Expert perspectives on the evolution of retina practice, procedures, technologies and instrumentation.


Development of Anti-VEGF Therapy for Ocular Angiogenesis

Leo A. Kim, MD, PhD, FASRS; Joan W. Miller, MD

The origin of vascular endothelial growth factor (VEGF) as a target for pathologic ocular neovascularization dates back to at least 1948, when I.C. Michaelson first hypothesized about the existence of Factor X, a “factor in the retina capable of affecting the growth of vessels” and “associated with the metabolism of the retinal tissue.”[1] In 1971, Judah Folkman published his seminal theory that angiogenesis plays a role in tumor growth and metastasis[2]. He proposed the existence of a tumor angiogenic factor that mediated endothelial cell growth and vascular proliferation into the tumor. He further suggested that “anti-angiogenesis” may be used to restrict the blood supply to a tumor and induce dormancy of the tumor. This idea of anti-angiogenic therapy is the foundation of current treatment modalities for a wide array of ocular conditions characterized by aberrant angiogenesis.

Judah Folkman. Photo courtesy of Boston Children’s Hospital Archives, Boston, Massachusetts.

In 1983, Harold Dvorak isolated vascular permeability factor (VPF), which was 50,000 more potent than histamine[3]. Then in 1989, Ferrara and Henzel cloned, sequenced, and characterized VEGF from pituitary follicular cells[4]. Concurrently, Connolly and colleagues identified human vascular permeability factor (hVPF) from a human histiocytic lymphoma cell line[5]. It was subsequently found that VEGF and hVPF shared the same cDNA sequence, and were in fact, the same molecule [6,7].

The elucidation of VEGF as Michaelson’s “Factor X” was the culmination of work from a group of researchers in Boston starting in the 1990s. First, Adamis et al. demonstrated that VEGF was secreted by the retinal pigment epithelium (RPE) in culture[8] and was responsive to hypoxia[9]. At the same time, Miller and colleagues identified VEGF in aqueous fluid samples from a nonhuman primate model of laser-induce retinal vein occlusion and iris neovascularization.  This was the first demonstration in vivo of a correlation between VEGF protein levels and ocular angiogenesis[10].  Thereafter, this correlation was demonstrated in patients[10] and confirmed in a larger study that patients with active proliferative diabetic retinopathy, iris neovascularization, and central retinal vein occlusions, all had elevated expression of VEGF within intraocular fluid[11, 12]. Next, VEGF was shown to be an essential driver of neovascularization, with complete inhibition of neovascularization in the nonhuman primate model achieved using intravitreal injection of an anti-VEGF antibody (the precursor of bevacizumab). Finally, VEGF injection directly into normal nonhuman primate eyes led to iris neovascularization and neovascular glaucoma, recapitulating the pathology observed clinically with retinal ischemia[13]. VEGF alone was both sufficient and necessary for ocular neovascularization—we had solved for Factor X. Altogether; this body of work formed the foundational basis of a key role for VEGF in ocular neovascularization and the resulting development of successful anti-VEGF therapies.

Anthony Adamis and Joan Miller at Massachusetts Eye and Ear circa 1994. Courtesy MEEI

Development of anti-VEGF therapies soon followed with studies investigating anti-VEGF antibodies[14], soluble VEGF receptor[15], and anti-VEGF aptamers[16].  Since it was postulated that full length antibodies might not cross the retina, experiments using intravenous delivery of fluoresceinated anti-VEGF antibodies demonstrated their localization to choroidal neovascularization (CNV) in nonhuman primate[17].   An anti-VEGF antibody fragment (rhuFab VEGF, a precursor to ranibizumab), was developed and its efficacy demonstrated in the laser-induced CNV model in 2002[18].  These studies supported clinical studies to further investigate the use of anti-VEGF therapy in patients.

The first anti-VEGF therapy approved for the eye was pegaptanib, an anti-VEGF aptamer developed by Eyetech Pharmaceuticals.  Pegaptanib was shown in phase 2 and phase 3 trials to slow the progressive loss of vision associated with neovascular age-related macular degeneration (nvAMD)[19], and was approved by the FDA on December 17, 2004. Although they had lost the lead to be first to market, Genentech developed the anti-VEGF antibody fragment, ranibizumab, for intravitreal injection as they also developed a full-length anti-VEGF antibody, bevacizumab, for intravenous delivery in cancer. Ranibizumab was dramatically effective in the treatment of nvAMD with actual gains in vision as shown by the pivotal MARINA and ANCHOR trials[20, 21], the first time a treatment for nvAMD had been able to achieve improvement in vision.  Based on these studies, ranibizumab was approved by the FDA on June 30, 2006 for the treatment of nvAMD. In 2005, at the time of the announcement of the positive ranibizumab results, Philip Rosenfeld presented a case study of a patient with nvAMD treated with intravitreal bevacizumab.  The combination of remarkable success in trials of the anti-VEGF antibody fragment, combined with the promise of success with off-label use of the full-length antibody, led to widespread use of bevacizumab as an effective intravitreal anti-VEGF therapy. Subsequently, the large multicenter Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) led by Dan Martin, demonstrated that ranibizumab and bevacizumab had similar efficacy for the treatment of nvAMD[22].  Other agents continue to be developed.  Aflibercept, a chimeric fusion protein of VEGFR1 and VEGFR2 developed by Regeneron, functions as a decoy receptor with high affinity to VEGF[23]. Phase 3 results from the VIEW trials revealed that 2 mg of aflibercept every 2 months was not inferior to ranibizumab dosed monthly[24].  Aflibercept was approved by the FDA on November 18, 2011.   Brolucizumab, a humanized single chain antibody fragment targeting VEGF was developed by Novartis. Based on the phase 3 results of the HAWK and HARRIER trials[25], the FDA approved brolucizumab for the treatment of nvAMD on October 8, 2019. However, post marketing reports have highlighted the risk of drug associated intraocular inflammation, retinal vasculitis, and retinal arterial occlusion tempering the use of brolucizumab[26]. Newer anti-VEGF gene therapies using AAV viral vectors to deliver anti-VEGF molecules are currently being developed in early clinical trials and larger trials are pending.  RGX-314 developed by REGENXBIO uses AAV8 to deliver an anti-VEGF antibody fragment, similar to ranibizumab (NCT04832724).  Similarly, ADVM-022 developed by Adverum Biotechnologies uses AAV.7m8 to deliver aflibercept (NCT04645212). Beyond nvAMD, the class of anti-VEGF drugs has now been expanded for the treatment of a wide array of neovascular conditions of the eye including diabetic retinopathy and retinal vein occlusions.

Winners of the 2014 Antonio Champalimaud Award Vision Award. Napoleone Ferrara, Evangelos Gragoudas, Joan Miller, Anthony Adamis, George King, Patricia D’Amore, and Lloyd Paul Aiello. Courtesy MEEI.

The VEGF story, from the discovery of Factor X to the widespread success of anti-VEGF therapy for so many retinal conditions, highlights the importance of basic and clinical research in improving the care of our patients.  Prior to the development of anti-VEGF therapies, many of these conditions were often treated with ablative laser therapy or simply observed with a gradual decline in vision. The development of pharmacological treatments for retinal diseases has completely revolutionized the field of ophthalmology, improving vision outcomes and quality of life for millions of people.  The importance of this therapeutic approach was recognized by the awarding of the 2014 Antonio Champalimaud Award Vision Award for the development of anti-angiogenic therapy for retinal disease[27]


  1. Michaelson IC. The mode of development of the vascular system of the retina, with some observations on its significance for certain retinal diseases. Transactions of the ophthalmological societies of the United Kingdom 1948;68:137-180.
  2. Folkman J. Tumor angiogenesis: therapeutic implications. The New England journal of medicine 1971;285:1182-1186.
  3. Senger DR, Galli SJ, Dvorak AM, Perruzzi CA, Harvey VS, Dvorak HF. Tumor cells secrete a vascular permeability factor that promotes accumulation of ascites fluid. Science 1983;219:983-985.
  4. Ferrara N, Henzel WJ. Pituitary follicular cells secrete a novel heparin-binding growth factor specific for vascular endothelial cells. Biochemical and biophysical research communications 1989;161:851-858.
  5. Connolly DT, Olander JV, Heuvelman D, Nelson R, Monsell R, Siegel N, Haymore BL, Leimgruber R, Feder J. Human vascular permeability factor. Isolation from U937 cells. The Journal of biological chemistry 1989;264:20017-20024.
  6. Leung DW, Cachianes G, Kuang WJ, Goeddel DV, Ferrara N. Vascular endothelial growth factor is a secreted angiogenic mitogen. Science 1989;246:1306-1309.
  7. Keck PJ, Hauser SD, Krivi G, Sanzo K, Warren T, Feder J, Connolly DT. Vascular permeability factor, an endothelial cell mitogen related to PDGF. Science 1989;246:1309-1312.
  8. Adamis AP, Shima DT, Yeo KT, Yeo TK, Brown LF, Berse B, D'Amore PA, Folkman J. Synthesis and secretion of vascular permeability factor/vascular endothelial growth factor by human retinal pigment epithelial cells. Biochemical and biophysical research communications 1993;193:631-638.
  9. Shima DT, Deutsch U, D'Amore PA. Hypoxic induction of vascular endothelial growth factor (VEGF) in human epithelial cells is mediated by increases in mRNA stability. FEBS letters 1995;370:203-208.
  10. Miller JW, Adamis AP, Shima DT, D'Amore PA, Moulton RS, O'Reilly MS, Folkman J, Dvorak HF, Brown LF, Berse B, et al. Vascular endothelial growth factor/vascular permeability factor is temporally and spatially correlated with ocular angiogenesis in a primate model. The American journal of pathology 1994;145:574-584.
  11. Adamis AP, Miller JW, Bernal MT, D'Amico DJ, Folkman J, Yeo TK, Yeo KT. Increased vascular endothelial growth factor levels in the vitreous of eyes with proliferative diabetic retinopathy. American journal of ophthalmology 1994;118:445-450.
  12. Aiello LP, Avery RL, Arrigg PG, Keyt BA, Jampel HD, Shah ST, Pasquale LR, Thieme H, Iwamoto MA, Park JE, et al. Vascular endothelial growth factor in ocular fluid of patients with diabetic retinopathy and other retinal disorders. The New England journal of medicine 1994;331:1480-1487.
  13. Tolentino MJ, Miller JW, Gragoudas ES, Jakobiec FA, Flynn E, Chatzistefanou K, Ferrara N, Adamis AP. Intravitreous injections of vascular endothelial growth factor produce retinal ischemia and microangiopathy in an adult primate. Ophthalmology 1996;103:1820-1828.
  14. Adamis AP, Shima DT, Tolentino MJ, Gragoudas ES, Ferrara N, Folkman J, D'Amore PA, Miller JW. Inhibition of vascular endothelial growth factor prevents retinal ischemia-associated iris neovascularization in a nonhuman primate. Archives of ophthalmology 1996;114:66-71.
  15. Aiello LP, Pierce EA, Foley ED, Takagi H, Chen H, Riddle L, Ferrara N, King GL, Smith LE. Suppression of retinal neovascularization in vivo by inhibition of vascular endothelial growth factor (VEGF) using soluble VEGF-receptor chimeric proteins. Proceedings of the National Academy of Sciences of the United States of America 1995;92:10457-10461.
  16. Robinson GS, Pierce EA, Rook SL, Foley E, Webb R, Smith LE. Oligodeoxynucleotides inhibit retinal neovascularization in a murine model of proliferative retinopathy. Proceedings of the National Academy of Sciences of the United States of America 1996;93:4851-4856.
  17. Tolentino MJ, Husain D, Theodosiadis P, Gragoudas ES, Connolly E, Kahn J, Cleland J, Adamis AP, Cuthbertson A, Miller JW. Angiography of fluoresceinated anti-vascular endothelial growth factor antibody and dextrans in experimental choroidal neovascularization. Archives of ophthalmology 2000;118:78-84.
  18. Krzystolik MG, Afshari MA, Adamis AP, Gaudreault J, Gragoudas ES, Michaud NA, Li W, Connolly E, O'Neill CA, Miller JW. Prevention of experimental choroidal neovascularization with intravitreal anti-vascular endothelial growth factor antibody fragment. Archives of ophthalmology 2002;120:338-346.
  19. Gragoudas ES, Adamis AP, Cunningham ET, Jr., Feinsod M, Guyer DR, Group VISiONCT. Pegaptanib for neovascular age-related macular degeneration. The New England journal of medicine 2004;351:2805-2816.
  20. Rosenfeld PJ, Brown DM, Heier JS, Boyer DS, Kaiser PK, Chung CY, Kim RY, Group MS. Ranibizumab for neovascular age-related macular degeneration. The New England journal of medicine 2006;355:1419-1431.
  21. Brown DM, Kaiser PK, Michels M, Soubrane G, Heier JS, Kim RY, Sy JP, Schneider S, Group AS. Ranibizumab versus verteporfin for neovascular age-related macular degeneration. The New England journal of medicine 2006;355:1432-1444.
  22. Group CR, Martin DF, Maguire MG, Ying GS, Grunwald JE, Fine SL, Jaffe GJ. Ranibizumab and bevacizumab for neovascular age-related macular degeneration. The New England journal of medicine 2011;364:1897-1908.
  23. Holash J, Davis S, Papadopoulos N, Croll SD, Ho L, Russell M, Boland P, Leidich R, Hylton D, Burova E, Ioffe E, Huang T, Radziejewski C, Bailey K, Fandl JP, Daly T, Wiegand SJ, Yancopoulos GD, Rudge JS. VEGF-Trap: a VEGF blocker with potent antitumor effects. Proceedings of the National Academy of Sciences of the United States of America 2002;99:11393-11398.
  24. Heier JS, Brown DM, Chong V, Korobelnik JF, Kaiser PK, Nguyen QD, Kirchhof B, Ho A, Ogura Y, Yancopoulos GD, Stahl N, Vitti R, Berliner AJ, Soo Y, Anderesi M, Groetzbach G, Sommerauer B, Sandbrink R, Simader C, Schmidt-Erfurth U, View, Groups VS. Intravitreal aflibercept (VEGF trap-eye) in wet age-related macular degeneration. Ophthalmology 2012;119:2537-2548.
  25. Dugel PU, Koh A, Ogura Y, Jaffe GJ, Schmidt-Erfurth U, Brown DM, Gomes AV, Warburton J, Weichselberger A, Holz FG, Hawk, Investigators HS. HAWK and HARRIER: Phase 3, Multicenter, Randomized, Double-Masked Trials of Brolucizumab for Neovascular Age-Related Macular Degeneration. Ophthalmology 2020;127:72-84.
  26. Mones J, Srivastava SK, Jaffe GJ, Tadayoni R, Albini TA, Kaiser PK, Holz FG, Korobelnik JF, Kim IK, Pruente C, Murray TG, Heier JS. Risk of Inflammation, Retinal Vasculitis, and Retinal Occlusion-Related Events with Brolucizumab: Post Hoc Review of HAWK and HARRIER. Ophthalmology 2021;128:1050-1059.
  27. Miller JW. VEGF: From Discovery to Therapy: The Champalimaud Award Lecture. Transl Vis Sci Technol 2016;5:9.

(Milestone essay published 2021)