EDITOR’S NOTE
— A breakthrough for cancer
“CANCER BREAKTHROUGH.” You’d expect to see this headline on a tabloid. So it was quite startling when Science magazine, the paragon of scientific publication, proclaimed cancer immunotherapy its breakthrough of the year in 2013 – although there was a good amount of hand-wringing accompanying their choice.
Rightly so. One should never use the word breakthrough lightly, especially not with the war on cancer. The campaign has been long, the gains have been hard won and glacially slow, and there have been many devastating defeats.
The treatments have involved slashing, burning or poisoning in the hope of harming the tumour more than the patient. This scorched earth policy underlines the central problem of cancer: the enemy cells are our own.
Yet Science was justified in using the word breakthrough, and three years on, we dare to use the word too. The reason is that a new army has been deployed and is continuing to ratchet up victories. That army is the immune system. Medical wisdom has long held it could not be recruited to the cause – the immune system is designed to attack invaders and home-grown cancer cells would not show up on its radar.
But it turns out the immune army is extremely smart. It is able to detect tumour cells. Indeed clinicians often find a tumour riddled with immune soldiers known as tumour infiltrating lymphocytes (TILS). So why aren’t the TILS doing anything? It turns out tumours cells are very smart too. They have cracked the communications codes of the immune army, specifically one that tells the TILS to lay down their arms. In other words, the tumours were disabling the immune army.
Once researchers decoded this enemy strategy, they designed a foil – drugs that counter-block the “lay down your arms” signal. Those drugs are called checkpoint inhibitors. And their success continues to grow. The greatest gains have been in advanced melanoma, lung and kidney cancer where the responses are good enough to win the drugs formal approval by the US FDA.
Other types of cancer are also starting to show responses. The agony of all this is that it’s still a turn of the roulette wheel. Some patients count their remissions in years, others only months. For them the disappointment is all the more bitter for the hype.
Yet unlike many other cancer tales, there is an optimism amongst many cancer researchers – a sense that they are witnessing something quite new. They are just starting to learn how to take command of an extremely sophisticated army.
For David Bowtell, who as former head of Melbourne’s Peter Maccallum Cancer Centre has seen many cancer therapies come and go, this does not have the feel of a Gallipoli defeat but the beginning of a successful D-day invasion.