to cellular stress or damage is an early step
`in the apoptosis cascade. When the MPT pore
`opens, mitochondrial proteins are released from the
`intermembrane space. Some of these appear to act
`directly in apoptosis, such as nucleases that degrade
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`Surv Ophthalmol 54 (3) May--June 2009
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`DONNENFELD AND PFLUGFELDER
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`known to inhibit the P-glycoprotein--mediated multi-
`drug resistance pump,
`thereby
`increasing the
`residence time and efficacy of chemotherapeutic
`agents. As noted earlier, cyclosporine inhibition of
`the calcineurin/NF-AT pathway may also reduce
`proliferation and increase apoptosis of retinoblas-
`toma cells.35
`
`IV. Ophthalmic Use of Cyclosporine:
`Pharmacy Formulation
`Cyclosporine formulated by a pharmacy has been
`used for topical treatment of a number of ocular
`inflammatory diseases. Chief among these is vernal
`keratoconjunctivitis, a condition that primarily af-
`fects young (!10 years) males. Usually it is treated
`with antihistamines, mast-cell inhibitors, and topical
`or systemic steroids. In severe cases, 18 of 21 children
`experienced symptomatic relief within 3 to 4 days
`with cyclosporine 2%, and 16 of 21 were controlled
`during the 6-week treatment, but only 5 of 21 patients
`needed no other therapy 2 months after discontinu-
`ation.16 A trial of 20 patients had similar results: signs
`and symptoms were controlled while taking cyclo-
`sporine 2%, but recurred when treatment ceased.102
`In another trial of 24 children taking cyclosporine
`2%, a significant difference was found versus vehicle
`in subjective (p ! 0.005) and objective (p ! 0.001)
`scores, and at 4 months, serum eosinophil cationic
`protein levels were lower than before treatment
`(p 5 0.009).88 Assessment of 52 children with severe
`vernal keratoconjunctivitis who received cyclospor-
`ine 1.25% or 1% for 4 months found that subjective
`symptoms and objective signs were significantly
`decreased at 2 weeks and at 4 months (p !
`0.001).107 The minimal concentration of cyclospor-
`ine in this oil-based pharmacy formulation for
`controlling shield ulcers associated with vernal
`keratoconjunctivitis was 1%.24 Analysis of severe
`vernal keratoconjunctivitis patients taking cyclospor-
`þ
`þ
`and CD23
`cells in
`ine 2% drops showed that CD4
`conjunctival
`impression cytology samples signifi-
`cantly decreased.10 Topical cyclosporine appears to
`be an effective alternative for
`severe vernal
`keratoconjunctivitis.
`Atopic keratoconjunctivitis, unlike vernal kerato-
`conjunctivitis, persists for many years, and patients
`become dependant on topical steroids with their
`attendant side effects. In a trial of cyclosporine 2%
`four times daily (in addition to their usual therapy),
`9 of 12 of patients ceased steroid use, compared with
`1 of 9 placebo patients.49 Final steroid use was less
`for cyclosporine 2%, 2.6 versus 27.7 doses per week
`(p 5 0.01), and steroid use decreased by 85.5 doses
`per week relative to placebo, to 13.9 doses per week
`
`(p 5 0.005).49 Clinical signs and symptom scores
`were reduced to a greater extent with cyclospor-
`ine.49 Topical cyclosporine 2% appears to be a safe
`and effective steroid-sparing agent
`for atopic
`keratoconjunctivitis.
`Childhood phlyctenular keratoconjunctivitis, also
`known as childhood ocular rosacea, is characterized
`by phlyctenules, small inflammatory nodules on the
`cornea and conjunctiva. Hypersensitivity to staphy-
`lococcal antigens such as peptidoglycan and protein
`A is responsible. Topical cyclosporine 2% instilled
`4 times daily (n 5 13 eyes) controlled corneal
`inflammation in steroid-dependent disease within
`14 days.31 Inflammation did not recur during a mean
`follow-up of 12  8 months, and treatment was
`stopped in 10 eyes with no recurrences in 10  3
`months.31 Topical cyclosporine 2% appears safe and
`effective for long-term therapy of phlyctenular
`keratoconjunctivitis.
`Five patients diagnosed with Theodore superior
`limbic keratoconjunctivitis were treated with cyclo-
`sporine 0.5% four times daily. All exhibited im-
`provement in irritation and foreign-body sensation,
`injection, and filamentary keratitis over 6 months to
`4 years.83 Topical cyclosporine may be useful as
`primary or adjunctive therapy for superior limbic
`keratoconjunctivitis or to prevent recurrence.
`Herpes simplex virus induces an immunological
`response that contributes to corneal scarring and
`neovascularization. In one study, 10 patients re-
`ceived topical cyclosporine 2% four times daily
`along with acyclovir 3% ointment. Stromal infiltra-
`tion resolved in all the patients after 2 months, and
`visual acuity increased by 2 lines or more in 8 of 10
`cases.43 In another study, topical cyclosporine 2%
`was given three times daily with acyclovir 3%, and
`keratitis resolved in 12 of 18 patients.47 Persistent or
`progressive inflammation was apparent in 6 of 18
`patients, who required steroid treatment also, and
`4 patients experienced a recurrence of stromal
`keratitis when the cyclosporine was tapered off.47
`These results suggest that noninfectious, immuno-
`logic herpes simplex virus stromal keratitis can be
`treated successfully with topical cyclosporine.
`Thygeson superficial punctate keratitis is a chronic
`nummular keratitis of the cornea that may last for
`a decade and is traditionally treated with topical
`corticosteroids. Cyclosporine 2% was administered
`to 42 adult eyes and 10 pediatric eyes with this
`condition. Complete suppression of epithelial and
`subepithelial opacities was achieved in 71.5% of
`adults and 40% of children, and healing occurred in
`31% of adults and 20% of children.91 Cyclosporine
`may be useful
`to control Thygeson superficial
`punctate keratitis and avoid corticosteroid side
`effects.
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`TOPICAL OPHTHALMIC CYCLOSPORINE
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`Topical cyclosporine has been administered to
`treat corneal allograft rejection after penetrating
`keratoplasty. In one trial of 16 eyes, cyclosporine
`0.5% cured 9 eyes,
`improved 6 eyes, and was
`ineffective for 1 eye.127 Rejection occurred after 12
`to 24 months in 3 of 9 eyes, but could be resolved by
`resumption of cyclosporine.127 In another study of
`cyclosporine 2% as an adjunct to steroids, 69.7%
`(60/86 eyes) were rejection-free versus 45.4% (44/
`97 eyes) of controls (p 5 0.030).54 Cyclosporine
`0.5% was substituted for steroids in 52 eyes with
`postkeratoplasty glaucoma
`and steroid-induced
`hypertension. At first
`follow-up, 92.3% showed
`reduced intraocular pressure (IOP), with a mean
`reduction of 7.9 mm Hg, and at last follow-up, the
`IOP reduction was 8.2 mm Hg.81 Graft clarity was
`maintained in 88% of eyes, and of 6 allograft
`rejections, 5 were reversed with steroids.81
`A recent preclinical study investigated the phar-
`macokinetics of an episcleral cyclosporine implant
`as an alternative treatment option to topical
`cyclosporine in preventing corneal allograft rejec-
`tion. The implant
`led to corneal cyclosporine
`concentrations of 0.09  0.05 mg/mg within 3 hours
`and maintained corneal cyclosporine concentra-
`tions in the inhibitory range for T-cell activation
`and vascular endothelial cell proliferation for at
`least 1 year.64 Clinical examinations showed no signs
`of ocular toxicity over the 1-year period.64 Further
`studies are needed to determine the clinical efficacy
`of these devices in penetrating keratoplasty models.
`Topical cyclosporine 2% was used to treat Sjo¨gren
`syndrome in a randomized, double-masked, pla-
`cebo-controlled trial. After 2 months, there was
`a significant increase in tear breakup time and
`decrease in rose bengal staining in the cyclosporine
`group versus the placebo group (p ! 0.01).42
`Shirmer scores were not significantly affected.42
`the
`Mooren ulcer is a chronic ulceration of
`cornea that may have an autoimmune etiology.
`Topical cyclosporine 1% plus topical resection and
`lamellar keratoplasty provided a cure rate on the
`first procedure of 73.7% (84/114) versus 69.3%
`(205/296) for topical resection and lamellar kera-
`toplasty alone.26
`
`therapeutically useful. The hydrophobic nature of
`the cyclosporine molecule, however, presented
`a challenge to developing an effective ophthalmic
`formulation. The poor water solubility of cyclospor-
`ine means that aqueous solutions at clinically useful
`concentrations are likely to be unstable. Attempts to
`overcome this have led to ophthalmic cyclosporine
`prepared in castor, corn, olive, and peanut oils.
`Burning, redness, itching, and epithelial keratitis
`limit the use of such oil vehicles.116
`To improve delivery of cyclosporine to ocular
`tissues, an emulsion formulation in castor oil that
`also includes glycerin, polysorbate 80, and sodium
`hydroxide (to adjust
`the pH) was developed
`(Restasis [package insert]. Irvine, CA: Allergan,
`Inc.; 2004).116 Upon instillation, cyclosporine parti-
`tions from the oil droplets in the emulsion into
`ocular surface tissues. Animal studies showed that
`topical administration of the emulsion formulation
`achieved cyclosporine concentrations sufficient for
`immunomodulation in the cornea and conjunctiva,
`but resulted in very low concentrations (! 1 ng/ml)
`in the aqueous humor, vitreous humor, and plasma.2
`Topical administration of cyclosporine 0.05% or
`0.1% ophthalmic emulsions in dry eye patients who
`participated in the phase 3 clinical trials resulted in
`plasma levels of cyclosporine that were undetectable
`in those receiving 0.05% cyclosporine and were very
`low in those receiving 0.1%.97,104 Using highly
`sensitive high-performance liquid chromatography
`(HPLC) tandem-mass spectroscopy with lower limit
`of quantitation of 0.1 ng/ml, cyclosporine was
`detected in only 6 of 310 blood samples, all from
`patients administered cyclosporine 0.1%.97,105 The
`concentrations detected were several orders of
`magnitude less than trough plasma concentrations
`(75--400 ng/ml) of cyclosporine during systemic
`immunosuppressive therapy for psoriasis, rheuma-
`toid arthritis, and organ transplant patients.116
`Because of the extremely low blood concentrations
`of cyclosporine after topical administration of cyclo-
`sporine 0.05% or 0.1%, systemic side effects were not
`anticipated, and nonocular treatment-related ad-
`verse events were not observed in clinical trials of
`the cyclosporine ophthalmic emulsions.12,97,104
`
`V. Pharmacokinetics of Topically
`Administered Ophthalmic Cyclosporine
`0.05%
`Successful treatment of ocular surface inflamma-
`tory conditions using topical cyclosporine formula-
`tions compounded by pharmacists suggested that
`a commercially available ophthalmic formulation of
`cyclosporine with increased bioavailability might be
`
`VI. Pharmacology of Ophthalmic
`Cyclosporine 0.05%
`topical
`the pharmacologic effects of
`Many of
`cyclosporine on the ocular surface are consistent
`with what is known about its molecular mechanism
`of action. Treatment with topical cyclosporine has
`been shown to reduce cell surface markers of
`activated T lymphocytes and apoptotic cells in
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`DONNENFELD AND PFLUGFELDER
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`conjunctival biopsies of dry eye patients and to
`restore the normal architecture of
`the lacrimal
`gland in dogs with dry eye. Cyclosporine treatment
`was also shown to reduce expression of a proinflam-
`matory cytokine and increase goblet cell densities
`toward the normal
`range in the conjunctival
`epithelium of dry eye patients.
`
`A. REDUCTION OF ACTIVATED T LYMPHOCYTES
`
`Expression of the immune activator marker HLA-
`DR was found by flow cytometry analysis to be
`significantly increased in conjunctival epithelial cells
`from dry eye patients compared with those of
`healthy subjects.22 This marker is expressed by
`conjunctival epithelial cells that have been exposed
`to inflammatory cytokines produced by activated T
`cells such as interferon-g (IFN-g). It is important to
`note that similar levels of HLA-DR were detected in
`samples
`from subjects with Sjo¨gren and non--
`Sjo¨gren syndrome keratoconjunctivitis sicca.22,109,110
`Treatment of dry eye patients with cyclosporine
`0.05% ophthalmic emulsion for 3 or 6 months was
`significantly more effective in reducing HLA-DR
`levels than treatment with vehicle (p # 0.034).21 A
`second study also demonstrated significant reduc-
`tions of HLA-DR and a marker of activated T-cells,
`CD11a,
`in conjunctival biopsies
`from dry eye
`patients following 6 months of cyclosporine 0.05%
`ophthalmic emulsion treatment (p # 0.05).62,97
`These observations indicate that treatment of dry
`eye patients with topical cyclosporine significantly
`decreases expression of inflammatory markers by
`the conjunctival epithelium and decreases
`the
`number of activated T-cells in the conjunctiva,
`phenomena that are directly or indirectly related
`to the recognized ability of cyclosporine to inhibit
`T-cell activation and cytokine production.
`
`B. REDUCED MARKERS OF APOPTOSIS
`
`Molecular markers of apoptosis, such as CD40,
`CD40 ligand (CD40L, also known as CD154), and
`Fas, have been shown to be elevated in the
`conjunctival epithelia of dry eye patients compared
`with those of healthy control subjects.20,22 Treat-
`ment of dry eye patients with cyclosporine 0.05%
`ophthalmic emulsion caused significant reductions
`in levels of CD40 (p 5 0.049) and CD40 ligand (p #
`0.008) and in the percentage of cells expressing Fas
`(p # 0.046).22 These results are consistent with
`studies of conjunctival apoptosis in animal models
`of dry eye, which showed reductions after treatment
`with cyclosporine 0.05% ophthalmic emulsion in
`the number of apoptotic epithelial cells and in levels
`of activated caspase-3, a protease that is important
`for apoptosis.38,114 They are also consistent with the
`
`known ability of cyclosporine to block key steps in
`the apoptosis cascade, although it has not been
`established whether such mechanisms are responsi-
`ble for the drug’s effect on the ocular surface
`epithelium. Determining the effects of
`topically
`administered cyclosporine on apoptosis of ocular
`surface cells in dry eye promises to be a fruitful area
`of research in the future.
`
`C. REDUCTION OF PROINFLAMMATORY
`CYTOKINES
`
`A number of proinflammatory cytokines, includ-
`ing IL-1a, IL-1b, IL-6, IL-8, TNF-a, and TGF-b1, are
`elevated in the tears and/or conjunctival epithelium
`of dry eye patients relative to healthy subjects, with
`the greatest difference seen for IL-6.84,105,106 Levels
`of IL-6 mRNA in conjunctival epithelial biopsy
`samples from dry eye patients were analyzed by
`quantitative reverse transcriptase polymerase chain
`reaction and then normalized to levels of mRNA
`encoding
`glucose-6-phosphate
`dehydrogenase,
`a ‘‘housekeeping’’ gene used as an internal control.
`Biopsies from dry eye patients treated with cyclo-
`sporine 0.05% ophthalmic emulsion for 6 months
`showed a significant decrease in IL-6 mRNA relative
`to pretreatment biopsies.120 This result indicates
`that production of proinflammatory molecules in
`the conjunctival epithelium of dry eye patients may
`be reduced by treatment with topical cyclosporine.
`
`D. EFFECT ON CONJUNCTIVAL EPITHELIUM
`AND GOBLET CELL DENSITY
`
`Squamous metaplasia, a condition of increased
`proliferation and abnormal differentiation of the
`conjunctival epithelium, may be observed by stained
`impression cytology and biopsies from aqueous
`tear--deficient dry eye patients. After 6 months of
`treatment with topical cyclosporine, the percentages
`of proliferating conjunctival epithelial cells, as
`measured by the cell division marker KI-67, were
`significantly decreased in conjunctival biopsies from
`non-Sjo¨gren dry eye patients (p ! 0.05).61 This
`suggests that cyclosporine has a normalizing effect
`on conjunctival squamous metaplasia associated
`with dry eye.
`A marked reduction in conjunctival goblet cells,
`which secrete the soluble mucin MUC5AC into the
`tear film,
`is a feature of squamous metaplasia.
`Because of this reduction in goblet cell density,
`soluble mucins, which help maintain proper tear
`viscosity and minimize thin spots in the tear film,
`were found to be reduced to 14% of their normal
`concentration in tears of dry eye patients.128
`Treatment of dry eye patients with cyclosporine
`0.05% ophthalmic emulsion for 6 months caused an
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`TOPICAL OPHTHALMIC CYCLOSPORINE
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`increase in conjunctival goblet cell density of 191%
`(p 5 0.014), which was significantly greater than in
`biopsies of vehicle-treated patients (p 5 0.013).61,97
`The mechanisms for development of squamous
`metaplasia and of goblet cell loss in dry eye have
`not been established, although it
`is likely that
`alterations in tear film composition of dry eye
`patients, such as in the balances of cytokines and
`growth factors, may promote the change in the
`epithelium from a healthy, properly differentiated
`state to this pathologic state. Nor is it understood in
`detail how cyclosporine acts to reverse this state.
`Alterations of tear composition in dry eye patients
`and how tear composition may be affected by
`treatment with topical cyclosporine remain impor-
`tant areas of ongoing research.
`
`VII. Clinical Effects of Cyclosporine
`0.05% Ophthalmic Emulsion
`
`A. KERATOCONJUNCTIVITIS SICCA
`
`sicca, or dry eye ocular
`Keratoconjunctivitis
`surface disease, traditionally has been thought of
`as a disease of tear insufficiency, whether due to
`decreased tear secretion by lacrimal glands or
`increased tear evaporation. A number of ocular
`surface conditions may trigger dry eye disease or be
`associated with it, including many of those discussed
`subsequently. Continuing advances in research have
`led to an evolved understanding in which altered
`composition of
`the tear film and pathological
`changes of ocular surface tissues, such as conjunc-
`tival squamous metaplasia, play major roles in the
`disease.85,105,109 Disruption of corneal epithelial
`barrier function may result in aberrant signaling
`from the dense array of corneal nerves to the central
`nervous
`system,
`the lacrimal gland, and other
`secretory glands. Release of chemokines from the
`diseased ocular surface epithelium triggers T-cell
`infiltration into the conjunctiva and lacrimal glands.
`Cytokines liberated by the infiltrating T-cells, such as
`IFN-g, have the reported capability of interfering
`with conjunctival epithelial differentiation and
`sensitizing mucosal epithelia to apoptosis via FasL.
`This leads to cyclic, self-amplifying dysfunction of
`the ocular surface.85,105,109 These T-cell--mediated
`events are likely targets of cyclosporine therapy of
`dry eye.
`Patients with dry eye disease describe their ocular
`sensations variously as burning, dryness, sandiness
`or grittiness, or a foreign-body sensation. Blurred
`vision is common, probably as the result of an
`unevenly spread tear film and corneal epithelial
`pathology—together, the tear film and the cornea
`supply a large proportion of the refractive power of
`
`the eye. Symptoms are frequently exacerbated by
`desiccating environmental conditions or by pro-
`longed visual concentration with reduced blink rate,
`such as during computer use or reading, which
`cause excessive exposure of the tear film and ocular
`surface without redistribution of the tear film. Until
`topical ophthalmic cyclosporine became available,
`treatments for dry eye disease were limited to
`palliative measures. Supplementation of the tear
`film by instillation of artificial tears could provide
`temporary symptomatic relief, and occlusion of the
`lacrimal drainage system with punctal plugs helped
`conserve the limited tears (which often contain
`inflammatory mediators) produced by the lacrimal
`glands.
`The efficacy of cyclosporine 0.05% ophthalmic
`emulsion for treatment of dry eye was first examined
`in a randomized, double-masked, placebo-con-
`trolled, dose-ranging clinical trial.111 Ninety patients
`with moderate to severe dry eye disease were
`assigned to instill cyclosporine 0.05%, 0.1%, 0.2%,
`0.4%, or vehicle BID for 12 weeks (16-20 patients
`per
`treatment group). No clear dose-response
`relationship was seen, but the cyclosporine 0.05%
`and 0.1% emulsions provided significant improve-
`ments in symptoms, superficial punctate keratitis,
`and rose bengal staining from baseline.111
`Two larger phase 3 clinical trials were undertaken
`to further evaluate the efficacy of cyclosporine
`0.05% and 0.1% ophthalmic emulsions. The two
`randomized, double-masked, placebo-controlled tri-
`als were identical, so the results were combined for
`analysis.97 Altogether, 877 moderate to severe dry
`eye patients were randomized to instill cyclosporine
`0.05% (n 5 293), cyclosporine 0.1% (n 5 292), or
`the emulsion vehicle (n 5 292) b.i.d. for 6 months.
`Patients could continue to use artificial tears as
`necessary for temporary relief of ocular discomfort.
`The best and most consistent improvements in signs
`and symptoms of dry eye were seen in the
`cyclosporine 0.05% group, although it should be
`noted that the emulsion vehicle showed surprising
`efficacy for some signs and symptoms, especially
`earlier in the 6-month treatment period, making
`significant differences versus placebo more difficult
`to achieve. Reductions in p