Drug Design, Development and Therapy
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`Open Access Full Text Article
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`open access to scientific and medical research
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`
`Aflibercept in wet AMD: specific role
`and optimal use
`
`F Semeraro1
`F Morescalchi1
`S Duse1
`F Parmeggiani2
`E Gambicorti1
`C Costagliola3
`1Department of Medical and Surgical
`Specialties, Radiological Specialties
`and Public Health, Ophthalmology
`Clinic, University of Brescia, Brescia,
`italy; 2Department of Ophthalmology,
`University of Ferrara, Ferrara, italy;
`3Department of Health Science,
`Ophthalmology Clinic, University
`of Molise, Campobasso, Italy
`
`Background: Vascular endothelial growth factor (VEGF) is a naturally occurring glycoprotein
`in the body that acts as a growth factor for endothelial cells. It regulates angiogenesis, enhances
`vascular permeability, and plays a major role in wet age-related macular degeneration. The
`consistent association between choroidal neovascularization and increased VEGF expression
`provides a strong reason for exploring the therapeutic potential of anti-VEGF agents in the
`treatment of this disorder. Blockade of VEGF activity is currently the most effective strategy
`for arresting choroidal angiogenesis and reducing vascular permeability, which is frequently
`the main cause of visual acuity deterioration. In recent years, a number of other molecules
`have been developed to increase the efficacy and to prolong the durability of the anti-VEGF
`effect. Aflibercept (EYLEA®; Regeneron Pharmaceutical Inc and Bayer), also named VEGF
`Trap-eye, is the most recent member of the anti-VEGF armamentarium that was approved by
`the US Food and Drug Administration in November 2011. Because of its high binding affinity
`and long duration of action, this drug is considered to be a promising clinically proven anti-
`VEGF agent for the treatment of wet maculopathy.
`Objective: This article reviews the current literature and clinical trial data regarding the efficacy
`and the pharmacological properties of VEGF-Trap eye and describes the possible advantages
`of its use over the currently used “older” anti-VEGF drugs.
`Methods: For this review, a search of PubMed from January 1989 to May 2013 was performed
`using the following terms (or combination of terms): vascular endothelial growth factors, VEGF,
`age-related macular degeneration, VEGF-Trap eye in wet AMD, VEGF-Trap eye in diabetic
`retinopathy, VEGF-Trap eye in retinal vein occlusions, aflibercept. Studies were limited to those
`published in English.
`Results and conclusion: Two Phase III clini cal trials, VEGF Trap-eye Investigation of
`Efficacy and Safety in Wet AMD (VIEW) 1 and 2, comparing VEGF Trap-eye to ranibizumab
`demonstrated the noninferiority of this novel compound. The clinical equivalence of this com-
`pound against ranibizumab is maintained even when the injections are administered at 8-week
`intervals, which indicates the potential to reduce the risk of monthly intravitreal injections and
`the burden of monthly monitoring.
`Keywords: aflibercept, AMD, neovascularization, VEGF, VEGF inhibition, VEGF-Trap eye
`
`Correspondence: Francesco Semeraro
`Ophthalmology Clinic, Spedali Civili di
`Brescia, Piazzale Spedali Civili 1,
`25123 Brescia, italy
`Tel +39 030 399 5308
`Fax +39 030 338 8191
`email semeraro@med.unibs.it
`
`Introduction
`The neovascular form of age-related macular degeneration (AMD), also known as wet
`AMD, is characterized by the formation of subretinal choroidal neovascularization
`(CNV) and is the cause of most cases of blindness in the elderly. Wet AMD is the major
`cause of severe vision loss in developed nations and is estimated to affect .2.5 million
`people worldwide.1,2 The patients affected by exudative AMD often experience rapid
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`loss of fine resolution central vision over several months,
`and early visual stabilization is a key issue in preserving
`visual acuity.3
`Vascular endothelial growth factor (VEGF) is a naturally
`occurring glycoprotein in the body that acts as a growth fac-
`tor selective for endothelial cells. It regulates angiogenesis,
`enhances vascular permeability, and plays a leading role in
`wet AMD. The consistent association between CNV and
`increased VEGF expression provides a strong reason for
`exploring the therapeutic potential of anti-VEGF agents for
`the treatment of this disorder.4 Blockade of VEGF actions is
`currently the most effective strategy in arresting choroidal
`angiogenesis and reducing vascular permeability, which is
`frequently the main cause of visual acuity deterioration.5
`Although pegaptanib (Macugen®; Eyetech Pharmaceu-
`ticals Inc, FL, USA and Pfizer Inc, New York, NY, USA)
`was the first VEGF inhibitor approved by the US Food and
`Drug Administration (FDA). Important advances in the on-
`label treatment of CNV in AMD have been achieved with
`the introduction of ranibizumab (Lucentis; Genentech USA,
`Inc, San Francisco, CA, USA) in 2006. The off-label use of
`bevacizumab (Avastin; Genentech USA, Inc) has also shown
`efficacy for treating wet AMD and other exudative retinal
`diseases and despite the lack of clinical trials to support its
`safety or efficacy, anecdotal evidence led to its widespread
`popularity prior to the approval of ranibizumab.
`Aflibercept (EYLEA®; Regeneron Pharmaceutical Inc,
`Tarrytown, NY, USA and Bayer, Basel, Switzerland), also
`named VEGF Trap-eye, is the most recent member of the
`anti-VEGF family. This drug has been recently developed
`to afford a more potent and prolonged anti-VEGF effect and
`was approved by the FDA in November 2011.6 This article
`reviews the efficacy and summarizes the pharmacological
`properties of VEGF Trap-eye and describes the possible
`advantages of its use over the currently used “older” anti-
`VEGF drugs.
`Overview of VEGF
`and its pathological
`effects in neovascular AMD
`VEGF-A (usually simply referred to as VEGF) is a growth
`factor encoded by a gene family that also includes placental
`growth factor (PIGF), VEGF-B, VEGF-C, VEGF-D, and
`the orf virus encoded VEGF-E.7 Differences in exon splic-
`ing result in the generation of four main VEGF isoforms:
`VEGF121, VEGF165, VEGF189, and VEGF206, which have 121,
`165, 189, and 206 amino acids after cleavage of the signal
`sequence, respectively.8
`
`VEGF stimulates the growth of vascular endothelial cells
`derived from arteries, veins, and the lymphatic system.9 It
`also induces the formation of thin-walled endothelium-lined
`structures (ie, angiogenesis) in a variety of in vivo models,10
`and induces rapid elevations in microvascular permeability.11
`VEGF acts also as a survival factor for endothelial cells, both
`in vitro and in vivo.12,13 Although endothelial cells represent
`the primary target of VEGF, several studies have demonstrated
`that VEGF has mitogenic effects on nonendothelial cell types14
`and promotion effects on monocyte migration.15 VEGF protects
`neurons from insults such as hypoxia and glutamate toxicity16
`and it stimulates neurogenesis in vitro and in vivo.17
`VEGF contributes mainly at the initiation stage of CNV
`by promoting both angiogenesis and vasculogenesis. It
`acts as an endothelial cell specific mitogen as part of the
`angiogenesis pathway, and also as a chemoattractant for
`endothelial cell precursors, inducing their mobilization and
`differentiation in the vasculogenesis pathway.16 In addition
`to these activities, VEGF affects vascular permeability by
`inducing formation of pores in vascular endothelial cells17,18
`and by disrupting the intercellular junction between these
`cells.19 In turn, this leads to extravasation of fluid, proteins,
`and circulating cells which disrupts the retinal anatomy and
`separates the retina from underlying structures, potentially
`causing severe vision loss.
`Although other growth factors can induce the develop-
`ment of blood vessels (ie, transforming growth factor-β,
`interleukins, insulin-like growth factor-1, and epidermal
`growth factor), only VEGF appears to be both sufficient
`and essential for physiologic and pathologic angiogenesis.
`For this reason, the biochemical pathways involving VEGF
`are the most studied targets for new potential drugs against
`neovascular pathologies. Anti-VEGF therapy can arrest
`choroidal angiogenesis and reduce vascular permeability,
`which is frequently the main cause of visual acuity deterio-
`ration. Pegaptanib and ranibizumab have been approved by
`the FDA for the treatment of wet AMD, and the off-label
`use of a third agent, bevacizumab, has shown efficacy for
`treating wet AMD and other exudative retinal diseases.
`Pegaptanib was the first anti-VEGF drug FDA approved in
`December 2004.20–22 However, because it was proven to be
`less efficacious than other anti-VEGF drugs, possibly owing
`to its selective binding of VEGF165, it is no longer widely
`used in most countries. Ranibizumab and bevacizumab,
`which are nonselective anti-VEGF drugs, are currently the
`most extensively used drugs worldwide for wet AMD as
`well as for many other ocular diseases in which VEGF is
`overexpressed.23
`
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`Aflibercept: the most recent compound in the treatment of neovascular AMD
`
`The development of new agents for wet AMD has focused
`on both improving efficacy and extending the duration of
`action in comparison with the commonly used anti-VEGF
`drugs ranibizumab and bevacizumab, which are considered
`the standard drugs. Ranibizumab is a monoclonal humanized
`antibody fragment and bevacizumab is a whole monoclonal
`antibody, and both show a high binding affinity for all isoforms
`of VEGF. These agents appear to have similar efficacy profiles
`and mechanisms of action, ie, they block the extracellular avail-
`ability of VEGF which can arrest choroidal angiogenesis and
`reduce vascular permeability for a limited period of time.24–27
`Bevacizumab has a lower binding affinity for VEGF than
`ranibizumab.28 However, bevacizumab is approximately three
`times larger than ranibizumab (149 kDa versus 48 kDa), and
`its substantially higher molecular weight results in an intra-
`vitreal half-life that is 36% higher than that of ranibizumab.
`Accumulating clinical evidence has demonstrated that the
`effects of a single intravitreal dose of either bevacizumab
`or ranibizumab effectively reduces the effect of VEGF on
`CNV for 4–6 weeks in most eyes.29,30
`Ranibizumab, which is the only widely used drug that is
`currently approved by the FDA for the treatment of neovas-
`cular AMD, is most extensively studied. Several ranibizumab
`Phase III clinical trials that have studied different treatment
`schedules, doses, and populations have obtained good results
`with monthly injections, ie, a mean number of 25 intravitreal
`injections over 2 years.31,32
`Despite the off-label status of bevacizumab, however, it
`is preferred over ranibizumab by nearly 60% of physicians33
`because of its significantly lower price (ranibizumab, US
`$1,950 versus bevacizumab, US $50) and similar efficacy.
`The FDA originally approved bevacizumab in 2004 for the
`treatment of metastatic colorectal cancer.34 To deliver an intra-
`vitreal injection, the physician or pharmacist makes numer-
`ous unit doses from a vial of bevacizumab, dramatically
`lowering the cost of the drug. Moreover, many reports and a
`2-year multicenter, randomized clinical trial (the Compari-
`sons of Age-Related Macular Degeneration Treatment Trial
`[CATT]) demonstrated its near equivalency to ranibizumab
`with monthly dosing (+7.8 letters versus +8.8 letters) and
`insignificant poorer outcomes with as-needed dosing (+5.0
`versus +6.7 letters).24,25 Moreover, while the systemic half-life
`of the unbound product of bevacizumab (20 days) was longer
`than that of ranibizumab (6 hours), severe systemic adverse
`events occurred at similar frequencies in patients receiving
`bevacizumab and ranibizumab in the CATT trial.26,35,36
`The main problem with the current anti-VEGF therapy
`is that monthly intravitreal injections are required for
`
`maintaining vision. This necessitates an excessive time
`commitment from patients and institutions, and increases the
`physical and psychological discomfort and financial burdens
`for the patients. On the other hand, evidence from the SAILOR
`(Safety Assessment of Intravitreous Lucentis fOR AMD),37
`PIER (A Phase IIIb, Multicenter, Randomized, Double-
`Masked, Sham Injection-Controlled Study of the Efficacy and
`Safety of Ranibizumab in Subjects with Subfoveal Choroidal
`Neovascularization [CNV] with or without Classic CNV
`Secondary to Age-Related Macular Degeneration),38,39 and
`EXCITE (Efficacy and Safety of Ranibizumab in Patients With
`Subfoveal Choroidal Neovascularization [CNV] Secondary
`to Age-Related Macular Degeneration)40 studies indicates
`that the efficacy decreases if treatment frequency is reduced.
`After the loading dose of monthly injections for 3 months of
`ranibizumab, vision decreases or returns to baseline in most
`patients if the frequency is reduced to one injection every 2,
`3, or 4 months.
`Although monthly injections of anti-VEGF represent
`the best way to preserve vision, most retina surgeons use
`individualized treatment protocols with monthly assessments
`after the first three intravitreal injections of anti-VEGF, and
`further injections are given only if signs of disease activity
`persist as observed on optical coherence tomography (OCT).
`This strategy is also abbreviated as “PRN dosing” from the
`Latin phrase Pro Re Nata, which means “as circumstances
`arise.” The PrONTO (Prospective Optical Coherence
`Tomography [OCT] Imaging of Patients With Neovascular
`AMD Treated With Intra-Ocular Ranibizumab) study used
`this strategy and obtained visual outcomes similar to those
`achieved with monthly injections while reducing the num-
`ber of injections from 25 to 10 over 2 years.41 However,
`even with this dosing regimen, patients are still required
`to make monthly visits to the office and undergo frequent
`and expensive testing because of the constant risk of CNV
`recurrence.
`A treatment approach that aims to reduce the number of
`injections and the number of visits is the “treat and extend”
`method. It consists of 3 monthly injections and a follow-up
`examination after 6 weeks. If the follow-up examination
`shows evidence of exudation, the patient is treated and told
`to undergo a follow-up examination in 4 weeks, otherwise
`the patient is still treated but the follow-up period is extended
`to 8 weeks. A similar evaluation is performed at the next
`follow-up visit. However, there is not much evidence in favor
`of this treatment method. Thus, research on new compounds
`is focused on inhibiting the VEGF signaling pathway for a
`more prolonged period.1
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`VEGFR-2
`
`1 2 3 4 5 6 7
`
`Kinase
`
`Aflibercept
`
`2 3
`
`2
`
`3
`
`FC
`
`VEGFR-1
`
`1 2 3 4 5 6 7
`
`Endothelial
`cell
`membrane
`
`Kinase
`
`Figure 1 Diagram showing the structure of the vascular endothelial growth factor
`receptor-1 and -2 and the structure of aflibercept (VEGF Trap-eye).
`Notes: Aflibercept (VEGF Trap-eye) is generated by a fusion that includes the
`second binding domain of vascular endothelial growth factor receptor (VEGFR)-1 and
`the third binding domain of VEGFR-2 attached to a FC fragment of a human IgG.
`Abbreviation: FC, fragment crystallizable region.
`
`The intermediate size of aflibercept (115 kDa compared
`to 48 kDa for ranibizumab and 148 kDa for bevacizumab)
`results in an estimated intravitreal half-life of 7.1 days and
`a duration of clinical action possibly as long as 2.5 months,
`which exceeds the 1-month intravitreal binding activity of
`ranibizumab.54,55 The molecular configuration of afliber-
`cept allows it to bind to all of the VEGF isoforms more
`tightly than their native receptors (the dissociation constant
`[Kd] of aflibercept for VEGF165 = 0.49 pmol/L).42 Thus,
`this compound effectively prevents VEGF from binding
`and activating its cognate receptors (the Kd of VEGFR-1
`and VEGFR-2 for VEGF165 are 9.33 and 88.8 pmol/L,
`
`2 3
`
`VEGF
`
`2
`
`3
`
`VEGF
`
`Aflibercept
`
`VEGFR
`
`VEGFR
`
`K i n a s e
`
`Kinase
`
`Figure 2 vascular endothelial growth factor binds to two vascular endothelial
`growth factor receptors which induces the angiogenic response by activating the
`tyrosine kinase.
`Notes: vascular endothelial growth factor receptor (VEGFR)-2 is shown.
`Aflibercept (VEGF Trap-eye) binds all vascular endothelial growth factor (VEGF)
`isoforms more tightly than their native receptors, thus preventing binding of VEGF
`to its cognate receptors.
`
`Semeraro et al
`
`Aflibercept (EYLEA®; Regeneron Pharmaceutical Inc and
`Bayer), or VEGF Trap-eye, is a novel compound derived from
`the native VEGF receptor (VEGFR) that binds to all VEGF
`and VEGF-B isoforms as well as to PlGF.42 VEGF Trap-eye
`promises to decrease the injection frequency in conjunction
`with the “treat and extend” or “PRN” strategies and appears to
`serve as an effective alternative drug for patients who are less
`responsive to the previously approved anti-VEGF drugs.
`
`Structure and mechanism of action
`The FDA approved VEGF Trap-eye (EYLEA®, Regeneron
`Pharmaceutical Inc, and Bayer) for the treatment of subfoveal
`CNV caused by wet AMD on November 18, 2011.43 VEGF
`Trap-eye is an intraocular formulation of aflibercept, a prod-
`uct used in oncology (Zaltrap; Regeneron Pharmaceutical
`Inc), that has been specifically purified and buffered to mini-
`mize the risk of eye toxicity when injected intravitreally.44
`It is a fully human, recombinant fusion protein that has the
`property to “trap,” that is to catch, hold, and block certain
`molecules. Aflibercept was constructed from portions of the
`human VEGFR fused to the FC portion of a human IgG1.45
`Circulating VEGF initiates a biochemical cascade by acti-
`vating three membrane spanning tyrosine kinase receptors:
`VEGFR-1, VEGFR-2, and VEGFR-3.46,47 VEGFR-1 (fms-
`like tyrosine kinase-1, Flt-1) was the first VEGF receptor
`identified more than a decade ago.48 VEGFR-1 releases tissue
`specific growth factors, recruits endothelial progenitors, and
`induces matrix metalloproteinases. It is thought to modulate
`VEGFR-2 signaling and to act as a dummy/decoy receptor
`by sequestering VEGF and preventing it from binding to
`VEGFR-2.7 VEGFR-2 (kinase insert domain-containing
`receptor or KDR) is considered the major mediator of the
`mitogenic, angiogenic, permeability enhancing, and anti-
`apoptotic effects of VEGF.7
`Both VEGFR-1 and VEGFR-2 have seven Ig-like binding
`sequences for VEGF (two of which are incorporated in VEGF
`Trap-eye) in the extracellular region, a single transmembrane
`region, and a consensus tyrosine kinase sequence that is inter-
`rupted by a kinase insert domain.49–51 The third member of
`the same family of receptor tyrosine kinases is VEGFR-3.52
`This protein is not a receptor for VEGF, but binds VEGF-C
`and VEGF-D.53 Because VEGFR-1 possesses a higher affin-
`ity for VEGF than VEGFR-2, drug developers have used its
`binding sequences for VEGF Trap-eye.
`Structurally, aflibercept is a soluble decoy receptor of
`115 kDa that is made by the second binding domain of
`VEGFR-1 and the third binding domain of VEGFR-2, which
`then are fused to the FC region of a human IgG1 (Figure 1).
`
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`Aflibercept: the most recent compound in the treatment of neovascular AMD
`
`respectively) (Figure 2).56 Moreover, the binding affinity of
`aflibercept (Kd = 0.49 pmol/L) is almost 100 times higher
`than that of ranibizumab (Kd = 46 pmol/L) and bevacizumab
`(Kd = 58 pmol/L).54,55 This was primarily attributed to the
`association rate constant for aflibercept binding to human
`VEGF165, which is almost 80 times faster than the corre-
`sponding association rate constant values for ranibizumab
`and bevacizumab.
`Because of these characteristics, the ability of aflibercept
`to block VEGF induced activation of VEGFR-1 and -2 in vitro
`is much stronger than that of ranibizumab and bevacizumab.
`Additionally, it blocks both PlGF-1 and PlGF-2 medi-
`ated activation of VEGFR-1, whereas ranibizumab and
`bevacizumab do not show such activity. A presumably
`important functional difference between aflibercept and the
`other anti-VEGF drugs currently in use is that it can bind
`and inhibit VEGF as well as PlGF-1 and -2 and VEGF-B,
`which have also been implicated in pathological vascular
`remodeling. Experimental evidence shows that targeting
`VEGF-B and PlGF inhibits CNV and suggests that PlGF
`synergizes with VEGF in promoting vascular pathology in
`wet AMD.57
`
`Pharmacodynamics,
`pharmacokinetics, and metabolism
`Aflibercept forms a stable, inert 1:1 complex with either
`VEGF, VEGF-B, or the PlGF ligand preventing the acti-
`vation of their receptors, VEGFR-1 and -2.56 The highest
`intravitreal dose used in pivotal trials for aflibercept is
`2 mg, which is 100-fold lower than the dose allowed in
`oncology (4–6 mg/kg).44,60 Following intravitreal injection
`of 2 mg of aflibercept, the drug can be detected in plasma
`as a free drug (a minor quantity) or in a complex bound
`with VEGF. The drug is rapidly cleared from circulation
`via pinocytotic proteolysis and glomerular filtration after
`forming a complex with VEGF via the same pathways that
`metabolize antibodies.
`Following intravitreal injection of 2 mg of aflibercept, the
`mean maximal plasma concentration of unbound VEGF Trap-
`eye is attained in 1–3 days, and was estimated to be 200-fold
`lower than the concentration required for maximal systemic
`VEGF binding. The systemic half-life of unbound aflibercept
`is 1.5 days, which is inferior to that of bevacizumab (20 days)
`and closer to the systemic half-life of ranibizumab (6 hours).59
`Free aflibercept has never been detected in plasma at 2 weeks
`after intravitreal injection and cannot accumulate in plasma
`in the loading phase.44 Thus, an intravitreal aflibercept dose
`of 2 mg would be predicted to cause negligible systemic
`
`activity and have a systemic safety profile similar to that of
`ranibizumab.
`
`Therapeutic efficacy
`The first surveys regarding the use of aflibercept in treatment
`of wet AMD emerged from a preclinical study conducted on
`animal models. This study, published in 2003, showed the
`first evidence that VEGF Trap-eye is capable of suppressing
`CNV and VEGF mediated breakdown of the blood–retinal
`barrier in transgenic mice with laser induced CNV, which was
`treated with subcutaneous or intravitreal administration.58 The
`initial use of aflibercept for wet AMD consisted of intrave-
`nous injections with doses between 0.3 mg/kg and 3 mg/kg
`(the usual oncologic dose is 4 mg/kg) and administered every
`2 weeks to 25 patients.60 Macular thickness decreased by
`an average of 66% and vision improved in many patients.
`Patients receiving the higher dose (3 mg/kg) experienced
`more systemic hypertension and proteinuria than those
`treated with the lower dose (1 mg/kg). However, the promis-
`ing effects obtained intravenously encouraged researchers to
`transition the trial to intravitreal injections.
`The Phase I Clinical Evaluation of Anti-angiogenesis in
`the Retina Intravitreal Trial (CLEAR-IT 1)60 investigation was
`a small trial (21 patients) designed to determine the maximum
`tolerated dose, the bioactivity, and the safety and tolerability
`of intravitreally administered aflibercept in patients with wet
`AMD. This study confirmed that aflibercept doses between
`0.05 mg and 4 mg were well tolerated. At 6 weeks after a
`single injection, most patients experienced an improvement
`in visual acuity (mean visual gain, 4.4 letters) and showed
`a decrease in macular thickness (−105 µm). Almost 50%
`of the patients followed for 12 weeks did not show retinal
`leakage and maintained vision gain.61,62 On the basis of the
`results of CLEAR-IT 1, the developers hoped to show that an
`intravitreal formulation of aflibercept could be administered
`less frequently than once a month.
`In a Phase II dose and interval ranging trial, 159 patients
`with wet AMD (CLEAR-IT 2) were randomized into five
`treatment groups: the first two groups received 3 monthly
`aflibercept injections of 0.5 mg or 2 mg and the other three
`groups received only one aflibercept injection of 0.5 mg,
`2 mg, or 4 mg.64 Final global evaluations were performed
`at 12 weeks. Although visual improvement at week 8 was
`similar in patients receiving a single dose or two doses (5.7
`letters), the average vision in all groups improved more in
`patients treated monthly (mean gain of $8 letters) at 12
`weeks. After 12 weeks, the reduction in macular thickness
`experienced by the patients receiving three monthly injections
`
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`exceeded that of patients treated only once.63 For this reason,
`a second part of the CLEAR-IT 2 study was designed in
`which aflibercept treatment was provided as needed (PRN)
`from week 12 to 52 and monthly OCT and fluorescein
`angiography (FAG) examinations were performed, starting
`with a reinjection of all patients at week 12.64 A decision
`to perform reinjection was made if any of the following
`conditions were observed: central retinal thickness increase
`of $100 µm, loss of at least five lines in the visual acuity
`chart approved by the Early Treatment Diabetic Retinopathy
`Study (ETDRS),65 persistent fluid on OCT, new onset of
`classic neovascularization, persistent leakage on FAG, or the
`presence of a new hemorrhage on clinical examination. An
`average of two injections was required, with a mean time to
`the first injection of 129 days. After 1 year (week 52), the
`average improvement in vision was +5.3 letters. Patients
`initially treated with 2 mg every 4 weeks had the best visual
`improvement (mean gain of 9 letters).
`The CLEAR-IT 2 study provided the first indication that
`aflibercept may be dosed as needed with excellent gains in
`vision.66 Additionally, patients receiving a monthly “loading”
`dose for 3 months achieved superior visual results than those
`receiving single injections. Many patients required only two
`injections after the loading phase and at the last visit after
`1 year. Thus, three different dosing regimens were identified
`for the Phase III studies:67 0.5 mg monthly, 2 mg monthly, or
`2 mg every 2 months after the loading phase of three initial
`monthly doses.
`In Phase III, two equivalent pivotal clinical trials of
`VEGF Trap-eye, VEGF Trap-eye Investigation of Efficacy
`and Safety in Wet AMD (VIEW) 1 and 2, were conducted
`to determine if VEGF Trap-eye was noninferior and clini-
`cally equivalent to ranibizumab, the drug considered to be
`the standard against which all subsequent drugs should be
`compared.66,67 The VIEW 1 study enrolled 1,217 patients
`in the US and Canada, and the VIEW 2 study enrolled
`1,240 patients in Europe, Asia, Japan, and Latin America.
`Each trial randomized patients among three treatment
`regimens: 0.5 mg of aflibercept given monthly, 2 mg given
`monthly, and 2 mg given every two months after 3 monthly
`loading doses for 3 months. Both studies evaluated the
`noninferiority efficacy in comparison with a fourth arm
`of the study in which patients received 0.5 mg of ranibi-
`zumab monthly. The first noninferiority endpoint was the
`percentage of patients who maintained their visual acuity
`(decrease in vision less than −15 letters); the second non-
`inferiority endpoint was the percentage of patients who
`gained vision.
`
`After the first year, both the VIEW 1 and 2 studies were
`continued for a second year (52–96 weeks) in which a modified
`PRN strategy was adopted. Patients were assessed monthly
`and were treated only if necessary (with the same drug and
`dose as in the first year), but the injection was repeated at least
`every three months in all cases. At week 52, the proportion of
`patients who maintained their vision (lost ,15 ETDRS letters)
`was approximately 95% when using 2 mg of aflibercept
`(either monthly or every 2 months after the loading phase).
`The same results were obtained with 0.5 mg of ranibizumab
`given monthly. The gains in vision were comparable among
`the drugs administered monthly: a mean gain of +10.9 letters
`and +7.6 letters in the aflibercept group and a mean gain
`of +8.1 letters and +9.4 letters in those receiving ranibizumab,
`in VIEW 1 and VIEW 2,67 respectively.
`In VIEW 1, patients receiving 2 mg of aflibercept every
`4 weeks gained more vision than those receiving ranibizumab
`(+10.9 letters versus +8.1 letters; P = 0.0054).67 Improvements
`in macular thickness were not statistically different among
`any of the treatment groups. VIEW 2 patients receiving 2 mg
`of aflibercept every 8 weeks showed bimonthly fluctuations
`in macular thickness without corresponding fluctuations in
`visual acuity.67 The safety of aflibercept was excellent and
`was comparable with that of ranibizumab in both the VIEW 1
`and VIEW 2 studies. Severe extraocular adverse events such
`as stroke and myocardial infarction occurred with similar
`frequencies in patients receiving aflibercept (0.7% and 2.6%,
`respectively) and in patients receiving ranibizumab (1.6%
`and 2.6%, respectively) in both VIEW trials.
`In VIEW 1, the mean vision gain from the baseline (best
`corrected visual acuity) BCVA at week 52 was greater in the
`2 mg aflibercept every month group when compared with the
`ranibizumab group (mean gain of +10.9 versus +8.1 ETDRS
`letters).67 Conversely, a statistically significant difference
`was not found in vision gain in comparison to ranibizumab
`(mean gain of +7.6 letters versus +9.4 letters) in VIEW 2.67
`The reason for this difference in vision results is unknown.
`However, it is likely that racial and ethnic differences existed
`between the two trials. Several reports have suggested that
`the incidence of polypoidal choroidal vasculopathy, which
`has been suggested to be a variant of neovascular AMD, is
`markedly high in African-American people, relatively high in
`the Asian population, and low in white people with AMD.68,69
`Polypoidal CNV does not respond well to anti-VEGF therapy
`alone and should be treated with a combination of photody-
`namic therapy and anti-VEGF therapy for better results. Thus,
`a limitation of the two trials was the inclusion of all CNV
`types by using FAG but not indocyanine green angiography.
`
`716
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`Drug Design, Development and Therapy 2013:7
`
`Mylan Exhibit 1011
`Mylan v. Regeneron, IPR2021-00880
`Page 6
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`Joining Petitioner: Apotex
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`Dovepress
`
`Aflibercept: the most recent compound in the treatment of neovascular AMD
`
`A comparative subanalysis of the data will be required to
`address this difference.
`However, both VIEW studies showed that 2 mg injections
`of VEGF Trap-eye every two months delivered a comparable
`gain in visual acuity to monthly ranibizumab (+7.9 versus
`+8.1 letters in VIEW 1; +8.9 versus +9.4 letters in VIEW 2).67
`Additional efficacy was not demonstrated when VEGF Trap-
`eye was administered every 4 weeks compared with every
`8 weeks, thus suggesting that patients would not require
`monthly examinations. In the two trials, approximately one
`third of patients receiving 2 mg of aflibercept every second
`month experienced a