In the summer of 1956, two scientists met in Mill Hill at the edge of London at the National Institute of Medical Research, the seven-storey building where the influenza virus had been discovered in 19331 and which was later used as the fictitious psychiatric hospital Arkham Asylum for the 2005 movie Batman Begins. Jean Lindenmann, aged thirty-one, was Swiss and a relative newcomer to scientific research. British scientist Alick Isaacs was three years older and had already achieved an international reputation for his experiments with viruses, having spent three years in Australia working under Nobel laureate Macfarlane Burnet.2 Lindenmann had studied physics first, at the University of Zurich, but switched to medicine when use of the atom bomb changed his view about what he should do with his life.3 As a teenager, he suffered from tuberculosis and lived apart from his parents for many years. Perhaps because of this, Lindenmann was quiet and shy. Isaacs, on the other hand, liked to whistle operas for his colleagues to identify.4 Scientific discussion often works well when one person is lucid and explorative, with the other more restrained and able to funnel the excitement into specific plans for experiments. In this case, the collaborative efforts of these two people with different backgrounds and different temperaments would lead to one of the greatest scientific breakthroughs of the twentieth century.5
Before meeting Lindenmann, Isaacs had, for many years, been trying to solve a long-standing mystery about viruses.6 At least as far back as the nineteenth century, it had been noticed that it was relatively uncommon for someone to be infected with two different viruses at the same time. Charles Darwin’s grandfather, Erasmus Darwin, commented on the fact that he had never seen a patient with measles who had smallpox.7 The mystery – why the presence of one virus seemed to block the growth of another – wasn’t studied systematically until 1937, when it was established that monkeys infected with one type of virus, Rift Valley fever virus, were protected against infection with another virus, yellow fever virus.8 Even for cells growing in a culture dish, when two different viruses were added, often only one grew well.
Mysterious as this was, it wasn’t widely thought of as a pressing issue when Isaacs met Lindenmann. The hot topic at the time, especially in the Mill Hill institute, was how flu spreads in an epidemic. Isaacs’ research team was focused on this – work on his pet project having shrunk to make way for it – and they had found out, for example, that flu which was rampant in the UK in 1951 involved two different versions of the virus. This, and the work of many others in Mill Hill at that time, was pioneering because it informs the way we nowadays use computers to predict the evolution and global spread of flu, which is essential to how the World Health Organization selects strains for each year’s flu vaccine.
Understanding how epidemics spread was, and still is, self-evidently important. It would have been much less clear whether studying why one virus blocks the growth of another was a worthwhile endeavour. Deciding what is important enough to get to the bottom of – which might mean spending years working on it – is the biggest decision that any scientist has to make. Some have a gut feeling about what to pursue, but many analyse the possible causes of an observation and ask if any would be groundbreaking if they proved true. If your computer crashed, would working out why lead to a major discovery? Probably not, so it’s best to just turn the computer off and on, and not waste time worrying about what happened precisely.
When Isaacs and Lindenmann met, they soon found themselves discussing why one type of virus blocked the growth of another, because Lindenmann had stumbled across the phenomenon in unpublished experiments he had carried out in Zurich. By the time Lindenmann arrived in London, with a year’s salary funded by a Swiss fellowship, Isaacs had already worked out how much of one virus was required to stop another and had demonstrated that one virus could stop the growth of all kinds of other viruses, but the heart of the mystery – how one virus stops another – remained. Together they talked about possible reasons. One possibility was that a protein molecule that viruses were known to depend on in order to gain entry to cells got used up, or removed, when one virus entered a cell, preventing a second virus gaining access to the same cells. Another possibility was that a molecule required by a virus in order to replicate might get used up, meaning that a second virus could enter the same cells but would be unable to multiply. They realised that either of these answers would be big discoveries if proved true, because as well as revealing how viruses work, they would expose a way in which viruses are vulnerable. It seemed to them both that this problem deserved more attention than it was getting. And so after discussing the issues over tea, they began experiments together on 4 September 1956. Medical science and their personal lives were forever changed by what they uncovered.
Their now-celebrated experiments involved infecting pieces of membrane from the shell of fertilised chicken eggs with flu virus. But instead of infecting the membrane cells directly with virus, they used virus that had first been mixed with red blood cells.9 Lindenmann and Isaacs knew that the virus would stick to the red blood cells, which are about 10,000 times bigger, but reasoned that this would not prevent the virus from infecting the chicken membrane cells with its genetic material (sending its genetic material into cells is how the flu virus works to replicate itself). However, once the genetic material had emerged from the virus, its outside coating would remain stuck to the red blood cells. These could then be washed off the membrane, bringing the outside coats of the viruses with them. The red blood cells with virus coats stuck to them could then be tested to see if they could still stop a viral infection when added to fresh chicken cell membrane. If so, they reasoned, it would demonstrate that the outside coat of a virus is what blocks a second infection, as opposed to the genetic material of the virus. The experiment took hours – membrane and red blood cells were left to swish about in test tubes rotating on rollers – and while they waited, Isaacs liked to talk about ideas for more experiments, or politics.
They found that red blood cells that had been coated with virus and washed off from chicken membrane cells could indeed still stop another virus infection. This seemed to fit with the idea that the outside coat of a virus was the important factor for blocking a second infection. But this interpretation completely relied on their assumption that the outer coat of a virus would be left stuck on red blood cells. To check this, they looked at the cells in their experiments with an electron microscope (the same type of microscope Steinman used to get a detailed look at dendritic cells). The pictures were blurred and they couldn’t tell whether there were husks of virus left on the red blood cells or not. Worse than this, the electron microscope pictures showed that some of the virus had simply detached from the red cells, probably while the cells and virus swished about on rollers. This worried them. It seemed possible that fully intact virus might have detached from the red blood cells, which was what was blocking a second infection. If so, their experiment hadn’t revealed anything new at all. By tackling this worry with a new experiment, they struck gold; actually, something far more valuable than gold.
In order to check whether freely roaming intact viruses were present, they carefully decanted the liquid from their test tubes, separating it not just from the chicken egg membrane but also from the virus-coated red blood cells as well. They then added this liquid to fresh chicken membrane cells, and found that it – or something in it – could also stop cells from being infected. But when Lindenmann and Isaacs checked the liquid, they found it contained very few, if any, dislodged viruses, which meant that they had no explanation for what was going on.
They decided to repeat the experiments without the complication of adding red blood cells. Now they found that the liquid taken from a test tube which contained virus and membrane cells was also able to stop virus from infecting fresh cells. Something in the liquid – just the liquid – stopped viral infections. This was the observation that got them on the right path to making an important discovery, but at the time it didn’t feel like anything like a eureka moment because they just didn’t know what to make of it. They were flummoxed.
Isaacs suggested that something able to interfere with viruses might have been generated in the liquid, but both scientists were also aware that something less exciting might have happened. If the liquid had turned acidic, for example, maybe that could stop viruses? Or perhaps nutrients had been used up by one virus which stopped a second infection? In amongst the back-and-forth about what they should do next, Lindenmann chose to name whatever it was that was causing the interfering activity interferon, to sound like a fundamental particle of the universe, like an electron, neutron or boson. He thought it was about time that biologists had a fundamental particle to work on, as the physicists already had so many. On 6 November 1956, just over two months since they started working together, Isaacs titled a new section of his lab notebook: ‘In search of an interferon’.10 And the hard work began.
It no longer mattered that Isaacs was more of an expert than Lindenmann; in uncharted territory, everyone’s a rookie. Like detectives arriving at the scene of a crime, not quite sure what they were looking for, they probed the liquid’s capabilities for any sort of clue. They found that heat destroyed its antiviral effect, while storage in a fridge did nothing. These results suggested that the pH of the liquid was not important after all – this wouldn’t be affected by heat – but that some kind of heat-sensitive factor was the active ingredient. They tested if centrifugation had any effect. It didn’t, which argued against the possibility that a large particle in the liquid was causing viral interference (as anything large would have been spun down to the bottom of the tube). They tested if the liquid could stop different types of virus – and it could. Over time, they ruled out uninteresting and circumstantial explanations and began to grow confident that something as yet unidentified, equipped with the power to stop viral infections, was actively at work; in other words, that there really was an interferon.
Reflecting on this time, Lindenmann later wrote: ‘If some people feel attracted to research, it is because its real excitements lie precisely in those phases of groping exploration that must seem tedious and dull to an outside observer. A few vainglorious moments of triumph fade fast; the satisfaction of an intellectually honest effort is more enduring. But it is perhaps just as well that this aspect of scientific work hardly ever comes through in popular writing. There ought to be secret joys that science reserves exclusively to those bold enough or naïve enough to answer its call.’11
By the end of February 1957, they decided that they had accumulated enough evidence to warrant writing up their claim of a new cell-derived, virus-induced factor which could interfere with virus replication. The head of the Mill Hill institute they worked in, Christopher Andrewes, was renowned for having discovered the flu virus in 1933, and as a fellow of the Royal Society he helped them publish their results across two papers in the society’s Proceedings.12 We now know that the ideas in these two papers were correct, but not many people agreed with them at first.
The trouble began when Lindenmann first presented interferon at a scientific meeting in Switzerland in June 1957. After his talk, a Swiss virologist commented that the idea was contrary to all he had read and had to be rubbish.13 When Isaacs’ and Lindenmann’s formal papers came out in October, several eminent scientists, especially in the USA, doubted that they had really discovered a new molecule.14 The sceptics argued that some of the virus must have contaminated their samples and caused the effects which they had attributed to a new molecule. Rumours spread that the work was fanciful and interferon was given alternative names; the misinterpreton or the imaginon.15 As is often the case with something new, scepticism was not simply malicious. The early experiments were complicated – cells and viruses were incubated together, liquid siphoned off and reused – and it was open to debate as to what exactly in this process produced the interfering factor. Also, the complexity of the experiments meant it was hard for other scientists to reproduce the results.
Every scientist dreads that their experiments will not be trusted by others. Even worse is if their personal integrity and honesty is doubted. Lindenmann’s integrity came under fire when he returned to Switzerland, after his year in London. His former boss, Hermann Mooser, decided that he should have been credited in the interferon papers with Isaacs because, Mooser claimed, the work built upon the unpublished experiments that Lindenmann had done in Mooser’s lab in 1955, before the work with Isaacs began. Mooser was highly respected (for his work on typhus bacteria) and his accusation was so disastrous for Lindenmann’s career that he had to leave Switzerland. He moved from job to job – a couple of years in Bern, three years in Florida – and then finally moved back to Zurich, only after Mooser had retired.16
Mooser died believing that he was a co-discoverer of interferon and he had been treated unfairly.17 In truth, many labs had carried out experiments which had produced interferon – almost any experiment involving live viruses and cells – but they weren’t aware of it. At the time Isaacs and Lindenmann reported interferon, there were various hints within the annals of science that factors might cause immune cells to react in some way.18 All research happens alongside other research and Mooser did not do enough to be widely recognised as a co-discoverer of interferon.
Isaacs confidently rebuked his claims but he was profoundly disillusioned by the criticism of others. He suffered from depression which sometimes required hospitalisation and medication.19 As one friend observed, he was ‘an imaginative scientist who saw the grand picture…[and was] full of ideas, but when depressed he was difficult to get along with’.20 Isaacs sometimes talked with his closest colleagues about whether or not the discovery he made with Lindenmann could have, after all, just been due to traces of virus in the liquid which they didn’t detect. Perhaps the sceptics were right, perhaps interferon didn’t exist.
Ideally, this should have been a matter for investigation with new experiments rather than self-doubt, but despite the objective tone of scientific papers, the pursuit of new knowledge is an intensely personal endeavour. Isaacs had a nervous breakdown in the autumn of 1958. To most scientists in Mill Hill, he was joyous and passionate, full of enthusiasm and energy, but hidden from view, his life was complicated. As a young doctor, he had married psychiatrist Susanna Gordon, in 1949. Theirs was a happy marriage,21 but because she wasn’t Jewish, Isaacs lost the support of his Orthodox family and his father disinherited him.22 The scientific community was like a surrogate family to Isaacs which meant that its support of his work was exceptionally important to him.
Intensifying the pressure, interferon wasn’t only debated at scientific conferences but also in mainstream newspapers and TV. Not that there was great public interest in Lindenmann and Isaacs solving the long-standing problem of viral interference of course, but everyone realised that if interferon could stop viral infections it could be a new wonder drug. The story was covered by the Daily Express in 1957, and then much more widely, including on BBC TV, after Isaacs presented interferon at a reception at the Royal Society in May 1958.23 Interferon even entered the lexicon of popular culture: in a Flash Gordon comic strip from 1960, drawn by Dan Barry, spacemen infected with a lethal extraterrestrial virus are saved by a just-in-time injection of interferon. (In fact, there’s a subtle error in the comic strip: interferon was shown to work by bringing down the temperature of the ill spacemen but in reality interferon raises a fever when having its effect.)
The government also kept watch over interferon. Parliament and the Medical Research Council, which funded the Mill Hill institute, were still reeling from the fact that penicillin, discovered in 1928 by Alexander Fleming in London, had been developed and patented in the US. The government was bitter about losing penicillin royalties, and if someone else had just stumbled on something big, they were not going to let it slip away again. Placing interferon squarely in that category, someone – it’s not clear who, maybe Isaacs himself – described interferon as ‘antiviral penicillin’.
There was great pressure on Isaacs, from the government, the scientific community and the public, to prove that interferon was real, that it could work as a drug and to obtain a patent for it. He suffered deeply from the stress and, unknown to his colleagues, attempted suicide at least twice.24
Meanwhile, in Isaacs’ lab, twenty-eight-year-old chemist Derek Burke was given the task of purifying the interferon molecule so that its chemical nature and its activity could be more clearly established. ‘It is essential to know what interferon is chemically in order to understand fully how it is produced and how it acts in the cell,’ Burke and Isaacs wrote in New Scientist magazine in June 1958.25 Isaacs thought this would take Burke about six months and then his ideas would be proved right. But purifying interferon turned out to be a Herculean task. The liquid siphoned off from cells and virus contained minuscule amounts of interferon and Burke filled up twelve notebooks ploughing through chemical processes in his attempts to isolate it.26 In hindsight, it was hopelessly naïve to think this would take six months. It took fifteen years.
On New Year’s Day 1964, long before that work had been completed, Isaacs suffered a brain haemorrhage. The haemorrhage was likely related to an abnormal tumorous blood vessel revealed by an angiogram, but out of reach to surgery.27 Isaacs returned to work three months later but was relieved from his position as head of a division and instead appointed head of a small research team of himself and two others. After returning to work, he suffered, as one colleague put it, from ‘a series of episodes of profound mental disturbance’.28 A second haemorrhage in January 1967 proved fatal. He was forty-five. A year before he died, he was elected a member of the Royal Society, and after his death a symposium was held in his honour in London, which included two Nobel laureates, Ernst Chain (who worked on penicillin) and Francis Crick (co-discoverer of the structure of DNA).29 ‘The field had lost its patron saint,’ one colleague lamented.30 Isaacs’ scientific legacy would eventually be celebrated widely, but he died with it in doubt.
In the last years of his life, a series of small clinical trials of interferon were disappointing and pharmaceutical companies lost interest. Soon after he died, however, the promise of interferon was revived by cancer research. Most cancers have nothing to do with a viral infection but there are a small number of viruses that have been associated with cancer.31 Ion Gresser, a New Yorker working in Paris, tested in mice whether or not interferon could stop cancer caused by a virus, in the same way it stops other viral infections. His experiments showed that it could. But a bigger discovery came out of his nothing-should-happen control experiment – that is, the version of the experiment that all scientists conduct alongside their main experiment, which is identical in all respects except for the exclusion of the one factor being assessed and is performed with the hope and the expectation that nothing will result from it, thus validating the outcome of the main experiment. In this case, Gresser performed the same test on other types of cancer that have nothing to do with a virus, thinking that these more common types of cancer would not be affected. Unexpectedly, he found that animals injected with all different types of cancer cells survived when treated with interferon. In 1969, he reported that, at least in mice, interferon could cure cancer.32
A cure for cancer may be a scientific holy grail but this particular cure was met with more scepticism than celebration. The biggest problem was that Gresser hadn’t used interferon as such. Nobody had isolated it yet, so he could only use an impure biological liquid siphoned off from cells and viruses, like cream skimmed from milk, allowing others to argue, as they did with Isaacs, about precisely what the active ingredient was. Gresser recalls a colleague trying to comfort him by saying that one day other scientists would repeat his discovery – and forget that he ever did it first.33
Separately from these provocative experiments, a passing observation of Gresser’s happened also to influence the course of progress towards our understanding of interferon. In one of his lower-profile research papers, published in December 1961, Gresser noted that, like other cells, human white blood cells mixed with viruses also led to the production of interferon.34 He speculated that this might play some role in the body’s immune defence against viruses and suggested that the production of interferon might be used as a diagnostic test for the presence of a viral infection. This caught the imagination of a Finnish scientist, Kari (pronounced ‘Kory’) Cantell. A loner who preferred to avoid popular research areas, Cantell reasoned that although most human cells mixed with viruses would lead to the production of interferon, perhaps human white blood cells are especially good at making interferon, and if so, these cells could be used to produce interferon in large amounts in the lab. It was a good idea, but it wouldn’t have led to anything if luck hadn’t played its part next.
Cantell tested his idea on a virus that he happened to have in his freezer called Sendai virus, which is a little like the flu virus, named for the Japanese city where it was discovered. We now know that Sendai virus is especially effective at getting white blood cells to make interferon. Had he used another virus, or even a different strain of the same virus, his first experiment would have failed and he might never have persevered.35 As it happens, in his first experiment – begun on 8 May 1963 – white blood cells produced ten times more interferon than any other type of human cell he tested. That’s not to say it was all down to luck. Cantell insists that having a permanent job at the outset was also important, otherwise his work would not have been funded for the length of time it ended up taking him to purify interferon after this first experiment – nine years.36
The complexity of the process he finally worked out gives a sense of why it took him so long. The process relied on the fact that different protein molecules will solidify out from a solution (i.e. precipitate), at different levels of the solution’s acidity. Cantell found that he could extract interferon by stirring an initial crude preparation in cold acidic alcohol and then slowly raising the pH of the liquid by adding other chemicals. Impurities came out of the solution quicker than interferon, and could be removed by centrifugation. The whole process had to be repeated several times. Cantell recalls that chemists thought this process very unusual: ‘But I was not a chemist, and my ignorance gave me freedom from prejudice.’37 It had been fifteen years since Isaacs and Lindenmann reported interferon and, just when public interest in the topic was at a low point, Cantell found a way to purify it, opening the way to put their thesis to the test once and for all.
A handful of cancer patients were treated with Cantell’s interferon and encouraging anecdotes spread among clinicians and scientists. The public, meanwhile, were thrilled by the idea of a medicine that is produced in and by the human body itself. It fitted with a desire for remedies to be more natural than, say, radiation therapy.38 In truth, defining any medicine as ‘natural’ is difficult in a rigorous scientific or philosophical sense because every treatment is an intervention, and all medicines are derived from nature at some level. The US cancer research community were also thrilled by these early results with interferon because they were under pressure to deliver new medicines after President Nixon signed the 1971 ‘war against cancer’ Act.
Swiss-born US virologist Mathilde Krim, whose media tycoon husband was influential in the US Democratic Party, lobbied for funding for interferon research. Krim was well connected with government administrators, pharmaceutical companies and other researchers.39 Several prominent US patrons for science, including Mary Lasker and Laurence Rockefeller, lent their support to interferon research largely because of Krim’s campaigning.
But all clinical-grade interferon was produced in Finland, controlled by Cantell, and for anyone wanting to test interferon in patients there were two hurdles to overcome. One was raising enough money to buy interferon from Cantell. The second was getting him to agree to sell it. He was bombarded with requests from scientists and clinicians as well as wealthy individuals hoping to save their own lives or lives of loved ones.40 Time magazine called Cantell ‘stubborn’41 but he had to be, because supplies were limited, and he wasn’t prepared to distribute interferon to whoever happened to be the highest bidder.
Oncologist Jordan Gutterman, working in Houston, Texas, obtained $1 million from Mary Lasker’s foundation to test interferon on cancer patients. Gutterman first met Lasker after she asked the head of a cancer centre to line up a few talks for her on the hottest research.42 Gutterman, at age thirty-six the youngest speaker in the line-up, caught Lasker’s attention – he was, and still is, a great explainer – and a friendship began.43 To persuade Cantell to sell him interferon, Gutterman flew to Arlanda airport, Stockholm, to catch Cantell as he was passing through to give a lecture.44 The effort paid off and he promised Gutterman the interferon he needed – with a 50% discount.45
Lasker was keen for Gutterman to test interferon on breast cancer patients because a close friend of hers had the disease and hadn’t responded to other treatments.46 Gutterman’s first patient had said that, because of her tumour, she felt bad that she hadn’t been able to move her arm to comb her hair. After treatment with 3 million units of interferon on 12 February 1978, Gutterman looked into her room and saw her combing her long grey hair. In these first tests, five out of nine women, whose other options had run out, showed a partial regression of their tumour.
He later found that interferon helped six out of ten people with myeloma, a cancer arising from immune cells in the bone marrow, and six out of eleven with lymphoma, cancer that affects the lymphatic system. Other scientists reported similar good news, albeit in just handfuls of patients. Side effects were common – fever, chills and fatigue – but these were minor compared to those associated with other cancer drugs. In August 1978, the American Cancer Society gave what was, at the time, its largest ever award – $2 million – to Gutterman for testing interferon. In July 1979, Life magazine proclaimed that interferon was all but certain to be a new wonder drug.
In truth, the early tests of interferon weren’t rigorously controlled because there wasn’t enough interferon available for a proper clinical trial: nearly all of the world’s supply of interferon still came from Cantell in Finland. Others found it hard to reproduce his success in isolating interferon because his method was full of small tricks optimised through hundreds of trials and errors. Cantell never patented his methods; he had no wish to make any personal profit, one reason being that he thought his own financial gain would be inappropriate given that his research had been paid for by public funds. But he knew, for example, that using particular round bottles led to greater production of interferon and it was hard to convince others that such nuance was important – at least until they had failed a few times first.47
The situation began to change in March 1978 when Cantell took a call from Charles Weissmann, from the University of Zurich, whom he didn’t know. The revolution of genetic engineering was in the air, the biotech industry was expanding. San Francisco-based company Genentech had just shown that a human gene could be inserted into bacteria, and these genetically modified bacteria would then produce the human protein encoded by that gene.48 This works because the chemical machinery which makes proteins inside cells is essentially the same in bacteria as it is in us: bacteria treat an inserted human gene just as they would any other gene and produce the protein that the gene codes for. In 1982, Genentech would make it big when the FDA approved the sale of the first genetically engineered medicine, human insulin.49 On the phone to Cantell in 1978, Weissmann talked about the genetic engineering revolution, and how he planned to isolate the interferon gene and use it to produce the protein in bulk. It sounded like science fiction to Cantell – and it almost was. Cantell was cautious about working with Weissmann, but Weissmann invited himself over to Helsinki two days later so that he could explain his plan in person. And then Cantell was won over.
Weissmann explained that when Cantell coaxed white blood cells into making lots of interferon, the process must involve an increase in the activity of the interferon gene, and that they could exploit this to isolate the gene. When a cell makes a protein molecule, such as interferon, it isn’t made from its gene directly. First, the gene for that protein is copied into RNA, a chemical very similar to the DNA of the gene itself. The RNA version of the gene is often trimmed or modified (the final version being called the messenger RNA or mRNA) and it then leaves the cell’s nucleus to act as a template from which the cell makes the protein. If lots of a particular protein is needed, the cell makes lots of copies of the corresponding RNA template. This was the fact that Weissmann’s team exploited to isolate the interferon gene. They first isolated the messenger RNA from white blood cells treated by Cantell’s methods, knowing that much of this RNA would be for interferon (others would be for other proteins the cell was making). Then, to isolate the RNA specifically for interferon, Weissmann’s team injected the different RNA into frogs’ eggs and picked out those which produced interferon. The team then used enzymes to convert the RNA template back into DNA, ending up with the interferon gene.50 The gene was then inserted into bacteria to produce the interferon protein in copious amounts.51 Each of these steps was tough, at the frontier of biotechnology, and the long hours required meant that Weissmann kept a sleeping bag in his office.52
Weissmann led the work as an academic-entrepreneur and co-founder of the biotech company Biogen.53 At first Cantell didn’t realise that his collaboration with Weissmann was part of a commercial enterprise, but looking back, he says that he probably would have gone ahead with it anyway had he known.54 In fact, all sorts of financial dealings, which Cantell was unaware of, were happening behind the science. The US pharmaceutical company Schering-Plough paid $8 million to part-own Biogen when the company was close to bankruptcy.55 $8 million appeared to be a bargain when Biogen announced at a press conference on 16 January 1980 that they had produced interferon from genetically modified bacteria and the stock price of Schering-Plough jumped up by 20%.56
While the stock market was elated, the science became complicated (as it tends to). Interferon disappointed delegates at the 1982 American Society of Clinical Oncology when only a small percentage of treated patients showed a partial decrease in tumour size.57 Many drugs look hopeful in a handful of patients only to fail when tested more carefully on larger numbers of people, perhaps partly because the few people tested initially are cared for especially well or are unwittingly selected so that they do better than average. In November 1982, another problem with interferon surfaced: it became all too clear that the side effects of using interferon weren’t as benign as once thought. Four patients treated with interferon in Paris died of heart attacks.58
By 1984, the consensus was that interferon was not going to be a cure for cancer in any simple way.59 Some cancers responded better than others, and in 1984 interferon was approved for use in a particular type of leukaemia, but most successes with interferon were partial or didn’t last.60 By this time, it was also clear that there wasn’t just one type of interferon. Tadatsugu ‘Tada’ Taniguchi, working in the Japanese Cancer Research Institute, had isolated an interferon gene from skin cells which was different to the one Weissmann isolated from immune cells.61 And several different teams discovered that interferon wasn’t the only type of protein molecule able to influence immune cells. Beginning in 1976, a series of international workshops set out to classify the various protein molecules of this type that different labs had found. The first meeting was held in Bethesda, USA, and the second, in 1979, in Ermatingen, Switzerland.62 At first, this was a small backwater of immunology63 – the mainstream focused on how specific immune responses were triggered – but in time, a new understanding of human biology emerged from these workshops.
There is much that bears witness to every person’s existence but one of the especially great reasons to be a scientist is that what you leave behind includes new knowledge. Lindenmann died in 2015, having lived nearly twice as long as Isaacs, but for both lives, long and short, their one year together, the discovery of interferon, is a huge part of what they left behind. Their labour endures because so many others built upon it. Author Margaret Atwood once wrote: ‘In the end, we’ll all become stories.’64 Lindenmann and Isaacs are scientific heroes because their story has become an origin story.
Eventually, the existence of interferon opened the world’s eyes to a whole host of soluble proteins like it which are in the body for the same purpose: communication between cells and tissues and coordination of the immune system. We now know that there are over a hundred different proteins like interferon, some of which have been studied across thousands of labs while others have been discovered only recently. Collectively they are called cytokines; they are the immune system’s hormones. Our immune cells bathe in a cacophony of cytokines – some switch the system on, others turn it off, many nudge its activity up or down a shade.65 Their purpose is to shape an immune response to fit the type of problem, say a viral or a bacterial infection, and connect the immune system to other body systems. Their actions are incredibly complex – there are cytokines that regulate the cytokines – but as we shall now see it is hard to overstate their importance in how the body works or their potential for new medicines.
All human cells can be invaded by microbes and this is often damaging: many viruses, like influenza or polio, kill their host cell once they’ve multiplied (often just as they leave to infect another cell). Other viruses, like hepatitis B, keep their host cell alive but cause havoc by upsetting the normal chemical reactions of the cell, and a few types of virus can cause cells to become cancerous. To defend against this, almost all human cells can sense when they have been invaded by a germ, using pattern-recognition receptors to detect their telltale signs. As we have seen, some types of pattern-recognition receptors detect a germ by locking onto a molecular shape which is alien to the human body, such as the outer coating of a virus or bacteria. Other pattern-recognition receptors detect the presence of a germ because they lock onto molecules, such as DNA, which are not alien to the body but are in a location where they shouldn’t be, giving away that they are part of an invading germ. Dendritic cells have a vast array of different pattern-recognition receptors, which makes them especially adept at detecting different kinds of invading germs, but almost all cells in the body have some types of pattern-recognition receptor. When any cell’s pattern-recognition receptor locks onto the telltale sign of a germ, this triggers the cell to start producing interferon. In this way, almost any type of human cell can be induced to produce interferon when, for example, it is infected with a virus.
Interferon turns the infected cell, and other cells nearby, into a defensive mode. It does this by switching on a set of genes appropriately called the interferon-stimulated genes.66 These genes produce proteins which help stop bacteria and other germs, and are especially potent at dealing with viruses: they can block viruses from being able to enter nearby cells, stop viruses already inside cells from getting into the nucleus of cells (where they need to go to replicate), and prevent viruses from usurping the cell’s machinery to make the proteins needed for new copies of the virus. A protein called tetherin, just one of the proteins made from interferon-stimulated genes, thwarts the spread of disease in the body by grabbing onto a virus, such as HIV, just as it tries to leave one cell to infect another.
In the case of some viruses, this response – our innate immune response – is enough to keep the infection under control, but often this only dampens an infection for a few days until our adaptive immune response – led by our T cells and B cells – develops to eliminate the problem completely and provide long-lasting immunity. One reason that an interferon-stimulated response often can’t wipe out an infection is that viruses, and other types of germs, counteract its effects. HIV, for example, can destroy the tetherin protein, so that the virus is free to move away from one cell and infect another.67 Showing how important this is, one out of the ten genes that make up the influenza virus – in other words, 10% of all that it is – is devoted to counteracting the effects of interferon. We once thought that the positions of stars affect our health, but the truth is even more fantastical: our body is locked in an everlasting arms race with minuscule germs.
We each respond to germs in the same way, but only to a first approximation. One reason that some of us are more likely to suffer especially badly from a flu infection is because of a variation in our interferon response genes. About 1 in 400 Europeans has, for example, a non-functional version of one of the interferon-stimulated genes called IFITM3.68 Normally, the protein made from the IFITM3 gene interferes with how the influenza virus enters cells, though precisely how is not yet understood. (We know that this same gene is used by animals, as mice genetically modified to lack the gene are more susceptible to flu infection.) And people who have a non-functional version of this gene simply lack this component of our immune defence against the virus. In 2012 the non-functional form of this gene was found to be especially common in people hospitalised by an influenza infection. Those in intensive care were seventeen times more likely to have the defective gene.69 Variations of this gene are also particularly common in Japanese and Chinese people.70 Because of this, Japanese and Chinese people may be at higher risk for developing severe illness from flu, but this remains to be tested directly.71
However, most people with a dysfunctional IFITM3 gene will still be able to fight off a flu infection without a problem, as it is one of many components of our immune response. In fact, it may even be beneficial to lack a functional IFITM3 gene in other illnesses, such as those conditions in which an immune response is the cause of the problem. Indeed, the fact that there is such high prevalence of this genetic variation in Japanese and Chinese people might suggest that there is some situation which is more common in that part of the world in which this variation confers an advantage.
Although we don’t yet fully understand this situation, there are at least two different ways in which we can exploit what we do know. Firstly, we could prioritise people for flu vaccination based on their genetic make-up, targeting those who are at higher risk of responding badly if they should get infected. Right now, we don’t screen genes routinely, and it may not be cost effective to increase our capacity for genetic analysis solely for flu, because it is cheaper to offer vaccines to everyone anyway. But this may be what’s to come, when genetic analysis is more commonplace. Peter Openshaw, who leads influenza research at Imperial College London, thinks it may be especially useful to screen people with Chinese or Japanese ancestry for whom variations in the IFITM3 gene are common.72
The second way that this knowledge is useful is by indicating a way to tackle influenza without a vaccine – which may be needed in an unexpected flu pandemic – by boosting our interferon response. This has already been shown to work in mouse cells: the amount of protein made by the interferon response gene IFITM3 has been increased in mouse cells (by suppression of an enzyme which normally limits it) which in turn increased the defence that mouse cells had against an influenza infection.73 While mice may celebrate, this idea is not yet medically useful for humans because we don’t yet know a way to boost the human IFITM3 protein.74 Further knowledge is needed here.
Although interferon never lived up to its early hype as a cure for cancer, it is important in the treatment of melanoma and some types of leukaemia, usually given as an injection several times a week.75 As of July 2015, there were still over a hundred open clinical trials testing the use of interferon against a range of cancers.76 The chief reason that interferon doesn’t work as well as we once hoped is that it doesn’t stop cancer cells directly. We know now that most, if not all, of the way interferon helps fight cancer is by stimulating our immune system. The problem is that cancer cells are not easy for our immune system to detect – after all, they are the body’s own cells gone awry rather than being alien to the body – and so there’s a limit on how great an immune response boosted by interferon can be.
There are many different types of interferon – at least seventeen – produced by different cells in the body.77 Most of our cells can produce the type of interferon that Lindenmann and Isaacs discovered – nowadays referred to as interferon alpha – to limit the spread of an infection.78 Today, interferon alpha forms part of the treatment for hepatitis B and C infections.79 Other forms of interferon are more specialised: interferon gamma, for example, is mainly produced by some types of white blood cell in order to amplify an ongoing immune response. The genes switched on by each type of interferon are being catalogued in an ever-expanding online database.80 Many of the other cytokines, discovered after interferon, are called interleukins, so named for being the proteins that act between (inter-) leukocytes, a formal name for white blood cells.81 Abbreviated to IL, each type of interleukin is assigned a number, IL-1, IL-2, IL-3 and so on, currently up to IL-37.82 Like interferon, some of these cytokines also come in slightly different versions (IL-1 has an alpha and beta form, for example), and some differently numbered cytokines have features in common, so that there is an IL-1 family which includes IL-18 and IL-33, for example. The actions of all these cytokines in the body are wondrous.83
Each has a multitude of specific effects and here’s just one example: IL-1 acts on, among other cells, neutrophils, which are the most abundant immune cells in the bloodstream. Neutrophils are recruited to a cut or wound within minutes.84 They can engulf germs and destroy them directly. But one of the especially wondrous things that neutrophils do for our defence is that they shoot out a sticky web, or net, made from strands of DNA and proteins, to capture germs moving by.85 Think Spider-Man, but on a minuscule scale of cells and germs. These webs contain antimicrobials which kill the captured germs. Neutrophils have a short lifespan, just a day or so in the blood, but at the site of an infection, the cytokine IL-1 increases their lifespan dramatically so that they can battle on, shooting out webs and killing germs for up to five days.86
To take a second example, IL-2 has a dramatic effect on other white blood cells, such as Natural Killer cells, a type of white blood cell that is especially adept at killing cancerous cells and some types of virus-infected cells.87 (I’ve written about these white blood cells in detail in my first book The Compatibility Gene.) In my own lab we often use IL-2 to switch on these cells, having isolated them from blood. It’s easy to see the effect IL-2 has, just by watching them under a microscope. When IL-2 is added, these cells elongate from a sphere into a Y-shape and change from being inactive in the culture dish to literally crawling about, the front end of the cell pushing against the surface of the dish while the rear part lets go, propelling the cell forward, probing for diseased cells to attack. If a Natural Killer cell meets a diseased cell, a cancer cell or a virus-infected cell, for example, it will latch onto it, flatten up against it and, within a few minutes, will kill it. The white blood cell then detaches itself from the debris of the dead diseased cell – which looks like a bubbling mess down the microscope – and searches for others to attack.
One of the cytokines which turn off immune responses is IL-10. Discovered in 1989, isolated in 1990 and studied by thousands of scientists since, we now know that this cytokine helps protect the body against unwanted immune reactions.88 IL-10 curbs inflammation when an infection has been eliminated and signals for the body’s healing process, the repair of damaged tissues, to begin. IL-10 is also important in our gut, where it keeps immune cells in a relatively inert state to prevent unwanted reactions against harmless bacteria. Mice genetically altered to lack IL-10 suffer from an inflammatory bowel disease.89 In humans, an overreactive gut immune system can cause Crohn’s disease and ulcerative colitis, which affect more than 300,000 people in the UK.90
Our knowledge of cytokines leads to a big idea for medicine: to manipulate their levels in the body in order to boost the immune system to fight infections or cancer, or dampen immune reactivity as treatment for an autoimmune disease. As we’ve seen, boosting the immune system with interferon has been partially successful, but there are multitudes of other cytokines that can be tried. One pioneer – some say the pioneer91 – in boosting the body’s immune response to cancer is Steven Rosenberg.
Rosenberg became the chief of surgery at the National Cancer Institute, Bethesda, USA, on 1 July 1974, at age thirty-three, overseeing nearly a hundred staff and an annual budget of millions of dollars. He has stayed there ever since – because he feels it is ‘the ideal place in which to do solid basic science and take it to the bedside’92 – and has co-authored over 800 scientific papers.93 In a wonderful book, A Commotion in the Blood, about the pioneers of immune therapies, science writer Stephen S. Hall calls Rosenberg ‘immensely confident’. ‘To some,’ Hall says, ‘he may have pushed too far and too fast; to others, he was just the right person to do the heavy lifting in a field with a reputation for sacrificing far too many mice in order to save far too few human lives.’94 Rosenberg says of himself: ‘I know I am focussed. Perhaps focus is another word for ruthlessness’.95 He is careful with his time: ‘I rarely attend large conferences; if I go at all it is to give a talk and leave.’96
His focus – ‘I want to cure cancer and everybody who ever has it’ – stems from a patient he met while finishing his surgical training in 1968.97 Twelve years earlier, the patient had a large tumour removed but the surgeon had found other tumours which he couldn’t remove. The patient was told that there was nothing more to be done; he was sent home to die. Yet, here he was, a dozen years later, talking to Rosenberg. Rosenberg could easily have dismissed the case as a mistaken diagnosis but he investigated the records, checked the patient carefully, and scrutinised the old microscope slides he found in the hospital’s storage.98 There was no mistake. This person had had several large tumours and, without any treatment for them, miraculously recovered. Spontaneous regression of metastatic cancer is one of the rarest events known to medicine.99 How did this happen? ‘The single most important element of good science,’ Rosenberg wrote later, ‘is to ask an important question. This was an important question.’100
He reasoned that it had to be because of the patient’s immune system. In his first attempt at a cancer therapy, he took blood from the patient and gave it to another, an elderly veteran dying of stomach cancer, to see if it helped. The veteran patient joked that he had been taking long shots all his life and that he was due for one to come good.101 But it didn’t work, and he died within two months. Rosenberg himself later acknowledged that the idea was naïve – ‘almost embarrassing in its simplicity’102 – but also that he just had to try.103
Next, Rosenberg tried all kinds of different experimental therapies. One involved isolating immune cells from a patient’s blood, growing them in the lab to increase their numbers and then infusing them back into the patient’s blood. To culture immune cells in the lab, Rosenberg built upon the discovery that the cytokine IL-2 could be used to stimulate human immune cells to multiply. The precise conditions in which immune cells could be cultured had to be worked out by trial and error – even today, culturing human cells is as much craft as it is science. And even with large numbers of immune cells, it wasn’t obvious that they would survive when added back to a patient or retain any ability to kill a patient’s tumour. There were so many unknowns in what Rosenberg was trying that most scientists wouldn’t even have entertained the idea of such an ambitious programme, but no matter how many ifs and buts there were, Rosenberg was driven by one thought; that if things did work out, he would be able to cure cancer.
None of Rosenberg’s first sixty-six patients was saved by his experimental therapies. Then, in 1984, his sixty-seventh patient, Linda Taylor, walked in. A navy officer aged thirty-three, she came to see Rosenberg with metastatic melanoma, a cancer that attacks the skin as well as other organs.104 Two years earlier, she had been diagnosed after a mole appeared to bubble over, and she had been given seventeen months to live. She had tried an experimental dose of interferon, but it hadn’t helped.105 Tired of treatments which didn’t work, she thought that travelling to Europe might be the best use of her time left. But her family pushed her to keep fighting – and to see what Rosenberg could do.
Rosenberg treated her with infusions of her own white blood cells and several high doses of the cytokine IL-2.106 The treatment was far from easy; three doses of IL-2 per day and immune cell infusions every two or three days. Taylor vomited often, felt too weak to see her family and she had trouble breathing. One time she stopped breathing. Her pulse collapsed to just twenty beats a minute and she survived only with an emergency resuscitation. Rosenberg pushed against what Taylor’s body could take because he was determined to find out if his experimental treatment held any promise. After sixty-six failures, he knew that his efforts would have to end soon if he didn’t see any sign of success.107 He gave Taylor far higher doses of IL-2 than had previously been administered to anyone.
Two months later, Taylor told Rosenberg that she felt her tumours were disappearing. And she was right. Her tumours had died and the clumps of dead tumour cells were being cleared away by her body. Everyone thought that her tumours would probably come back. But they didn’t. Taylor had been cured of cancer.108
The feud between humankind and cancer is special. One person being saved by a new kind of medicine is international news. Taylor’s story fronted newspapers around the globe.109 Wisely cautious, Rosenberg tried to play things down with the New York Times: ‘this is a promising first step’.110 In his autobiography, he described how he felt at the time as ‘satisfied. Not triumphant or vindicated…Satisfaction speaks to something deep inside oneself, a fulfilment, a peacefulness and fulfilment deeper than triumph can reach’.111 Thirty years later, Taylor went back to visit Rosenberg and the moment was filmed for a TV documentary. They hugged, emotions welled up and she said, ‘I never cry, except around you.’112
Trials with larger numbers of patients showed that IL-2 was the important ingredient in Rosenberg’s treatment, not the immune cells.113 But alas, it soon became clear that IL-2 is not a wonder drug. Less than a year after Rosenberg’s success with Taylor, another patient given high doses of IL-2 died. This patient had many tumours – twenty in his liver – and only had months to live, but it was Rosenberg’s experimental treatment that killed him. IL-2 hindered his body’s normal immunity against a bacterial infection and caused fluid to partially fill his lungs. ‘It was a dark time,’ Rosenberg wrote later.114 The patient’s mother didn’t blame Rosenberg but wrote letters to him about her son’s life. To Rosenberg, brought up by religious Jewish parents, the gesture reminded him of something he had learnt about the Holocaust: that ‘those who suffered in it had most feared not being remembered’.115
IL-2 seemed to offer patients either spectacular success or tragedy – and neither Rosenberg nor anybody else could predict which it would be. Various clinical trials, large and small, have since proven that IL-2 is best in treating people with melanoma or advanced kidney cancer. The overall response rate for patients with these types of cancer varies across different studies, but is around 5–20%.116 A small fraction of those who respond are left with no trace of cancer remaining; they are truly cured.
Why IL-2 works for only some types of cancer is not clear. Melanoma, the type of cancer which Taylor had, involves more mutations than most other cancers. So one possible reason why IL-2 helps against melanoma more than most other cancers is that their large number of mutations mark out melanoma cells as being especially different from healthy cells, making them relatively easy for the immune system to detect and react against. Why some patients respond well to treatment with IL-2, but others don’t, remains, unfortunately, unknown. It is possible that the treatment works best in people with a level of immune reaction already ongoing against their tumour, there to be boosted by the treatment.
Altogether, this band of pioneers, from Lindenmann and Isaacs to Gutterman and Rosenberg, discovered the existence, and then the power, of cytokines. They seeded an enormous scientific endeavour – cancer immunotherapy – which now has hundreds of branches, each studying a different way of boosting our immune response to cancer. A multitude of cancer treatments, with many more on the horizon, are the outcome. We will return to this endeavour later. Now we will turn to an altogether different therapeutic revolution that came from our understanding of cytokines, not in the fight against cancer but for treating autoimmune diseases, not by boosting immunity, but by stopping it. Enter the anti-cytokine.