Long ago, as an overstretched twentysomething, I had a mild bout of depression. Prozac was much in the news then, so I went to the doctor to find out if it would help me. It didn’t. He then prescribed another drug, then another. The third time proved lucky: I recovered, and fortunately have not faced the issue again.
But I have never forgotten the feeling that the psychiatrist was essentially playing chemistry set with my brain. He had no idea which drug might work, and was simply trying one molecule after another until something stuck.
Two decades later, I am getting a close-up view of an entirely different kind of medicine, after a female relative was diagnosed with stomach cancer. Though only 65 per cent of people diagnosed with the disease are still alive after five years, her doctors told her she was one of the lucky ones. A particular drug has been found to be effective in treating her relatively rare strain of cancer. The medicine not only has a significantly higher success rate than medicines for other stomach cancers but also far fewer side effects because its potency is trained on specific cancer cells. She is only a year into the process but so far, so good.
The rise of “personalised” or “precision” medicine is revolutionising the way doctors and pharmaceutical companies approach disease. Using genetic sequencing, medical professionals are now able to separate people with similar symptoms into far narrower groups and target medicines at them. In June this year, researchers from the Wellcome Trust Sanger Institute announced they had determined that the most common and dangerous form of leukaemia is actually 11 distinct diseases that each respond very differently to treatment.
The implications of this new approach were on full display earlier this month when US pharmaceuticals group Bristol-Myers Squibb announced that its new lung-cancer drug had failed to come up to scratch in late-stage trials. Opdivo, part of a new class of drugs that encourage the body’s immune system to attack cancer cells, had been viewed as a potential blockbuster. But Bristol-Myers found the drug was no better than conventional chemotherapy at extending the time a patient can live without their lung cancer getting worse. The announcement shocked scientists and investors because, in results announced in June, a very similar drug called Keytruda, made by Merck of the US, had performed much better.
The difference appears to be personalisation. Both drugs are so-called checkpoint inhibitors, which seem to work best against tumours that produce a lot of a protein called PD-L1. Merck used a diagnostic test to restrict its patients to people whose tumours had levels of at least 50 per cent of the key protein. Bristol-Myers opted for a wider field: those with 5 per cent PD-L1 or more.
The tougher requirement gave Merck a smaller potential market but one where the drug had a better chance of working. That gamble paid off.
Advocates of personalised medicine say these kinds of narrowly targeted drugs, tied to clear genetic or chemical markers, are the future. They argue that the current state of medicine, in which everyone is given the same drug and it works for some but not others, will soon be seen as barbarous.
One crucial reason for the shift is the rapidly falling cost of genetic testing. The first complete human genome sequence was published 15 years ago but the cost of analysing an individual’s DNA remained prohibitively expensive for years. Now that is changing. Earlier this year, Massachusetts-based Veritas Genetics announced it had pushed the price of sequencing a whole genome below $1,000 for the first time. With more DNA information available, studies are now starting that link a person’s genes with specific medicines and even diets.
Helix, a start-up backed by private equity firm Warburg Pincus, aims to cut the costs even further by making genetic sequencing a mass-market product. The California-based company uses the same high-end machines as the big US medical schools but is reworking the laboratory process to use the equipment more efficiently. The goal is to run millions of tests a year and store the results online, where they can be accessed and used — with the customer’s permission — whenever genetic information might be helpful.
“The whole idea of Helix is that by getting a more complete view of your DNA you only need to do it once,” says chief executive Robin Thurston. “We want to make it easy for the consumer to understand and personalise their experience [across] health, lifestyle, genealogy, nutrition, fitness and family.”
Helix’s backers foresee a world where you would get your genes sequenced and then be able to choose not only the right cancer treatment but the best over-the-counter painkiller, birth-control pill and even fitness routine based on your DNA.
In truth, this kind of genetically based lifestyle is probably some way from reality, and granting widespread access to individual DNA information would raise profound privacy questions. But if Helix’s backers are right, blockbuster treatments that get decent results for millions of people, but flop or cause crippling side effects for others, will eventually become a thing of the past.
Pharma groups will instead have to offer a much wider array of narrowly tailored medications, and doctors, from oncologists to psychiatrists treating depression, will be able to care for patients far more efficiently. The treatments are likely to cost more — certainly many of the first-generation precision drugs do — but the benefits would be life-changing.