Why was this experiment so important? Because once the monkey cell took up the foreign DNA, the bacteria’s genes could begin to produce the same proteins that they would inside a bacteria cell. In other words, the bacteria’s genes could co-opt the machinery of the monkey cell and re-directed it to manufacture new molecular products. For drug hunters, it was the opposite kind of recombinant DNA that was so promising—taking the genes out of a mammal cell and inserting them into a bacterium. In 1975, a rabbit gene that creates hemoglobin became the very first mammalian gene to be transferred into another organism when it was inserted into an E. coli bacterium in a Petri dish. These bacteria cells could now be engineered to produce rabbit hemoglobin, marking a watershed moment in genetics—and the birth of genetic medicine.
That same year witnessed one of the first and most important conferences about the spectacular advances in recombinant DNA, the Cold Spring Harbor Symposium on Quantitative Biology. I remember my thesis advisor returning from the conference and sharing what he had learned with great excitement. “Any human gene can now be harnessed to make human proteins in a test tube,” he gushed. “And the place to start is obvious. We should clone the insulin gene and use it to make human insulin.”
The insulin gene turned out to be a great choice for the early attempts at developing genetic medicine, and not just because of the huge demand for insulin. The gene for insulin is extremely short, and the smaller a gene the easier it is to manipulate. In 1976, Herb Boyer (a biochemistry professor at the University of California, San Francisco) and Robert A. Swanson (a venture capitalist) started a new company in San Francisco to develop drugs using the new recombinant DNA technology. Genentech’s very first project was to manufacture human insulin.
This was an entirely new approach to drug hunting. Instead of searching for new molecules in plants during the Age of Plants, or searching for new synthetic tweaks to existing molecules during the Age of Synthetic Chemistry, or searching through the soil for new bacteria-fighting compounds during the Age of Dirt, Genentech was searching through the human genome for fragments of DNA that could produce useful protein-based drugs. But even though the library of potential genetic drugs was new, the drug hunting story was the same as always. Finding useful drugs is very, very hard, and gets even harder the longer the search goes on.
It took Genentech more than a year to isolate the human insulin gene, and by then they were running out of money fast. They needed a new financial partner to help continue funding their drug development, a partner who could supply enough cash to allow the insulin project to reach a commercial conclusion. There were two obvious targets for Genentech to potentially partner with: Eli Lilly and E. R. Squibb. Even in the late 1970s, Lilly remained the unchallenged leader in insulin production, controlling about 95 percent of the United States insulin market. Squibb, in contrast, was a much smaller niche player who controlled the remaining 5 percent of the market. Genentech’s executives reasoned that Squibb might be the better choice, since Squibb would presumably be interested in boosting their undersized market share and recombinant human insulin offered an unprecedented opportunity to do exactly that.
Genentech reached out to Squibb and proposed teaming up. Though Squibb was a large pharma corporation with a huge research staff, they had no experience at all with recombinant DNA technology. So Squibb did the same thing that all Big Pharma companies do when they do not understand some new science: they hired a consultant. Sir Henry Harris, Regius Professor of Medicine at Oxford University, was a pharma consultant with a very impressive resume. Harris had been trained as a physician before spending an admirable career researching tumor cells. Unfortunately, none of Harris’s experiences in the biology lab qualified him to evaluate the Genentech proposal, which dealt with cutting-edge genetic technologies that he had never encountered before. But if Harris lacked the apposite expertise, he did not lack in self-confidence.
Harris reviewed the details of Genentech’s proposed method for manufacturing human insulin in bacteria cells and rendered the following analysis: Proteins are three-dimensional molecules. The precise three-dimensional shape of any particular protein matters greatly to the operation of physiological processes that use the protein. The specific amino acids that compose any molecule of protein can combine in many different geometries to form many different shapes, but for a given protein to function properly in the body it must be in the proper shape for the body to recognize it and make use of it. So far, so good, but now Harris made an unjustified claim.
He insisted that if human insulin genes were put inside bacteria cells, the bacteria would manufacture insulin protein molecules in a different three-dimensional shape than when the molecules were manufactured in human cells. Since it would be impossible to re-configure the geometry of the improperly-shaped insulin molecules, Genentech would never be able to produce true human insulin. Thus, Harris told Squibb to pass.
Squibb took Harris’s considered opinion very seriously and, on the basis of his advice, rejected Genentech’s collaboration request. Genentech was surprised by Squibb’s reaction, but the Squibb executives refused to believe Genentech’s earnest attempts to show why Harris’s thinking was wrong. After all, all Genentech could offer was a promise that they would be able to solve the geometry problem, without any concrete evidence that they could.
So Genentech turned to Eli Lilly.
Lilly appraised the situation in an entirely different way. They recognized that there was a small but meaningful chance that Genentech would be able to produce human insulin. If Genentech succeeded and Lilly was not involved, the economic consequences would be catastrophic for Lilly. Insulin was one of the most important market franchises for Lilly—they basically owned the only known treatment for diabetes—and they simply could not risk the possibility of losing the entire market, so matter how unlikely that potential loss. Thus, in 1978, Lilly agreed to collaborate with Genentech.
Sir Henry Harris’s analysis of the difficulty of creating properly-shaped proteins using recombinant DNA technologies turned out to be wrong. He guessed that insulin produced by human genes inserted in E. coli would have the wrong shape. He was right about that. But in short order Genentech solved this seemingly intractable problem. It developed a biochemical process by which the improperly-shaped insulin harvested from E. coli was successfully re-folded into its correct shape. Using Lilly’s funding, Genentech produced the first batch of human insulin, manufacturing the precious protein inside a test tube. In 1982, human insulin went on sale for the first time. Today, virtually all insulin is produced using recombinant DNA technologies—and Eli Lilly remains the world leader in insulin production to this very day.
Sir Henry Harris’s erroneous opinion had an outsized influence on the course of my own career. In the late 1970s, I was very intrigued by all the new developments in recombinant DNA, and I was eager to use the new technology in my own drug hunting. But I was hired by Squibb in 1981, just after Harris had delivered his pessimistic pronouncement about genetic medicine, and my manager informed me that the company had absolutely no interest in using recombinant technologies to make protein drugs. Squibb missed out on one of the most momentous revolutions in the history of drug hunting—and so did I. Instead, I was assigned to use molecular biology methods to develop traditional drugs, and that is exactly what I did for the rest of my career.
While I was hunting for conventional drugs in the library of dirt and the library of synthetic chemistry, there was a mad rush through the shelves of the newly opened library of genes. Pharmaceutical companies raced to identify new therapeutic proteins they could grow inside bacteria. Since many hormones are proteins, many of the earliest efforts focused on pharmaceutical hormones. After the tremendous success of recombinant insulin, the next recombinant protein to go on sale was human growth hormone (HGH), a treatment for dwarfism, in 1985. Genentech manufactured HGH because the hormone was relatively easy to produce using recombinant technology, even though the market for HGH is far smaller t
han that for insulin. HGH was followed by interferon, a cancer treatment, by Biogen in 1986; erythropoietin by Amgen in 1989 to treat kidney failure; and clotting factor VIII by Genetics Institute in 1992 to treat hemophilia A.
At first, Big Pharma was thrilled by the realization that recombinant technology granted them virtually unlimited ability to cure any disease caused by a missing protein. But this initial flush of excitement soon dimmed. The fact of the matter is that there are simply not that many diseases caused by missing proteins. By the early 1990s, after producing about a dozen new recombinant drugs, the industry was running out of diseases to treat. Drug hunting followed the same trajectory it always did: a new library of potential molecules is discovered, there are a few major discoveries, the entire industry swarms through the library, and in short order the library is exhausted. Of course, there always seems to be a new library to search and the biotechnology industry soon found another one, known as recombinant monoclonal antibodies.
Here’s how monoclonal antibodies work. In response to the presence of a pathogen, the human body’s white blood cells produce antibodies—chemicals that attack the invading bacterium, virus, fungus, parasite, or other foreign agent. But since every pathogen is different—sometimes extremely different (just consider the difference between, say, athlete’s foot fungus and tapeworms)—each pathogen is vulnerable to a different type of antibody. Thus, if we want to kill an intruder, our body needs to produce the right kind of antibody. Or, even better, produce multiple kinds of pathogen-specific antibodies, which each inflict different damaging effects on the target. Our white blood cells accomplish this using a very sophisticated process. When a germ is detected, the white blood cells (specifically, the B cells) start to rapidly reproduce, but each child cell is a different variant of the parent white blood cell. The body can produce literally millions of white blood cell variants in a very short period of time. Each of these variants produces a different kind of antibody. Thus, we might say the body uses a just-in-time “weapons on demand” system: if it detects an enemy jet fighter, it produces different types of anti-aircraft missiles; if it detects an enemy tank, it produces different kinds of anti-tank rockets; if it detects enemy soldiers, it produces different types of guns.
If a drug hunter thinks that a particular type of antibody might make a useful drug, then he can put human white blood cells into a petri dish and manipulate them into producing the specialized white blood cells that manufacture the desired antibody (typically this is done by exposing the white blood cells to a substance that will trigger the formation of the requisite specialized cells). Next, the drug hunter can isolate the specialized cells that produce the target antibody and then, using recombinant DNA methods, extract the specific genes from these cells that are responsible for creating the antibody, and then use these genes to churn out as much of the antibody as he needs. Finally, he can take this antibody and convert it into a useful drug. Antibodies produced in this fashion are known as monoclonal antibodies because the compounds are from one highly specific type of white blood cell (mono-clonal means “single-branch”). The library of monoclonal antibodies is now a mainstay of recombinant DNA drug development and has generated drugs for diseases ranging from multiple sclerosis to rheumatoid arthritis.
The Nobel Prize committee recognized the historic research effort that led to the original development of animal-based insulin by awarding the 1923 Nobel Prize in Medicine to Frederick Banting and J. J. R. Macleod. As you may have guessed, Banting did not react to this award with delight or pride. Instead, he was furious that the Nobel committee forced him to share the prize with Macleod. In Banting’s mind, since he had come up with the basic idea for extracting insulin from dogs by clamping shut their pancreatic ducts, he deserved all the credit, even though without Macleod providing him with a laboratory, an assistant, a biochemist, and credibility, Banting would never have been able to bring his vague (and unoriginal) idea to fruition. Banting refused to attend the Nobel award ceremony Stockholm and just stayed home.
I wish I could tell you that drug hunters are a courtly and charitable bunch, but Banting illustrates one of the most enduring facts about my profession. Every successful drug hunter is as distinct as the drug he (or she) discovers.
10
From Blue Death to Beta Blockers
The Library of Epidemiological Medicine
John Snow’s map of cholera
“Superior doctors prevent the disease from happening, mediocre doctors treat the disease before fully evident, inferior doctors treat the disease after it is apparent to everyone.”
—Huang Dee Nai-Ching, 2600 BC
Cholera is a particularly nasty disease of the small intestine whose prime symptom is “rice water,” a watery diarrhea redolent of fish. A victim may excrete up to five gallons of diarrhea each day. Vomiting and muscle cramps are common. The resulting dehydration is often so drastic that a victim’s electrolytes become unbalanced, debilitating the heart and brain. Cholera is called “the blue death” because the afflicted’s skin can turn bluish-gray from the extreme loss of fluids. Without treatment, about half of the disease’s victims die.
Throughout the nineteenth century, wave after wave of cholera pandemics swept through Europe and much of the world. The second wave decimated Ireland in 1849, killing off many of those who had been lucky enough to survive the Irish potato famine. The epidemic then washed up on American shores via ships crammed with Irish immigrants, eventually infecting President James K. Polk. The disease swept west and extinguished some six thousand to twelve thousand travelers along the California, Mormon, and Oregon trails, mostly pioneers hoping to make their fortune in the California Gold Rush before the ill fortune of rice water put an end to their dreams. As this virulent wave was finally winding down, a brand new globe-hopping wave of cholera came bursting out of India and smashed into London in 1853.
The Blue Death claimed the lives of more than ten thousand Londoners in a single year. One man who became obsessed with the terrifying intestinal disease was an English physician named John Snow. The son of a coal laborer, Snow had grown up in poverty in one of the poorest neighborhoods in York, where his family’s ramshackle house was flooded every time the nearby River Ouse overflowed its banks—and it overflowed often. Snow was working as an anesthesiologist at St. George’s Hospital in London during the new pandemic, and on August 31, 1854, he took charge of treating cholera patients in the Soho district where he lived. Over the next three days, 127 Soho residents died. By the end of the following week, three quarters of the entire population of Soho had fled, rendering the vacant neighborhood a ghost town. By the end of the next month, out of the scant citizenry left behind, another five hundred had died, with far greater losses throughout the rest of England. Snow later called it “the most terrible outbreak of cholera which ever occurred in this kingdom.”
Nobody had the vaguest idea what caused cholera or what its risk factors might be. The London outbreak occurred seven years prior to Louis Pasteur’s publication of the germ theory of disease and forty years before Robert Koch (who won the Nobel for showing that a bacterium caused tuberculosis) finally convinced the medical community that cholera and other diseases were truly caused by germs. Snow set out to investigate the cause of one of humankind’s most loathsome scourges without any knowledge of infectious pathogens, at a time when the leading explication of disease was miasma theory.
Miasma theory—the notion that disease was caused by “foul air”—certainly seemed like a plausible explanation for cholera. Blue Death was prevalent in many lower-class neighborhoods, locales that inevitably featured the reek of animal and human feces blended with the wet stink of rotting garbage. Another popular opinion held that the supposed moral depravity of the lower classes somehow weakened their constitutions and made them more vulnerable to disease. Snow was skeptical of both miasma theory and depravity theory, however. He suspected, instead, that there might be something in the water. But if you do not know about germs or have
the technology to detect them, how can you confirm that water hides some kind of contagion?
Snow approached his investigation in a wholly original manner—so original, in fact, that it would lead to the founding of an entirely new field of medicine. He scrutinized a map of the Soho neighborhood and began to systematically document where each case of cholera had occurred. (Today, this area is the Carnaby Street shopping district in Westminster.) At each location where an afflicted Soho resident lived, he drew a short black bar, stacking multiple bars perpendicular to the adjacent street. He drew 578 bars in total. Next, he marked the location of each public water pump in the neighborhood. London’s water supply consisted of a system of shallow public wells where people could pump out water to carry back home. These wells were supplied with water through a jumble of water lines controlled by about a dozen water utilities. As convoluted as London’s water system was, the city’s sewage system was even more chaotic and ad hoc. Personal privies emptied into cesspools, cellars, or an unfathomable tangle of sewer pipes. Worst of all, the London aquifer allowed for the easy mixing of the liquids in the cesspools and wells.
Snow noticed several interesting features on his marked-up map. Even though a large Soho workhouse just north of the Broad Street pump housed over five hundred paupers, very few of its residents came down with cholera. Similarly, not a single person who worked at a brewery one block east of the Broad Street pump contracted the disease. Nevertheless, despite these two anomalies, Snow’s map made one thing perfectly clear: most of the cholera deaths occurred in residents who lived near the Broad Street pump.
Convinced that whatever was responsible for the disease must be coming out of the well on Broad Street, Snow approached the local city council and demanded that they remove the pump. The council was skeptical. How could that well be polluted? After all, they pointed out, the water from Broad Street was clear and tasted better than most pumps in Soho. In fact, many people avoided the water in their local well and traveled all the way to the Broad Street pump to obtain its clean water, especially residents who lived near the smelly Carnaby Street pump.
The Drug Hunters Page 14