THE holy grail of medicine in the 20th century was to find a cure for cancer. Given there are more than 200 types, this was an awesome task, dominating the lives of an army of scientists, each of whom chipped away at the marble rockface of this much feared disease. You won’t find a better description of what this entailed than Siddhartha Mukherjee’s The Emperor of All Maladies, an enthralling account of the race to find answers.

As with any prolonged battle, it was (and continues to be) a story of advances and reversals, sometimes achieved in the face of daunting obstacles. Many decades on, despite the resources poured into the fight, cancer has not yet been vanquished. It is still a diagnosis everyone dreads. It still claims far too many lives. But since with some cancers it is possible to have treatment that is effectively curative – that slows its progress sufficiently that you’re more likely to die of something else – the situation is light years away from what it was in the 1950s.

Meanwhile, the search continues for ways of combatting even the most intractable forms of the disease. Such have been the advances, it is now conceivable that eventually every form of cancer, if caught in time, will be treatable, to the extent that sufferers can live with it for the rest of their lives.

Today, no medical breakthrough catches headlines like the prospect of a cure for Alzheimer’s, which has become this century’s greatest medical challenge for those in the West. In the past 20 years we’ve read countless articles about pharmaceutical companies trialling drugs which – they all hope – will take the sting out of dementia. In the end, however, the outcomes have always been a disappointment. In scientific circles, the old joke is that for the past 30 years, they’ve “always been five years away” from a life-changing treatment.

At the moment, the results of three promising stage three trials by different firms – Roche, Eisai and Biogen, and Eli Lilly and Company – are expected imminently. (Stage three is the final hurdle before seeking approval for drugs to go on the market.) Although each takes a different approach, all of them are targeting the build up of a toxic protein called amyloid, widely considered to be the root of the brain degeneration caused by Alzheimer’s.

On one side of the medical fraternity are the optimists, who think these drugs might represent the eureka moment we’ve all been waiting for. They believe that, although they won’t eradicate dementia, if taken after an early diagnosis they could offer an additional three years of good quality of life. And that’s just the start. Once these medicinal building blocks have been confirmed as efficacious, they can be adjusted to suit a variety of needs. In this scenario, many of us might one day find ourselves taking a cocktail of medicines at sundown as easily, and regularly, as a G&T.

Pessimists, however, are less convinced by the powers of these supposedly super-drugs. Some, indeed, think that the focus on amyloid as the cause of Alzheimer’s is misguided. Robert Howard, Professor of Old Age Psychiatry at University College London, is one of the sceptics. “There is a clear indication that somehow amyloid is involved in Alzheimer’s,” he says, “but it’s not clear that the presence of amyloid in your brain drives the disease. It might be like a tombstone that happens at the end, where the amyloid is actually a protective protein that the brain produces to try and protect itself. We don’t know. But removing amyloid doesn’t seem to make any difference to the course of Alzheimer’s disease.”

Imagine having worked for years on the assumption that getting rid of amyloid is key, only to learn that you have been following the wrong trail. You might think that is a definition of tragedy, of spectacularly wasted effort and energy. On discovering this, how could someone find the motivation to get out of bed and head back to the laboratory?

Yet you’d be wrong. Even if eliminating amyloid is not the solution, and even if the latest drugs fall short, this is simply the nature of medical research. Samuel Beckett’s exhortation, “Ever tried. Ever failed. No matter. Try again. Fail Again. Fail better.”, should be pinned to every lab door.

The speed with which effective vaccines for Covid were formulated has perhaps blinded us to the reality of how treatments are generally found. The hunt for a cure is as much about elimination as hitting the bull’s eye. Of course there are occasional happy accidents or blinding revelations, but miracles in medicine are almost as rare as unicorns. The laborious task of following one line of enquiry until obliged to reject it and find another, is how the process works. Every triumph is built on the work of unheralded legions of pharmacologists and medics, racing to explore every possible avenue of inquiry. Even though the vast majority of them will never win the Nobel Prize, their endeavours, and their errors, are essential to the success of those who do.

A case in point is malaria, which for a century has eluded the finest brains in medicine. Last year, a vaccine was finally approved for use in children, and this year Oxford University has been trialling a vaccine thought to offer up to 80% protection, at an affordable price. Since around 409,000 people a year die from malaria worldwide, this is a game-changer in terms of global health. Yet the fact it has taken 100 years to get to this point shows not only how difficult a challenge it has proved, but that despite dedicated teams of scientists, some ailments remain stubbornly resistant to intervention. Those suffering from Motor Neurone Disease – to name but one of several as yet incurable illnesses – are only too well aware of this.

With Alzheimer’s, it looks as if there are good reasons to be hopeful. Currently 143 different drugs are undergoing stage three trials, each of them approaching from a different angle. You could see the disease as being like a bolted door, at which medics have been hammering for decades. They’ve used pick-axes, battering rams, rocket launchers, and still it’s not giving in. But everybody knows it’s only a matter of when. Will it happen in my lifetime? I couldn’t say. In our grandchildren’s? I’d be prepared to bet on that.