2010 Lasker~DeBakey Clinical Medical Research Award

Anti-VEGF therapy for wet macular degeneration

The 2010 Lasker~DeBakey Clinical Medical Research Award honors a scientist who discovered vascular endothelial growth factor (VEGF), a key participant in blood-vessel formation, and exploited this knowledge to devise an effective treatment for wet age-related macular degeneration (AMD). Napoleone Ferrara (Genentech) has provided a therapy that can, for the first time, improve sight for people with this illness, many of whom were previously destined for blindness. Ferrara's work has uncovered the lynchpin for one of the body's most important physiological processes and unlocked a novel approach for combating a serious eye disorder.

People have known since Aristotle's time that blood nourishes the body, yet the molecular underpinnings of blood-vessel formation remained mysterious for millennia. Initial insights arose from the study of cancer and eye disorders. Starting in the late 19th century, scientists reported that blood vessels proliferate before and during tumor expansion and that rapid tumor growth depends on a rich vascular supply. They documented that tumor cells release diffusible factors that foster angiogenesis, the creation and remodeling of new blood vessels from existing ones. The eye, too, could host troublesome blood-vessel growth, and in 1948, Isaac C. Michaelson (University of Glasgow) proposed that the retina contains an angiogenic factor that contributes to a form of blindness associated with premature birth.

These ideas found their first theoretical clinical application in 1971, when Judah Folkman (Harvard Medical School) suggested that restraining angiogenesis could thwart cancer. Although this concept sparked tremendous research activity, no one gained much traction in identifying physiologically relevant angiogenic factors — or in finding ways to block them — until Ferrara's breakthrough.

In the 1980s, many groups reported proteins that promoted growth of vascular cells. Available technology and information, however, did not permit easy identification of the genes responsible for their production, which was essential to confirm the molecules' biological roles. By the mid 1980s, two proteins — acidic and basic fibroblast growth factor (aFGF and bFGF, respectively) — had become frontrunner candidates. They spurred blood vessel cells as well as a wide range of other cells to divide in culture and induced angiogenesis when placed at sites in an animal that normally lack blood vessels. However, analysis of aFGF and bFGFgenes revealed a snag: They did not contain the hallmark sequence that allows proteins to exit cells. It was hard to explain how an intracellular molecule could diffuse and prompt cells in neighboring blood vessels to reproduce and migrate.

When Ferrara began a postdoctoral fellowship at the University of California, San Francisco (UCSF) in the early 1980s, he was studying particular cells in the cow pituitary gland that seemed likely to help regulate blood-vessel development. Ferrara cultivated these cells in laboratory dishes and collected the broth in which they grew. When he added this medium to cells that line blood vessels — vascular endothelial cells — they divided vigorously. In contrast, cells from other tissues ignored the material. The active substance thus fulfilled key requirements for being a secreted molecule that provokes growth of vascular endothelial cells. Ferrara pursued the protein after he moved to Genentech in 1988. The following year, he isolated the gene that encodes it from cows as well as humans, and discovered that its amino acid sequence did not match that of any known protein. Crucially, it contained a sequence that allows proteins to escape from cells. Because the molecule exerts its effect only on vascular endothelial cells, Ferrara called it vascular endothelial growth factor (VEGF).

Simultaneously, an independent group at Monsanto Company, led by Daniel Connolly, uncovered the gene for vascular permeability factor (VPF), a protein from guinea pig tumors that Harold Dvorak (Harvard Medical School) had identified in 1983 on the basis of its ability to incite blood-vessel leakage. Sequence comparison showed that the VPF and VEGF genes were identical.

Thirsty for blood

VEGF could induce proliferation of blood-vessel cells in culture, but no one knew whether it did so in animals. Ferrara showed that, in rats, Vegf gene activity correlates temporally with blood-vessel growth and VEGF binding correlates spatially with blood vessels. However, these links did not clarify whether VEGF instigates or simply accompanies angiogenesis. To resolve that issue, Ferrara wanted to assess whether quelling VEGF obliterates formation of new blood vessels in a live creature. He thus sought ways to foil the protein in experimental animals.

Inactivating the Vegf gene provided one such method. In 1996, Ferrara's group and a team led by Peter Carmeliet (Flanders Interuniversity Institute for Biotechnology, Leuven, Belgium) independently reported that disrupting a single copy of Vegf in mice caused embryos to die early in development. This result was surprising, as the embryos retained one operational copy of the gene. Furthermore, the finding indicated that other members of the VEGF family, which had surfaced by then, don't compensate for even partial loss of VEGF. These observations indicated that the rodents are exquisitely sensitive to VEGF dosage and established the protein as a crucial player in embryogenesis.

To probe VEGF's role in a mature animal, Ferrara harnessed the discovery of its receptor, which he made in 1992 with Lewis T. Williams (UCSF). This protein dwells on endothelial cells, where it binds VEGF and, in response, triggers cellular activities. Ferrara shortened the receptor so it would not associate with cells; instead it intercepted VEGF and impeded its function. In grown rats, the modified receptor almost completely wiped out angiogenesis in tissue that is normally loaded with blood vessels, Ferrara reported in 1998; furthermore, it prevented the tissue from performing its biological tasks. This study demonstrated VEGF's importance in normal adult physiology.

Meanwhile, Ferrara had been pursuing other methods of inactivating VEGF, aiming to tackle disease. Toward that end, he developed a mouse monoclonal antibody that neutralizes human VEGF. In 1993, he reported that this agent foils the ability of several human tumor cell lines to multiply after they have been implanted into mice. These results provided the first direct evidence that tumor growth depends on angiogenesis and opened the door to clinical use of anti-VEGF compounds.

Envisioning better sight

In 1994, Ferrara turned his eye toward retinal disease. He and Lloyd Paul Aiello (Brigham and Women's Hospital and Harvard Medical School) analyzed fluid from the eyes of patients with retinal disorders that stemmed from different underlying causes. VEGF appearance correlated with conditions that involve formation of new blood vessels, but not with other illnesses.

To test whether subduing VEGF might dispel eye diseases caused by pathological angiogenesis, Ferrara injected a derivative of the VEGF receptor into the eyes of mice with that type of retinal malady. The extent of new blood-vessel formation plunged in 46 out of 47 animals, he reported in 1995. The next year, with Anthony Adamis (Children's Hospital, Boston), he conducted experiments on monkeys that suffered from a related eye condition. The same monoclonal antibody that Ferrara had used to obstruct tumor growth stymied blood-vessel formation in that setting. These experiments suggested that anti-VEGF agents might fight a human disease that also arises from inappropriate vascularization — wet AMD, a leading cause of severe, irreversible vision loss in the elderly.

See change. Every month, patients' eyes were injected with 0.5 mg Lucentis® (top curve) or prepared for treatment, but not injected (bottom curve). The drug improves average visual acuity, as can be seen by enhanced ability to read an eye chart. At the end of two years, the group that received Lucentis ® could see, on average, 21.4 more letters than the sham-treated group, which lost vision during that period. CREDIT: Cassio Lynm

Ferrara decided to groom the mouse monoclonal antibody rather than the soluble receptor for therapeutic use, in part because he knew that he could render it tolerable to the human immune system by engrafting the VEGF-binding portion onto a human antibody. Ferrara and his colleagues considered delivering the product — called bevacizumab — to the eye by injecting it into the bloodstream. They worried, however, about the systemic presence of an agent that interferes with blood-vessel formation in a population — elderly people — that has a high risk of cardiovascular disease. Therefore, the scientists chose to administer it directly into the eye. With that goal in mind, Ferrara and Henry Lowman (Genentech) developed a smaller derivative of the anti-VEGF antibody, ranibizumab, which they anticipated would penetrate the retina better than its parent, be more potent, and carry a lower risk of certain inflammatory responses.

In 2000, Ferrara and colleagues, including Philip J. Rosenfeld (University of Miami Miller School of Medicine) and David M. Brown (Methodist Hospital, Houston), began wet AMD clinical trials with this anti-VEGF antibody. Encouraging data led to multi-center trials on more than 1000 patients. The drug not only stops vision loss, but improves sight in many patients after a year of monthly injections (see graph); its effects persisted through the second year of the study. Other available therapies are modestly effective at halting disease and do not restore vision. On June 30, 2006, the US FDA approved ranibizumab (Lucentis®) for the treatment of wet AMD. Two years earlier, the parent compound (Avastin®) had been approved for metastatic colon cancer, and many individuals are receiving this drug 'off label' for wet AMD.

Ferrara's work is revolutionizing quality of life for many of the estimated 1.2 million individuals in the United States who have wet AMD. Upwards of a million AMD patients worldwide have already received anti-VEGF antibody therapy. Many more will likely benefit in the coming decades, as disease frequency increases rapidly due to the world's aging population.

by Evelyn Strauss

Key publications of Napoleone Ferrara

Ferrara, N. and Henzel, W.J. (1989). Pituitary follicular cells secrete a novel heparin-binding growth factor specific for vascular endothelial cells. Biochem. Biophys. Res. Commun. 161, 851-858.

Leung, D.W., Cachianes, G., Kuang, W.-J., Goeddel, D.V., and Ferrara, N. (1989). Vascular endothelial growth factor is a secreted angiogenic mitogen. Science. 246, 1306-1309.

Kim, K.J., Li, B., Winer, J., Armanini, M., Gillett, N., Phillips, H.S., and Ferrara, N. (1993). Inhibition of vascular endothelial growth factor-induced angiogenesis suppresses tumour growth in vivo. Nature. 362, 841-844.

Presta, L.G., Chen, H., O'Connor, S.J., Chisholm, V., Meng, Y.G., Krummen, L., Winkler, M., and Ferrara, N. (1997). Humanization of an anti-VEGF monoclonal antibody for the therapy of solid tumors and other disorders. Cancer Res. 57, 4593-4599.

Ferrara, N., Damico, L., Shams, N., Lowman, H., and Kim, R. (2006). Development of ranibizumab, an anti-vascular endothelial growth factor antigen binding fragment, as therapy for neovascular age-related macular degeneration. Retina. 26, 859-870.

Ferrara, N. (2009). History of discovery: Vascular endothelial growth factor. Arterioscler. Thromb. Vasc. Biol. 29, 789-791.

Award presentation by Richard Lifton

"A revolution is an idea which has found its bayonets." These words, written by a military and political leader of Genoese ancestry, Napoleon Bonaparte, are exemplified in the work of today's Lasker~DeBakey Award recipient, a basic and clinical science leader and another notable Napoleone of Italian ancestry, Napoleone Ferrara. For decades, scientists had the idea that there was a diffusible factor that promotes blood vessel growth and, in turn, that inhibiting this growth might be useful in the treatment of certain diseases. But the identity of this factor proved maddeningly elusive, and the concept remained untested. Napoleon Ferrera gave this important idea its bayonets by identifying and characterizing this factor and developing specific antibodies that prevent its function. Ferrara indeed started a therapeutic revolution by showing that inhibition of this molecule's action is highly effective in preventing blindness in people with wet age-related macular degeneration (AMD).

Wet AMD is a devastating and common cause of blindness that affects 1.5 million Americans and countless more world-wide. The disease is uncommon before age 60, but increases rapidly thereafter, affecting nearly 10% of the population over age 80.

Wet AMD arises when blood vessels behind the retina of the eye proliferate abnormally. As proteins leak out of these fragile vessels, there is progressive loss of vision that can be both rapid and tragic. At the time of diagnosis, patients typically already have significant vision loss, and without treatment within three years 75% will deteriorate to blindness, defined as vision worse than 20/200. AMD is particularly devastating because it selectively affects the macula, the center of the visual field; the ability to read is consequently lost early in the course of disease, robbing elderly affected people of one of their remaining connections to the outside world. There was great need for new effective treatment since photodynamic therapy, the previous state-of-the-art treatment, still left 40% of patients with progressive disease, and few had any restoration of vision that had already been lost.

The key to improving the treatment of wet AMD proved to be Napoleone Ferrara's identification of a novel protein that elicits blood vessel growth. Every human cell needs a supply of oxygen and nutrients provided via blood vessels; the local blood supply to tissues is dynamic, capable of being remodeled throughout life in response to changing metabolic demands. For example, since the work of Virchow 100 years ago, it has been recognized that some cancers make a substance that attracts blood vessels. In the eye, Michaelson proposed in 1948 that a diffusible factor might be responsible for development of both normal and abnormal blood vessel growth, and by 1954 Ashton had demonstrated that increasing oxygen concentrations diminished blood vessel growth in the eye, while reduced oxygen levels increased vessel growth.

These observations set the stage for the work of Napoleone Ferrara. Trained as a physician in Italy and specializing in obstetrics, he was deeply interested in reproductive biology and came to the lab of Richard Weiner at the University of California at San Francisco intending to work on reproductive hormones made in the pituitary gland. Here he noted an unusual pituitary cell type that made no hormone but made intimate connections with blood vessels. In an astonishing intuitive leap, Dr. Ferrara guessed that these cells might be making a substance responsible for blood vessel growth. He showed that after growing these cells in culture, the cell-free medium promoted proliferation of endothelial cells, the intrinsic cell of all blood vessels. This provided the basis for a courageous effort to purify and identify this factor using classical biochemical techniques, which Ferrara undertook after becoming a Research Scientist at Genentech. In 1989 he succeeded in this endeavor and showed that this factor was a novel protein that selectively induced proliferation of endothelial cells; he named this factor vascular endothelial growth factor (VEGF). He subsequently isolated the complete VEGF gene and showed that when it was expressed in mammalian cells, VEGF protein was secreted into the medium and promoted endothelial cell proliferation.

An enormous body of work on VEGF has followed, both from Dr. Ferrara's lab and others worldwide. Low oxygen levels in many normal tissues and tumor types led to increased secretion of VEGF. It was shown that VEGF directly binds to a specific receptor on the endothelial cell surface to stimulate proliferation, and this receptor and its signaling pathway was identified and characterized. Finally, genetic ablation of even one of the two chromosomal copies of Vegf in the mouse was found to be lethal in embryonic development due to failure of normal blood vessel development. These findings collectively documented the essential role of VEGF in the development and dynamic maintenance of a normal blood supply to tissues.

Having the purified VEGF protein enabled Dr. Ferrara to develop highly specific antibodies that selectively bound to VEGF, which he showed blocked its biological activity. This permitted investigation of the utility of these antibodies in the treatment of specific diseases.

One of those diseases was wet AMD. Levels of VEGF were found to be increased in the eyes of patients with wet AMD, potentially accounting for the abnormal blood vessel growth in this disease and suggesting a therapeutic role for anti-VEGF antibodies. Numerous hurdles were overcome in developing the right antibody, formulation, and dosage, after which two pivotal phase III clinical trials were begun. One of these was the ANCHOR trial, a two-year study of 423 patients with classic wet AMD who were randomized to either photodynamic therapy or intraocular injections of anti-VEGF antibodies. The results were dramatic, obvious, and clinically important. Seemingly miraculously, there were significant improvements in visual acuity in patients receiving anti-VEGF treatment after just one injection; these improvements continued through the first three months and were sustained throughout the two-year trial. In contrast, vision significantly deteriorated in the photodynamic therapy group. After twoyears the anti-VEGF group showed an average gain of about two lines on a standard eye chart exam versus a loss of two lines in the photodynamic treatment group. This difference is clinically dramatic— at the end of the trial, 61% of the patients in the photodynamic treatment group had progressed to blindness, twice the number at the start of the trial. In contrast, only 20% in the anti-VEGF group were blind, which actually represented a decline from the start of the study. These dramatic results led to FDA approval of the use of anti-VEGF antibodies in wet AMD in 2006.

Since that time, there has been extremely rapid adoption of this new treatment, with an estimated 1 million people treated worldwide, attesting to the great unmet medical need and patient recognition of the efficacy of treatment. This constitutes a remarkable advance in the prevention of blindness in the elderly, and also suggests potential future uses of anti-VEGF therapy for other ophthalmologic diseases featuring abnormal blood vessel growth.

The discovery of VEGF by itself was a major scientific advance driven by a desire to understand the basic rules governing blood vessel growth. The development and clinical application of anti-VEGF antibodies to the treatment of wet AMD constitutes a major therapeutic triumph. That Dr. Ferrara not only made the fundamental discovery of VEGF but also developed the therapeutic anti-VEGF antibodies and was deeply involved in the clinical development program demonstrating their utility in wet AMD constitutes a true tour de force and provides testimony to Dr. Ferrara's intellectual breadth and talent. Napolean Bonaparte also said, "Ability is nothing without opportunity," and special mention should be made of the enabling scientific environment Dr. Ferrara found when he started this work at Genentech as well as this company's support for Dr. Ferrara's early basic studies at a time when there was little expectation of therapeutic payoff. Dr. Ferrara's success in the prevention of blindness in wet AMD with anti-VEGF antibodies is a spectacular achievement and serves as a potent reminder of the crucial links between outstanding basic science and disease-transforming therapeutics. From this Napoleone's work comes hope and expectation that we will see many more great scientific ideas turned into therapeutic bayonets.

 

Napoleone Ferrara

Acceptance remarks, 2010 Lasker Awards Ceremony

 

 

 

 

 

 

 

 

 

 

 

 

 

Nature Medicine Essay


I am honored and humbled to receive the Lasker~DeBakey Clinical Medical Research Award. I offer my most sincere thanks to the Lasker Foundation and the Lasker Jury members for this wonderful recognition.

I joined the angiogenesis field almost accidentally over 25 years ago. My interests began as a basic science question on the physiology of some poorly known pituitary cells, just to satisfy my intellectual curiosity. It would have been difficult to predict that these studies could one day have broad biological implications, even less that they would result in therapeutic advances for devastating diseases like cancer and neovascular age-related macular degeneration. I could also never have imagined those many years ago that one day I would be here taking to such a distinguished audience and accepting a Lasker Award. I feel extremely fortunate to have had the opportunity to undertake such a journey.

I believe that joining a company like Genentech, with outstanding human and scientific resources, was particularly helpful to achieving these goals. I was indeed fortunate to work with many wonderful people for over two decades. Undoubtedly, all of this greatly facilitated the translation of basic science discoveries into potential treatments.

I wish to acknowledge many colleagues in the angiogenesis field — both in academia and industry — for their enthusiasm and innovation. Their contribution played a major role in advancing the field.

I mention the inevitable frustrating hours in the lab because they define the life of a scientist. Our moments of breakthrough and discovery are so joyous precisely because they are so rare. I am thankful for having had the opportunity to witness my scientific discoveries move from the bench to the clinic.

I feel that while scientific discovery is hugely exciting, the ability to translate that work into potentially helping someone lead a better life is even more rewarding. This Award is dedicated to the patients I come to work each day hoping to serve. My thoughts go to them. I would like finally to thank my wife Chika for her patience and continued support over many years.

Key publications of Napoleone Ferrara

Ferrara, N. and Henzel, W.J. (1989). Pituitary follicular cells secrete a novel heparin-binding growth factor specific for vascular endothelial cells. Biochem. Biophys. Res. Commun. 161, 851-858.

Leung, D.W., Cachianes, G., Kuang, W.-J., Goeddel, D.V., and Ferrara, N. (1989). Vascular endothelial growth factor is a secreted angiogenic mitogen. Science. 246, 1306-1309.

Kim, K.J., Li, B., Winer, J., Armanini, M., Gillett, N., Phillips, H.S., and Ferrara, N. (1993). Inhibition of vascular endothelial growth factor-induced angiogenesis suppresses tumour growth in vivo. Nature. 362, 841-844.

Presta, L.G., Chen, H., O'Connor, S.J., Chisholm, V., Meng, Y.G., Krummen, L., Winkler, M., and Ferrara, N. (1997). Humanization of an anti-VEGF monoclonal antibody for the therapy of solid tumors and other disorders. Cancer Res. 57, 4593-4599.

Ferrara, N., Damico, L., Shams, N., Lowman, H., and Kim, R. (2006). Development of ranibizumab, an anti-vascular endothelial growth factor antigen binding fragment, as therapy for neovascular age-related macular degeneration. Retina. 26, 859-870.

Ferrara, N. (2009). History of discovery: Vascular endothelial growth factor. Arterioscler. Thromb. Vasc. Biol. 29, 789-791.

Interview with Napoleone Ferrara

Video Credit: Susan Hadary